Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

ASI1600mm cool


Andyb90

Recommended Posts

2 hours ago, David_L said:

I don't see any reason to go for short subs with this camera unless you're not guiding -:-)

Does that not counter the primary argument that many people note for using this or other CMOS cameras over CCD, which is the ability to take shorter integrations?  If you are going to shoot 10 minute subs anyway would you not benefit from a 16bit CCD?

Not being awkward, just wonder why you would use a CMOS camera and then promote longer subs?

Link to comment
Share on other sites

  • Replies 982
  • Created
  • Last Reply
24 minutes ago, RayD said:

Does that not counter the primary argument that many people note for using this or other CMOS cameras over CCD, which is the ability to take shorter integrations?  If you are going to shoot 10 minute subs anyway would you not benefit from a 16bit CCD?

Not being awkward, just wonder why you would use a CMOS camera and then promote longer subs?

Nope - does't counter the argument for CMOS over CCD - my comments encourage CMOS for its versatility :-)

As I mentioned - short subs are great if you don't want to guide - or your guiding is poor

But the results of many using longer subs demonstrate that there doesn't appear to be any reason to take many short subs at really high gain....with the added processing time and disc space required - when you can get better (from what I've seen) results with longer subs of 5-10 min - which is still shorter exposure times than most CCD approaches (of c. 20-30min)

The great thing about this new approach (CMOS) has been people trying out different techniques - the CMOS format appeared to require many short exposures - but I've just noticed from experience and the results of others that longer subs work better.

David

 

Link to comment
Share on other sites

8 minutes ago, David_L said:

Nope - does't counter the argument for CMOS over CCD - my comments encourage CMOS for its versatility :-)

As I mentioned - short subs are great if you don't want to guide - or your guiding is poor

But the results of many using longer subs demonstrate that there doesn't appear to be any reason to take many short subs at really high gain....with the added processing time and disc space required - when you can get better (from what I've seen) results with longer subs of 5-10 min - which is still shorter exposure times than most CCD approaches (of c. 20-30min)

The great thing about this new approach (CMOS) has been people trying out different techniques - the CMOS format appeared to require many short exposures - but I've just noticed from experience and the results of others that longer subs work better.

David

 

Ok thanks.  I'll wait to see some of the longer integration CMOS images appearing and see how they fair against the CCD ones as the shorter integration ones aren't yet comparable IMO.

Link to comment
Share on other sites

You can't get away from the fact that most modern CCDs have greater dynamic range than this camera, so a larger amount of smaller frames will help even that discrepancy out. Same number of photons captured, just in the representation. The ASI1600 is good at most DSO imaging and very good at the brighter targets, and used to its strengths, it is a winner, but it doesn't beat all comers in all situations.

Link to comment
Share on other sites

19 hours ago, RayD said:

If you are going to shoot 10 minute subs anyway would you not benefit from a 16bit CCD?

From what I understand for a camera to have 16bit dynamic range it needs a combination of low read noise and a larger full well capacity. Would this not take you into a higher price bracket than the ASI1600mm cool?

Andy.

Link to comment
Share on other sites

25 minutes ago, Andyb90 said:

From what I understand for a camera to have 16bit dynamic range it needs a combination of low read noise and a larger full well capacity. Would this not take you into a higher price bracket than the ASI1600mm cool?

Andy.

Probably.  I've not questioned the cost of the camera, it is cheap, as are the whole range of ZWO cameras.  I only asked why you would use a CMOS camera with reduced dynamic range, and then rather than using its primary benefit of shorter integration requirements, use it like a CCD i.e 10 minute subs.  That was answered and it's interesting seeing what data and images people are getting, which is good.

Link to comment
Share on other sites

Yep, a much bettrr bet, but I was looking for a camera whose pixel size would be a good match for my 80mm f/4.4 and give me a larger sensor than my 694. The 1600 filled that spec, plus the BF with the ZWO FW meant I could use my 1.25" Astrodons.

A win all round to my mind, plus I could afford it.

Link to comment
Share on other sites

5 minutes ago, DaveS said:

Yep, a much bettrr bet, but I was looking for a camera whose pixel size would be a good match for my 80mm f/4.4 and give me a larger sensor than my 694. The 1600 filled that spec, plus the BF with the ZWO FW meant I could use my 1.25" Astrodons.

A win all round to my mind, plus I could afford it.

I'm not knocking the camera, I'm enjoying seeing the range of images coming from it.  I just answered the question raised that 16 bit CCD naturally means additional cost, as that isn't necessarily the case.  I have a couple of smaller ZWO cameras and rate them, and Sam is great.

My earlier query was about using longer integrations as I understood the main benefit of CMOS was using shorter ones, as in the above image, so was surprised to see a post noting that better results are gained from longer integrations.

I don't know, I don't have one, and as a new camera it seems there is still quite a bit of experimenting with integrations/gains, of which I'm trying to understand :thumbright:

Link to comment
Share on other sites

Fog/mist here this night so I couldn't successfully test with longer subs. Deleted all this evening subs in fact as they were rubbish. And I won't be seeing stars for a while, the forecast says.

Clear skies,

Alex

Link to comment
Share on other sites

I think the reason for shorter subs is the short ADC, to keep it from saturating hence the 5 min subs I used for my Rosette trial. Had I been using the 694 I would have gone for 10 min subs at least. Guiding is not a problem with the DDM60 :D.

May be a clear night tomorrow so maybe....

Link to comment
Share on other sites

30 minutes ago, Filroden said:

If it's a 12bit camera, shouldn't you expose for 1/16 of the time you would have done for a 16bit camera and then take 16 times as many subs?

Not really, but you have to take at least 16 subs to recover the dynamic range.

Link to comment
Share on other sites

1 hour ago, Filroden said:

If it's a 12bit camera, shouldn't you expose for 1/16 of the time you would have done for a 16bit camera and then take 16 times as many subs?

That's the way I look at it.

Link to comment
Share on other sites

21 minutes ago, MattJenko said:

Another observation I have is that anything over 2 minutes ends up with amp glow, which is not trivial to remove. My darks don't seem to do brilliantly with it, but 2 mins and under results in clean as a whistle subs.

Yes, that's what I've found and even 2 minutes is giving me a problem with amp glow.  I think I should stick with a minute or less and just take twice as many subs.  This image shows a very faint DSO - Simeis 147 - imaged with 2m subs and 600 gain with a temperature of -30C.  This is 122 lights in Ha processed with BPP with calibration in PixInsight - it needs more.  The other DSO in the frame is IC410, the Tadpole Nebula.  This image integration has been histogram stretched to show Simeis 147 in the top left corner.

IC05 410 Simeis 147 04.png

Link to comment
Share on other sites

Having a 16bit A to D on a CMOS would not in itself give it higher dynamic range....its all to do with well depth. Essentially the dynamic range is governed by the size of the capacitor that they can fit onto the chip and that has actually tended to get smaller as pixels have gotten smaller. My 1000D has more dynamic range with a 12 bit a/d than a 760D has with its 14 bit a/d the problem being that to access that dynamic range a lower ISO has to be selected. CCD has a different construction / way of working that enables higher dynamic range. You only need sufficient resolution in your a/d to cover the dynamic range available any more and your just over sampling.

The amp glow is one thing that put me off this chip not the 12bit vs 14bit or 16 bit argument. But even that is not to say anything is wrong with it or that its not capable of stunning results especially compared to my current camera. I just think that I will bide my time and wait for a second generation Cooled Mono CMOS camera to come along......assuming that someone makes more mono CMOS chips of this size or larger.....might be a long time coming so I may end up choosing to go with a CCD after all.

From what I have read this camera is very accessible in that you dont need to be able to track well and dodging cloud is easier as you can compensate for its downsides vs ccd by taking many many more shorter images and for that reason alone it is still very appealing to me.

Link to comment
Share on other sites

I've noticed the amp glow too but my darks eliminate it well enough for me.

I'm getting better results with longer subs, but according to the specs of the camera discussed here - I don't know why LOL! :-)

I do like the fact that if I can use the ASI1600 with my Sky Watcher Star Adventurer, unguided, and get stunning results.

Not something I could with my old CCD where I needed at least 15 minute exposures to make it worth taking the dust cover off the scope.

So versatility is the key difference with this camera  as far as I can see - no matter how long your subs are :-)

David

Link to comment
Share on other sites

Can I just check what mean ADU is about right for taking flats? I've used the flats wizard in SGPro. I got a reading of approx 22,000 ADU with the ASI1600.

Is this okay for flats or a bit on the high side?

Andy.

Link to comment
Share on other sites

Here's a second attempt at the Rosette this time with gain 200, Ha 30 x 90s, -25c. I wanted 50+ subs, but had to throw many away due to bad guiding. I think I prefer this version to my attempt at gain 300. I'll try gain 139 next. 

rosette 5 processed.jpg

Also grabbed a few frames of the NAN before it went behind the house, Ha 9 x 90s, gain 200, -25c

nan processed 3 kappa sigma.jpg

I'm absolutely loving this camera :-). It amazes me whats possible to achieve with it given such short integration time.

Andy.

Link to comment
Share on other sites

I see numerous references and examples of amp glow in this thread.

Does this amp glow exist in a master bias?  For instance what happens if a master bias is created from, say, 100 bias frames?

If the edge glow exists in the master bias, then it isn't "traditional" amp glow with an underlying thermal cause but it could well be the same kind of edge glow effect seen in other Sony sensors:  https://stargazerslounge.com/topic/283484-edge-glow-on-master-bias/

Just curious ...

Mark

Link to comment
Share on other sites

20 minutes ago, Andyb90 said:

Here's a second attempt at the Rosette this time with gain 200, Ha 30 x 90s, -25c. I wanted 50+ subs, but had to throw many away due to bad guiding. I think I prefer this version to my attempt at gain 300. I'll try gain 139 next. 

rosette 5 processed.jpg

Also grabbed a few frames of the NAN before it went behind the house, Ha 9 x 90s, gain 200, -25c

nan processed 3 kappa sigma.jpg

I'm absolutely loving this camera :-). It amazes me whats possible to achieve with it given such short integration time.

Andy.

Very nice! I hope I'll be eventually able to use this camera out of the city and point towards a higher altitude. I also get a horrible gradient, I can't get not even close with such short integration time.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.