592 replies to this topic

[A. Viegas]

So after over 5 months of speculation  ( see this old EAA thread https://www.cloudyni...-8mp-43-sensor/ ) we now have a new exciting camera from ZWO that is ideally suited for our EAA needs!!!

 

I hope to beta test this under live sky conditions this coming Saturday night (right now forecast looks good - September 16).  I will be on www.nightskiesnetwork.com  & my channel name is "BigAppleSkies"   -  right now I am not sure if I will use a 8-11" SCT with 0.63 reducer or my F8 refractor.  If anyone has strong opinion on which they would rather see please let me know.

 

 

The sensor specs are here: http://www.sony-semi...mx294cjk_e.html

 

The key point about this new camera for EAA and for Astrophotographers to consider are:

 

1.  Large pixels  (ASI 1600 has 3.63um  this camera is 4.63um)

2.  ADC Bits  --  ASI 1600 is 12bit   this camera is 14 bit

3.  High frame rate - this new camera is capable of 120fps in 10bit mode vs about 23 fps for the ASI1600  (60fps in HDR mode)

4.  Sensitivity !!    a mv rating of 2,000 !!   this is amazing!  

5.  4:3rds size sensor  21mm diagonal (same as 1600)  

6.  10mb  in (3704 × 2778) for aspect ratio 4:3, UHD (3840 × 2160) for 16:9, and 4096 × 2160 for 17:9

7.  USB 3  with hub for 2 additional USB 2  connections

8.  TEC cooled  (not sure but assume its same or better than ASI 1600 - down to -40 my guess)

9.  Comes with additional 16.5mm and 21mm spacers  (see 2nd pic)

10. Unknowns right now...  1) dark current... assume its very low like most of the new CMOS...   2)  Price...  unknown... but probably close to 1600 i am guessing.

 

I will try and get some dark frames over the next few days ahead of first light!

-Al

 

 

 

[alphatripleplus]

Al,

 

I see it is a OSC camera. It might be more  interesting if they had a mono version as well. Did Sam indicate if a mono is available?

[Dragon Man]

Thanks Al.

Specs sound good.

Will be interesting to see your results.

I wonder who else will 'invent' this camera.

[alphatripleplus]

Let's stay on topic about this camera from ZWO please. If any other camera vendor "invents" the same camera, we have more competition, which is great, and we can do a comparison thread when that happens.

[A. Viegas]

Al,

 

I see it is a OSC camera. It might be more  interesting if they had a mono version as well. Did Sam indicate if a mono is available?

Hi Errol

Its a sony Starvis sensor.  As we always bemoan,  EAA and Astro applications for Sony sensors is a one-off 'bumped-toe' moment for Sony... they don't really give a hoot.   I suspect that this imx294 is geared toward the drone marketplace as its a nice sensor for that market.  Hence, I very much doubt there will be a mono version.   If Sony comes out with a mono version it would have to have some specific demand from a user marketplace that actually matters to them and given the high sensitivity now in so many new CMOS sensors, frankly the usefulness of mono is diminishing by the second.   I am sure there will be mono sensors in the future but they will be very few and far in-between...      so... meanwhile...  lets give a cheer for a new sensor for our little corner of the universe!

Al

[Astrojedi]

Unfortunately, there is no mono version of this sensor.

Al, looking forward to seeing your results.

[Relativist]

Use as fast of a focal ratio as you can. Also use any hardware binning mode that is available. The faster the better for testing. Start at max gain, with very short exposures and work your way up. Do not worry about noise, let stacking take care of that. Once you find a place where the signal seems to pop out, take some darks at that setting to further clean up the view. Oh and make sure your at temperature when you start testing.

In theory with binning this should have similar sensitivity to my A7s.

[A. Viegas]

Use as fast of a focal ratio as you can. Also use any hardware binning mode that is available. The faster the better for testing. Start at max gain, with very short exposures and work your way up. Do not worry about noise, let stacking take care of that. Once you find a place where the signal seems to pop out, take some darks at that setting to further clean up the view. Oh and make sure your at temperature when you start testing.

In theory with binning this should have similar sensitivity to my A7s.

Thanks for the suggestion Curtis

 

I was thinking about using the SCT with 0.63x reducer because so many EAA'ers have this combination.  My fastest scope is a F6.5 APO refractor and I dont have a paired reducer for it, although I could try and use a 0.5x 2" reducer but its low quality and I am not sure it would work but I can try it...

[Relativist]

Use the biggest aperture, since thy are larger pixels, extra focal length is a good thing.

[alphatripleplus]

If 4.63 microns is now considered large, then my Lodestar's 8.6 micron pixels are enormous .  I guess it is all relative.

[mclewis1]

I was thinking about using the SCT with 0.63x reducer because so many EAA'ers have this combination.  My fastest scope is a F6.5 APO refractor and I dont have a paired reducer for it, although I could try and use a 0.5x 2" reducer but its low quality and I am not sure it would work but I can try it...

Al,

 

Certainly try the SCT reducer, but you may run out of in focus travel. Even though this reducer is also a coma corrector you may not notice any issues as the field of a fast apo is also quite curved and the corrector part does help in some cases I've seen. I've also tried it on my own f7 TMB apo and the field didn't look too bad at all but that was only with a small type 1/2" sensor. I couldn't get it to work on my 80mm ED refractor because of limited in focus travel. You'll need about 90mm of T thread spacers.

 

A DSLR reducer is also an option (will certainly cover the big chip well) but are usually only .8x ... but an f5.2 apo with that chip should be a nice combo for a lot of objects. You'll also need about 40mm of T thread spacers.

 

Another option is the Antares .7x 2" reducer. A 2" barrel to thread adapter a few T thread spacers should be all you'll need here.

Edited by mclewis1, 12 September 2017 - 06:23 PM.

[A. Viegas]

 

I was thinking about using the SCT with 0.63x reducer because so many EAA'ers have this combination.  My fastest scope is a F6.5 APO refractor and I dont have a paired reducer for it, although I could try and use a 0.5x 2" reducer but its low quality and I am not sure it would work but I can try it...

Al,

 

Certainly try the SCT reducer, but you may run out of in focus travel. Even though this reducer is also a coma corrector you may not notice any issues as the field of a fast apo is also quite curved and the corrector part does help in some cases I've seen. I've also tried it on my own f7 TMB apo and the field didn't look too bad at all but that was only with a small type 1/2" sensor. I couldn't get it to work on my 80mm ED refractor because of limited in focus travel. You'll need about 90mm of T thread spacers.

 

A DSLR reducer is also an option (will certainly cover the big chip well) but are usually only .8x ... but an f5.2 apo with that chip should be a nice combo for a lot of objects. You'll also need about 40mm of T thread spacers.

 

Another option is the Antares .7x 2" reducer. A 2" barrel to thread adapter a few T thread spacers should be all you'll need here.

 

Hi Mark

 

Thanks for that.  My 0.5x 2" reducer is an OPT brand of the generic 0.5x you normally see from Antares or Agena....  I think the proper spacing is 78mm if I recall...   Honestly, I have not had much luck with this 0.5x reducer and its mostly spent its life in a box.   I think I will just go with the 0.63x reducer on my C11 and see how the focus of this new camera compares with the focus point for my ASI1600 mono.   Its not apples to apples here, one being OSC and the other mono, but I wonder if the sensitivity of the new imx294 sensor will be close to that of the ASI1600...  Maybe someone has seen it published somewhere but what is the sensitivity of the Panasonic 1600 OSC chip?  I have seen the 174 color chip and I think its like 900mv  

 

Al

[Relativist]

If 4.63 microns is now considered large, then my Lodestar's 8.6 micron pixels are enormous . I guess it is all relative.

So because I recommend binning, that equates to larger pixels if it's done. Also if the binning is retaining color information then it's harder to quantify, but we can guesstimate that it's equivalent to larger pixels. I highly recommend using color binning if available.

[mclewis1]

I've never seen a mv rating for the Panasonic chip. Even if Panasonic did produce one there would still be the uncertainty of the value of comparisons with the Sony chips due to differences in the test conditions. Heck even within Sony's family of products there have been different test conditions which makes some of the mv comparisons a problem.

[alphatripleplus]

 

If 4.63 microns is now considered large, then my Lodestar's 8.6 micron pixels are enormous . I guess it is all relative.

So because I recommend binning, that equates to larger pixels if it's done. Also if the binning is retaining color information then it's harder to quantify, but we can guesstimate that it's equivalent to larger pixels. I highly recommend using color binning if available.

 

Yes, I missed the recommendation on binning...You are right, the binned pixels will be at least as large as those of an unbinned Lodestar.

[A. Viegas]

This new camera supports up to bin 4x4. Thanks to the very low read noise of these Starvis CMOS you can effectively bin 2x2 and still basically retain HDMI sized frame (in pixels) with much improved time to exposure ratio. I am really curious to see how it will do against the same sized ASI 1600. I have the mono so it will give this camera a run for its money. I will try unity gain for both to try and normalize for the differences

[A. Viegas]

A few interesting specifics of this new imx294 based camera 

 

 

Note the Fw(e-) is 63k vs. just 20k for the popular Panasonic 4:3rds based cameras

 

-Al

 

 

 

Attached Thumbnails

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[Astrojedi]

Looks very promising. 

[elpajare]

Waiting for the first results with impatience and interest

[Astrojedi]

There one thing very interesting in the charts above. At a gain of 120 the read noise drops below 2e and hence dynamic range jumps to 13 stops! That better than most sensors out there and implies a sweet spot for long exposure imaging. Although I will continue to use high gain and short exposures. : )

Edited by Astrojedi, 13 September 2017 - 11:08 AM.

[Relativist]

There one thing very interesting in the charts above. At a gain of 120 the read noise drops below 2e and hence dynamic range jumps to 13 stops! That better than most sensors out there and implies a sweet spot for long exposure imaging. Although I will continue to use high gain and short exposures. : )

It's unfair to the Sony sensor to compare at 'unity gain' since the high gain mode is such a huge advantage, you'd simply miss that if you did stick to unity gain. At a minimum I'd use a gain where that high efficiency mode kicks in.

[A. Viegas]

Can someone suggest a few targets to try and capture for comparison purposes?

I am thinking what I am going to try and do is use the same scope/reducer combination and then shoot the same effective 'gain' measure for each camera to show effective sensitivity.  To make it somewhat relatively similar is to use a gain that is about the same in terms of 'gain range' given the different cameras -- so lets say gain at 50% of max for all cameras.  Ideally I would like a target which can be challenging in terms of detail and where sensitivity can be effectively seen.    I am thinking of NGC6888 - the crescent nebula as the finer details require more sensitivity.  I would use the same exposure time for each camera - like 30s for instance and do both single frame and stack of like 20.  Any other targets?   In my possession I will compare  the new IMX294   with the imx224, imx290 mono and the ASI1600 mono. 

I will use my C11 with 0.63x reducer so we are going to be at 1750mm FL   the FOV will be: 34'x25' for the new camera and the ASI1600 while it will be a smaller 11'x6' for the smaller chip cameras.    So I may also pick something smaller like M57 and see what i can get with these various cameras and combinations.


Al

 

Sky conditions are so-so for Saturday...  hopefully it clears up

[Ain Soph Aur]

Very much looking forward to the results!

[Astrojedi]

Can someone suggest a few targets to try and capture for comparison purposes?

I am thinking what I am going to try and do is use the same scope/reducer combination and then shoot the same effective 'gain' measure for each camera to show effective sensitivity.  To make it somewhat relatively similar is to use a gain that is about the same in terms of 'gain range' given the different cameras -- so lets say gain at 50% of max for all cameras.  Ideally I would like a target which can be challenging in terms of detail and where sensitivity can be effectively seen.    I am thinking of NGC6888 - the crescent nebula as the finer details require more sensitivity.  I would use the same exposure time for each camera - like 30s for instance and do both single frame and stack of like 20.  Any other targets?   In my possession I will compare  the new IMX294   with the imx224, imx290 mono and the ASI1600 mono. 

I will use my C11 with 0.63x reducer so we are going to be at 1750mm FL   the FOV will be: 34'x25' for the new camera and the ASI1600 while it will be a smaller 11'x6' for the smaller chip cameras.    So I may also pick something smaller like M57 and see what i can get with these various cameras and combinations.


Al

 

Sky conditions are so-so for Saturday...  hopefully it clears up

Al, you will need to use flats which is quite easy to do in SharpCap. Without flats the vigenetting in the outer 1/3 of the frame will be severe.

[A. Viegas]

Hi Hiten

I have used my C11 with celestron 0.63x reducer and the ASI1600 with very little vignetting. Also for this Saturday if I get clear skies my goal is really first to try and assess the sensitivity vs the 1600 as a primary goal. In future testing I will try it more as an Astrophotography camera but that is for the following week.

Al

Edited by A. Viegas, 13 September 2017 - 07:09 PM.