DSLR colour balance...get it right.

[Peter Ward]

From my short time on ISS, I have to say it is an very enthusiastic group, polite, but often not very critical. By critical I am not suggesting you go around calling someone a boof-head!

When I look at a deep sky image the things I like to see are, excellent focus (this is the one thing you can nail every time), excellent tracking (i.e. round stars) accurate colour balance.
There are other aspects, but for now the above three really are essential to a good image.

As a case in point you would not be happy with a picture of your family/dog/cat that was out of focus, blurred and had a strong green colour cast from having the wrong white balance setting.

Focus and tracking are self evident. But getting the colour right on an object you can not physically see in colour with a warm human eye at the eyepiece is a little more tricky.

Happily there are many professional images out there, for example the treasure-trove of David Malin images taken with the AAT. A good deal of effort has been made to get the colour right in these images and can be considered as the gold standard of colour accuracy.

A case in point, the Tarantula Nebula is not blue, or cyan as rendered by many DSLR’s.

It’s RED.

Hence to post an image of it looking blue, unless you have used a narrow-band Hubble telescope like filter set, is just plain wrong. So how do you get the colour right?
After all, images you take in daylight look spot on.

The problem stems from the internal I/R cut-off filter used by most DSLR manufacturers, which only passes around 20% of the critical Hydrogen Alpha light in which most nebulae glow. As a result emissions from elsewhere in the spectrum will swamp what little red data is being let through. So you end up with a blue-green spider. There are 3rd party companies that will replace this filter for a more suitable one. Canon also made the 20Da for a time which has a factory fitted version.

Modifying a not inexpensive DSLR would make many hesitant. However armed with the knowledge your image data has very little deep red signal, you can use software like Photoshop to boost the curve of the red data and once again approximate reality. If you have not already done so, I suggest you give it a go. You may be surprised by the results!

[Hagar]

Hi Peter, I am one of the guilty who post blue images of Tarantula nebula. I think I understand what you are saying with regard to emmission nebula colour like that displayed in the Tarantula Nebula. I have one question. I notice on your web site an image of Eta Carinae Nebula taken with an SBIG CCD camera. It appears to all wants and purposes to have the same colour cast and tone as my images of Eta Carinae. I realy have trouble understanding why an item like Eta C can be so similar yet Tarantula so diferent. If the blue colour isn't there in reality, where is it coming from? Images of tarantula taken and corrected by Hubble show quite a blue core with red to pink surronds which I would have thought indicated a large reflective base for this nebula.
How on Gods earth do you decide which image requires added red. We are not all fortunate or financial enough to purchase a large format CCD which displays true colours, much and all as I would like to. After all most of us are taking photos to develope some skills and for our own gratification and if the colour is wrong does it realy matter.:shrug:

[edwardsdj]

Colour is so subjective in these images. I'd be more interested in getting a pleasing, detailed result than attempting to replicate some colour that might be visible in a huge apeture.

Most professional images are false colour to highlight features of interest anyway. Surely getting as much detail as you can in an aesthetically pleasing way is the ultimate goal for the amateur?

[tornado33]

Ahh yes, the colour balancing can be a hairy issue. My old 300D did just that, showing even known to be fairly red nebulae such as Eta carina as a bluish pink, and the tarantula a strongly blue. Photoncollector (Paul) showed me that using Curves in photoshop on the red channel could bring out more red without making too much of an overall red cast. Also, I found out that by using a nebula filter like the Baader UHCS, Lumicon Deep sky or equivalent, and using high ISO to get around the filter factor, a good deal more red would come through.

The software I use, Iris, has a commandline function called "white". I draw a small box on a dark area of sky with no stars inside, then enter "white". This tells Iris to balance the image to get a neutral grey on the sky background.

The Human eye, however, sees astronomical nebulae more like an unmodded DSLR. As an unmodded camera looses HA sensitivity dur to the IR cut filter, the human eye looses HA sensitivity because the Rod cells in the retina cannot detect low levels of HA light, and the more sensitive rod cells cannot either, only shorter wavelenghts, only very bright nebulae in big scopes such as M42 in a 20 inch dob will show much red. Some peoples eyes are better than others perhaps, but I struggle to ever see any red with my 10 inch scope and low power eyepiece.

With my modded DSLR, using a nebula filter brings out plenty of red, so much so that I need to be careful not to make it too intense.

here are some raw images processed only with canon's own Digital Camera professional software to show us the images without any external colourbalancing or any other adjustments done, they are "as shot" Similar shots with my old 300D would show the sky background as bluish, even with the filter in place.

Ive read that the one true way to colour balance, is to take a picture of a white card, preferably an official photographers colour chart, using the exact filterset that you will use to take astro images with, take note of the adjustments deeded to render the white card as white, then apply the same settings to the astro images. I might see about trying that out myself, take a pic of something I know to be white, in midday sunlight, run the image through Iris, and take note of the red-blue-green adjustments in order to get it looking white. Will be an interesting exercise. Another way would be to take a short exposure of a deliberately out of focus non saturated star of spectral type G2 (same as the Sun) and balance that as white.
Scott
EDIT: I should also say that turning OFF the Automatic White balance in the SLR camera might be a good idia too, and set it to Daylight instead, although with Iris, as it does its own debayering, the AWB might not matter

[Peter Ward]

Doug,

There are a couple of renditions of Eta on my website, a "blue" one http://www.atscope.com.au/newsky/etasho_stl.jpg was taken with a narrow band Ha, OIII and SII set, the other http://www.atscope.com.au/newsky/carina_stl.jpg with a standard RGB set...the latter being a red/magenta colour.

The centre of Eta, indeed a number of nebulae have quite a lot of H-Beta...with a strong blue component....which is what you may be seeing.

The core of the Tarantua has this as well, but the outer regions of both are well and truly H-alpha red.

Also I am not saying don't get out there, have a go and have some fun.

But when you post a blue NGC 2070, as I said earlier, it's like people with green skin....fun perhaps...but accurate? No.

The fix is so simple, and does not require a $10K CCD. Just ramp up the red channel in Photoshop.

Why strive for accuracy? Images with excellent colour fidelity tell a story about the real physical processes going on in an object. Plus getting it right, I believe helps other aspects of you image processing skills.

[theodog]

Hook, line and sinker. Here goes;



What criteria did you use to balance this image?





At best this must be an approximation, so
I think that should read material distribution.
Spectral analysis gives us the proper story.

Now to the modded DSLR.

How do you subtract the now strong IR componant in the image?
Do you use a IR filter as us CCDers do?

[ballaratdragons]

Don't make bland assumptions. To start with, I recieve very good (and extremely helpful) criticism of my images from talented and polite people like Jase, Bert, and a few others. Not everyone says just 'Nice image'.



. . . and those horrible neon green, blue, red etc reverse looking images are ghastly, and yet they are called 'magnificent'. Yes, the detail is nice. I might not like the colours used, but I admire the detail!


But are they having 'fun'??? I know I am with my incorrectly coloured images.

Quite frankly, I am getting fed up reading your posts! All they ever seem to say is 'you ain't doing diddly-squat unless you use all my expensive equipment and become like a professional!
Stuff that!!!

I may only use an ED80 on an EQ6 with an El-Cheapo Toucam, but I am having a blast, and if I'm happy with my images, who gives a poop? You apparently!

Enough said before I go further and it gets deleted!

[Peter Ward]

Jeff, that narrow band image I did of Eta Carina has purely arbitrarily assigned colours, and I'd be a little more than concerned if an image from my DSLR ended up looking like that :).... You are never going to get accurate colour by imaging through narrow bandpass filters that only look at very specific parts of the spectrum, hence this is not really relevant to my original post....I simply wanted to make sure people don't get the two confused.

The colour of a celestial object can tell you a lot about it. Malin's "Colours of the Stars" devotes a couple of hundred pages to the topic, and is well worth the read.

With a modified DSLR, as with CCD's stars will saturate to white from the IR component. Using an IR cutoff is pretty much standard issue as the fix ;)

[Peter Ward]

You missed the point entirely...... Some of my most satisfying images were taken with a DSLR, photo-tripod and 80mm APO.....

Yep, and cranking up the red channel in PS costs a motza.... Cheesh.

[EzyStyles]

i'm waiting for Jase for his opinion on this as I recall he had an excellent method to colour balance properly.


I agree with Ken, stuff all the expensive equipment lol im happy with what ive got and enjoy what im doing :)

[turbo_pascale]

Come on Ken! No one's trying to put anyone down! I think the gist of Peter's post is quite clear. A standard unmodified DSLR shot is low in red because of all the reasons mentioned. He clearly states that it would be good to fix that in PS to give a more accurate rendition.

Why does everyone on here get all edgy when someone gives constructive criticism? I didn't see the post say "buy an SBIG and your problems will go away". At best, there are some examples that go to show what can be done. I think if everyone just took a step back, took on board some of the advice of one of the leading astrophotographers in the country, we would all learn a lot.

Turbo

[ballaratdragons]

It wasn't about DSLR's and IR filters that was getting to me. That info is obvious. It's the constancy in other threads (and a little in this one) about how we 'need' the top gear. Read back thru them all if you've forgotten the theme in them (theme being the need for 'expensive gear'). Usually with many replies saying much of what I implied above. We often can't afford top gear and we are having fun with what we have for now.

It gets to me coz I tend to think of newbies coming in and reading about astrophotography. It would turn them off attempting it when they read that they probably need Paramounts, SBIG's etc to get an image worth posting. And now the colour balance has to be perfect (whatever perfect colour is).

Some are even worded and slanted to make me feel like I own crap equipment!

The information is probably correct, maybe just worded badly.

[tornado33]

Hi folks.
Here are 2 Tarantula neb images. Both have been dark subtracted, flatfielded, aligned and stacked, but no stretching, curves or the like.
The green one is not colour balanced in any way, I then drew a small box in a starless area of sky, entered "white" in the Iris commandline, and presto, a more balanced image
Scott

[edwardsdj]

If someone posts an image and I like it I will say "nice image". My criteria for what makes a nice image has as much to do with the experience, equipment and observing location of the imager as it has to do with the result itself.

If someone with little experience posts a green looking Tarantula and I can see detail in it to me that is great. It reminds me of the view at the eyepiece. I have never imaged the Tarantula so I'm not going to criticise someone who is achieving something I've never done myself.

I'd be thrilled to see anything at all in my first Tarantula image :)

[Peter Ward]

Scott's excellent example shows in a nutshell what I'm suggesting, which is not perfect colour, just accurate colour.

It's just a mouse click away :thumbsup:

P.S.
Ken. Unless English isn't your first language, for the life of me I can't see how you construed "buy brand X or live in misery" from this post. Have a lie-down and a Bex :)

[duncan]

Well i've said no. What determines accurate colour? Is it what you see through the eyepiece? or what you would see if you could get close to it?
Or is it what a very long exposure would show? Or what a spectrograph would show?

Open to whatever interpretation the individual desires i guess.
INDIVIDUALITY RULES!!!!!!

Cheers All,
Duncan:whistle:

[ballaratdragons]

"Ken. Unless English isn't your first language". Don't be a smart *rse!

I never said you said "buy brand X or live in misery". You do however imply that we 'need' the top shelf gear or our images aren't very good (in other threads, not this one).

"Have a lie-down and a Bex" Read my reply in the first line of this post again.

[h0ughy]

well now that you have mentioned the war - what is a dlsr killer (http://www.atscope.com.au/sbig/st4000xcmi.html) Peter? somehow i cannot see how a $6200 hunk of plastic and metal can be that much better than a modified cooled dslr or for that matter a non modified camera for instant pleasing results. geez for that money i would want hot and cold running maids to type in the cooords of the next object;):D. My filter is shown in the diagram below on a Canon 350D. All up mine would be worth 2600 australian for the body and the modification. I know this camera impressed a certain award winning gentleman who shall remain nameless;) for the instant result it gave. In the hands of a genius it will give more than a pleasing result (in my hands maybe not but i certainly will enjoy the butchers picnic). as for low noise for that particular model - show that will you. some little testing comparisons that were done are here (http://www.iceinspace.com.au/forum/showthread.php?t=20283&highlight=cooled+350d) just with my camera.

as for the colour - does anyone take in an ionised atmosphere, street lights, other IR sources and just processing because of a crappy monitor or eyesight. It all comes down to the person and artistic license. What looks good to you?



http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html and have a look here (http://www.geocities.com/ariane1au/Page029b.htm) (also note that with age we all suffer colour vision loss and hearing loss:lol:)


also look here-----------------> http://www.pbase.com/terrylovejoy/dark_noise__a_closer_look

[Peter Ward]

So this was in Mandarin?



or what mental leap did you make to work out my inexpensive suggestion on getting accurate colour, was a thinly veiled attempt to get everyone to run out and buy a metre class RC?

Yep, now I'm being a smart arse :)

[duncan]

Unless it is purerly for science it is a MUTE! point.
As i said individuality rules. Lets not start WW3 over such whimsical nuances.
Just my opinion. If i could afford $100K worth of gear it might mean something different to me,LOL.
Cheers:whistle:

[Peter Ward]

Houghy,

While it was on special the ST4000 was a pretty good buy. I can mention all the reasons why I still think this is so, but this is *totally* going off my original post..... I'd be happy to discuss that elsewhere.

The Tarantula nebula is not inherently blue or cyan. Unless you failed the Ishihara test, it would look red if you retina had cones that worked in the dark.

The fix, and I'm not talking about photometrically/pantone accurate dead nuts on colour, just a "shade" or two fix, is to simply use, well Iris, like Scott pointed out, or PS and simply adjust the red curve.

There is no law that says this is necessary, and sorry to harp on, but I suspect Canon would have a problem pedaling happy snap cameras that made skin-tones look green (unless Marvin the Martian is your best buddy)

[dugnsuz]

I look forward to your posts Peter for the rough n' tumble that follows!!!:lol:

I don't want to get into the s@#t fight, but just want to say thanks for the tip regarding playing around with the red channel in the Curves tool.

It's these tips that are so helpful to us novice guys - Thanks

Doug:thumbsup:

[rat156]

Hi All,

Here's my tilt on the subject.

I work hard to get an accurate colour balance in my images. I try to get the Ha the right colour, which can be seen, just not from astronomical objects, I try to get stars with colour, I try to get a neutral grey background.

If someone has taken an image which is good except for the colour I'll tell them I think the colour is off, if they care, they'll try and fix it.

I now rarely comment on others images mainly because of the comments like Ken's vitriolic replies that Peter has had to put up with. I believe, at least in this thread that Peter was merely pointing out something that can be fixed easily. Something beginners may not know.

I have some pretty high end gear (none of it purchased from Peter), but I still love some of the first images I took with my DSLR, even then I struggled with colour balance. I'll never say your images are crap because you don't have the right gear unless the person has reached the limitations of their gear and are asking why their images are crap, which sort of shows that they realise what's going on anyway.

Cheers
Stuart

[ballaratdragons]

It's not the fact that Peter gave a great tip for a simple colour adjutment. That's fine.

It just carries that implication that if an image isn't the correct colour, it isn't very good.

It's just that it has that 'put-down' feel like some of these samples of other posts by Peter:

"If you want to have a bit of fun and don't take astro imaging seriously, get the EQ5/6" .

"The small sample of EQ6's I've tested ran at about +/- 50 arc sec....and landing on a chip after a 150 degree slew? ...give me a break"


For his 1st quote, does that mean that those of us with EQ5 or 6 are not trying to be serious about our imaging????

For his 2nd quote, I'm not the only one with dead accurate GoTo's on an EQ6.

I slew all over the sky all night and get spot-on GoTo's, and that it with a Toucam which is equivelent to a 6mm EP. That's Damn good accuracy! Give me a break!

Peter, you are probably dead right in all that you say, but sometimes the wording is very discouraging. It has the feeling that you are putting down others attempts.
You may not mean to do this, but it comes across that way.

Some of the replies from others to some of your previous posts should indicate that:

*On the topic of winning awards - if the only way to win an award is to use high end equipment then I would have to question what it is that is being awarded? Unfortunately however, often this may be the case. I think it sends a bad message though to those who may choose to submit images using cheaper equipment. (why even bother if high end equipment always wins?)

*this thread is pointless, if it is going to be a bickering session between the very experienced.

*Not that i mind a good discussion, I feel too that some will be discouraged in submitting there work because it doesn't come up to standard.

*No insult or anything else towards Peter, great images and all that, But how can he even start to compare his images taken with his semi professional gear to the average amateur on this site.

*I will post mine and you post yours let the viewer decide " is in my opinion getting a bit childish. Naturally His images have to be better, otherwise what a waste. The more experienced amateur on this site would love to have Peters equipment, I am sure. But this ‘my images are better then yours’ is ludicrous.

*What really gets me going is the way some people throw around all these obscure theorums that try to prove that they are smarter than the next guy, (see earlier posts), and because of this they must be better astrophotographers.

*IIS is an amateur forum I assume formed to help us newbies (as we all were once) increase our knowledge and if wanted our photographic skills.
I love Peter Wards images and a lot of others peoples too but this forum in itself is not an imaging competition, we look or at least I do, at the pics submitted and relating them to the gear used judge them on that.

*Are Peters images spectacular when compared to his gear? l don't know.
Are EzyStyles images spectacular with his gear? you bet your a**e they are, how do l know? because l can relate to the gear and other images taken with similar gear, and let it not be forgotten these two probably have about a 30 year gap in experience. l use Eric as an example only and could have used many others, hope Eric dosen't mind.
Many of us didn't know a thing about astrophotography 2 years ago and l for one am more than happy with my progress as other are no doubt happy with theirs Ken, Barb & Dave as examples, if those that think their knowledge is superior want to banter amongst themselves fine but do it privately please, this is l think still an amateur forum.

*Well Peter I hope you are wrong on that score. I seriously hope we stop seeing competitions where the winner to every category is an Takahashi 6 inch refractor on a Tak mount.

*As mentioned by others previously it is not too hard to consider the relative merit considering the equipment used. Who would be bothered submitting images while such a view exists unless they own a Takahashi. (sorry about the thread diversion here but I think it is an important point because it is a hobby and even an achromat on an Eq6 is mighty expensive - and many of us are not flush with money to afford the great gear).

*Wasn't the winner of the last David Malin award a picture of comet McNaught through a camera lens? I wonder if it was an apo or an achromatic camera lens? (or indeed if it should matter). If its ok to take images through an achromatic camera lenses why not achromatic telescopes? Another was a picture of the moon in colour - very imaginative. I dont think these won due to the fancy equipment used for the large part.

*I personally think forget the mount and equipment creep, focus on the technical aspects of the imaging and be happy as there is always better equipment (and you can always download HST images if you really want perfection).

As mentioned elsewhere in here and other Forums, text messages can be misconstrued in meaning coz it is hard to replace every emotion with a smilie. So my hope is, Peter, that you are not putting down the efforts of many because of their 'cheap' gear.

[vash]

I Prefer the natural look that the camera puts out with my images, Most of the bright nebula turn out just fine and don't need to much touching up, but some nebula such as the tarantula come out completely blue, at least the times that I have tried it.

I also have spent countless hours trying to figuring out how to do things in photoshop when I get bored, but it's not easy to pull out red when the data captured is blue, thats just the light the camera has collected. This is compounded with the fact that most of the people with unmodded cameras are just starting out and aren't sure how to process images to there full limit. Only by posting their Images and getting positive feed back and helpful info can they learn this art.

I don't mind seeing a posted picture with incorrect colour, because I think to myself, " hey, thats what mine looks like, It's not me then". This helps me pluck up courage to post my images.

With adjusting curves in photoshop, it's not that simple to just boost up the red, this introduces more noise to the image I have found and to takes a long time to get them all balanced out. BUt I haven't found the sweet spot yet, I'm sure there is one though.

[ballaratdragons]

But, on the topic point :lol:

I do try to get my images to a point where they are hopefully the right colour.

I do this by googling the object in google images, and what pops up?

Heinz soup! 57 varieties!!!! I end up choosing the colours that look most pleasing to me from the vast selection (many by professional astronomers). That also tells me that even professionals can't be decisive about the 'right' colours.

[Luke Bellani]

Hi All,
IMHO which carries very little weight, colours would depend on what my aim is.

I would dare to say that 90% of the beautiful images published from Hubble are enhanced with false colours. and that is usually stated.

If my aim is to bring out subtle detail in nebular images then the use of false colours would IMO enhance the image.

On the other hand, if my aim is to produce a wide field image of Eta Carinae then getting the colour about right would be my aim.

I like seeing images with lots of detail. To me "true" colour is secondary.

But then I'm not a scientist and I don't do astronomy for its scientific value.
I just like to do it my way, get better at it at my own pace and get the most out of the gear that I have.

It will be a long time before my abilities exceed the abilities of my gear. when it does, if ever, then I may or may not upgrade. It will depend on my finances. I can say one thing for sure however. A $6000 camera will never be on my shopping list. It certainly cannot produce images as good as Hubble and I can't afford a one of those either:lol:.

When I find myself being influenced by what someone else thinks is acceptable or not in this hobby then it will be time for me to give it away.

Cheers:hi:,
Luke.

[Peter Ward]

No implication about it. When someone takes a colour image of NGC2070 using a bog standard DSLR and it looks blue then I don't think it's a very good rendition.

Yet it is so easy to fix, and I mentioned how.

You'd think this was the opening sequence to Life of Brian and I said "Jehovah!"

Saying that's "nice" for the sake of being PC is just like my mum would have said before she put a crayon picture on her fridge.




As for the Ken's tirade...aye carummba....what has that got to do with getting colour accurate? Is there something in the water out there?

[ballaratdragons]

My Mum honestly did like my Crayon drawings.

She told me so :whistle:


What is in our water out here depends on the colour of the water :)

The correct colour being brown :P

[Peter Ward]

:lol: Can't argue with that!

[Alchemy]

why is it peter that wherever you go a hornets nest is stirred up?
i passed mostly previously, but are you deliberately doing this?

re color balances and images.... i have added a post to one of your images, you will find the coments i have made are factual, although not in the spirit of the forum as a rule, the image was poted by you on the 13th of january called Carina and SAG triplet (its the second image)... i suggest we all have a look closely. My previous comment in this thread was for the other image i passed on the second one out of politeness.

People do this as a hobby for pleasure.... every now and then a tip is given gently to people to help their problems, i personally am happy with the color that i get from my dslr, the nebs turn out pink but so what, thats how my camera sees it, others wash red all over everything , well thats their perogative if they like it, so be it. And what should we ban unmodified DSLRs

if we insisted everyone check their images for a GV2 color balance before they posted.... well id go elsewhere.

i agree with ken on most of his points, something may not be written but thats the message i am recieving too.

[Bassnut]

Sheesh Guys, Ive read 1st Peters post a few times, seems clear to me, it was about colour balance not dollars. Sure, dont have to be red, most of my pics arnt (NB), and you can do what you want, but you all know hes right, in RGB Astro, red is prominent, it must be, Hydrogen is everywhere ;-). I like a bit of Argy bargy, stirs the blood, but dont make it personal.

[Hagar]

Enough! Enough!

Peter, How do do feel about black and white images(monochrome)? These certainly do not fit the colour correct nature you seem to be expounding. Some of the greatest imagers and photographers only use monochrome imaging devices, usually for their sensitivity. These are also award winning images which are definitly not colour correct.

[Peter Ward]

Love H-Alpha B&W!

This one O.K.?

http://www.atscope.com.au/newsky/ngc2070haf7.jpg

Note shape of edge stars...not too comatose and blobby :)

[Alchemy]

No edge stars are ok, but.... around some of the brighter stars there are off centred halos, is this just an optical defect.

[acropolite]

If the colour is pleasing to the eye and has impact then it's OK by me.

[Peter Ward]

Nup, I trust the optics. I hear the Vatican will be making Roland the patron Saint of refractors soon.

Probably a reflection off the filter

this one also has the same problem

http://www.atscope.com.au/BRO/images/halphacarina.jpg

....dammed Yankees :)

[edwardsdj]

To my eye those halos seem to be pointing towards the centre of the frame. Was this imaged with a refractor or RCOS?

[gregbradley]

Hello,

My name is Greg Bradley and this is my first post in this group.
I frequent the Meade Melbourne Group and others but its nice to have
an Aussie forum and its distinctly in your face style.

Here is a link to my images site:

http://tinyurl.com/2fyepd

I can relate to a lot of your posts as I also have not been doing this "that" long - about 3 years now, starting with a Meade LX90 (a lot of fun).

I have done a lot of imaging with DSLRs and have modified quite a few.

Colour balancing with a stock DSLR is a little tricky depending on the model. But stock standard they tend to be baised towards the blue and inhibited in the red.

This is because the chips are sensitive to UV as well as Infrared and the filter in front of the DSLR chip is called a hot mirrored filter and reflects the UV and IR components.

With these removed you increase the red sensitivity many times and the general sensitivity of the camera about 2.5 times.

When processing modified cameras it helps to have a custom white balance which is a shot of a Photographic 18% grey card ( about $20 from a photographic store) taken at midday in sunlight. That handles a lot of the red bias.

The new Canon 40D seems to be a lot more sensitive to the red than any other camera I have seen used and also has a 14 bit converter (Sbig and others use 16 bits ie. 65535 shades of grey, 14 bit is about 1400 or so, 12 bit is 256 so its quite a jump).

I have been thinking about getting a Canon 40D recently as it is such a leap forward for DSLRs. Probably the first major improvement over the venerable 350D.

Balancing colour is a tricky subject and one that I am not particularly expert in as I tend to process my images too saturated in colour and have to show restraint! Some use G2V stars and process until they look white. Most though use the histogram feature in Photoshop that shows the histograms of each colour channel and you can easily see which one is biased and then pull it back using curves or levels. Auto-colour in Photoshop always seems to make images too green to me.

I had to laugh about the post about the Tak 6 inch refractor on a Tak mount winning competitions. Funny, I have one of those and was thinking of upgrading!:rofl:

Oh well, everyone has their own viewpoint otherwise life would be dull indeed.

Nice to be a newbie on this group.

Greg.

[Bassnut]

Welcome Greg, nice to see you here. Tell us about the gear you have, and post some pics :welcome:.

[sheeny]

:lol:...but did we get away with it?:lol:

I voted yes, but so is artistic licence. If you want to show true colours, colour balance is critical. If you want to show detail, maybe enhanced colour or narrowband monochrome is the way to go - both are extreme examples of artistic licence. Monochrome has been around for so long, that I bet a lot of people don't think of it as "artistic licence" - the colours certainly aren't true!;)

In terms of the basics of photography though, colour balance is up there with focus, composition, exposure, etc. So I see it as important, and then if you want to exercise your artistic licence after you've got the basics - go right ahead.

Sometimes a technically true image just doesn't cut it. If what you are after are the true colours then it has to!... but if you are after an aesthetic image, and even to highlight some detail, sometimes artistic licence helps. Example - last year I posted some views in the Blue Mountains. Mike commented on how green the country looked, so I fessed up. I had used the selective colour tool to add more yellow to the greens to give it a bit of kick. It made a drab drought photo look lush and appealing. The effect was what I wanted, it was obviously interpreted as I wanted, but technically the colours were not true and criticism of that would have been valid. It depends on the intended purpose of the photo... obviously colour correctness is very important in forensics, but for some forensic work enhanced colour is used to bring out details.

I know I'm a little off topic, but I see colour balance as a photographic basic to get right before before applying artistic licence, but I also admit sometimes some great pieces of art are the result of a mistake that's best left uncorrected.

Al.

[gregbradley]

Hi Fred,

This is a recent image I did that I liked.

The Vela Supernova Remnant. For some reason it isn't often imaged by Southern imagers (it is a bit faint and hard to find).

http://www.pbase.com/gregbradley/image/91296123

Tak FSQ106N, SBig STL11000 and Tak NJP mount at my dark site observatory.
About 4 hours worth.

Gear I use now is FSQ106N (a dream come true scope - too easy to use)
Tak FS152 (6 inch) with field flattener and RCOS 12.5 inch (when its not windy) all on a Tak NJP mount (very easy to use, very accurate tracking, not many bells and whistles but its extremely fast to setup and get running accurately). Camera is an Sbig STL11000 class 2 with Astrodon filters and Baader narrowband. I also have a Starfish camera to be used as a guide camera and also planetary imaging.

I also imaged a lot with a Canon 20D which I modified myself and initially used a Nikon D70 which I also modified myself.

This may be relevant to the thread as the colour in this one isn't accurate most likely but chosen for effect as someone mentioned in the thread. I mean I like it, but others may go -oohh arrrgh- too pink.

Its O111 LRGB and I think some Ha in there ( I say I think as I switched filter sets during the imaging and one set may have been mislabelled).

I could reprocess it to make it more "natural" and it might be a fun exercise.

Greg.

[iceman]

Obviously this thread has gone on and off topic a few times :) I think it's something to do with the first comment about people being too nice and not being critical enough :)

I try to be constructive if I'm going to be critical about an image. Other times I don't have time to respond in depth, so if the image is good "for them", then a simple "well done" helps to give encouragement and keep them going.

Anyway, that's the off-topic part.

On-topic, I think you're absolutely right Peter. I think the problem is that most of the DSLR imagers are quite new in what they do and so probably don't realise that the red is missing for a start, and that there *should* be red given the type of object and the emission it's producing.

You're right - the fix is easy and i'm glad you brought it up - it will give people a lot to think about. For some people, they might start to think more about *what* they're imaging and what the colour should be. For others, improving on what they've done before (regardless of accurate colour balance) is enough for them.

Even though you bring some contraversy with you at times, Peter, I enjoy your posts and your images and I hope that some of your knowledge can be passed along the way.

btw Welcome Greg, great to have you on-board.

[h0ughy]

;) i like marvin:D

but you cant just group all dslr's in the one basket Peter, especially with colour balance

[Peter Ward]

Welcome Greg,

But, Jehovah ! If you want a quiet time...ignore Fred :)

[Peter Ward]

Marvin is great. Arguably the most dedicated amateur out there. Bugger chopping a tree or two...he said...to Buggs I believe...and this may be not quite verbatim..

"Oh Dear Earth is blocking my view of Venus...I'll just have to get rid of it..."




I've got 3 DSLR's. No they are not the same. But they all make NGC2070 blue/cyan and skin tones, well, not like Marvin's.

[sheeny]

Well said, Mike. I had a couple of goes at responding but the words just wouldn't work for me. You captured some of what I wanted to say but couldn't wordsmith in my post (hence I left that bit out!;)).

I'm a confessed "that's nice" feedbacker on a lot of astro images, too. If I feel I can add valid constructive criticism I will, but as a novice astro imager I don't feel confident to comment on colour balance of many astro images - because I just don't know. In the meantime, if I like an image I'll say so and offer encouragement. If I don't like an image, well I won't say so unless I can say why and do it in a constructive way.

I appreciate the constructive criticism of everyone's images, not just my own, because I can learn from that too...;)

Al.

[erick]

Seems to me we could use an article "Colour Balance in Astrophotography" for the Articles section - any volunteer or volunteers to write one?

[gregbradley]

Here is an example of colour not being accurate.

Rosette, Ha O111 S11. It didn't turn out in normal Hubble palette but even though it is way red I liked it.

http://www.pbase.com/gregbradley/image/91703069

Greg.

[tornado33]

Howdy Jeff, with my camera I ordered the clear AR coated glass option rather then an IR cut filter that cuts in after the Ha line, as I want to dabble in IR photography. Ive also purchased an IR pass filter that blocks all visible light Here is an example of its use.
Its Planetary nebula MZ3, where the red has been assigned to the IR image, grenn to the red, and blue to the green. Its interesting how MZ3's central star appears yellow whereas no others do
Scott

[h0ughy]

ok well go back and have a good look at my initial post Peter. you will see the attached graph. You have avoided talking about modified DSLR's for some reason? if you are going to lump the colour balance discussion (and the reporting thereof on MelbMeadeScopes@yahoogroups.com by some members) then make it a balanced discussion.

I fully agree that most images are not right, so what? I admit that I frequently say "nice image" - just because that person or persons who posted the image need encouragement or maybe not to be discouraged from posting. They will find the day when they discover for themselves that their images are not good and have improved out of sight with subsequent attempts. Some just never get it right (i am in this group) and some just don't care. I would like to thank you for your posts, frank discussions and I do hope that you have recovered from that stray shot from Marvin- btw - one from a pentax from the lunar eclipse last year

[Peter Ward]

Dave? Sorry, Houghy?

I am happy to discuss the points you raise, but this is getting off the point of my original post quite a bit.

I had not idea my suggesting that NGC2070 is in fact , red, (and to argue just what shade, would be silly) would make it over to MMS, and have only responded there a few minutes ago.

It's late. How about a new thread specifically dealing with the points you raise is looked at later.

[rat156]

I'm sorry this sentence makes no sense.

Is there an insinuation that by poking fun at you guys for getting your knickers in a twist that I did something wrong?

I was merely pointing out that the discussion may be of some interest to the many imagers in the MMS group, at all levels. I did it in the time honoured MMS way, by not taking it all that seriously. It states on the homepage of the MMS group "Warning: Aussie humour can lead to fedinkim drongo prangs :)"

So by saying that Peter had set the Cat amongst the Dobs, I thought most would get the humour. Just in case let me spell it out.

This is a play on words, parodying the saying "set the cat amongst the pigeons" meaning to cause a stir. Most of the Meade group have or have had in the past a Meade GOTO SCT (or catadiatropic scope, Cat). A lot of the IIS group have Dobsonian mounted Newtonian reflectors (Dobs). Peter Ward has a selection of scopes including an RC (a type of Cat), hence he had set the Cat amongst the Dobs.

I'm sorry but if you find that offensive in some way, don't read it, or contribute to the discussion in THAT forum, not this one.

Off to colourbalance my narrowband images now.

Cheers
Stuart

[h0ughy]

That would be great :thumbsup:

Perhaps you might like to explain how one may "ramp up the red channel" for those in the novice class with Photoshop. Some may not fully understand the term?

I personally struggle with the IR component having a modded DSLR, take M45 for example (http://www.iceinspace.com.au/forum/showthread.php?t=22908&highlight=m45), I have seen and indeed butchered the colour balance of that object. I am happy to send the fits/tiff/jpeg file to you to see how you balance that :shrug:


Rat156 I hope your NB images go well;) as for the postings - where ever you feel most welcome :shrug: Peter's comments have been educational and yet at the same time interpreted in a terse manner. Peter seems to have that abrasive touch ;), yet somehow conveys a message. It’s the abrasive touch that rubs up some people. We are a diverse mob, but sometimes the gene pool does narrow, no matter what the band:D:whistle:

[gregbradley]

Hi Houghy,

Your M45 shot looks very nice.

I don't see excessive red there at all, as there is a bit of background red in the nebula of M45.

The usual heavy red from a modded camera requires the custom white balance I mentioned in the earlier email or using colour processing and pulling back the red a lot.

In your M45 image the black though is a bit too black - so some data has been "clipped" and this also includes some of the fainter nebula. I used to do this all the time.
A good read on Photoshop is Wodaski's Zone System. Goes over everything.

You can send me the jpegs and I can have a go.

bradgregley10@yahoo.com

Cheers mate,

Greg.

[gregbradley]

Hi Scott,

I was thinking of doing IR photography also. Where did you order your IR filter from? Hutech?

Is it a 67mm external screw on filter?

Greg.

[tornado33]

Howdy Greg, my actual 350D was bought new and modded from Hutech with the clear AR coated glass option, my IR pass filter I got off Ebay, some links here
http://search.ebay.com/search/search.dll?from=R40&_trksid=m37&satitle=infra+red+filter&category0=
Mines a 58mm which suites my Canon kit lens, I bought separately a stepdown ring from a local photo store so I can fit it to my 50mm f1.8 lens. Yes I can shoot IR hand held in daylight with fast enough shutter speeds. Mind you a 40D would be better with its live view. With my 350D I have to take pics then check focus by trial and error.
Normally a 58mm filter is too big for a 2 inch focuser but it will fit in behind mine so I can use it in my telescope.
My filter is 850 nm cutoff
First shots here
http://www.iceinspace.com.au/forum/showthread.php?t=11499&highlight=infra+red
Scott

[Alchemy]

Curious as to whether this camera gives much more of the reds rather than the cyan colours previously discussed.

[avandonk]

The real problem here folks is that a DSLR is designed to give an image that closely represents the 'average' human eye's spectral sensitivity to any object illuminated by daylight. There is an adjustment for artificial light by allowing for colour balance or by auto white balance and other more complicated methods. But this is marginal compared to astro images.

We barely perceive H Alpha and so a unmodded DSLR does not either. I think that is what Peter was trying to point out. Hands up those who did not know that? Ok.

David Malin pioneered careful use of RGB filters with black and white film and then by a colour process which was the opposite of colour separation as in movie film as in the earliest colour movies. He used to put together 'colour' images of many nebs etc.

The problem has always been H Alpha, what colour is it? As only our scotopic (night) vision barely has a chance to perceive it and even then it is in black and white or grey tones!

The argument is basically about assigning what colour that the parts of the EM spectrum we can't perceive.

I personally like a 'normal' colour assignment to various spectral emission lines as in O3, Hb, SiII, and Ha.

Where the problem really is that modern CCD's with no filtration are really good at a far wider spectral sensitivity than the human eye. If you could buy a DSLR without a Bayer Matrix Filter and the filter in front of the sensor end of argument. Then just treat like the DSLR as an astro CCD. Unfortunately this is not the case. So we make do with the so called shortcomings because of the cost factor. One good thing is that the Bayer Matrix filters are essentially transparent to HA and IR, this is more correct for the 'red' Bayer filters.

Colour balance has no relevance in astro imaging as the spectral width of the incoming light from stellar nebs etc is far greater even accounting for atmospheric absorption and scattering than our spectral perception.

To me it is a non issue. For one simple reason. We can record a signal and then produce an image from it. Do we throw away any signal that we cannot normally see? No just incorporate it into the final image. I do not care if it looks too red!

Bert

[OneOfOne]

As a person who took their first shot of the Moon just two nights ago I don't have any technical background concerning how the colour balance is altered or how it differs with different equipment, but I think there are some points that are probably quite basic if you are talking about images as percieved by the human eye.

If you were to take an infrared image of an object, how do you get the colour balance correct? The only "reasonable" answer would be totally black as this would be the perception seen by the eye.

If you take an image in the visible band with an imager that is lacking in sensitivity in one area, say red, should you push the red to the point that it makes up for the imbalance? The image, after all, is a "true representation" of what the imaging equipment saw (more or less).

Because we don't really perceive colour in most objects, it is difficult to really decide what is correct. I guess we go by what we see in books and therefore what we expect to see.

I think that unless you are performing some observation for scientific analysis, the correct colour balance is the one that creates a pleasing result. Unfortunately, it is all very subjective. Of course if you took a shot of M42 and "deleted" the red channel, you would get a result that most people would say was "wrong" (including me). If it looks "natural" then you can't be too far wrong. If it looks like you have been tripping out on LSD, you probably have it wrong!

[Phil]

Hi Peter i agree with what you say but at the end of the day its the imager who has to be happy with what they have. I myself tend to process my images to get then close to what the colour should be. But i don't get myself work up over the colour if its a bit off, as long as i am happy with what i have, that's the most important thing to me. I sometimes find the processing of these photos harder then taking then.
Phil

[Peter Ward]

There has been a lot of rumination over what I would have thought was a pretty straight forward suggestion, in metaphorical terms: the emperor has no clothes.

NGC2070 can be mooted to be various shades of red.

But most certainly, it is not blue/cyan..and if we want to argue the Physics...come in spinner!

Artistic license aside....and sure your can make the sky look green with Photoshop or a badly calibrated camera....emission nebulae are red, red, red, just as the sky is blue.

Where is the problem with this patently obvious observation?

[Zuts]

The problem is that someone assigned an arbitrary primary colour to Ha. The red part of the spectrum contains every shade of red there is. Infra red is not red, it is below red and has no colour that the eye can really perceive. Some night vision goggles assign green to infra red and this is just as correct as assigning red.

Ha accounts for a tiny wavelength of the red colour of the spectrum, at the most it is a very very very dark shade of red.

The hubble palette is just a convention and i reckon assigning Ha to red is just a convention as well.

As far as artistic license is concerned. Well, shooting DSO's is like someone who just likes to shoot a small subset of say cat's. There are only so many and they get done over and over and over and over again and again the same one. Fine, i like doing this, and if my tarantulas come out blue, well i like that ghostly look.

The reason i am posting this is again you have made a value judgement. You havn't just said hey i think nebs are red and left it at that, you are trying to force your opinion down everyones throat. Well good luck to you. I got what you wanted to say in the first post, so cant you just leave it at that?

Paul

[Peter Ward]

Paul,

H-alpha has a wavelength of 656.281 nanometers. This is not my opinion.
It just is. If you've ever looked through a H-Alpha solar telescope, the colour is vivid red, and quite striking, but just a heck of a lot brighter that
your average emission neb.

I am not suggesting we should legislate to ban the blue ghostly look :)

If you are happy with that look, then good on you. :thumbsup:

[Hagar]

[quote=Peter Ward;287395]From my short time on ISS, I have to say it is an very enthusiastic group, polite, but often not very critical. By critical I am not suggesting you go around calling someone a boof-head!

When I look at a deep sky image the things I like to see are, excellent focus (this is the one thing you can nail every time), excellent tracking (i.e. round stars) accurate colour balance.
There are other aspects, but for now the above three really are essential to a good image.


Hi Peter, Just reading your initial statement again (This has definitly gone off track) I notice you say we are not very critical and items such as round well tracked stars and excelent focus. This to some extent may be true but to some degree you are missing your own point. Most of us here are fairly new to imaging and rely on people such as yourself for constructive criticism. I would be most helpful if the likes of yourself were to actively criticise but also to give some pointers or ideas on how these faults can be fixed.
I for one have been trying very hard to produce good images. I have spent many sleepless hours attempting to get tracking and guiding correct. Focus is also a problem I have spent hours working on. I am now starting to produce reasonable images (fantastic for me) but from a semi professional view point probably quite poor.

I think the views and almost war scene in this thread are based on these facts.
1. We can't all afford the pro type setup.
2. We are all trying very hard to achieve our best.
3. We are all very proud of our improvement.
4. We find it dificult to get real help with the problems listed above.
5. Equipment is expensive and even the semi pro dealers such as yourself don't provide sufficient information or advise on equipment.
Most of us have equipment bought from retailers tha now lives in a box and will probably never be used again because it is not suitable for our equipment.
6. A lot of passed on knowledge on sites like this is from someone who knows as little as you do.

Peter it is pleasing to get criticism but please attempt to assist with a fix or some ideas of a fix.

To turn a thread like this into a war is of no benifit to anyone and some look back a previous posts could give some ideas as to why this has happened.

The knowledge you possess is what most of us are after. Please don't just be critical but try to help as well.

[Peter Ward]

Doug,

Woah...slow down there...The whole point of my initial post was to do exactly what you allude to, by simply giving constructive criticism, plus a fix, instead of albeit an encouraging "that's great/nice/stick with it" I'd suggest will help people improve their imaging efforts.

I have gone to some lengths to say this is not an equipment issue, the fix being simple & cheap. I even posted a succinct PS tutorial to clarify the method.

Some thought this was a sleight of some kind, and there was clearly another agenda. I certainly took issue with that!

I agree, anyone can be a critic and I certainly would not endorse that alone. Constructive criticism, by way of, "how 'bout trying this, or that"
will give us all a leg up :)

[edwardsdj]

Thanks for the tutorial Peter :)

Useful advice that helps me get better is much appreciated.

[allan gould]

I've read through all of the posts in this thread but want to stay away from the controversy. I used Peter's suggestion of modifying the red curve properties in photoshop as I had used a 350D to photograph eta carina nebula and had noted how "blue" it looked. After PS I find that the Bok and other features look better. As a scientist I understand the arguements but must admit that there is "more" information for me to see in the PS adjusted photo.
Thanks for the suggestion Peter and admit that I prefer the "redder" photo as a personal taste. Surely cheaper than modding the 350D but I think I will be getting a 40D as it certainly looks great.

[gregbradley]

That's a nice sharp image.

You caught the jet coming out of the Keyhole Nebula nicely.

Greg.

[gregbradley]

Here is my latest. Mid Dec I added to data I collected in Aug and only now processed them.

http://www.pbase.com/gregbradley/image/91736469

This one is 4:25 hours and needs more luminance and some more red or Ha.

One point I may make generally speaking now- with DSLR images, often the images are very "short" exposures. By that I mean less than a hour.

Almost any object will look great with enough exposure. A rough rule of thumb is a minimum of 2 hours total.

DSLRs have the ISO setting so you can adjust the sensitivity whereas CCD cameras that gain is set by the manufacturer. This means you can artificially crank up the camera and it can invite you to take less exposure time than is really required.

With DSLRs one rule of thumb is to set your sub-exposure time to below where the sky glow becomes intrusive. If you live in a light polluted area (most would) then an light pollution filter helps. You can even do Ha with a DSLR although it requires a 2 inch screw on type (more expensive).

ISO 800 is often quoted as a good sensitivity. I always used 1600 or 3200.

Another thing that might help with DSLR imaging and this may be a more advanced technique. To take a short exposure for the stars only and longer for the main object. Photoshop allows you to remove the stars from one image and blend in the stars from another. DSLR images often have white stars with no colour. This is the most obvious difference between DSLR and CCD images. The CCD camera can expose longer without spilling over than most DSLRs (although the Caon 5D has lower noise and higher almost everything than an STL11).

The new breed DSLRs are now 14 bit and extremely low noise (Canon's at least - not sure about the Nikon's). The gap is narrowing especially now CCD cameras have a range of one shot colour cameras available and seem to be increasing in popularity. Apogee Ascent series are a lot cheaper and closer in price to DSLR top range and Sbig is bringing out a 10.5mp CCD camera shortly that is supposed to be fairly "cheap".

For autoguiding there are heaps of options now. The Orion Starshoot, the Meade DSI, the Celestron Neximage, The ToUcam (modified) and a hot one is the QHY 1.3mp CMOS chipped autoguiding camera which is US$245. That's a real bargain and use it with PHD guiding software (free). It may or may not need a Shoestring Astronomy adapter for your mount depending on what you are using.

Cheers,

Greg.

[Geoff45]

See this thread (http://www.iceinspace.com.au/forum/showthread.php?t=25867&highlight=blue+halos) for a discussion (and pics) of star halos

[tornado33]

Ye PS curves really worked well in Allans Eta Carina image for sure.
I agree with Greg, 2 hours is a good imaging time, though I guess for very fast systems shorter will do. As for length of subs, for me, I try to get the histogram about 1/3 the way across from the left, showing the sky background has well and truly been reached. For me in Newcastle an image throuhg my 10 inch f5.6 scope and modded 350D using just the IDAS uv/ir filter, I cannot go more then 5 to 10 mins @iso400. With the UHCS filter I can go 1/2 hour subs, but in my uncooled camera I performed a test which showed I get less noise taking 3x10 mins rather then a single 30 minute sub.

I believe most dedicated CCD camera users dont normally do more then 10 minute subs anyway? I believe SBIGs can do up to 1 hour subs?

What Id do if I was the owner of SBIG was approach Canon to see about buying a run of their SMOS sensors but without the bayer filter array, ( in otherwords a mono chip) and tee that up to a 16 bit ADC. I could then sell a 10 megalixel dedicated astro camera for less then half the price of an STL11 with similar overall performance but considerably less dark current and absolutely positively no blooming. :)
Nice M45 shot Greg too, and thanks for the tip re the guide cameras. The QHY6 looks like a great buy, $300 here (http://web.aanet.com.au/gama/qhy%20cmos%20prices.html)
Scott

[sjastro]

Interesting discussion.

Here is an image of the Tarantula by one of the best in the business R.J Gabany.
http://www.cosmotography.com/images/small_ngc2070.html

Of course the blue is a deliberate effort to impact on the image.

I have been doing astrophotography/astroimaging for 18 years and it is a shame so much artistic license is used these days.

Clear skies

Steven
http://users.westconnect.com.au/~sjastro/small/

[Prickly]

Someone earlier in this thread mentioned about false colour. Interestingly when the ST4 and ST6s were first released some years ago I remember looking at some demo shots, some taken in false colour. But for some reason this doesnt seem to have been very popular in amateur circles - although it does bring out detail very nicely sometimes.

Does anyone know of any software capable of this?

By the way, there are some great images on this post. I'd be quite proud of the green tarantula. Guess thats what your eye would see via the eyepiece (if it were brighter). Obviously in addition to Ha there is a fair amount of emission in the green part of the spectrum too which is quite interesting to me (In fact I was discussing this only a few nights ago with a friend).

Thanks Scott for the IRIS hint. Also increasing the red channel does work well to enhance the Ha Peter when your sensor is not very red sensitive.

David

[leon]

What a very interesting discussion, there should be more of it, I have learned so much, and now intend to try and put it into practice.;)

I actually didn't know that the Trantula Neb was red. :shrug:

Leon :thumbsup:

[dugnsuz]

It's not leon, it's blue...and remember the customer is always right!!:P:poke:

[leon]

Bloody Hell Doug now you have really got me confused :shrug: :lol:

Leon :thumbsup:

[Bassnut]

no matter, Tarantula is SO much better in narrow field NB anyway ;-).

[monoxide]

i think if you have a modded dslr or some form of astro ccd then yes you should get the colour balance 'right'

but to me, for an unmodded dslr its just rediculous even saying that the colour isn't right because its not red, of course it isn't because its not picking up anywhere near the amount of Ha as an astro ccd or modded camera and i don't think saturating the red channel is a real solution to this because you just wont have the Ha data there with an unmodded cam.

Im sure its easy for someone that has all the fancy gear to tell someone that struggles with lesser equipment that this and that is wrong with their image but noone gets out there with the intention to take an out of focus or poorly tracked or even the most disastrous, wrong colour image.

all you can do is get out there and give it your best shot and if thats not good enough for some people then i guess its bad luck :)

i just find it horrible that people spend hours capturing an image that they get told they got horribly wrong when they have done nothing wrong, it is just a limitation from their equipment.

[leon]

I understand that the Un-Modded DSlR has its limitations in picking up the HA in any deep sky object, however I am quite amazed that my Canon 5D actually picks up a considerably amount , and this has been commented on buy some of this group. :shrug:

Although my images are sometimes struggling to be up there with some of the others posted . I am very happy with the results.;)

To be able to capture these wonderful objects at all is just awesome.

Leon :thumbsup:

[dugnsuz]

Agree wholeheartedly with you leon.:)

[EzyStyles]

Totally agree with you there TJ. Unmodded DSLR's will not be able to pickup as much HA's as a modded version. Ive been playing both with modded and unmodded, it is a "HUGE" difference. Unmodded DSLR will pickup the Oiii's in the tarantula without any problems that is why most unmodded DSLR images of the spider are blue not because they want it to be blue. Raising the red channel will pretty much change that oiii data to red. You can raise it but don't overly do it too much.

[ballaratdragons]

All good and well to 'adjust' the colour to red in Photoshop, but are all stars red?

What I see in the examples shown in this thread of 'Red Adjustment' is a red nebula surrounded by dark red space full of red stars.

If you feel you want to adjust the Nebula to red, then adjust ONLY the parts that should be red. Not everything.

The finished RED image looks worse than the original wrong coloured image, but atleast in the original image, the stars are still the right colour.

Rather than me just criticise, here's is a fix you can try.

If you feel you must 'redden' the nebula in PhotoShop, AND you have PhotoShop actions (Noel Carboni or others),:
1. Open the image.
2. In PS Actions, choose 'select brighter stars'.
3. In the top toolbar, choose 'Select' and click on 'Inverse'.
4. Now set your colour Balance to how red (or any other colour) you want the neb.
5. Now use 'Curves' to take the red out of the sky and balance sky and neb.
6. Click on Lassoo tool, then right click on image and 'Deselect'.

Now you will have a nicely balanced red nebula with the stars remaining in their natural colours.

Geez, who'da thunk it that I'd be giving image processing tips :lol:

[Gribbit39]

Howdy!

From what very little knowledge I have on astrophotography, an ir filter is almost essential when imaging through a refractor although they see more blue than anything else and you need to process this away. Is there a difference when using a refractor to a reflector?? I have just bought a Canon 40D and a couple of ED refractors to start imaging through, but please don't anyone hold their breath for my first pic!

Cheers
Al