Are those fancy astro cameras worth it?

[jimmyh1555 (James)]

Hello everybody! Over the last few weeks I have been watching all your photos, and it seems to me that the majority of you use ordinary DSLR cameras! Most of your posted photos are beautiful. I have been trying to get a handle on ZWO 224 and 1600 mono - and so far all I seem to get is rubbish. I have tried Omega, Eta and Jewel box many times and have taken last week 60 x 30s at Eta, and 40 off 30s at 4755 with mono ASI1600 LRGB and not a skerrick of colour , Should I use my Pentax and crank it up to 1600 ISO and try total 30 minutes? The only times I used my Pentax at Orion M42, I got quite decent colour, but very small image!
What's the go with these fancy special astro cameras? There must be a trick to using them somehow, or is it just a gimmick to relieve keen photographers of their money.
For now, I'll be screwing my trusty Pentax to the scope - at least I can get some colour and sparklies that way - not just round white blobs, AND I have no problems with JPEG. I have tried RAW and have never seen any improvement.

[lazjen (Chris)]

What are you using to process and combine your data? What settings are you using for the cameras?

[leon]

James the trusty DSLR can do an incredible job with some fine images to be proud of.
I always used a Canon 5D and was very happy with the results.

Leon

[raymo]

Leon is spot on, in the hands of a talented, skilled operator, a DSLR can produce fine results; Sarah Wager, one of the world's best known
amateur snappers used a DSLR earlier in her career, but when she
became highly accomplished she had no choice but to change to astro dedicated cameras in order to produce the results she knew she was
capable of.
I agree with you about JPEGs, I don't see much improvement using
raws at my level of ability, but I imagine people up in the stratosphere
of AP need to use them.
raymo

[LewisM]

If you aren't combining your separate Lum,R, G and B in astro-processing software, then indeed, you won't see any colour. All 4 need to be combined using specific algorithms within the programmes (like in DSS, CCDStack, PixInsight, AstroArt etc).

Whilst DSLR is OK, you will get vastly superior results with properly handled mono CCD (combined to colour) or even a One Shot Colour CCD due to the cooling and other factors.

[LewisM]

Regarding RAW - there is again a significant advantage to RAW, as you can get more precise colour, lossless compression, ability to correct lens issues (like barrel distortion etc).

Most notable is the ability to greatly alter and correct the colour, exposure etc. Every single professional or even pro-amateur photographer uses RAW.

When I shot DSLR astro images, I exclusively used RW because of the inherent gains over lossy-JPEG (JPEG is really a crappy format, sorry to say, but makes web-display easy). After working in RAW, 99% of photographers will convert to TIFF or PNG (lossless) rather than JPEG. If JPEG is used, most will elect to use JPEG for WEB technology, which retains colour and can vary the compression (amount of detail loss)

[Atmos (Colin)]

Good images can be taken with both a standard DSLR or a not so fancy astro camera.
Unmodded Nikon D7200
QHY163M cooled astrocamera

I always taken my images in RAW as it preserves the dynamic range.

[Slawomir (Suavi)]

Martin Pugh shared a link to his data in astrophotography section and encouraged people to download it and to process it.

It might be worth having a look and seeing what really good mono raw data looks like to give some idea how much input into an astro image is needed is from the equipment and how much from skilfully processing the data.

[kens (Ken)]

There's quite a learning curve with mono cooled (I assume you have the cooled version?) cameras versus DSLR.
Why not upload your mono subs to Dropbox or wherever and see what others can do with them and how.
Given you already have the ASI1600 , see if you can get hold of a Ha filter and try again with, say, Eta Car or any other emission nebula.

[xelasnave]

Nah my advice is to sell it cheap...to me☺
Alex

[Camelopardalis (Dunk)]

Try plain RGB combination first and see what you get, I find combining with L washes the colour out unless they are very closely matched in intensity.

Also, what gain are you using? Short exposures can work out OK on the 1600 but you need to be usin sufficient gain.

[jimmyh1555 (James)]

Thanks guys for your comments. On my attempt at Eta, I did the following:
ASI 1600 mono UNcooled
10 off exposures 30s each in L, R, G, B - ie 40 exposures.
Gain was 213
I did it in SharpCap
I then loaded all those 40 .png files into DSS and it stacked them (I think) ie like just opened each file in turn and put it on the list. Then I registered them and they got stacked. I saved the resulting file as a .FTS and then loaded it into Star tools.
Then the fun started because I tried all those boxes down the left hand side like Decon, contrast, HDR, and lots of others. The image was quite dim when I started it and it didn't improve! what stars there were, ended up as white dots with halo's around them . Ghastly!

[jimmyh1555 (James)]

OH, and dont mention masks - flashing green, invert, shrink, grow, AAAAGGGGGGGGHHHHH

[kens (Ken)]

It's unfortunate you got an uncooled mono as the cooling is one of the principal advantages over a DSLR.
Sounds like you are trying torun before you can crawl with the post processing. If you used PNG files they are compressed which greatly limits what StarTools can do.
Like I said, upload the unprocessed PNG files so we can advise on what you should do.

[Shiraz (Ray)]

Originally Posted by jimmyh1555

Thanks guys for your comments. On my attempt at Eta, I did the following:
ASI 1600 mono UNcooled
10 off exposures 30s each in L, R, G, B - ie 40 exposures.
Gain was 213
I did it in SharpCap
I then loaded all those 40 .png files into DSS and it stacked them (I think) ie like just opened each file in turn and put it on the list. Then I registered them and they got stacked. I saved the resulting file as a .FTS and then loaded it into Star tools.
Then the fun started because I tried all those boxes down the left hand side like Decon, contrast, HDR, and lots of others. The image was quite dim when I started it and it didn't improve! what stars there were, ended up as white dots with halo's around them . Ghastly!

Hi Jimmy
Apologies if I got this wrong, but your description suggests that you stacked all of the LRGB images into a single file - which will destroy the colour information.
the LRGB files have to be aligned the same way, but then they need to be separately stacked to produce four different files representing L and the three colours (DSS can align and stack them). These four files are then combined to form a colour image - StarTools can do that http://forum.startools.org/viewtopic.php?f=12&t=1148) and https://www.youtube.com/watch?v=nk3zTZzd9kY Cheers Ray

[tlgerdes (Trevor)]

Any particular reason why your subs are so short? Astro imaging usually starts at about 5mins per sub.

Also, your gain seems a tad too high. My QHY runs at 0 gain.

[Lognic04 (Logan)]

Originally Posted by tlgerdes

Any particular reason why your subs are so short? Astro imaging usually starts at about 5mins per sub.

Also, your gain seems a tad too high. My QHY runs at 0 gain.

Well, i recently learned that with astroimaging you want to be about 3x above the noise floor in signal, which means that you want short subs and LOTS of them (a common misconception is, "i wont capture faint data though!" This is actually incorrect, for the noise floor lowers the more subs you get, which will end up bringing out the faint data) For the asi 3x read noise turns out to be about 30 second subs, so that is the ideal exposure time with the ASI. DSLRs are similar in that they use about 30-45 second subs ideally.

[Shiraz (Ray)]

Originally Posted by Lognic04

Well, i recently learned that with astroimaging you want to be about 3x above the noise floor in signal, which means that you want short subs and LOTS of them (a common misconception is, "i wont capture faint data though!" This is actually incorrect, for the noise floor lowers the more subs you get, which will end up bringing out the faint data) For the asi 3x read noise turns out to be about 30 second subs, so that is the ideal exposure time with the ASI. DSLRs are similar in that they use about 30-45 second subs ideally.

Hi Logan. The sky background, not the target signal, needs to be about 3x the RN. As well as RN and sky background brightness, the optimum sub length also depends on the scope fnumber, filter bandpass, optics efficiency, camera gain and detector quantum efficiency. Agree though, that much shorter than CCD-normal subs are needed with the 1600 and for luminance on a reasonably fast system under dark sky, a minute or so is typical. Cheers Ray

[jimmyh1555 (James)]

thanks guys for your comments. My subs are "so short" because the scope is unguided and I am worried that any longer might stuff up the roundness of the stars. I thought 30s seems ok - isnt it? Camera is uncooled but here in Tas, temp was about 10 deg C at the time. (Cant afford a cooled one yet)
From everybodies advice, I figure this is what should be done: (for say Eta)
Do say 20 frames at 30s in L
Do 20 frames at 30s each in RGB (ie 60 frames of 30s)
All done in SharpCap with .png and about 100 gain
Do say 10 frames of darks.
Go to DSS and individually stack 4 lots of 20 frames, adding the darks
I would now have 4 files of .FITS and a dark file'
I would now go to Star Tools 1,4 and guess I would open the Luminescence file?
Then I will press the RGB button and assume that Star Tools will now combine the lot...
Is that about right??
Comments appreciated!
PS I aint got a clue what a noise floor is.
Oh, the scope is Esprit 100, camera ASI 1600 mono
Should I use more gain if I am only doing 30s subs? I will try to do many more subs but am concerned the laptop will die, or clouds will roll in, or the HEQ5 will have a tantrum. A couple of weeks ago, I was photographing Eta and it was very high in the sky and I looked at the Esprit and OH DEAR, the camera was about to hit the pier, so I had to stop quick smart!

[Camelopardalis (Dunk)]

James, you should save the raw frames from Sharpcap in FITS format as it has greater precision. Light frames and Dark frames.