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ZWO ASI 294 MM PRO: First impressions and test images.

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#26 bobzeq25

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Posted 03 September 2020 - 09:33 AM

 

lower (35C vs. 45C) temp delta (a minus)

Not a serious one.  Dr. Robin Glover has pointed out most CMOS don't need to be cooled very low to reduce thermal noise below the noise floor.  You'd have to be in the tropics for that to be a concern, maybe (probably?) not then.
 


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#27 CCD-Freak

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Posted 03 September 2020 - 09:36 AM

Interesting....I love shooting Ha so I may have to invest in one when the become available.  If the ever come out with a mono version of the ASI2600 I will be all over that.

 

John

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#28 calypsob

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Posted 03 September 2020 - 09:41 AM

Man this is going to be an incredible camera. The data you have so far is superb.

How much backfocus does this have? Can you easily pair the fw with an EOS lens?

#29 Dean J.

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Posted 03 September 2020 - 10:04 AM

This is awesome. I have the 2600MCpro, and was waiting on the 2600MM to replace my 1600MM, but now I'm thinking I could go with this camera instead and not have to sell off my 31mm filter wheel and Astrodon filters. QE is seemingly around 75% on this chip. Looking at the ZWO site they estimate it to be that, though there's no hard numbers. The 1600 is 60% QE, so this camera seems better in almost every way. The 2600 QE is 80%. I'm wondering how much the bayer matrix lowers the QE or if QE is really only about the sensor efficiency.

On paper the mono ASI294 does look better than the ASI1600 if we assume the mono ASI294 has the same performance specs as the color version.  It will probably be less expensive than the mono ASI2600 when it does appear.  A potential added benefit of trading up to the ASI294 from the ASI1600 would be the elimination of the 1600's problem with bright stars that some experience - myself included. 
 


Edited by Dean J., 03 September 2020 - 10:07 AM.


#30 r3g

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Posted 03 September 2020 - 12:05 PM

On paper the mono ASI294 does look better than the ASI1600 if we assume the mono ASI294 has the same performance specs as the color version.  It will probably be less expensive than the mono ASI2600 when it does appear.  A potential added benefit of trading up to the ASI294 from the ASI1600 would be the elimination of the 1600's problem with bright stars that some experience - myself included. 
 

 

Agreed, if the 294 is the same chip both it and the 2600mm will be an upgrade over the 1600 but the 2600 will be a set above the 294 (assuming the 2600 uses the same chip as the new qhy268m). 



#31 bvalente

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Posted 03 September 2020 - 12:46 PM

The 294 is a back side illuminated sensor so if I am not mistaken it does not have micro lenses.

afaik back side illumination does not play a role if the chip has microlenses.

 

 

Brian



#32 CCD-Freak

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Posted 03 September 2020 - 01:00 PM

Most modern CMOS sensors have micro-lenses.  Anti reflection coatings help reduce artifacts caused by said micro-lenses so let's hope the 294 sensor cover slip and window are AR coated.

 

John

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Edited by CCD-Freak, 03 September 2020 - 01:01 PM.

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#33 eekeek77

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Posted 03 September 2020 - 03:30 PM

Pretty sure there is no 294 mono sensor and it's actually a IMX492 binned to match the 294



#34 Dean J.

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Posted 03 September 2020 - 03:34 PM

Pretty sure there is no 294 mono sensor and it's actually a IMX492 binned to match the 294

Are you absolutely sure?  Can you provide information?



#35 wargrafix

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Posted 03 September 2020 - 03:49 PM

Will the odd cooling issue be resolved?

#36 andysea

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Posted 03 September 2020 - 04:07 PM

Most modern CMOS sensors have micro-lenses.  Anti reflection coatings help reduce artifacts caused by said micro-lenses so let's hope the 294 sensor cover slip and window are AR coated.

 

John

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You're right! I am not sure where I got that idea from.

 

Pretty sure there is no 294 mono sensor and it's actually a IMX492 binned to match the 294

I am thinking the same thing. I will post the CCD parameter screenshot later.

 

Will the odd cooling issue be resolved?

I don't think it was ever a cooling issue. I think the issue with the 294 color was more related to flats not working correctly. That was true for the sensor across different manufacturers. I tested two different brands. This mono camera has no calibration issues that I could find.


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#37 jdupton

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Posted 03 September 2020 - 04:09 PM

eekeek77,

 

Pretty sure there is no 294 mono sensor and it's actually a IMX492 binned to match the 294

   I sort of doubt it but it would be easy to test. If Andy could look at a Bias frame closely and determine the pixel value "stride factor" it will show whether the underlying sensor is 12 bit or 14 bit in its A/D. The IMX492 is a 12 bit readout sensor while the IMX294 is 14 bits. My bet is on 14 bits showing in the Bias Frames.

 

 

John


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#38 jdupton

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Posted 03 September 2020 - 05:37 PM

Andy,

 

   To follow up on my prior post, here is the simple test for A/D depth on your ASI294MM camera.

 

   The test goes like this:

  • Just open up PixInsight and the Histogram Transformation Tool.
  • Open up a single raw Bias Frame (or short dark frame) from the camera.
  • Click the Track View icon at the bottom of the HT process window.
  • Set the Horizontal Zoom (Input Histogram) to 500 as shown in the screen shot below.
  • Set the Plot Resolution to 16 bit (64K)
  • Scroll the horizontal scroll bar on the HT preview windows until the expanded histogram comes into view.
  • Note the discrete values of the data in the histogram.
  • Hover the cursor over a few adjacent peaks on the histogram.
  • Note the values in the readout area just below the horizontal scroll bar.
     
  • If the value of adjacent peaks differs by 4, then this is a 14 bit A/D readout sensor.
  • If the value of adjacent peaks differs by 16, then this is a 12 bit A/D readout sensor.

ASI294MC_Bias_Histogram.png

Checking A/D bit depth via pixel value "Stride Factor"

 

   Since the IMX492 and the IMX294 sensors differ in this fundamental aspect of A/D bit depth, ruling one out is easy.

 

 

 

John


Edited by jdupton, 03 September 2020 - 06:30 PM.


#39 andysea

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Posted 03 September 2020 - 08:18 PM

John I'm not sure if this is what you are looking for but here are the screen shots.

For what it's worth if I look in the front window of the camera I can see "294" printed on the board.

 

Happy to do more tests if you provide direction.

Attached Thumbnails

  • Screen Shot 2020-09-03 at 6.13.01 PM.jpg
  • Screen Shot 2020-09-03 at 6.13.14 PM.jpg
  • Screen Shot 2020-09-03 at 6.13.28 PM.jpg


#40 andysea

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Posted 03 September 2020 - 08:33 PM

Man this is going to be an incredible camera. The data you have so far is superb.

How much backfocus does this have? Can you easily pair the fw with an EOS lens?

Wes the back focus is the same as the ASI 1600mm pro or the 183mm pro or the 294 mc pro.

6.5mm without the 11mm t2 ring and 17.5mm with the ring. 

When paired with the filter wheel the back focus is 26.5mm I have an old ZWO EOS adapter that will allow me to attach eos lenses. I also have an old ZWO Nikon adapter for Nikon lenses. I have not checked on the ZWO website to see if they are still offering those adapters.



#41 AnakChan

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Posted 03 September 2020 - 08:39 PM

Andy, not certain if you recall of cuivenor's issue with the ASi294MC sensor (https://www.cloudyni...d-nb/?p=9374592). Would you know if this happens to the new ASI294MM too? Of it that issue was specific to the bayer on top of the sensor (which the ASI294MM wouldn't have)?


Edited by AnakChan, 03 September 2020 - 08:40 PM.


#42 andysea

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Posted 03 September 2020 - 08:48 PM

I did two narrowband imaging runs and the data looked normal to me. I used 5nm ha and 3nm Oiii and Sii. All Astrodon.

Unfortunately I don't have one of those triad filters and I am not sure that it would be usable with a monochrome camera.

 

I can share some 300s narrowband subs if you like.


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#43 andysea

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Posted 03 September 2020 - 09:22 PM

This is the link to a 300s master dark, gain 120 -10c from the 294MM pro.

https://drive.google...iew?usp=sharing

 

This is a 300s master dark gain 120 -20c from my old 294 MC pro.

https://drive.google...iew?usp=sharing


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#44 jdupton

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Posted 03 September 2020 - 10:32 PM

Andy,

 

John I'm not sure if this is what you are looking for but here are the screen shots.

For what it's worth if I look in the front window of the camera I can see "294" printed on the board.

 

Happy to do more tests if you provide direction.

   No further information is required. The pixel value stride factor is 4 which shows that the camera has a 14 bit A/D. It cannot be based on an IMX492 sensor.

 

   Your three screenshots show a values of 2547, 2551, and 2556 ADU. These are showing that the difference between data values in the pixels is are always multiples of 4. (The exact cursor position is off center to the left from the peak on the first two.) A stride factor of 4 means that the on sensor ADU values were multiplied by 4 by the driver during conversion to 16 bit FITs. (A 14 bit value times 4 becomes a 16 bit value.) Had this been a 12 bit sensor like the IMX492, the driver would have converted to 16 bit by multiplying by 16.

 

   So this is a 14 bit sensor and I no reason to doubt that it is an IMX294.

 

   The only other question in my mind is whether Sony is now producing mono versions of some of their popular sensors or are they are being modified after production. Once the mono versions of cameras like the 294 and 2600 start appearing, we may learn the answer. I think it would be great if Sony has begun to see value in the astronomy market or if some other industry is also demanding mono versions of their most popular sensors. Either would be a big plus for the future of astro-imaging.

 

 

John


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#45 AnakChan

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Posted 03 September 2020 - 11:01 PM

This is the link to a 300s master dark, gain 120 -10c from the 294MM pro.

https://drive.google...iew?usp=sharing

 

This is a 300s master dark gain 120 -20c from my old 294 MC pro.

https://drive.google...iew?usp=sharing

Thanks. OK I may have misunderstood the issue then. I thought it was obvious on NB filters but looks like it's only particular (dual/tri/quad) filters that it's more apparent on; rather than an MC vs MM issue.



#46 Oleg_Lviv

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Posted 04 September 2020 - 02:01 AM

Thank you for info about 294mm because had 294mc and sale, live in pollution city and color bad for me, and bought 1600mm(h-alpha,OII,SII) and happy!



#47 vehnae

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Posted 04 September 2020 - 04:28 AM

ZWO said on FB that the sensor is indeed the IMX492. If the accessible full resolution is the same as with ASI294MC then they are most likely binning the tiny 2.3um 12-bit pixels internally so that the camera looks like that it has 4.6um 14-bit pixels.

 

  ++ Jari



#48 leviathan

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Posted 04 September 2020 - 06:04 AM

Why would they do that instead of providing this as an option to end user ?



#49 Dean J.

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Posted 04 September 2020 - 08:41 AM

ZWO said on FB that the sensor is indeed the IMX492. If the accessible full resolution is the same as with ASI294MC then they are most likely binning the tiny 2.3um 12-bit pixels internally so that the camera looks like that it has 4.6um 14-bit pixels.

 

  ++ Jari

It will be interesting to see the specifications on the camera.  My plan is to wait for a mono IMX571 camera.



#50 aatdalton

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Posted 07 September 2020 - 11:23 PM

Same, I plan to wait on the QHY268M. Every other spec on that cam/sensor is just better than this 294.




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