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ASI294MC Pro

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#1 iandh2010

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Posted 08 September 2019 - 05:48 PM

Hi Guys,

I am considering my options for a CMOS imaging camera.

 

I have a Celestron 11" SCT with 2700mm focal length and therefore I am looking for a large format sensor with reasonably large pixels so that I am not over-sampling and still have enough chip to accommodate most faint fuzzies. I would normally use an F6.3 focal reducer but still need a fairly large format chip. Unfortunately I can't afford much more than about £1000/$1300!

 

I was therefore considering the ASI 294MC Pro. However, I noticed that several different retailers were quoting the ADC on this camera with a 12bit max. resolution and others were quoting 14bits. So I went onto the Sony IMX294 web page and found that the chip could be set to 10,12 or 14bit. Not sure whether ZWO implement all three!

 

However, when I was on the  Sony website I discovered  that it uses what they call Quad Bayer Coding:

https://www.sony-sem...x294cjk_e.html 

 

Looking at this, I reckon that the resolution of this chip is going to be ½ what it would appear from the number of pixels on the silicon chip. With a normal RGGB Bayer mask.

 

I assume that the debayering algos for a normal Bayer mask, take the first group of four RGGB pixels and calculate a colour in the centre and then move 1 pixel horizontally and recalculate using the GRBG next four pixels, until the end of the row then drop down one row and repeat, and so on,  therefore one gets basically the same number of coloured pixels as actual underlying pixels in the chip. Is this correct?

 

I don't see how this can work with the Quad Bayer Coding of the IMX294!

 

Can anyone who is using the ZWO ASI 294MC Pro camera advise me what resolution images you get after debayering please.

 

Is anyone using this camera with AstroArt-7 to do the debayering as this is my Astro-imaging control program that I have been using for many years,  in its previous versions!

 

Thanks


Edited by iandh2010, 08 September 2019 - 06:19 PM.


#2 OleCuss

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Posted 08 September 2019 - 06:50 PM

I don't know all the specifics for how the Bayer Matrix works for the ASI294 but we've some serious experts on the forum and the net effect is that you are not getting an effective reduction in the number of active pixels.  You'll be just fine with that ASI294.

 

Given your budget I think the ASI294MC Pro is about as good as you can get - and that's pretty good.  For long exposure DSO imaging I think the folk are a little happier with the ASI071MC Pro but the price increment is pretty significant.  The pixel size is also just a little bigger for the ASI071 so slightly less over-sampling.  But for these low-noise cameras over-sampling doesn't carry much of a noise penalty.

 

And yes, ZWO implements the 14-bit ADC but you can select 12-bit or 10-bit if you don't need the dynamic range and want a faster frame rate.

 

Also, IIRC ZWO and QHY have made more of the IMX294 pixels active which gives an effectively larger sensor than if you get one of the ToupTek-derived cameras.



#3 Swanny

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Posted 08 September 2019 - 06:51 PM

I see on ASI site it is listed as 14 bit.

#4 jdupton

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Posted 08 September 2019 - 07:36 PM

Ian,

 

   The ASI294MC-Pro gives a 4144 x 2822 pixel image with an RGGB Bayer Matrix pattern when using the ASI ASCOM driver. I use the ASI ASCOM driver with my camera but understand from others that the native driver defaults to the same. You can set different modes but I just always use the 4144 x 2822 mode. Even though the ADC on the sensor reads out in 14 bits, the ASCOM driver internally translates that (multiplies by four) to 16 bits for the FITs file delivered to the image capture software you are using to connect to the camera.

 

   The net is that you get 4144 x 2822 16 bit FITs files to save and work with. The internal chip logic always delivers the net Bayer matrix. Internal to the sensor chip, the Quad Bayer matrix is only used in special video modes for HDR effects in low light. Those modes are not used by the ASCOM driver to the best of my knowledge.

 

 

John



#5 iandh2010

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Posted 09 September 2019 - 02:58 AM

Hi John, Swanny and OleCuss,

 

Thank you all for coming back so promptly. Your responses have allayed my concerns. It was not at all apparent from the Sony website how that Quad Bayer Matrix worked.

 

The reason for considering the camera were threefold: 

1. The physical size of the chip which I calculate will cover 23 x 16 arc mins of sky on my F10, 2700mm fl, Celestron Nexstar, which should cover most faint fuzzies completely, apart from M31 and M33 (in standard setup) or 37 x 26 arcmins with an f6.3 focal reducer. It will certainly manage one of my favourites M51!

 

2. To have a camera that will work under AstroArt-7 which it will do via ASCOM.  John - I note your comment regarding some features not supported via ASCOM. I trust that the temperature set point does? Are there any that you would have liked to have been able to use but can't through ASCOM? Presumably these could be used through ASICAP.

 

3. I was also tempted by the sales blurb that said it could also be used as a planetary camera because of its rapid frame rate, but with the larger pixels, its not going to be all that high a definition on anything but Jupiter and Saturn!

 

So anyone that is using this camera, what is your opinion on it and what do you not like about it?

 

Thanks so much!



#6 iandh2010

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Posted 09 September 2019 - 03:16 AM

Hi Guys,

One supplemental question that has just sprung to mind:

On the ASI294MC Pro, can one bin at 2x2 and 4x4 in colour? 

 

As you have probably figured out, I am from the UK, where we have very limited observing time, which is one of the reasons for going for the one shot colour!

 

Thanks.



#7 OleCuss

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Posted 09 September 2019 - 05:00 AM

I don't know about binning in color.  I'm pretty sure I've seen images people have done which showed color and were binned 2x2 but I cannot swear to that.

 

If you try to do high-quality planetary AP using the ASI294 with that 11" SCT you will probably end up using a Barlow.  By usual standards you'll be over-sampling like crazy using the ASI294 in that configuration.  I doubt you will find you are losing much (if any) detail due to the size of the IMX294 pixels.



#8 iandh2010

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Posted 09 September 2019 - 07:23 AM

Hi OleCuss,

Yes thanks on the planetary AP, some of my mates are using C11 SCTs with high speed planetary cameras and getting great results including hints of details on Jupiter's moons! Certainly resolving the disks of the moons! So if I really seriously wanted to do more than take a passing pop at a planet, when in a good position, then I would probably go down that route.



#9 jdupton

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Posted 09 September 2019 - 07:52 AM

Ian,

 

   In regards to the features of the ASCOM driver, I find it has all I would need. You can set the basic Mode, Gain, Offset, and Bus Bandwidth using the driver and then just use it. When using ASCOM, you are generally using the camera for long exposure DSO imaging. Video modes are not supported by the ASCOM driver (so far as I have seen). For ASCOM, the camera takes an image and then downloads it. The frame rate is limited as the camera operates in "single shot mode.

 

   I have not used the native drivers so am not familiar with any additional features you can select there. In order to do video, you would probably want to connect through the Windows DirectShow driver which allows full access to all adjustments as needed for planetary video imaging.

 

   The ASCOM driver fully supports temperature control. I use Sequence Generator Pro for image capture and all of the camera features I need for DSO imaging are supported.

 

   I like the camera a lot. If you search Cloudy Nights and other astronomy discussion sites, you will see a lot of complaints early on about multi-colored background gradients / splotches. I also saw these early on but have now tamed them on my camera. I have not seen a lot of reports recently. The camera has a few quirks that I have been able to work around. Now that I know how to use the camera to its full advantage, long exposure DSO photography with my EdgeHD 11" SCT (mostly used with the EdgeHD 0.7x Focal Reducer) is as easy as any other camera I have used. There is nothing that detracts from this camera in my mind. I am having a ton of fun using mine.

 

 

John



#10 OleCuss

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Posted 09 September 2019 - 08:22 AM

Hi OleCuss,

Yes thanks on the planetary AP, some of my mates are using C11 SCTs with high speed planetary cameras and getting great results including hints of details on Jupiter's moons! Certainly resolving the disks of the moons! So if I really seriously wanted to do more than take a passing pop at a planet, when in a good position, then I would probably go down that route.

 

I should just point out that if you decide to go to the high-quality planetary AP route, you should consider the possibility that when combined with a Barlow and 11" SCT the ASI294 might be a really good high-speed planetary camera.  It may not be quite as good as some others but I'd expect it to be good indeed.

 

I'd expect to define a small ROI and maybe decrease the bit-depth and at that point you'll have a fairly high-speed planetary camera!  I'm not thinking it will be the best planetary camera around but I'd expect it to be pretty good.



#11 Dunc

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Posted 09 September 2019 - 08:27 AM

Hi iandh2010

 

I have a ZWO ASI294 MC Pro, I have used it on an old Meade LX90 8" UHTC with and without a Baader Alan Gee II Telekompressor (to correct and widen the field and make it f5) and have got some great shots. With the telekompressor I can get 95% of M31 in the field so I don't know how you will fare with your C11 on that one :)  Currently I mostly use a 6" f4 TS1506UNC Newtonian.

 

One thing I have found is that the camera driver offset needs to be around 4 or 8 not the default 30 or I get blotches of colour in my DSO images (not ones I want!). Also you have to modify your processing routine, there are plenty of threads on CN about it. Basically flats need to be around 3s minimum and use Flat Darks not Bias frames as they really mess things up. Dark Optimisation doesn't work properly either.

 

But once you have it produces great images, let down by my abysmal processing skills. I use APT, NINA and Voyager (learning this one at present) with a smattering of SharpCap Pro as capture programs which means a combination of ASCOM and Native support and everything works as it should. I've tried the 3x & 4x colour binning but I've not yet found a reason for using them, maybe EEA? The 2x binning works well for previews and focusing. You can do mono binning as well (in-driver selection) but I've not used that either!

 

Hope that helps,

 

Duncan



#12 iandh2010

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Posted 09 September 2019 - 08:32 AM

Thanks John,

That's good enough to convince me on the ASI294MC Pro!

 

The best scope I ever bought was my first GOTO, an 8" LX200 Classic, why, because it was easy to use, it was the first scope that I found M1 in, even though I had been looking in the right place for many years with my essentially push to, 10" truss tube Newtonian! Not only that It actually enthused me to go out and use it on as many nights as possible, even though I had to set it up and align every night! 

 

When I saw your comment regarding having fun using the ZWO ASI294 MC Pro, that resonated with me!

 

I also noted that you listed Outreach on your signature strip and also the atm-workshop.com. I am chairman of our local astro club http://www.midkentastro.org.uk and we do a lot of outreach so I visited your website which is very interesting and helpful.

 

I am also having to purchase a new laptop to run my new astro camera as my old one is rapidly grinding to a halt! So I will definitely be setting up the red night vision mode on it. I used to have a 32 bit program that did that automatically under Win 7 when run.

 

Does your setup also set extension screens up in red mode as well?


Edited by iandh2010, 09 September 2019 - 08:43 AM.


#13 lucam

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Posted 09 September 2019 - 08:40 AM

Ian,

 

   In regards to the features of the ASCOM driver, I find it has all I would need. You can set the basic Mode, Gain, Offset, and Bus Bandwidth using the driver and then just use it. When using ASCOM, you are generally using the camera for long exposure DSO imaging. Video modes are not supported by the ASCOM driver (so far as I have seen). For ASCOM, the camera takes an image and then downloads it. The frame rate is limited as the camera operates in "single shot mode.

 

   I have not used the native drivers so am not familiar with any additional features you can select there. In order to do video, you would probably want to connect through the Windows DirectShow driver which allows full access to all adjustments as needed for planetary video imaging.

 

   The ASCOM driver fully supports temperature control. I use Sequence Generator Pro for image capture and all of the camera features I need for DSO imaging are supported.

 

   I like the camera a lot. If you search Cloudy Nights and other astronomy discussion sites, you will see a lot of complaints early on about multi-colored background gradients / splotches. I also saw these early on but have now tamed them on my camera. I have not seen a lot of reports recently. The camera has a few quirks that I have been able to work around. Now that I know how to use the camera to its full advantage, long exposure DSO photography with my EdgeHD 11" SCT (mostly used with the EdgeHD 0.7x Focal Reducer) is as easy as any other camera I have used. There is nothing that detracts from this camera in my mind. I am having a ton of fun using mine.

 

 

John

John,

 

I have read your threads - thank you for your testing and reporting. I have recently acquired a ASI294MC Pro and while the lights are of solid quality, I am still struggling with calibration. 

 

1) With 60sec subs and a master dark built with matching dark frames (temperature, gain, offset, duration) I have some leftover amp glow in the starburst pattern on the right side. Is this usual or should I try shooting another set of darks?

2) Flats don't work at all. As I understand it, the problem is that when I look at the peaks of the histogram in the non-debayered flat, I see three distinct peaks corresponding to the R, G, and B photosites with on peak much lower than the other two. The SNR of the flat correction will certainly be affected and I am wondering if that has something to do with the bright red background in the darker corners after flat correction. What mean ADU do you target for your flats?

 

thank you for any advice you may have!

 

Luca


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#14 iandh2010

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Posted 09 September 2019 - 08:44 AM

Hi OleCuss and Dunc,

Many thanks for your replies that came in as I was responding to John.

 

Sounds like the 294MC Pro should do the job for me!

 

Regarding the colour blotches, I seem to recall a thread on CN that was suggesting that the cold finger was the culprit as it does not adequately cover the back face of the chip.

 

Anyway, I am now looking forward to getting the camera and "having some fun" with it!

 

Is there a good thread on CN discussing everything to do with imaging with the 294MC in particular?

 

Once again many thanks to you all for your advice it is very much appreciated!



#15 mewmartigan

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Posted 09 September 2019 - 08:56 AM

John,

 

I have read your threads - thank you for your testing and reporting. I have recently acquired a ASI294MC Pro and while the lights are of solid quality, I am still struggling with calibration. 

 

1) With 60sec subs and a master dark built with matching dark frames (temperature, gain, offset, duration) I have some leftover amp glow in the starburst pattern on the right side. Is this usual or should I try shooting another set of darks?

2) Flats don't work at all. As I understand it, the problem is that when I look at the peaks of the histogram in the non-debayered flat, I see three distinct peaks corresponding to the R, G, and B photosites with on peak much lower than the other two. The SNR of the flat correction will certainly be affected and I am wondering if that has something to do with the bright red background in the darker corners after flat correction. What mean ADU do you target for your flats?

 

thank you for any advice you may have!

 

Luca

When stacking in Pixinsight, make sure that "optimize dark frames" is NOT checked. This worked for me in calibrating out all the amp glow.

 

For my flats, they are about 2.5s long and the target ADU is around 22,000 give or take. I also use flat darks instead of flats. These are darks taken at the same exposure time as your flats. 

I think the general consensus for flats with the 294 was for them to be in the 2-5s range.



#16 lucam

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Posted 09 September 2019 - 09:23 AM

When stacking in Pixinsight, make sure that "optimize dark frames" is NOT checked. This worked for me in calibrating out all the amp glow.

 

For my flats, they are about 2.5s long and the target ADU is around 22,000 give or take. I also use flat darks instead of flats. These are darks taken at the same exposure time as your flats. 

I think the general consensus for flats with the 294 was for them to be in the 2-5s range.

Marcus, thank you.

 

Unfortunately, I already followed all these best practices (3sec flats, mean ADU in the mid-20,000, flat darks, no 'optimize dark frames', do not use bias frames for calibration, aggressive dithering) but the result is unsatisfactory. I don't want to derail this thread any further. I'll put start a separate thread with my data and hopefully you or other people who have been successful at calibraing ASI294MC Pro data will be able to help me sort it out.

 

--Luca



#17 iandh2010

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Posted 09 September 2019 - 09:34 AM

Hi Marcus and Luca,

So is this a known problem with the 294MC Pro and how bad is it?

 

I thought that the DDR3 RAM was supposed to cure the amp glow problem?

 

Oh boy, I was literally just about to purchase the 294MC when I saw your comments, now I'm not so sure!

 

Just how bad is this problem????



#18 jdupton

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Posted 09 September 2019 - 10:57 AM

Ian,

 

   Calibration in general is a known problem with the IMC294 sensor. It is very sensitive to both image capture procedures and the calibration processing. The residual amp glow issue is due to incomplete calibration by the Master Dark Frame. I have not had that problem to any great extent but think I understand where it originates. My own current "best practices" procedures have eliminated all traces of it for me. 

 

   The severity of the tricky calibration problems ranges from mild to severe for some users. Once the causes are understood, I think anyone can get good results with the IMX294 based cameras. The camera may not be for everyone but I feel it can be tamed and produce great results.

 

 

Duncan,

 

One thing I have found is that the camera driver offset needs to be around 4 or 8 not the default 30 or I get blotches of colour in my DSO images (not ones I want!). Also you have to modify your processing routine, there are plenty of threads on CN about it. Basically flats need to be around 3s minimum and use Flat Darks not Bias frames as they really mess things up. Dark Optimisation doesn't work properly either.

   You are correct that once you learn how to best calibrate your data from the IMX294 sensor, it can produce very nice images. I am severely limited now by my ability to get the most out of my processing rather the camera.

 

   I will note that the solution you are using, setting the Offset to a very low value, works mostly because it is clipping large amounts of data to black in the background. Once the background is clipped, the colored gradients cannot show up as they have been discarded. There are other ways to eliminate the great bulk of the background color by using a different procedure while gathering images. 

 

   I can explain what I have found once Luca opens his new thread as it is probably more appropriate there.

 

 

Ian,

 

I also noted that you listed Outreach on your signature strip and also the atm-workshop.com. I am chairman of our local astro club http://www.midkentastro.org.uk and we do a lot of outreach so I visited your website which is very interesting and helpful.

 

I am also having to purchase a new laptop to run my new astro camera as my old one is rapidly grinding to a halt! So I will definitely be setting up the red night vision mode on it. I used to have a 32 bit program that did that automatically under Win 7 when run.

 

Does your setup also set extension screens up in red mode as well?

   Sort of off-topic in this thread thread but it is your thread... Yes my club does quite a bit of outreach. We work with area schools, the local university, and one of the local cities to hold star parties for the public. It is a lot of fun and very rewarding also.

 

   Regarding setting up Windows 10 for Night Vision mode, some things have changed a bot since the tutorial was written. The latest Windows update moved a few options around and eliminated others but the basic idea still works well. I will have to find time to update the tutorial to match Windows' new way of using themes. I have never tried the Night Vision mode on multiple monitor systems but since it uses the basic Windows Theme constructs, it should work the same on all screen simultaneously.

 

 

   I can dive into specifics on getting the most out the camera once Luca starts his thread. In the meantime, here is a sample from a recent project to image the planetary nebula NGC6781 in Aquila. This was just over eight hours of imaging time from bright suburban skies measured at ~18.75 mpsas. I used my ASI294MC-Pro camera at Gain=200, Offset=30, Temp=0°C with 60 second sub-exposures. The data is better than it looks as I need to improve my processing skills more to get all the camera has offered me.

 

NGC6781_g200_o30_0c_486x_060sec_Full.jpg

Full Frame: 8+ Hours on NGC6781 with ASI294MC-Pro

 

 

NGC6781_g200_o30_0c_486x_060sec_100pctCrop.jpg

100% Crop of Frame: 8+ Hours on NGC6781 with ASI294MC-Pro

 

   I am currently working on another imaging project from my light polluted back yard. This will for a galaxy group in Aquarius. I currently have 14 hours of data and am shooting for about 20 hours before I call it done. Once again, the camera has outdone my ability to process the data and bring out all the details.

 

 

John



#19 iandh2010

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Posted 09 September 2019 - 11:12 AM

Hi John,

Yes sorry for the off-topic but wanted to catch you while I could! Sounds very similar to what we do  at MKAS.

 

Yes Luca, can you please let us all know when you start your new thread please, as I will certainly need to learn ASAP, if I do decide to get the ASI294MC!



#20 lucam

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Posted 09 September 2019 - 11:55 AM

Hi Marcus and Luca,

So is this a known problem with the 294MC Pro and how bad is it?

 

I thought that the DDR3 RAM was supposed to cure the amp glow problem?

 

Oh boy, I was literally just about to purchase the 294MC when I saw your comments, now I'm not so sure!

 

Just how bad is this problem????

Ian, I am not trying to discourage you from the 294MC as many people are creating wonderful images with it. 

 

Amp glow is something that is quite common among most CMOS sensors. Some sensors have more severe amp glow pattern than other. For example, the ASI1600MM Pro even with 8 minute exposures at unity gain has very mild amp glow. The ASI183MM Pro on the other hand has a much more severe star-burst pattern that calibrates out nicely. 

 

With the ASI294MC Pro I have not been able to successfully remove all amp glow with dark calibration, but it may be my mistake. It's possible that I started collecting dark frames too soon and now wait long enough for the sensor to equilibrate. 

 

I think it's fair to say that there are easier and more forgiving cameras to use but I am not claiming that good data cannot be generated from the ASI294.



#21 jgraham

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Posted 09 September 2019 - 12:16 PM

I have two ASI294MC Pros (odd story how I ended up with 2 of them) and the uncooled ASI294MC. Ugh, I once did a resolution test on the moon using my ASI294MC Pro, ASI071MC Pro, and ASI1600MM-c v3 expecting the 1600MM to come out on top as I was planning on migrating the 1600MM over to lunar imaging. Much to my surprise the ASI294MC Pro actually produced the sharpest images. One of these days I want to do another test, but for now the ASI294MC Pro has become my primary high resolution lunar camera. I still want to test it with planetary, but I have not hade a chance to try this yet.

 

Bit-wise, yep, 14 bit ADC. That coupled with deep wells is a great combination.

 

The only complaint that I have about the ASI294MC Pro is that it has proven to be such a nice camera that I tend to use it more than my ASI071MC Pro.  I still like my 071 when I want to go as wide as I can, but the 294 is such a solid performer, is a little lighter and smaller than the 071, and cools a bit better that it has become my primary camera.

 

Binning-wise, you really can't hardware bin a color camera. Even those that offer on-camera binning are really doing it in firmware after the data has been read from the chip. I software bin my images in Nebulosity and that has worked fine for me. 

 

John; love the picture of NGC6781! I do all of my imaging from my Bortle 8 backyard where my lensed SQM is typically 18.5 mpsas and I have gotten similar results on this lovely little planetary. Nicely done!

 

Food for thought...


Edited by jgraham, 09 September 2019 - 12:20 PM.

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#22 mewmartigan

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Posted 09 September 2019 - 12:53 PM

Hi Marcus and Luca,

So is this a known problem with the 294MC Pro and how bad is it?

 

I thought that the DDR3 RAM was supposed to cure the amp glow problem?

 

Oh boy, I was literally just about to purchase the 294MC when I saw your comments, now I'm not so sure!

 

Just how bad is this problem????

Hi Ian,

 

I wouldn't call it a problem, just a recommended way of doing things. I have no problems at all calibrating out the amp glow (which occurs on almost all CMOS cameras) and I think the results I get from the camera a great. I am very happy with it and wouldn't hesitate to recommend it. In regards to calibration frames, I had read a few things online and just followed them so I have no idea if my results would be the same or worse using bias frames and less than 1 second flats. I found what worked and just stuck with it.



#23 jgraham

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Posted 09 September 2019 - 01:33 PM

To be honest I forgot all about the amp glow. The only time I see it is when I goof and apply the wrong set of darks. For me, calibration cleanly removes the rather interesting looking amp glow.
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#24 iandh2010

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Posted 09 September 2019 - 03:53 PM

Hi All,

I don't want to go off-topic so can anyone point me to a CN thread or other weblink, that deals with image capture and processing when using the ASI294MC?

 

I am a pretty seasoned Astro-Imager with around 12 years experience on CCDs. I am used to accurate collimation (SCT!), fine focusing, Lights, Darks and Flats, then calibrating the image and final tweaking in Photoshop! But, it sounds like the ASI294 needs rather more!

 

I am off to La Palma in the Canaries for some imaging (hopefully) at 8000ft so I need to know what I should do special for the ASI294 to ensure that I capture some fantastic subs for post processing during the winter months back home?

 

I will most likely take the plunge on the ASI294MC Pro tomorrow but I am still open to any comment suggestions......

 

Thanks for all your help guys, I will of course, let you know the outcome!



#25 lucam

lucam

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Posted 10 September 2019 - 09:46 AM

I will eat some humble pie and say that I found what the problem was with my calibration. I had reused a sequence in SGP for shooting dark and bias frames and not realized that I has applied gain and offset settings for the ASI183 instead of the ASI294. The light and dark gain and offsets did not match and this was the cause of all the issues (including the flat mismatch, even though the flat master was good).

 

I reshot dark frames to match the lights and everything calibrates wonderfully. No issues with flats or residual amp glow. I just used BPP in PI for calibration without having to do anything special.


Edited by lucam, 10 September 2019 - 09:47 AM.

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