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Old 09-05-2016, 09:00 PM
glend (Glen)
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The Beta Tester on the Cloudy Nights ASI1600 thread is reporting bad AMP Glow issues on long darks. ZWO sent him a new driver but I can't see that fixing what is usually a firmware issue. I am holding off on my order until I find out what is happening with this and if it is backed up by other testers.
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Old 10-05-2016, 09:01 AM
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Originally Posted by glend View Post
The Beta Tester on the Cloudy Nights ASI1600 thread is reporting bad AMP Glow issues on long darks. ZWO sent him a new driver but I can't see that fixing what is usually a firmware issue. I am holding off on my order until I find out what is happening with this and if it is backed up by other testers.
Glen, many device drivers upload firmware to the device as part of their initialisation process...
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Old 10-05-2016, 09:05 AM
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40GB of data for 34 minutes of integration...that's going to take data storage requirements to a whole new level !
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Old 10-05-2016, 09:17 AM
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that is a crazy result for 1 second subs, what would you need for narrowband, 6 seconds??
would like to see what an actual sub looks like.

im guessing M51 is pretty bright but still. With 1 second respectable deep space images are we going to see a time where a large goto dob with 20 second subs will be fine for narrow band?
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Old 10-05-2016, 10:11 AM
glend (Glen)
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Beta tester Tolgagumus has an image up on CN now, in the Beginners imaging section,

http://www.cloudynights.com/topic/53...a-test/page-11

it too is very large. He shot 125 x 60" subs, even with having to throw out some the folder was 20 gig. Final image is very nice.
Here is his Astrobin image:

http://www.astrobin.com/full/248375/None/

Last edited by glend; 10-05-2016 at 10:43 AM.
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Old 12-05-2016, 09:11 AM
glend (Glen)
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I have gone ahead an ordered a ASI1600MM-Cooled from Bintel. I am told by John that they expect the first shipment from ZWO at the end of this week (today?), and that they hold enough pre-orders to pretty much run out the initial delivery.
Now I am looking for a 36mm filter wheel that suits (as I already have a set of 36mm narrow band filters and I don't wish to sell them). The Starlight Express wheel looks promising.
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Old 12-05-2016, 07:27 PM
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I have gone ahead an ordered a ASI1600MM-Cooled from Bintel. I am told by John that they expect the first shipment from ZWO at the end of this week (today?), and that they hold enough pre-orders to pretty much run out the initial delivery.
Now I am looking for a 36mm filter wheel that suits (as I already have a set of 36mm narrow band filters and I don't wish to sell them). The Starlight Express wheel looks promising.

I look forward to your review Glen. Its potentially a very nice camera.

Greg.
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Old 12-05-2016, 09:07 PM
glend (Glen)
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Thanks Greg. I bought a QHY 5 position 36mm filter wheel today from Cyclops Optics in Hong Kong to go with the new camera. I have 36mm narrowband filters already so i did not want to downsize. Looks like the camera will screw right onto the filter wheel. I will probably sell my mono cooled 450D down the track if this ASI1600 is everything its cracked up to be.
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Old 12-05-2016, 10:19 PM
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Glen, to run the QHY filter wheel via USB will are going to have to basically flip a switch in the clear electronic area so that your computer will read it as a serial unit. Takes 5 minutes and is dead easy.

I run mine via the ASCOM QHYCFW Serial Driver.
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Old 13-05-2016, 12:37 AM
glend (Glen)
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Glen, to run the QHY filter wheel via USB will are going to have to basically flip a switch in the clear electronic area so that your computer will read it as a serial unit. Takes 5 minutes and is dead easy.

I run mine via the ASCOM QHYCFW Serial Driver.
Thanks Colin, that is just what i need to know, i was wondering about driving it. Cheers
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  #31  
Old 13-05-2016, 07:13 AM
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Glen,

I wonder about the viability of this lucky imaging and using a camera like that with 60 second exposures etc. That is still a DSLR approach.

I think this camera should be used with a CCD imaging approach where you expose to get a good signal above noise and not overexpose the bright areas of your image.

Is it because the target audience are used to using their DSLRs or planetary cams and think that way because of that?

Luminance 6 x 10mins 1x1 binning and RGB 10 minutes 2x2 binning all at -20C would put it right next to KAF8300 images for a direct comparison.

With 1.2 electron noise it could be great. The 3.8 micron pixels are quite small but with QE of something like 65% then 2x2 binning could be pretty hot on many setups. You get more well depth and sensitivity and lower noise. That would be the go for narrowband. All 10minutes at 2x2 or longer if your tracking can handle it.

Greg.
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  #32  
Old 13-05-2016, 08:07 AM
glend (Glen)
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Originally Posted by gregbradley View Post
Glen,

I wonder about the viability of this lucky imaging and using a camera like that with 60 second exposures etc. That is still a DSLR approach.

I think this camera should be used with a CCD imaging approach where you expose to get a good signal above noise and not overexpose the bright areas of your image.

Is it because the target audience are used to using their DSLRs or planetary cams and think that way because of that?

Luminance 6 x 10mins 1x1 binning and RGB 10 minutes 2x2 binning all at -20C would put it right next to KAF8300 images for a direct comparison.

With 1.2 electron noise it could be great. The 3.8 micron pixels are quite small but with QE of something like 65% then 2x2 binning could be pretty hot on many setups. You get more well depth and sensitivity and lower noise. That would be the go for narrowband. All 10minutes at 2x2 or longer if your tracking can handle it.

Greg.
Greg, personally I don't like the term 'Lucky Imaging" as it seems to demean peoples approach to imaging. I am buying this camera as my main imaging camera for the next few years. Yes the pixels are a little small at 3.8 micron compared to my 5.2 micron Canon however, they are fine for imaging off my 1000mm focal length Mak-Newt, and as you say binning will give me a larger effective pixel size for use with my 1250mm focal length 10" newt or even my RC08.

I don't know that the 'target audience' is DSLR people but alot of DSLR people are looking at this camera as a way forward for a few reasons: first is cost, it undercuts entry level CCDs substantially and is really going to change the game so to speak; secondly this camera represents the next generation CMOS technology leading to sCMOS and replacement chips for the coming CCD retirement by major chip makers; finally is it allowing people to change the way they approach imaging (if they choose to)..
Personally my approach to this camera is that it will be used for everything I do. Narrowband it top of my list.
Since you mentioned the venerable KAF-8300 chip I thought I would share this chart I ran across comparing the ASI1600 with the KAF-8300 (a chip that has an entry point $1000 above the ASI1600):

http://i64.tinypic.com/2zf1h6a.jpg
Attached Thumbnails
Click for full-size image (ASI1600 V KAF8300.jpg)
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Last edited by glend; 13-05-2016 at 08:22 AM.
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  #33  
Old 13-05-2016, 08:10 AM
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Shiraz (Ray)
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Glen,



I think this camera should be used with a CCD imaging approach where you expose to get a good signal above noise


Greg.
that's the point of this camera Greg - there is almost no noise, so subs can go almost as short as you like and even a tiny amount of signal will still be above the read noise (and apart from shot noise in the signal, there is no other noise at all, since these devices have little dark current when cooled).

The "CCD imaging approach" still applies, but it can be vastly modified from the assumptions used in the days of the 10-20e RN CCD dinosaurs, where you needed to soak the things with 10+ minute subs to see anything at all above the read noise. Those older chips can still produce great results, but they cannot do it with short subs - the new CMOS ones can.

low noise CMOS is finally coming into the mainstream and we are nearly at the theoretical limits for detectors - woohoo .

Last edited by Shiraz; 18-05-2016 at 09:15 PM.
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Old 13-05-2016, 08:44 AM
glend (Glen)
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There is an interesting post by mclark over on dpreview dealing with the SNR approach and 'lucky imaging'. His wobbling video examples are very interesting, and the high resolution results impressive.

http://www.dpreview.com/forums/thread/3992021

In my view "lucky imaging" is just as worthy (if not more) an approach as Adaptive Optics, and much cheaper. Why try to move surfaces to stablise an image when you can just align selected high rate exposures to produce a sharp stable result. As mclark at dpreview noted, dithering is a problem in high rate exposures due to the time taken to settle and you certainly could not do it on very short subs. This means to me that the use of flawed sensors that rely on dithering to process out the flaws probably is going to disappear as short sub video capture evolves around the new sensor generation.

Last edited by glend; 13-05-2016 at 09:05 AM.
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Old 13-05-2016, 09:41 AM
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There is an interesting post by mclark over on dpreview dealing with the SNR approach and 'lucky imaging'. His wobbling video examples are very interesting, and the high resolution results impressive.

http://www.dpreview.com/forums/thread/3992021

In my view "lucky imaging" is just as worthy (if not more) an approach as Adaptive Optics, and much cheaper. Why try to move surfaces to stablise an image when you can just align selected high rate exposures to produce a sharp stable result. As mclark at dpreview noted, dithering is a problem in high rate exposures due to the time taken to settle and you certainly could not do it on very short subs. This means to me that the use of flawed sensors that rely on dithering to process out the flaws probably is going to disappear as short sub video capture evolves around the new sensor generation.
Dithering may not be such an issue Glen, because you will not need to wait for a guider to settle - you won't need a guider at all if the subs are short enough. Just wait long enough for the mount to get to a new position (maybe a second?) and start imaging.

In fact, if we can reduce the exposures enough, mount quality becomes pretty much immaterial - something good enough to keep the scope off the ground and roughly pointing in the right direction should do. Expect an EQ6 renaissance and a lot of huff and puff from the top end suppliers.

In the words beloved of "consultants" from a decade or two ago, this is the foothills of a paradigm shift.

Last edited by Shiraz; 13-05-2016 at 10:16 AM.
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  #36  
Old 13-05-2016, 10:18 AM
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Agreed Ray, it is a new approach, borrowed from the planetary guys but enabled for DSOs by new generation high sensitivity, low noise, sensors. And yeah my NEQ6 is looking more than adequate now. I wonder about the future of the high end CCD manufacturers who have had a gravy train of high margin products for a long time. Many tech changes over the years simply strand users on platforms with no value in the new world. They will hang on for awhile but the future is taking the market elsewhere.
Early adopters always have some teething issues but i expect any problems can be managed. The owners of ZWO must be delighted with the market response, and their stratgy of leveraging their expertise in planetary high frame rate cameras coupled with DSO capable sensors is a winner. That business will certainly be growing.
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Old 13-05-2016, 03:04 PM
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Thanks Ray.

I am not sure, is this CMOS sensor considered to be an sCMOS?

My Sony A7r2 is backside illuminated, has copper wiring instead of aluminium, is 42.4mp for full frame size and very high QE.
To get that in perspective the cheapest backside illuminated CCD camera in the FLI range is around US$30K!!!

I read one test where read noise is about .3 electrons.

So yeah read noise in CCD is way high compared to the latest Sony Exmor R sensors.

Having said that, something in the implementation is off because it gets quite bad colour noise in the shadows of high ISO long exposure. Also a general light amp glow in the lower 1/3rd. Both of these are correctable.

The Olympus sensor sounds good. But every user of Micro 4/3rds sensor complains about noise kicking in even at lowish ISO levels. So it will have to prove itself as whilst read noise may be low there can be amp glow which is fine if its stable to dark subtract out. Some of these earlier ASI cameras from what I read did not have stable amp glow (perhaps because the temp regulation is not to a temperature but to an ambient, it needs to be regulated like an Astro CCD camera to within a close range of a target temp).

If you can dark subtract the amp glow and flat field it successfully it should be good.

Perhaps the PixInsight overscan bias technique may be useful with a camera like this.

Exciting times and hopefully it works out well. I personally would prefer a Sony Exmor R sensor like in the Fuji X series (16mp APSc) or 24mp APSc sized (around 25mm x19mm).

QHY list some Sony Exmor CMOS sensors on future models. They have large pixels and are large sensors. As you say Sony are quitting CCD to concentrate on CMOS so that is likely the way of the future. Sony mirrorless sensors have probably surpassed CCDs a while ago.

Greg.
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Old 13-05-2016, 03:20 PM
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Greg, I was using sCMOS as a generic term for the future of CMOS and not claiming the territory for ZWO's ASI1600. I too look forward to the larger chip sizes. I talked to Sam at ZWO about amp glow, as a beta tester on CN had reported it on long subs, it was not too bad from what I saw. The beta tester reported that Sam had provided him with some sort of driver update that cleaned it up substantially. Sam had posted a 300" Dark on the webpage for the camera, before the driver update, and it is almost undetectable. Sure it might be an issue at 600" but I don't really see a need to expose that long with this camera, even in narrowband, and besides I can process it out. If that's the only issue I'll be happy.
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Old 13-05-2016, 04:02 PM
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Definitely an interesting camera. Further to Greg's point, does it have set-point cooling? Edit: Nevermind, I found it down the bottom on the specs, the cooling is indeed regulated. Unregulated cooling would have been a deal breaker.

Additionally, what's the implication of a rolling shutter on shorter exposures? I know naught about this, but I thought I read somewhere that rolling shutters can create a ghosting effect where the previous frame can be somewhat visible in the next frame?

The big FOV, low read noise and small pixels are otherwise pretty attractive to me. With a decent QE I could almost consider replacing my cam... although I'm not sure what the minimum filter size would be on this. 36?
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Old 13-05-2016, 04:19 PM
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Greg, I was using sCMOS as a generic term for the future of CMOS and not claiming the territory for ZWO's ASI1600. I too look forward to the larger chip sizes. I talked to Sam at ZWO about amp glow, as a beta tester on CN had reported it on long subs, it was not too bad from what I saw. The beta tester reported that Sam had provided him with some sort of driver update that cleaned it up substantially. Sam had posted a 300" Dark on the webpage for the camera, before the driver update, and it is almost undetectable. Sure it might be an issue at 600" but I don't really see a need to expose that long with this camera, even in narrowband, and besides I can process it out. If that's the only issue I'll be happy.
Amp glow should subtract out with a good quality dark as long as the temperature is accurate. I suppose you could use scaled darks with a bias and that should also work.

In fact thinking about it if the temperature regulation is not to a setpoint then scaled dark subtracts would be the way to go.

Greg.
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