ASI294MM Pro - binning issues

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Mike Hooper
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ASI294MM Pro - binning issues

#1

Post by Mike Hooper »

Hello,
I have been trying to se my ASI294MM pro (mono) CMOS camera with SharpCap Pro and am confused that the binning options in the dropdown menu in camera settings are 1x1 or 3x3. I was hoping to use 2x2. Can someone please explain why this does not seem to be possible? I use 2x2 binning quite successfully with this camera when imaging is managed with APT.
Thanks very much
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Re: ASI294MM Pro - binning issues

#2

Post by admin »

Hi,

the 294MM camera is a bit special - it has two modes

11 Megapixel
47 Megapixel

The 11 megapixel mode is a bit like 2x2 binning on the 47 megapixel mode, but not quite (for instance some important camera noise characteristics work differently to how they would in a true 2x2 binned mode).

For that reason, SharpCap makes the 2 modes available in a 'Read Mode' control, but limits the binning choices to avoid offering 2x2 binning in 47 megapixel mode, since for that you need to choose 11 megapixel mode.

In summary:

Mode SharpCap Binning Other software Resolution
47 M 1x1 BIn1 8288x5644
11 M 1x2 Bin2 4144x2822
47 M 3x3 Bin3 ~2762x1880
11 M 2x2 Bin4 ~2072x1410

cheers,

Robin
Mike Hooper
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Joined: Mon Mar 07, 2022 11:13 am

Re: ASI294MM Pro - binning issues

#3

Post by Mike Hooper »

Hi Robin, thanks for your answer. I'm still a bit confused. I am attaching a screenshot of the settings I used the other evening:
46 Megapixel, resolution 4144x2822, binning 1. Am I getting confused with cropping the image on the sensor with actual binning?
Sorry for the dumb question.
Regards,
Mike
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SharpCap panel screen shot binning question.jpg
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Re: ASI294MM Pro - binning issues

#4

Post by admin »

Hi Mike,

yes, for one reason or another (possibly related to switching between the different modes and resolutions) you have ended up in a crop situation there, showing only 50% of the extend of the sensor in each direction. To go back to the full image, you would need to select 8288x5644 in the resolution control.

cheers,

Robin
Mike Hooper
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Re: ASI294MM Pro - binning issues

#5

Post by Mike Hooper »

Hi Robin,
thanks and I think I get it now. I initially tried the full uncropped resolution in live stacking mode, but the download time seemed a little long. I am connecting the camera via the USB3 port of my laptop, but perhaps I need to adjust the USB speed (although high speed mode is already ticked)? Anyway I think the live stacking routine is incredible, thank you! I have struggled for a long time with another scope (C11 SCT) and equatorial mount (NEQ6) with auto-guiding (via OAG) and cannot stop some elongated stars at focal lengths above 1700mm (and working at f/10 as high as 2800). However with my 20" f/4 Alt/Az mounted "light bucket" Dobsonian with goto and motorisation but no autoguiding live stacking gives me a much better result. My first attempt is attached which I am quite pleased with given its small size.
Thanks very much.
Mike
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Re: ASI294MM Pro - binning issues

#6

Post by admin »

Hi Mike,

a great image - glad that you are getting some good results.

With the ZWO cameras, the 'high speed mode' option has no effect in 16 bit modes - it's really designed for ultra high frame rates (50fps +). You can try turning up the Turbo USB to improve the download speed, but it's also worth working out what your pixel scale is. With the long focal length and small pixels in 46megapixel mode, I suspect that you are oversampling the seeing in a big way - you may find that going back to the 11 megapixel mode helps both in terms of download speed and final image quality.

cheers,

Robin
Mike Hooper
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Re: ASI294MM Pro - binning issues

#7

Post by Mike Hooper »

Hi Robin,
I thought I was over-sampling. So for this focal length and pixel size you think I should be working on 11 megapixel mode either selecting binning 1 or 2 (which are the options that show up). What about changing the resolution? This doesn't impact on binnng, it just alters sensor cropping? Sorry to labour the point.
Kind regards,
Mike
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Re: ASI294MM Pro - binning issues

#8

Post by admin »

Hi Mike,

yes, at 2800mm, even in 11 megapixel mode you will be at about 0.33 arc seconds per pixel. At 47 megapixels you are down to about 0.17 arc seconds per pixel, which is heavily over sampled.

As you say, changing the resolution just crops in on a smaller part of the sensor, it does not change the effective pixel size. The pixel size is controlled by the read mode and binning controls.

I would say your best bet is 11 megapixel, bin 1. Only go to 11MP, bin 2 if you really need to because of performance issues.

cheers,

Robin
Mike Hooper
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Re: ASI294MM Pro - binning issues

#9

Post by Mike Hooper »

Hi Robin,
thanks very much!
Mike
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