First light for a new camera


Dean Jacobsen
 

Hi All,

A couple of new mono CMOS cameras have come out over the last few months.  First a 4/3" sized camera using the back illuminated IMX492 and then most recently cameras using the back illuminated APS-C sized IMX571 sensor.

Both offer a substantial upgrade from my well loved ASI1600MM.  I ended up purchasing the ASI294MM-Pro with the 4/3" sized sensor.

The weather here in coastal Southern California hasn't been cooperating with me the last week or so but I did manage to get about 1.9 hours [29 x 240s] parked on the Rosette as a first light for the camera.  The conditions were less than optimal - greater than 85% humidity with milky white skies from the light pollution and the moisture in the air.  Had to shut down after 2 hours before everything got soaked when the approaching fog rolled in.

Here is a link to my 2 hour hydrogen alpha shot of the Rosette taken with the ASI294MM Pro and the FSQ-106 at f/5.  The full resolution image has been posted.  This image was just stacked and stretched.  No noise reduction or deconvolution.

https://www.astrobin.com/full/0ffdnz/C/ 

The ASI294MM Pro does a nice job, and at $1480 it gives great performance for the price in my opinion.  The body of the new camera has the same dimensions as my ASI1600MM so I was able to simply unscrew the ASI1600 from the filter wheel and screw the ASI294MM on.

The Mach2 and APCC performed flawlessly as usual.

Thanks for looking.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Marcelo Figueroa
 


Great image.
 
I'm thinking of doing the same camera upgrade. That' s the normal resolution mode, Bin2 I think, isn't it?


Benoit Schillings
 

wow. very clean !

-- benoit

On Sun, Feb 7, 2021 at 4:52 PM Marcelo Figueroa via groups.io
<marfig1970=yahoo.com@groups.io> wrote:


Great image.

I'm thinking of doing the same camera upgrade. That' s the normal resolution mode, Bin2 I think, isn't it?


Luca Marinelli
 

Nice one, Dean!

I have been enjoying imaging with that camera as well. The sensitivity is really impressive.

Luca


Dean Jacobsen
 

Thanks guys.

The camera appears to be a great performer for the price.  Definitely a step up from the ASI1600MM with the higher sensitivity and the larger well capacity.

@ Marcelo - Yes, this is the 2x2 bin mode at the HCG transition point of gain 120 with the "standard" unity gain offset of 30.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Don Anderson
 

Nice catch Dean! Turned out pretty good considering the challenging conditions. Would be interesting to see the same target using an IMX571 based camera.

Don Anderson


On Sunday, February 7, 2021, 04:28:07 p.m. MST, Dean Jacobsen <deanjacobsen@...> wrote:


Hi All,

A couple of new mono CMOS cameras have come out over the last few months.  First a 4/3" sized camera using the back illuminated IMX492 and then most recently cameras using the back illuminated APS-C sized IMX571 sensor.

Both offer a substantial upgrade from my well loved ASI1600MM.  I ended up purchasing the ASI294MM-Pro with the 4/3" sized sensor.

The weather here in coastal Southern California hasn't been cooperating with me the last week or so but I did manage to get about 1.9 hours [29 x 240s] parked on the Rosette as a first light for the camera.  The conditions were less than optimal - greater than 85% humidity with milky white skies from the light pollution and the moisture in the air.  Had to shut down after 2 hours before everything got soaked when the approaching fog rolled in.

Here is a link to my 2 hour hydrogen alpha shot of the Rosette taken with the ASI294MM Pro and the FSQ-106 at f/5.  The full resolution image has been posted.  This image was just stacked and stretched.  No noise reduction or deconvolution.

https://www.astrobin.com/full/0ffdnz/C/ 

The ASI294MM Pro does a nice job, and at $1480 it gives great performance for the price in my opinion.  The body of the new camera has the same dimensions as my ASI1600MM so I was able to simply unscrew the ASI1600 from the filter wheel and screw the ASI294MM on.

The Mach2 and APCC performed flawlessly as usual.

Thanks for looking.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Terri Zittritsch
 
Edited

Dean, thanks for posting the information.
Can you say what you think you're getting by replacing the ASI1600MM with the ASI294MM?     I have the ASI1600 and many great images are taken with this camera.   The biggest downside that I've noticed is the micro-lensing effect you can get on bright stars.     I know the ASI294 shows deeper well depth, and better DR, but do these directly relate to better images?     I know that some poo poo-ed the ASI1600 because it only has 12 bits of depth, but that didn't keep people from producing great images.     Since you've owned both, what are the benefits that you can see in the images?
Maybe a tough question.    I wonder if there is any micro-lensing?

I've recently purchase an ASI6200MM which is on my stowaway now.. and waiting to get a first image.   

Terri


Roland Christen
 

How much faster is this camera versus CCD technology?

Rolando



-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 7, 2021 5:28 pm
Subject: [ap-gto] First light for a new camera

Hi All,

A couple of new mono CMOS cameras have come out over the last few months.  First a 4/3" sized camera using the back illuminated IMX492 and then most recently cameras using the back illuminated APS-C sized IMX571 sensor.

Both offer a substantial upgrade from my well loved ASI1600MM.  I ended up purchasing the ASI294MM-Pro with the 4/3" sized sensor.

The weather here in coastal Southern California hasn't been cooperating with me the last week or so but I did manage to get about 1.9 hours [29 x 240s] parked on the Rosette as a first light for the camera.  The conditions were less than optimal - greater than 85% humidity with milky white skies from the light pollution and the moisture in the air.  Had to shut down after 2 hours before everything got soaked when the approaching fog rolled in.

Here is a link to my 2 hour hydrogen alpha shot of the Rosette taken with the ASI294MM Pro and the FSQ-106 at f/5.  The full resolution image has been posted.  This image was just stacked and stretched.  No noise reduction or deconvolution.

https://www.astrobin.com/full/0ffdnz/C/ 

The ASI294MM Pro does a nice job, and at $1480 it gives great performance for the price in my opinion.  The body of the new camera has the same dimensions as my ASI1600MM so I was able to simply unscrew the ASI1600 from the filter wheel and screw the ASI294MM on.

The Mach2 and APCC performed flawlessly as usual.

Thanks for looking.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ

--
Roland Christen
Astro-Physics


Emilio J. Robau, P.E.
 

The read noises are significantly lower than most CCDs.  Although I hate to admit it, CCD technology is not keeping up with the broader used CMOS technology.  The two new cameras are very interesting, but I would wait a little longer to purchase them as the end users finish up being beta testers for both QHY and ZWO.

The ASI 2600 and QHY 268 (Sony IMX 571) Mono are not widely available yet.  The first batch is being shipped now.   They are APS-C chips and look very very promising.  I will probably trade out my 16200 chip for this shortly when the first user adopters work out the bugs.   The difference in read noise and sensitivity is pretty stunning.  I will give up the size for being able to do NB with much much shorter exposures. 

I purchased the QHY 294 pro camera (Sony IMX492) Mono for the small pixel size at 2.3 or so microns but returned it and am waiting until the bugs are worked out to potentially repurchase it.  It is a very sensitive camera with a quirky chip.

I think these two cameras and price points are pretty dramatic advancements.  If we could only get the manufacturers to actually finish developeing their products before slinging it at the pay for testing user base, that would be great. 


Dean Jacobsen
 

Hi Terri,

I have only had the camera out for one session.  Based on that single data point it does seem to be an excellent performer.  However, I haven't had a chance to use it very much.

There were several things [mostly theoretical at this point] that prompted the purchase of the camera though:

1.  I had been using my ASI1600MM for 3.5 years or so.  Thus, I thought I might have been approaching end of life for some of the camera's components so perhaps it was time to upgrade to a newer camera.

2.  I had seen the microlens effect with my telescope-filter-camera combination so I wanted to eliminate that.  There were objects that I had been avoiding because of the bright stars in the field,

3. I wanted to get the more sensitive camera.  The ASI1600 mono works great but the new back side illuminated detectors are quite a bit more sensitive so I want to take advantage of that and be able to convert more photons to electrons per unit time.  The QE data for the camera has been published on ZWO's product page for the camera.  They also have an ASI294MM vs. ASI1600MM QE graph. 



4. The ASI294MM has a much larger full well capacity at the gain that I will be using it at [~20k e- at unity gain  vs. ~ 8k e- for the ASI1600 at 76 gain] so I wanted to take advantage of that for preservation of the colors of the brighter stars in the field in my color filtered images.

--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Dean Jacobsen
 

Emilio,

The camera and the ASCOM driver seems to work fine.  It has been on the bench taking dark frames and I have probably taken 90 test images with it.  No problems with the camera in the 2x2 or the "unlocked" 1x1 bin mode.  No hangups.  No weird artifacts or anything.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Dale Ghent
 

I have the ASI1600 with the Panasonic chip, 294 color, and IMX455-based QHY600 which is the same sensor as the ASI6200.

The Panasonic chip that's in the ASI1600 and other cameras has been a fantastic chip over the years and, like you said, the microlensing effect on super bright stars has been the only major complaint about it. The 12bit nature of its ADCs can be compensated with by just making more exposures. For what it is/was, it has been a very good standard in the CMOS realm. It was a sensor designed in the early 2010's with tech of that era, and despite that, it has decently controlled amp glow and dark current. And as a chip of that era, it is a front-illuminated design with a single gain domain. These are outdated designs now.

The IMX294/492 is back-illuminated which means more photons actually fall into the pixels, which raises the QE. The vast majority of current era designs from Sony are back-illuminated. The other thing that many current-era chips have in their corner is dual conversion gain. Dual conversion gain is where a good bit of the magic occurs in these sensors and lets them be flexible. DCG sensors came about to address the need for a sensor that can perform well in both bright and dim settings. The Low Conversion Gain (LCG) domain grants you a large full well, with the trade-off being read noise. The High Conversion Gain (HCG) domain gives you lower read noise at the cost of a shallower well. Both have DR curves that largely mirror each other. LCG is meant for exposing in bright environments where the deep well would be best suited, where the HCG domain is for dark scenes, where sensitivity and low read noise is needed. Both the IMX294/492 and IMX455, as well as others, are dual conversion gain sensors.

You can spot these types of sensors by looking at the graphs commonly posted by ZWO, QHY, and others. They have two distinct areas, like this one for the IMX455-based ASI6200MM:

https://astronomy-imaging-camera.com/wp-content/uploads/ASI6200-Performance.png

You can see the two domains clearly in the DR and Read Noise charts. LCG is on the left, starting at gain=0, and then the transition to HCG happens at what looks like gain=100. You can see that LCG and HCG start out more or less similarly, with the LCG having a larger well. Once you get to gain=100, the read noise drops, DR (mostly) recovers, and the downward progression resumes as gain increases. The difference is that at gain=0, you have a 50k e- well, and at gain=100 (the start of the HCG domain) you have what looks like a ~15k well. These charts aren't the greatest but that's my guess assuming they're on a log scale. But you can see the difference nonetheless.

So what does this mean in practice? You can shoot in two different ways:

1. At gain=0 and with long exposures
2. At gain=100 and with shorter exposures

both will yield effectively equivalent results. Which one is best to use (note: I'm purposefully avoiding the word "better" here) largely comes down to personal preferences. Personally I shoot at the start of HCG (the equivalent of gain=100 here) because that's where the sensor performs its best. The very slight hit to DR compared to gain=0 is more than made up by the larger number of exposures I can rip through. People doing photometry or planetary with these kinds of sensors might find the LCG domain a more useful place for their purposes. In this way, you can look at LCG vs. HCG more in terms of what's best for the use case.

If you have one of these kinds of dual conversion gain sensors and are not entirely sure where the LCG->HCG transition is on the gain scale, it's easy enough to figure out for yourself. Cap off the camera and run bias exposures in loop. Look at the histogram or image stats as you steadily increase the gain. As you increase the gain, you will likely also see an increase in the measured standard deviation. At some point, the stddev will suddenly drop. The gain value in which that drop in stddev happens marks the entry into the HCG domain, as stddev is a representation of the read noise.

As for IMX294/492 vs. IMX455, the 455 (and its APS-C analog, the IMX571) are hands-down the best we have on the consumer market right now. With zero amp glow, a good middling pixel size that applies to a wide range of focal lengths, QEs in the mid-70s for Ha/Sii and mid-80s for Oiii, and 16bit ADCs, they're really cement the fact that modern and highly compelling CMOS tech has arrived and is available. There's not much left to want for the amateur. These sensors are absolute monsters on fast optics as well.

On Feb 8, 2021, at 10:55, Terri Zittritsch <theresamarie11@gmail.com> wrote:

[Edited Message Follows]

Dean, thanks for posting the information.
Can you say what you think you're getting by replacing the ASI1600MM with the ASI294MM? I have the ASI1600 and many great images are taken with this camera. The biggest downside that I've noticed is the micro-lensing effect you can get on bright stars. I know the ASI294 shows deeper well depth, and better DR, but do these directly relate to better images? I know that some poo poo-ed the ASI1600 because it only has 12 bits of depth, but that didn't keep people from producing great images. Since you've owned both, what are the benefits that you can see in the images?
Maybe a tough question. I wonder if there is any micro-lensing?

I've recently purchase an ASI6200MM which is on my stowaway now.. and waiting to get a first image.

Terri


Luca Marinelli
 

 As I mentioned above, I have been imaging with the ASI294MM Pro since the end of December. It replaced a ASI1600MM Pro on a TS ONTC 10in f4 Newtonian astrograph.  These are the main differences between the two cameras as I see them:

ASI1600MM Pro:

Pros:

- It has been around for a long time, everyone can help you if you run into trouble

- Less expensive

- Very little amp glow even for narrowband imaging

- Data calibration is robust and straightforward


Cons:

- It has been around for a long time: it may get discontinued in the not too distant future. the ASI294MC took the place of the ASI1600MC.

- Microlensing artifacts around bright stars are obnoxious and difficult to eliminate (this is really an issue only around magnitude 2-3 stars or brighter)

- QE is modest (~50% @ Ha)

- 12bit ADC

 
ASI294MM Pro:

 Pros:

- New sensor with probably long life in front of it

- Two pixel sizes in one camera (2.3um, 4.6um)

- Extremely high QE (it's an amazingly sensitive camera, 80% @ Ha)

- very low noise and high dynamic range when high gain mode kicks in
- no microlensing artifact

- 14bit ADC instead of 12bit

 

Cons:

- More expensive than ASI1600MM

- Calibration is a bit trickier and requires some getting used to (flats have some swirly patterns that some people have had trouble with)

- Amp glow is pretty significant. It calibrates out well but again it requires flawless calibration practice to ensure high quality data is produced.

 
Low read noise combined with high sensitivity and 14bit ADC of this camera makes it compelling vs the older 1600MM. The questions Roland asked about speed compared to CCD cameras comes down to two factors:

1) QE: How sensitive is the camera? In comparison to the numbers above, the FLI ML16200 has QE of 45% @ Ha - quite a stark difference.
2) Read noise: Low read noise is meaningful in relation to noise from sky glow. That's why with CCD cameras subexposure times for narrowband imaging can be 20, 30 minute or even longer. With the ASI294MM even imaging faint targets I have found that I can achieve optimal exposure levels for narrowband imaging with 3nm filters under Bortle 5 skies in less than 8 minutes per sub. This means that I can guarantee not to lose any SNR efficiency in image integration and accumulate SNR as fast as total integration time. 

I recently completed an imaging project of an extremely faint planetary nebula (HFG1) that I started in September 2020. I collected most of the 82 hours of data with an ASI1600MM Pro but during the last month of data collection I switched to the ASI294MM. For the purpose of illustrating differences in sensitivity of the two cameras, I integrated 20x6 minute subexposures of OIII  signal from each of the two cameras. Pixel size is a bit different (3.8um vs 4.6um) and I registered all the images to the higher-resolution ASI1600MM data before image integration to try and reduce the effect of bigger pixels in the ASI294MM on image SNR. You can see the results of the experiment here:

https://astrob.in/tbilkr/B/

I am also imaging with an ASI6200MM Pro and while the sensitivity is comparable to the ASI294MM Pro (IMX455 sensor), the noise profile is even more favorable with lower read-noise, 16bit ADC, and no amp glow. The new APS-C sized IMX571 is expected to have similar characteristics.

--Luca



Bruce Donzanti
 

Nice comparative list, Luca.  I also went from the 1600MM Pro to the 294MM Pro and my 2600MM Pro arrives on Wednesday.  I am hoping it does have the characteristics, as you described, for the 6200MM Pro and if it does I'll part with the 294MM Pro.  I am anxious to compare the 2 side by side in my suburban skies. 

Bruce

On Mon, Feb 8, 2021 at 3:46 PM Luca Marinelli <photo@...> wrote:

 As I mentioned above, I have been imaging with the ASI294MM Pro since the end of December. It replaced a ASI1600MM Pro on a TS ONTC 10in f4 Newtonian astrograph.  These are the main differences between the two cameras as I see them:

ASI1600MM Pro:

Pros:

- It has been around for a long time, everyone can help you if you run into trouble

- Less expensive

- Very little amp glow even for narrowband imaging

- Data calibration is robust and straightforward


Cons:

- It has been around for a long time: it may get discontinued in the not too distant future. the ASI294MC took the place of the ASI1600MC.

- Microlensing artifacts around bright stars are obnoxious and difficult to eliminate (this is really an issue only around magnitude 2-3 stars or brighter)

- QE is modest (~50% @ Ha)

- 12bit ADC

 
ASI294MM Pro:

 Pros:

- New sensor with probably long life in front of it

- Two pixel sizes in one camera (2.3um, 4.6um)

- Extremely high QE (it's an amazingly sensitive camera, 80% @ Ha)

- very low noise and high dynamic range when high gain mode kicks in
- no microlensing artifact

- 14bit ADC instead of 12bit

 

Cons:

- More expensive than ASI1600MM

- Calibration is a bit trickier and requires some getting used to (flats have some swirly patterns that some people have had trouble with)

- Amp glow is pretty significant. It calibrates out well but again it requires flawless calibration practice to ensure high quality data is produced.

 
Low read noise combined with high sensitivity and 14bit ADC of this camera makes it compelling vs the older 1600MM. The questions Roland asked about speed compared to CCD cameras comes down to two factors:

1) QE: How sensitive is the camera? In comparison to the numbers above, the FLI ML16200 has QE of 45% @ Ha - quite a stark difference.
2) Read noise: Low read noise is meaningful in relation to noise from sky glow. That's why with CCD cameras subexposure times for narrowband imaging can be 20, 30 minute or even longer. With the ASI294MM even imaging faint targets I have found that I can achieve optimal exposure levels for narrowband imaging with 3nm filters under Bortle 5 skies in less than 8 minutes per sub. This means that I can guarantee not to lose any SNR efficiency in image integration and accumulate SNR as fast as total integration time. 

I recently completed an imaging project of an extremely faint planetary nebula (HFG1) that I started in September 2020. I collected most of the 82 hours of data with an ASI1600MM Pro but during the last month of data collection I switched to the ASI294MM. For the purpose of illustrating differences in sensitivity of the two cameras, I integrated 20x6 minute subexposures of OIII  signal from each of the two cameras. Pixel size is a bit different (3.8um vs 4.6um) and I registered all the images to the higher-resolution ASI1600MM data before image integration to try and reduce the effect of bigger pixels in the ASI294MM on image SNR. You can see the results of the experiment here:

https://astrob.in/tbilkr/B/

I am also imaging with an ASI6200MM Pro and while the sensitivity is comparable to the ASI294MM Pro (IMX455 sensor), the noise profile is even more favorable with lower read-noise, 16bit ADC, and no amp glow. The new APS-C sized IMX571 is expected to have similar characteristics.

--Luca



Don Anderson
 

Great explanation on CMOS sensor performance Dale. I have been thinking about a larger format camera for a few years now. With the demise of Truesense CCD production last year, I was torn between getting a camera based on the existing CCD technology before they were no longer available or waiting for one with the rapidly improving CMOS sensor. I currently use a Sony icx694 based mono camera with my TV NP127is with a .8X reducer as well as native FL on my AP900GOTO. I shoot narrow band from my heavily polluted (Bortle 8) big city skies so a sensitive camera is a must. Up to now, it has been hard to beat the 694 for sensitivity and low noise until the most recent CMOS offerings have come out. I will be watching The developments closely
Thanks

Don Anderson


On Monday, February 8, 2021, 01:22:29 p.m. MST, Dale Ghent <daleg@...> wrote:



I have the ASI1600 with the Panasonic chip, 294 color, and IMX455-based QHY600 which is the same sensor as the ASI6200.

The Panasonic chip that's in the ASI1600 and other cameras has been a fantastic chip over the years and, like you said, the microlensing effect on super bright stars has been the only major complaint about it. The 12bit nature of its ADCs can be compensated with by just making more exposures. For what it is/was, it has been a very good standard in the CMOS realm.  It was a sensor designed in the early 2010's with tech of that era, and despite that, it has decently controlled amp glow and dark current. And as a chip of that era, it is a front-illuminated design with a single gain domain. These are outdated designs now.

The IMX294/492 is back-illuminated which means more photons actually fall into the pixels, which raises the QE. The vast majority of current era designs from Sony are back-illuminated. The other thing that many current-era chips have in their corner is dual conversion gain. Dual conversion gain is where a good bit of the magic occurs in these sensors and lets them be flexible. DCG sensors came about to address the need for a sensor that can perform well in both bright and dim settings. The Low Conversion Gain (LCG) domain grants you a large full well, with the trade-off being read noise. The High Conversion Gain (HCG) domain gives you lower read noise at the cost of a shallower well. Both have DR curves that largely mirror each other. LCG is meant for exposing in bright environments where the deep well would be best suited, where the HCG domain is for dark scenes, where sensitivity and low read noise is needed. Both the IMX294/492 and IMX455, as well as others, are dual conversion gain sensors.

You can spot these types of sensors by looking at the graphs commonly posted by ZWO, QHY, and others. They have two distinct areas, like this one for the IMX455-based ASI6200MM:

https://astronomy-imaging-camera.com/wp-content/uploads/ASI6200-Performance.png

You can see the two domains clearly in the DR and Read Noise charts. LCG is on the left, starting at gain=0, and then the transition to HCG happens at what looks like gain=100. You can see that LCG and HCG start out more or less similarly, with the LCG having a larger well. Once you get to gain=100, the read noise drops, DR (mostly) recovers, and the downward progression resumes as gain increases. The difference is that at gain=0, you have a 50k e- well, and at gain=100 (the start of the HCG domain) you have what looks like a ~15k well. These charts aren't the greatest but that's my guess assuming they're on a log scale. But you can see the difference nonetheless.

So what does this mean in practice? You can shoot in two different ways:

1. At gain=0 and with long exposures
2. At gain=100 and with shorter exposures

both will yield effectively equivalent results. Which one is best to use (note: I'm purposefully avoiding the word "better" here) largely comes down to personal preferences. Personally I shoot at the start of HCG (the equivalent of gain=100 here) because that's where the sensor performs its best. The very slight hit to DR compared to gain=0 is more than made up by the larger number of exposures I can rip through.  People doing photometry or planetary with these kinds of sensors might find the LCG domain a more useful place for their purposes. In this way, you can look at LCG vs. HCG more in terms of what's best for the use case.

If you have one of these kinds of dual conversion gain sensors and are not entirely sure where the LCG->HCG transition is on the gain scale, it's easy enough to figure out for yourself. Cap off the camera and run bias exposures in loop. Look at the histogram or image stats as you steadily increase the gain. As you increase the gain, you will likely also see an increase in the measured standard deviation. At some point, the stddev will suddenly drop. The gain value in which that drop in stddev happens marks the entry into the HCG domain, as stddev is a representation of the read noise.

As for IMX294/492 vs. IMX455, the 455 (and its APS-C analog, the IMX571) are hands-down the best we have on the consumer market right now. With zero amp glow, a good middling pixel size that applies to a wide range of focal lengths, QEs in the mid-70s for Ha/Sii and mid-80s for Oiii, and 16bit ADCs, they're really cement the fact that modern and highly compelling CMOS tech has arrived and is available. There's not much left to want for the amateur. These sensors are absolute monsters on fast optics as well.


> On Feb 8, 2021, at 10:55, Terri Zittritsch <theresamarie11@...> wrote:
>
> [Edited Message Follows]
>
> Dean, thanks for posting the information.
> Can you say what you think you're getting by replacing the ASI1600MM with the ASI294MM?    I have the ASI1600 and many great images are taken with this camera.  The biggest downside that I've noticed is the micro-lensing effect you can get on bright stars.    I know the ASI294 shows deeper well depth, and better DR, but do these directly relate to better images?    I know that some poo poo-ed the ASI1600 because it only has 12 bits of depth, but that didn't keep people from producing great images.    Since you've owned both, what are the benefits that you can see in the images?
> Maybe a tough question.    I wonder if there is any micro-lensing?
>
> I've recently purchase an ASI6200MM which is on my stowaway now.. and waiting to get a first image. 
>
> Terri
>







Dean Jacobsen
 

We have some nice tools available to us these days.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Dean Jacobsen
 

On Mon, Feb 8, 2021 at 06:50 PM, Don Anderson wrote:
Up to now, it has been hard to beat the 694 for sensitivity and low noise until the most recent CMOS offerings have come out. I will be watching The developments closely
Don, when you are ready to get a new camera I think you will be pleased with the excellent choices that are available these days.
 
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Don Anderson
 

Yes. They are getting better. I am thinking of an APS C format ie imx571 mono camera. Will need to u/g my FW and filters though.

Don Anderson


On Tuesday, February 9, 2021, 09:26:09 a.m. MST, Dean Jacobsen <deanjacobsen@...> wrote:


On Mon, Feb 8, 2021 at 06:50 PM, Don Anderson wrote:
Up to now, it has been hard to beat the 694 for sensitivity and low noise until the most recent CMOS offerings have come out. I will be watching The developments closely
Don, when you are ready to get a new camera I think you will be pleased with the excellent choices that are available these days.
 
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Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


Dean Jacobsen
 

Here is the final iteration:

https://www.astrobin.com/full/0ffdnz/E/

The full res version is viewable by clicking on the button at the upper right corner.  

I really like the amount of detail that can be seen in the Bok globules/dark nebula considering I was using a 4” refractor.
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Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ


 

wonderful detail!


On Wed, Feb 10, 2021 at 10:19 AM Dean Jacobsen <deanjacobsen@...> wrote:
Here is the final iteration:

https://www.astrobin.com/full/0ffdnz/E/

The full res version is viewable by clicking on the button at the upper right corner.  

I really like the amount of detail that can be seen in the Bok globules/dark nebula considering I was using a 4” refractor.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ 
Amateur Radio Call Sign - W6DBJ



--
Brian 



Brian Valente