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Has the $1200 large chipped ASI 1600 made existing modestly priced CCDs obsolete?

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#351 PiotrM

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Posted 28 May 2016 - 12:29 PM

My understanding is the IMX174 is also Exmor R and BSI.  Pregius is their designation for a global shutter.  Global shutter takes a little extra real estate on chip, a few extra gates and control paths. This cuts QE a little bit and adds a little noise. 

 

http://1stvision.com...OS-sensors.html

 

It's not, check Sony description of that sensor.

 

Thanks, Piotr. So the 290 is a BSI. That would explain why it is so sensitive. 

 

For small pixels in CMOS sensors BSI rescues fill factor and allows the to work efficiently. IMX224 isn't BSI yet it's higly sensitivy with very little read noise. BSI on such sensor doesn't have the effect that BSI on large pixel CCD/CMOS has when designed for high end performance.



#352 Jon Rista

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Posted 28 May 2016 - 12:39 PM

My understanding is the IMX174 is also Exmor R and BSI.  Pregius is their designation for a global shutter.  Global shutter takes a little extra real estate on chip, a few extra gates and control paths. This cuts QE a little bit and adds a little noise. 

 

http://1stvision.com...OS-sensors.html

 

If the sensor is BSI, then the extra logic for the global shutter has no impact on Q.E. All the logic is on the opposite side of the light sensitive surface of the sensor with BSI. The transitors are small enough that you can actually pack quite a lot of more advanced readout logic into each pixel, especially if they are shared pixels. If they are shared pixels, then adding 2x2 binning is a no brainer. On top of that, the photodiodes are deeper, which creates an increased potential well surface area, so not only is the sensor more sensitive despite global shutter readout, the FWC increases as well. BSI is pretty much the best thing to happen to CMOS. I just wish it would find it's way into larger format sensors more quickly. Sony made their new 46mp FF Exmor used in the A7r II a BSI sensor. I would LOVE to see a mono version of that thing in an astro cam. ;) 



#353 Jon Rista

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Posted 28 May 2016 - 12:42 PM

Thanks, Piotr. So the 290 is a BSI. That would explain why it is so sensitive.

 
For small pixels in CMOS sensors BSI rescues fill factor and allows the to work efficiently. IMX224 isn't BSI yet it's higly sensitivy with very little read noise. BSI on such sensor doesn't have the effect that BSI on large pixel CCD/CMOS has when designed for high end performance.


BSI has the greatest benefit on small pixel sensors, where an FSI design would cost fill factor area to readout logic and wiring. On large pixel sensors, at least with smaller fabrication processes like 180nm and under, BSI doesn't help fill factor quite as much. The improved potential well surface area with deeper photodiodes that are required with BSI, however, could improve the FWC of even larger pixel sensors, improving dynamic range along with improving Q.E. a bit.

#354 PiotrM

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Posted 28 May 2016 - 12:52 PM

BSI variants of those bigger pixels usually offer much higher QE. Like http://qhyccd.com/QHY42.html - 90% vs 74%



#355 Jon Rista

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Posted 28 May 2016 - 12:55 PM

I believe the QHY42 uses an sCMOS sensor, which has a number of other technological and fabrication improvements which help it get to 90% Q.E. Like most of the newer sCMOS sensors, I think it uses dual-column gain, and only in the combined readout HDR mode do you actually get the 90% Q.E. The standard readout mode is 70% for that particular sensor, IIRC. There are some potential consequences to HDR mode that might not be ideal for astro because the signals from the two reads have to be blended...I don't know for sure.

Edited by Jon Rista, 28 May 2016 - 12:58 PM.


#356 tolgagumus

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Posted 28 May 2016 - 12:58 PM

I believe the QHY42 uses an sCMOS sensor, which has a number of other technological and fabrication improvements which help it get to 90% Q.E.


That chip costs $3K(front illuminated) . Double or triple it with a camera. There is already a camera out with this chip. It's $15000. Dhyana 90 made by Tucsen.

Edited by tolgagumus, 28 May 2016 - 01:03 PM.

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#357 PiotrM

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Posted 28 May 2016 - 01:17 PM

I believe the QHY42 uses an sCMOS sensor,

 

Tucsen would want you believe that it's an "sCMOS" but it isn't as sensor creator doesn't use this naming anywhere it its materials. sCMOS is trademarked and can't be used just for fun, so if vendor doesn't use it then there is no facts to claim it's a real sCMOS sensor.



#358 Jon Rista

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Posted 28 May 2016 - 01:45 PM

I believe the QHY42 uses an sCMOS sensor,

 
Tucsen would want you believe that it's an "sCMOS" but it isn't as sensor creator doesn't use this naming anywhere it its materials. sCMOS is trademarked and can't be used just for fun, so if vendor doesn't use it then there is no facts to claim it's a real sCMOS sensor.


Oh, it's really just me using the term sCMOS loosely. I understand the trademark is owned by Andor, I believe? I am just referring to these CMOS sensors that use modern fabrication technologies with small transistors to produce high dynamic range, low read noise, high frame rate CMOS sensors.

#359 gregj888

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Posted 28 May 2016 - 01:56 PM

PiotrM,  I'll stand corrected on the 174, thanks.  Was sure I had seen it referenced as an Exmor-R but don't see it now and nothing definitive.   

 

I agree too, the BSI on these chips doesn't have the same effect as the old CCDs.  Keep in mind though the sensors are at 75% QE FSI, so not the same there either.

 

  Wish Sony had a list od sensors, specs and technologies... but some camera makers would be stuck with a lot of inventory... :-)

 

Isn't this fun... :-)



#360 PiotrM

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Posted 28 May 2016 - 01:59 PM

 

 

I believe the QHY42 uses an sCMOS sensor,

 
Tucsen would want you believe that it's an "sCMOS" but it isn't as sensor creator doesn't use this naming anywhere it its materials. sCMOS is trademarked and can't be used just for fun, so if vendor doesn't use it then there is no facts to claim it's a real sCMOS sensor.

 


Oh, it's really just me using the term sCMOS loosely. I understand the trademark is owned by Andor, I believe? I am just referring to these CMOS sensors that use modern fabrication technologies with small transistors to produce high dynamic range, low read noise, high frame rate CMOS sensors.

 

 

 

Yes, it looks like a very good sensor. Naming is very important from marketing point of view. If it refers to those expensive sCMOS cameras then it can also cost more than usual ;) IMX035 was also called sCMOS in some cameras yet it isn't related to actual sCMOS cameras. It had low noise, good sensitivity but... at the hack of slow readout and low gain :) Where as 10x more expensive actual sCMSOS got that at fast framerate and higer, needed gain values :)



#361 Jon Rista

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Posted 28 May 2016 - 02:14 PM

Sure. I can refer to "scientific CMOS" sensors rather than specifically sCMOS sensors, as scientific CMOS sensors are kind of a class of sensors on their own rather than a specific brand. They employ certain technologies to achieve a more uniform field, mitigate DSNR & PRNU, improve Q.E. and DR, reduce read noise and still support high readout framerates. 

 

So far, I haven't seen any regular photography CMOS sensor that employs all of those technologies, and glows seem to be a growing problem with regular CMOS sensors, sadly. I have particularly not seen the kind of pixel technologies that reduce DSNU or PRNU, that stuff is pretty cutting edge, and I don't really even understand exactly how it works. 



#362 Konihlav

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Posted 28 May 2016 - 02:26 PM

Jon Rista: what do you think, would it be better to get a cooled Sony A7S from CentralDS or would a uncooled, ordinary Sony A7R II be a better alternative for a TWAN style imaging? The costs for me are equal due to import taxes and duties so if I get A7R II in EU I pay same price like for the A7S cooled imported from Korea... :-)

 

BTW I am up to get some OSC (though I said I never again buy a color camera) for say cometary work, nightscapes, some DSO with wide lenses, timelapse etc. My Canon EOS600D is kind of childs toy and totally blind in the dark...

 

as I am used to shoot DSO with 36x24mm chips I simply do not want anything smaller!

 

one more comment, I also consider ONE cmos camera for lucky imaging, was considering ZWO ASI 178 MC (color cooled).

 

Today I sold one of my superb mono cameras due to lack of time to actually use it :-( and I can't afford to own more than three cameras when cloudless night is 1 in 2 months :-(



#363 Jon Rista

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Posted 28 May 2016 - 02:53 PM

Personally, I think the sensor in the A7R II is actually better. It is a BSI sensor, and at least for regular photography, it has been testing to perform at least as well if not slightly better than the A7S. It's high ISO, low light performance is very good. It's dynamic range is also excellent. Now, I am not aware of anyone who currently uses the A7R II for astro, although I am sure there are some. So I don't have any knowledge of it's actual performance in that context. If you get one, I would be very, very interested in hearing how it performs. 

 

The one thing about the Sony cameras that I don't like is the lossy compression (which I believe is now optional with the A7R II, you can do uncompressed RAW) and the spatial filtering they force on you in bulb mode. If it wasn't for the spatial filtering, I'd have picked up an A7R II myself months ago. With proper oversampling, the spatial filtering does not seem to be a problem, at least so long as the stars do not clip. With wider fields of view, any stars that clip can invoke the wrath of bulb mode filtering, and the results can be...well, you'll see if you get one. :p That being said...with the high sensitivity of a BSI sensor in that form factor, you might not need more than 30 second subs, so bulb mode may not be necessary anyway.



#364 tncoltsfan

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Posted 12 June 2016 - 12:49 PM

I was going to get a ccd camera for astrophotgraphy...but after reading this thread it seems most folks on here want to argue about different chips and noise, etc. instead of actually observing and imaging the heavens. How do you guys have so much time to post all this stuff???



#365 fetoma

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Posted 12 June 2016 - 01:47 PM

We want to learn from each other. We post after work, on the weekends, just about any free time. I think we also want the best value for our dollar since this stuff ain't cheap!



#366 schmeah

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Posted 12 June 2016 - 05:21 PM

I was going to get a ccd camera for astrophotgraphy...but after reading this thread it seems most folks on here want to argue about different chips and noise, etc. instead of actually observing and imaging the heavens. How do you guys have so much time to post all this stuff???

 

Buy a CCD and start imaging. Then you'll understand the obsession. But yes you are right. Too much analyzing and bickering and not enough imaging.



#367 happylimpet

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Posted 13 June 2016 - 04:08 AM

I was going to get a ccd camera for astrophotgraphy...but after reading this thread it seems most folks on here want to argue about different chips and noise, etc. instead of actually observing and imaging the heavens. How do you guys have so much time to post all this stuff???

 

If my boss saw the times of my posts I'd be hauled up for a telling off.


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#368 rgsalinger

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Posted 13 June 2016 - 11:51 AM

Well, while the forum is useful as an exchange of information the best advice I know is to buy a book and join your local astronomy club. My favorite introductory book is the Deep Sky Imaging Primer by Bracken. It's very likely that a local club will be a great source of people who are already doing this. 

Rgrds-Ross


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#369 Ladyhawke

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Posted 13 June 2016 - 12:09 PM

I learn a lot just from reading those posts so please don't EVER stop. Soaking up the knowledge and when the clouds part I'll worry about imaging. ;)


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#370 bobzeq25

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Posted 13 June 2016 - 01:11 PM

I was going to get a ccd camera for astrophotgraphy...but after reading this thread it seems most folks on here want to argue about different chips and noise, etc. instead of actually observing and imaging the heavens. How do you guys have so much time to post all this stuff???

For me, it's partly clouds from El Nino, partly the fact that helping out beginners is a very big part of the hobby for me.   This thread may have been a slightly mischievous poke (the title certainly was <grin>), it succeeded beyond my wildest expectations.

 

But you're very right that beginners often focus too much on equipment and theoretical discussions about fine points among experts, irrelevant to them, when their time would be better spent imaging; getting experience, and seeing what works for them and what doesn't.

 

Maybe a bottom line for you.  If you're starting out in astrophotography, either an existing DSLR, provided it has LiveView, or a 1600, would be an excellent starter camera.  Forget the fine points.


Edited by bobzeq25, 13 June 2016 - 01:13 PM.

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#371 FirstC8

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Posted 13 June 2016 - 05:19 PM

I was going to get a ccd camera for astrophotgraphy...but after reading this thread it seems most folks on here want to argue about different chips and noise, etc. instead of actually observing and imaging the heavens. How do you guys have so much time to post all this stuff???


Because "CN" does not stand for "clear nights", rather "cloudy nights".😆

At any given moment unfortunately more people are subject to the latter.

If the entire earth atomesphere were to dissappear for just one night, you would have found no one posting here, not because we would have all been dead from asphyxiation, but because we would all be imaging.😊
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#372 Jon Rista

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Posted 14 June 2016 - 01:29 AM

I was going to get a ccd camera for astrophotgraphy...but after reading this thread it seems most folks on here want to argue about different chips and noise, etc. instead of actually observing and imaging the heavens. How do you guys have so much time to post all this stuff???

 

The time comes from all the endless cloud cover. ;P 

 

In my case, I also suffer from severe insomnia, and am currently going through a rather bad patch. I never sleep, the skies are cloudy...and I have only had less than four partially clear nights to point my ASI1600 at the sky (and most of that time was spent dealing with USB connectivity issues, then focus issues.) 

 

As for the debates...depending on what kind of things in the heavens you do want to image when the cloud cover isn't present, the specs and minutia may matter. 


Edited by Jon Rista, 14 June 2016 - 01:31 AM.

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#373 dpastern

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Posted 23 September 2017 - 07:49 AM

Seems that I'm in the wrong place, at the wrong time (I'm considering getting a ZWO ASI 1600 mono camera).  

 

I got through the first 4 pages before the fear mongering got to me and I couldn't read anymore.  I suspect too many people are worried that their super expensive CCD cameras will be obsolete soon.  

 

FYI for people - CCD is dead in the DSLR market and has been for many good years.  CCD's death took around 3 years tops, when it became apparent that CMOS was in most cases, a much better technology.  I expect the same thing to happen with CCD in astro imaging within the next 3-5 years.  

 

I've seen so many great images with the ZWO camera, that rival anything CCD has produced, and in a lot of instances, for a fraction of the cost.  


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