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

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#1 andysea

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Posted 02 September 2020 - 03:04 PM

About 1.5 months ago I was offered the opportunity to test the soon to be released ZWO ASI 294 MM Pro. This is a monochrome version of the well known 294 MC camera. I was particularly interested in this sensor because I was one of the early adopters of the MC version which was a perfect match to a telescope that I owned at the time.

 

The camera showed up just in time for the August new moon which coincided with a long stretch of clear weather, a rarity in the PNW. Given that the body and back focus are the same as other ZWO cameras that I own i.e. the 1600 and the 183, I was all set from the get go to use the 294. I didn't waste any time and put it to good use the same evening on the day it came.

 

After using the sensor for a few imaging sessions I keep being impressed by what it can do. Paired with fast optics it can gather light at incredible pace and produce respectable results even during just one late summer night of imaging. The calibration woes present in the color version did not make their way to the mono version. In fact the calibration is very straightforward and everything works as expected. The sensor is also very clean. I still recommend to dither which is good practice with all sensors, especially CMOS.

 

I didn't spend any time characterizing the sensor as it's been well documented through the years and the numbers have already been dissected every which way one can think of. Instead I was more interested in image quality. 
For the imaging runs I picked objects with faint nebulosity that one might even consider difficult targets to render in a proper way. In addition to that I shot a couple of NB objects from my house in Central Seattle. 

 

The official announcement will come from ZWO Shortly but I was authorized to share the images. So without further ado here they are. The details are in the Flickr descriptions.

 

I will be happy to field any questions regarding the images. At this point I have no release date or pricing details.

 

Just a heads up, the image of VDB152 shows bad collimation on one side - my mistake, apologies. I forgot to rotate the focuser to the angle that I had collimated the scope for.

 

50298984861_8d7b9eedbe_b.jpgB150 the Seahorse nebula. by Andy Ermolli, on Flickr

50298998481_d6547c12ac_b.jpgThe Dark Shark Nebula. by Andy Ermolli, on Flickr

50298326183_be6a4d613d_z.jpgM27 The Dumbbell nebula. by Andy Ermolli, on Flickr

50299170932_ab7c4ddf8f_b.jpgLBN437 by Andy Ermolli, on Flickr

50298345438_4e613bb59b_b.jpgvdb142 by Andy Ermolli, on Flickr

50299037546_f605ace7be_b.jpgvdb152 by Andy Ermolli, on Flickr


Edited by andysea, 02 September 2020 - 03:08 PM.

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#2 MikiSJ

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Posted 02 September 2020 - 03:19 PM

Andy, what is the difference in the MM versus MC version of the 294. Is it simply a difference in the readout circuitry or does the MM version have both a different pixel readout and lensing. If it is simply different readout circuitry, can a change in how the MC version readouts a pixel make the MC version into the MM version - a firmware modification?

 

I have the MC version of the 294 and I am just learning to get my C11 EdgHD/CGX working together. So far I think I am happy with my 294 MC but I am limited to <30 second exposure with my CGX.


Edited by MikiSJ, 02 September 2020 - 03:30 PM.

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#3 jdupton

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Posted 02 September 2020 - 03:20 PM

Andy,

 

   Great images. ZWO sure did keep this one undercover. I had not heard of any rumors that something like this was coming. I may have to rethink my plan for the (potentially rumored) ASI2600MM if such a beast materializes.

 

 

John


Edited by jdupton, 02 September 2020 - 03:21 PM.

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#4 andysea

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Posted 02 September 2020 - 03:26 PM

Andy, what is the difference in the MM versus MC version of the 294. Is it simply a difference in the readout circuitry or does the MM version have both a different pixel readout and lensing. If it is simply different readout circuitry, can a change in how the MC version readouts a pixel make the MC version into the MM version?

 

I have the MC version of the 294 and I am just learning to get my C11 EdgHD/CGX working together. So far I think I am happy with my 294 MC but I am limited to <30 second exposure with my CGX.

 

Are you in Seattle, which is somewhat similar to San Jose where I am with Bortle 6+ skies are to the east of the city?

The difference is that the MM version is a monochrome camera while the MC has the same sensor in the color version. The rest of the electronics and the sensor architecture, as far as I can tell, are identical. So the MM version will require filters but it should have a higher QE than the color version.

 

Andy,

 

   Great images. ZWO sure did keep this one undercover. I had not heard of any rumors that something like this was coming. I may have to rethink my plan for the (potentially rumored) ASI2600MM if such a beast materializes.

 

 

John

John, I have not used the 2600 but the 294 mono is a very impressive sensor.


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#5 tkottary

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Posted 02 September 2020 - 03:45 PM

Hi  Andy,

What is the pixel scale & Mega Pixels on  this? Does it have any amp glow?



#6 andysea

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Posted 02 September 2020 - 03:48 PM

Hi  Andy,

What is the pixel scale & Mega Pixels on  this? Does it have any amp glow?

Pixel size and count are the same as the 294 mc. There is amp glow and it calibrates out just fine. Like in the MC version. I will post some calibration frames for reference.



#7 Dean J.

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Posted 02 September 2020 - 03:50 PM

OK, so now I have to decide whether I am going to wait for the mono ASI2600MM or jump on this ASI294MM mono.


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#8 niccoc1603

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Posted 02 September 2020 - 03:58 PM

Same

#9 rockstarbill

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Posted 02 September 2020 - 04:16 PM

How square was the sensor? Any tilt issues?

#10 andysea

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Posted 02 September 2020 - 04:20 PM

I didn't see anything glaring but I have no way to test for that.

Unless I put it on the FSQ or the Stowaway and analyze the image. I can do that and report back.


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#11 bobzeq25

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Posted 02 September 2020 - 04:33 PM

Andy, what is the difference in the MM versus MC version of the 294. Is it simply a difference in the readout circuitry or does the MM version have both a different pixel readout and lensing. If it is simply different readout circuitry, can a change in how the MC version readouts a pixel make the MC version into the MM version - a firmware modification?

 

I have the MC version of the 294 and I am just learning to get my C11 EdgHD/CGX working together. So far I think I am happy with my 294 MC but I am limited to <30 second exposure with my CGX.

The difference is that the mono has no Bayer filter matrix sitting on top of the sensor.

 

It's a _big_ difference.  <smile>  Bayer matrix filters are really a terrestrial device, and engineered for that specific purpose.  They're not horrible for AP (I use both types of cameras), but they are inefficient.  Particularly noticeable in light polluted skies.

 

Really, the only drawback to mono is the substantial cost of the camera, filters, and filter wheel.  Data acquisition is a bit more complicated, but (especially if you use LRGB methods) total imaging time for the same signal to noise ratio is less.  I think color is better, the Bayer matrix is sloppy, and some red and blue photons are recorded as green.  You can compensate some in processing.

 

All this is not to say people don't make lovely images with OSC cameras with Bayer matrix filters.


Edited by bobzeq25, 02 September 2020 - 04:39 PM.

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#12 andysea

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Posted 02 September 2020 - 04:48 PM

Bob is right as usual!



#13 Dean J.

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Posted 02 September 2020 - 05:35 PM

Same

It is only a month or so until the QHY268M is supposed to be released.  I think that I will probably wait for what will probably be a better camera based on the mono IMX571.  I did get an ASI2600MC last month (fantastic camera) and that will keep me happy for a while. :-)



#14 rockstarbill

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Posted 02 September 2020 - 05:54 PM

Is this a mono modded chip or one that is mono from the factory? 


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#15 andysea

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Posted 02 September 2020 - 06:00 PM

Is this a mono modded chip or one that is mono from the factory? 

That I don't know.



#16 Stelios

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Posted 02 September 2020 - 06:35 PM

Does this sensor have the microlensing issue of the ASI1600MM-Pro on large stars?

 

Other than that the differences are slight, and almost all mildly favor the 294:

 

14-bit vs 12-bit

*slightly* larger sensor 

4.63um vs. 3.8um pixels (usually a plus).

larger full well capacity

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


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#17 rockstarbill

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Posted 02 September 2020 - 06:43 PM

Does this sensor have the microlensing issue of the ASI1600MM-Pro on large stars?

Other than that the differences are slight, and almost all mildly favor the 294:

14-bit vs 12-bit
*slightly* larger sensor
4.63um vs. 3.8um pixels (usually a plus).
larger full well capacity
lower (35C vs. 45C) temp delta (a minus)


The color version has a coated sensor. So it should not have that problem if the mono one has the same coating.

#18 EricCCD

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Posted 02 September 2020 - 06:51 PM

Very nice! It's exciting to see the number of options for mono cooled CMOS cameras opening up.


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#19 andysea

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Posted 02 September 2020 - 07:05 PM

To be honest I was never able to exacerbate the micro lensing issue on the 1600. Even when I tried on m45. Maybe I should have tried brighter stars.
The 294 is a back side illuminated sensor so if I am not mistaken it does not have micro lenses.

Edited by andysea, 02 September 2020 - 07:06 PM.

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#20 r3g

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Posted 02 September 2020 - 11:21 PM

This is exciting news, I loved my 294mc. I will hold out for the 2600m though because 16bit, APS-C, and significantly reduced amp glow.

Edited by r3g, 02 September 2020 - 11:22 PM.


#21 MikiSJ

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Posted 03 September 2020 - 01:35 AM

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

If I am mistaken, I apologize, but I believe microlensing is used on each pixel regardless of it being color or non-color.



#22 stryker66

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Posted 03 September 2020 - 08:06 AM

I might replace all my ASI1600MM for this, need more comparison data between the two if it is worth it. Thanks for the review.



#23 zerro1

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Posted 03 September 2020 - 09:15 AM

Great pics Andy and nice review! Let's not forget that while the camera is excellent, the skills of the operator is what really makes it produce! 


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#24 Dean J.

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Posted 03 September 2020 - 09:20 AM

Great pics Andy and nice review! Let's not forget that while the camera is excellent, the skills of the operator is what really makes it produce! 

+1


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#25 Lead_Weight

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Posted 03 September 2020 - 09:24 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.




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