OK! What do you buy next??

[coldlegs]

Ok! What do you buy next??


You decide enough's enough with your modded/hacked up 6 inch F5 scope. It's time to move up a notch and get a “serious” scope and camera to take pictures of the heavens. Thinking about all the fun and hassles so far you begin to realise some hard facts.
1/ Your stuck doing astrophotography from a heavily light polluted backyard due to health issues and the level of pollution is about 6-7.
2/ Any camera bought would have to have “very” low thermal noise as there's no point burying what few photons you get in thermal noise.
3/ You really want to specialise in getting some reasonable pictures of all the DSOs you can find.
4/ You wouldn't mind some trophy pictures of the planets but not at the expense of DSOs.
5/ Wide angle/ low F ratio is out due to the light pollution.
6/ Conditions seem to suggest something over 9 Inches and an F ratio above 6-7 which seems to rule out all the F4-5 things on the market.
7/ You don't mind a little electronic/mechanical work and are prepared to build your own focuser motor drives etc.
8/ You want to keep the camera/scope weight below about 18-19kg to allow for guider bits and pieces.
9/ You want a black and white camera that is more than a Toucam and maybe less than 10 megapixels. Perhaps 2-8 megapixels.




So you look through your box of junk for bits and pieces that might be useful and find


Mount NEQ6PRO with both wide and narrow heads
ADM side by side mount plus 75mm rings
Newt 6 inch/F5 (possible guider)
Newt 4 inch/F8 (possible guider)
Reflector 60mm tasco (possible guider)
Toucams 2 x Lx b/w, 1 x Lx colour, 2 x colour, 1 x b/w (they're like rabbits)
USBnStep drives x2
Barlows (1.25”).. Powermate X5, GSO X2.5, GSO X5
Reducer (1.25”).. GSO 0.5X plus 1' extender
Extenders (1.25”).. 1”, 1.5”, 2”
Extenders (2”)..1”, 2” (bought by accident!!)
Filter wheel + filters RGB (1.25”)
Reverse T adapter
Digikit 49mm adapter
Zoom lens (1.25”) 8-24
Plossies various
Motor focuser drives ...various


You figure you'll probably need fancy filters, expensive colour filters, maybe an electronic filter wheel so you set the budget at $4000.


What do you buy???


Stephen

[DiamondDust]

Ski pants and thermal underwear:lol:

[gregbradley]

I'd go an SBIG ST8300 and filter wheel plus narrowband filters.

Scope could be a number of refractors around 100mm and an ED doublet or triplet.

I think Orion was advertising an ED triplet 102 for a good price.

You could go 2nd hand from Astromart to get even more value for money.

Here's a couple:
http://www.astromart.com/classifieds/details.asp?classified_id=727102
http://www.astromart.com/classifieds/details.asp?classified_id=726545


Greg.

[Merlin66]

Why not cut your losses and come over to the "rainbow" side - invest in a grating spectroscope and see what the stars are all about!

[blink138]

theres an orion ed 120 a couple of columns down for sale at an amazing price
pat

[allan gould]

Go for a used QHY8 camera. Best bang for buck out there and both Peter_4059 and I image from 5 Km from Brisbane central with a lot of light pollution. We don't use filters but shoot normally 5-15 min subs with no I'll effects. Have a look at our recent efforts. Don't waste money on filters as they just block the light and add a bad colour cast.
Just my 2 cents.

[gregbradley]

Yes that is tremendous bang for your buck. I have seen those at Bintel and they are impressive in their machining quality. The test from that link has it at strehl ratio of 97.5 where 100 is perfect. That is very very high and the sort of quality TMB put out for 5 times the price.

Greg.

[coldlegs]

The ski pants are a good idea but the rellies would stir me crazy if I wore thermals!!



Camera's a possibility but I'm thinking I need a narrower field of view to combat light pollution. Never been to astromart! Interesting place. Thanks




To be honest, that has crossed my mind but for now it's DSOs.


Yes they are getting cheaper but still need more photons!!



Like the camera. Who sells it in australia??

[gregbradley]

I thought the 8300 chip was a relatively narrow FOV. Its only a bit bigger than the ST10 and a lot smaller than a DSLR.

Smaller than that would be the ST2000 size cameras. They do not compare even vaguely in terms of performance having used both.

ST10 is a fabulous camera but still quite expensive. The 8300 does not have its sensitivity but has more pixels and is a clean chip and is cheap. There are numerous excellent images around using the 8300 chip in various cameras.

The real solution to imaging in heavy light pollution is narrowband. Ask Fred. Or you are limited to imaging the brighter objects which is fine as there are quite a few. You will also probably need to use shorter exposure times and become adept at gradient removal processing of which there are several techniques. Gradient Xterminator would be the most important processing tool you will use. Other gradient techniques will supplement the job Gradient Xterminator will do.

Narrowband though is not everyone's cup of tea for look. Some love it.
A really good narrowband with RGB stars installed to replace the narrowband ones (which inevitably are not attractive) is a popular image.

Narrowband requires longer subexposures (meaning more precise tracking and polar alignment, more accurate autoguiding etc etc) and longer overall exposure times. Longer processing time. So keep that in mind if you don't want to do that then it won't be for you.

Greg.

[coldlegs]

Greg
You learn something every day on this website! Didn't know there was a thing called “Gradient Exterminator”. Did some investigation and it brought me to my old problem...how do I get a full copy of Photoshop with out pretending to be a student or paying more than a good RC costs. Damn that software's expensive. I'm just going to have to get used to trying to use freeware like gimp etc because I'm way to stingy to pay a small fortune for photoshop! Back to the problem at hand.
I've looked at the 8300 and although it's around the right price range, it's a reasonably heavy beast at 2lbs. I would be worried if I had that on the end of a barlow and a comma corrector and a filter wheel. Still people do it so it must work.
My thoughts at the moment are to but a QHY8PRO colour (about $2.3K) and a 10”F5 black diamond newtonian (about $550) with a baader coma corrector kit (about $350). That leaves me with roughly $800 that can be used to buy OIII/H-alpha/CLS filters or maybe some 2” powermate barlows. I would probably go 12”F4/F5 but the weight including guider etc would be getting up to the top end for an EQ6PRO. The 10” should give me at least two and a half times more photons than my 6” and I'm familiar with the F ratio. I looked at the RC's from Andrews but an affordable 8” wont give me much of a gain and a 10” is amazingly heavy and out of my range for the moment. A light bucket newt and a good colour camera will probably perk up my interest for a year or two.
Stephen

[Waxing_Gibbous]

Stop pretending to be a student.
Just sign up for a couple of distance learning courses and there ya go!
Perfectly legit.
Which kind of takes the fun out of it.

I can't comment on CCD imagers as they scare me, but a "light bucket" refractor is going to set you back a fair bit (that 120 is a good deal - so's my AL106 ;D ).
The various Astrotech-lensed 130s seem to have a good rep as do the TMBs of the same aperture. Used, they should come in under budget.
But some of the best images taken through refractors, that I've seen anyway, come from smaller instruments in the 90-110mm range.

[coldlegs]

Peter
If I could find a legitimate course on how to use photoshop for astronomy that cost less than $200 and enabled me to buy and register the student version, I'd be on it like a seagull on a hot chip!! Most of those courses cost as much if not more than the software.
Stephen

[gregbradley]

That sounds like a well thought out setup.

You can sometimes pick up a 2nd hand copy of Photoshop on Astromart. I got a copy of CS4 that way. It cost $200 as I recall.

New that is more like $1200 or something.

As far as 8300 versus QHY8. My first astro camera was a Nikon D70. It used a 6.3mp Sony chip which I believe is the same CCD chip in the QHY8. It was quite a good chip although in the Nikon it gave bad amp glow ( a purple glow area that worsened with longer exposure). That was the Nikon not the chip. I assume the QHY8 does not suffer from amp glow. Amp Glow is caused by the amplifier circuit that was heating up the chip in one part of the chip. Canon CMOS chips have the amplifier built into each pixel. They also shield the chip from other circuits. The Nikon had circuitry behind the chip touching the back of the chip. Not smart.

The ST body I thought was quite light. What does a QHY8 weigh? It must be very light. Sure weight factors in as you don't want flexure. But at F5 with no barlow if the focuser is half decent you should be ok.

It comes down really to mono CCD imaging versus one shot colour. Unless of course you get the 8300C which is the one shot colour SBIG.

One shot colour is fun. I did it for a while with an SBIG STL11000XCM. Its nice to see the download coming off the camera in colour.

It has advantages and disadvantages:

Advantages:

easier processing
every image counts whereas in mono you need LRGB (4 images) or at least RGB to make an image. So you often miss out in an imaging session if cloud comes in and interrupts and you only got LRG or something.
its cooled so its a step up from DSLR and cleaner electronics plus its CCD versus CMOS.

Disadvantages:

less sensitive
less flexible - not really ideal for narrowband imaging as only 1 in 4 pixel is really picking up anything ie Ha can still be done but slower. O111 and S11 are probably mostly impractical. If light pollution is an issue then you miss out on the ability to do narrowband as an option.
less resolution - mono is 4 times the resolution as every pixel registers part of the image rather than the pixels grouped in 4s to create the colour (called the Bayer matrix which is the layer of micolenses that are coloured and laid over the mono chip).
less noise and especially less colour noise ("smarties" in the background - lots of little red green or blue dots very often).
less noise and more response in the dimmer areas - nebulas often have dim areas of dust. One shot colour is weakest in the dim areas where the noise can get very bad. Mono also does this but nowhere near as bad.

So you have in the end one shot colour gives ease but comes at a cost of not as good quality images and less resolution with more noise.

Not to say of course you can't do a good one shot colour image. Of course you can and there are lots to prove that. But you may need to image for longer to make up for the lack of sensitivity (one shot colour chips are usually around 25-33% QE (QE is a measure of efficiency of a chip converting light to electrons) compared to around 55-60% QE in the mono so about twice as sensitive. It is a bit complicated to do a straight comparison like that as there are other minor factors so in the end it may be closer to 50% more sensitive.
Of course one shot is lighter (no filter wheel), cheaper - no filter wheel and no filters and easier. Mono may require more software.

So it can be a budget decision or it can be an make imaging easier decision. But like everything else in life - to get better results usually requires more effort.

Greg.

[coldlegs]

Greg
You are absolutely right about getting better results requiring more effort. I think by sticking with a one shot colour camera and ignoring narrowband imaging for the moment I'll get a much better idea of what I'm up against at my location as well as what targets are worth going for in the future. I've still got a lot to do... setup guiding and get it working reliably...build a pier...shift all the gear out of the granny flat into my new shed...setup the umbilical cord to the pier...decide what I like most and what I'll need to do it. By the time I've finished all that it will be 2012 and there will be a bunch of new cameras out (maybe) to choose from. Looked at the specs for the QHY8PRO (weighs 425g) which uses a ICX413AQ chip and it has a “PEAK QE” (??) of 60% green, 50% red/blue and H.a. Not sure how that works as the spec sheet seem to indicate it's better than that (see attached jpeg).
Amp glow would kill the deal though. Haven't heard any reports from qhy8pro users yet but will look around. Not sure how much glow would exist at -15/-20C as lowering the temp usually minimises the glow substantially.


“still looking”
Stephen

[Gama]

The QHY-8 Pro uses the ICX-453, not the ICX-413.

The QHY-8L uses the ICX-413.
Here is a few images from Daniel's QHY-8L, a fellow IIS member on this forum.
http://www.iceinspace.com.au/forum/showthread.php?t=71231&highlight=qhy8l

http://www.iceinspace.com.au/forum/showthread.php?t=70060&highlight=qhy8l

http://www.iceinspace.com.au/forum/showthread.php?t=69947&highlight=qhy8l

Theo

[coldlegs]

Theo
Now I'm confused. The spec sheet says it's an ICX413AQ in the pro.
See attached jpeg.
Stephen

Update 1:.. looks like somekind of old advertising material. According to the QHYCCD.com website they are indeed all 453s !! I stand corrected.
Thanks theo
Update 2/ The date on the blog was 2008. maybe something has changed since then?? Heck, now I'm really confused!!!

[mithrandir]

I don't have a QHY8Pro, but do have a QHY8.

Here's a 30 sec unmodified dark frame, the last in a sequence of 15. Converted from FITS to PNG. No other modification.

A few hot pixels. No sign of any amp glow.

[coldlegs]

Andrew
I can't wait to have darks like that! Hot pixels...heck the ones I thought were hot were dust on my screen. I even wiped the screen to try and find them and still couldn't. Anyway thanks for that. I feel a little more comfortable about the QHY8 although I'm still not sure what chip is in the pro version.
Regards
Stephen

Ahh found one ... big image that!

[Gama]

Hi Stephen,

Not confusing if you know whats occured:shrug:..
Basically, they saved time on documentation by just using the same document to use on the other models, and just forgot to edit it correctly.
Here is the first post that another user noticed like you did.
http://qhyccd.com/ccdbbs/index.php?topic=2756.0

I should mention to QHY that it still hasnt been fixed.
Hopefully, they will fix that in a day or two:rolleyes:.

But, ONLY the QHY-8L has the ICX-413 sensor.

Theo

[coldlegs]

Thanks for that Theo. Problem solved.
Regards
Stephen

[gregbradley]

QE of 60% in a one shot colour chip is either some sort of a world record or the seller is lying or being misleading. I see the graph says with no lens - does that mean the mono chip before they put the Bayer Matrix on it?

Looking at those images does not look like what a 60%QE camera registers in that amount of exposure time. My FLI ML8300 mono is 60% QE and it would register more than that in the same amount of exposure time.

Have a look at the Kodak Sensor Solution webste where they list QE for various models of chips.

60% QE is only the better mono chips. Colour is usually around the 25-30% range.

Perhaps Sony is better at making sensitive chips than Kodak but 60% seems unreal for a one shot colour.

Kodak has brought out a new type of lens covering on the colour chips and some of them have much higher QE.

I could be wrong as I am not that familiar with Sony chips and they may well be more sensitive than Kodak chips but I thought they were all up against the same technical barriers.

Greg.

[Gama]

The QE is correct Greg, and even FLI use Sony Supercad CCD devices in some of their Microline models.
You are also comparing QE from a CMOS Sensor and Not a Sony CCD sensor. The QE is stated by Sony, may be before the Debayer, i dont know. But Kodak specify one QE for both Color and Mono, so that theory may well be correct. The question on the High QE has been asked for years, so your not alone.
Finally, YES, the Sony Superhad totally kills the Kodak series of sensors.
There is plenty of info out their as to why, and manufacturers, like FLI, Apogee, StarlightXpress, etc, have the Sony sensors in their line of products for a reason
Further, you may well be impressed on Sony's technology in Sensors, with their breakthru technology in the new CMOS Back illuminated Sensors. Read about it here http://www.sony.net/SonyInfo/technology/technology/theme/exmor_r_01.html

Its a shame the dont make a Mono larger than the ICX-285 (Yet).

Theo

[gregbradley]

Thanks for the link Theo.

I saw after I posted that this had been discussed in the past at length.

That new Sony Cybershot with the back illuminated CMOS sensor looks the goods.

Greg.

[coldlegs]

Wow! love the new technology. What's the bet on when we see it in a camera? 2012?
Stephen

[Gama]

Its amazing that a consumer manufacturer (Sony) can create this sort of sensor (Back illuminated) for peanuts, yet, specialized ccd manufacter's struggle with old technology, and still charge a squillion for them..

Theo

[Waxing_Gibbous]

I think a great-big box to put it all in should be your next purchase.:)

[coldlegs]

Should have one of those by the end of May.
9.1M X 8.7M colourbond shed should be done and dusted by then!
Stephen

[renormalised]

What to buy next??.....one of these:):):)

http://www.planewave.com/index.php?page=1&id0=6&id=0

[coldlegs]

When I win lotto that's going in my back yard instead of the ferris wheel!!
Stephen

[gregbradley]

There's a guy in WA who is getting one of those. He is mounting it on a truck to make it portable. WA people think big.

Greg.

[renormalised]

You'd want a good truck to mount it on and plenty of shock absorption built into the mount to safely cart it around.

I'd stick to putting one up on a solid mount under a good dome:)