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New ZWO mono camera on the way?


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13 hours ago, Deeko said:

Installed the beta SDK and APT could see the camera via the ASCOM driver. The default out-the-box gain setting was something strange like 127 with 76 offset. I changed it to 56 gain 10 offset. Can anyone tell me what the readMode settings are for? Screenshot attached. I am not a fan of tinkering with extra settings to be fair. Also USB readout speed, is 0 fast or is it the slowest in this case? 

Untitled.png

The read mode settings are those shown on QHYs website. For the vast majority of situations you will be best off using High gain mode, aka mode #1. 

Offset 10 works for my chip but if you find that you have any clipped (0 value) pixels in your bias or dark frames then you will need to increase it.

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It's a super camera, it would want to be for the price. I haven't noticed any issues since i started using it in January. Zero amp glow, no reflection problems and nice deep wells. The cooling works b

First light with Heart Nebula, 4 hours of SHO with  80mm TS scope and flattener. The full moon did not help at all but at least I got to image something and check guiding etc. (camera is seriously hea

Apparently the ASI2600MM mono is coming soon  

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50 minutes ago, Spongey said:

The read mode settings are those shown on QHYs website. For the vast majority of situations you will be best off using High gain mode, aka mode #1. 

Offset 10 works for my chip but if you find that you have any clipped (0 value) pixels in your bias or dark frames then you will need to increase it.

Can you change the gain for each read mode?  When I choose different read modes the gain doesn’t change, and I have to manually choose eg 56. 
 

Why is the high gain mode the best setting?

Thanks 👍🏻👍🏻

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47 minutes ago, Spongey said:

The read mode settings are those shown on QHYs website. For the vast majority of situations you will be best off using High gain mode, aka mode #1. 

Offset 10 works for my chip but if you find that you have any clipped (0 value) pixels in your bias or dark frames then you will need to increase it.

Excellent, I will do this tonight. I also had a read through related content on cloudy nights and seems a few use 56 gain 25 offset. Will have  a play around. I have had  a few hiccups, the main one of which was a 5.5-2.1mm 12v extender cable that worked with the 294MM suddenly stopped working when I plugged in the 268M, seems like the cable (unknown to me) was only rated at a max of 3A, replaced it with  a better one and all good. now My 268M came with a 12v 6A power supply which did surprise me. The 268M seems to draw around 2A when cooled to -10C, according to deductions with the voltage reading on my pocket Pegasus Powerbox.

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1 minute ago, tooth_dr said:

Can you change the gain for each read mode?  When I choose different read modes the gain doesn’t change, and I have to manually choose eg 56. 
 

Why is the high gain mode the best setting?

Thanks 👍🏻👍🏻

Dr Q. of QHY chimed in with this thread here on read modes: https://www.cloudynights.com/topic/754530-qhy268m-read-out-modes-questions/

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4 minutes ago, Deeko said:

Dr Q. of QHY chimed in with this thread here on read modes: https://www.cloudynights.com/topic/754530-qhy268m-read-out-modes-questions/

Thanks Deeko, good read  

Im confused by QiuHYs post, screenshot below. What settings is he suggesting for 2)?

I was collecting Lum a couple of nights ago with 180mm/F2.8 scope, so I’m falling into his 2) description 

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32 minutes ago, tooth_dr said:

Can you change the gain for each read mode?  When I choose different read modes the gain doesn’t change, and I have to manually choose eg 56. 
 

Why is the high gain mode the best setting?

Thanks 👍🏻👍🏻

Yes, the gain and offset are independent of the read mode.

Further info on each of the read modes is here.

In short, High gain mode (#1) provides the best combination of dynamic range, FWC and read noise for most users (gear and conditions). If you're shooting with really large aperture and / or in heavy LP, then you might benefit from extended full well mode, but as long as you're not clipping too many star cores and swamping the read noise, then mode #1 is fine.

For mode 1, there is an argument to only ever shoot at gain 56, but with LRGB in moderate light pollution you'll swamp the read noise at gain 0 within a couple of minutes anyway. Shorter exposures at gain 56 have benefits such as tracking errors etc., but will also take up ~3x the disk space as an equivalent SNR stack from gain 0. 

This is why when asked for a 'set and forget' mode, I suggest Mode #1, gain 56 and offset 10(ish). If you want to get into the details and really pull the best from your skies, gear and other limitations then reading more into the different modes might help you. 

Edited by Spongey
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3 hours ago, Spongey said:

Yes, the gain and offset are independent of the read mode.

Further info on each of the read modes is here.

In short, High gain mode (#1) provides the best combination of dynamic range, FWC and read noise for most users (gear and conditions). If you're shooting with really large aperture and / or in heavy LP, then you might benefit from extended full well mode, but as long as you're not clipping too many star cores and swamping the read noise, then mode #1 is fine.

For mode 1, there is an argument to only ever shoot at gain 56, but with LRGB in moderate light pollution you'll swamp the read noise at gain 0 within a couple of minutes anyway. Shorter exposures at gain 56 have benefits such as tracking errors etc., but will also take up ~3x the disk space as an equivalent SNR stack from gain 0. 

This is why when asked for a 'set and forget' mode, I suggest Mode #1, gain 56 and offset 10(ish). If you want to get into the details and really pull the best from your skies, gear and other limitations then reading more into the different modes might help you. 

Thanks. Great resource page. I’m going to see what other fast scope users are doing 👍🏼

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Argh!

I made my BF calculations based on 12.5mm as in the spec.

However

Reading closely the mechanical drawings and the QHY blurb it's actually 14.5mm from the top, which is where the M54 adaptor attaches.

Bother.

I wondered why my focus was off after swapping the ASI 1600 out for the QHY 268 and using the same reducer which should have the same BF. My corner stars were elongated too, which was a clue that something was wrong.

Fortunately I have a TS "Massive Variable 48mm Extension", so will just mean swapping assorted adaptors and extension rings. Still a pain with the weather.

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On 12/02/2021 at 13:43, Spongey said:

Yes, the gain and offset are independent of the read mode.

Further info on each of the read modes is here.

In short, High gain mode (#1) provides the best combination of dynamic range, FWC and read noise for most users (gear and conditions). If you're shooting with really large aperture and / or in heavy LP, then you might benefit from extended full well mode, but as long as you're not clipping too many star cores and swamping the read noise, then mode #1 is fine.

For mode 1, there is an argument to only ever shoot at gain 56, but with LRGB in moderate light pollution you'll swamp the read noise at gain 0 within a couple of minutes anyway. Shorter exposures at gain 56 have benefits such as tracking errors etc., but will also take up ~3x the disk space as an equivalent SNR stack from gain 0. 

This is why when asked for a 'set and forget' mode, I suggest Mode #1, gain 56 and offset 10(ish). If you want to get into the details and really pull the best from your skies, gear and other limitations then reading more into the different modes might help you. 

Would you mind posting an image of your histogram for a dark frame please? I am tinkering with the offset value and wondered what other folks histograms look like.. Hoping to build out a darks library asap.

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11 hours ago, Deeko said:

Would you mind posting an image of your histogram for a dark frame please? I am tinkering with the offset value and wondered what other folks histograms look like.. Hoping to build out a darks library asap.

I'm afraid I'm away from my pc for a few days but I can tell you that the histogram is just off the left side. The best way to check if you're clipping values is to use a tool that will tell you the minimum pixel value of a bias / dark frame. PixInsight has a tool that will do this called 'statistics' if you use it.

The minimum value will vary by a few tens of ADU per frame based on noise, so as long as you don't clip any pixels in ~50 different frames you're safe. I think the minimum I saw in all my darks and bias frames was 27 ADU. This is cutting it a little close but fine for my chip. If you're concerned and just want to set and forget then choose an offset value of ~20 and forget about it.

It's worth noting that if you're taking narrowband subs then you may need to add a pedestal of ~200 ADU (or just over the average of a bias/dark frame at your offset) to your frames during calibration to avoid clipping when subtracting the dark / bias frame from your light. This shouldn't be an issue with LRGB as your noise floor will be much higher.

Edited by Spongey
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Thanks for the info! I am still tweaking atm attached are the stats for two 60sec darks at 56 gain 10 offset and 56 gain 20 offset, both in readmode 1 (high gain). I had to zoom in a bit on the histo to see the peak as it was v.close to the left. Is it normal for darks to have quite a long tail to the right of the curve? Top image is 20 offset, bottom is 10.

histo-20.JPG

histo-10off.JPG

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44 minutes ago, Deeko said:

Thanks for the info! I am still tweaking atm attached are the stats for two 60sec darks at 56 gain 10 offset and 56 gain 20 offset, both in readmode 1 (high gain). I had to zoom in a bit on the histo to see the peak as it was v.close to the left. Is it normal for darks to have quite a long tail to the right of the curve? Top image is 20 offset, bottom is 10.

histo-20.JPG

histo-10off.JPG

Looks good, and yes it is normal for darks to have a long tail as you say, this is due to hot pixels / dark current etc.

Your chip looks similar to mine, in that offset 10 should be fine. I'd double check a fair few frames though to make sure none of your pixels are clipping at zero.

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On 14/02/2021 at 11:38, Spongey said:

Looks good, and yes it is normal for darks to have a long tail as you say, this is due to hot pixels / dark current etc.

Your chip looks similar to mine, in that offset 10 should be fine. I'd double check a fair few frames though to make sure none of your pixels are clipping at zero.

All well so far! Moving onto flats. For my 294MM I was using an ADU value of 24000 for flats, what are you using for yours? 

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1 hour ago, Deeko said:

All well so far! Moving onto flats. For my 294MM I was using an ADU value of 24000 for flats, what are you using for yours? 

Glad to hear it :)

A value approx. 40-50% of the max ADU is a good place to aim, so 24000 is fine.

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  • 2 weeks later...

Only just getting first light with the 268m tonight! I am having some issues with getting all white images intermittently  using APT with latest beta drivers. It can happen at any exposure length. Not sure if it's a driver or APT issue. I may consider switching to NINA if it carries on as the dev of NINA seems very reactive with QHY drivers.

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5 minutes ago, Deeko said:

Only just getting first light with the 268m tonight! I am having some issues with getting all white images intermittently  using APT with latest beta drivers. It can happen at any exposure length. Not sure if it's a driver or APT issue. I may consider switching to NINA if it carries on as the dev of NINA seems very reactive with QHY drivers.

That's an odd one. Have you opened the images in another program you can stretch them such as PI to check.
I am using KStars on Linux and have had a few issues (my first try out tonight too) with KStars crashing and sometimes I have had very funny images (one was all white) in the Fits viewer KStars displays after each image has saved but when I opened them they were fine.

My viewing is pretty poor with cloud all around so probably will not get any useful data but it has been worth trying the camera out anyway.

Steve

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Has anyone else had an ASCOM Gain / Offset window pop up in their capture software? i have it in Maxim and posted a thread about it.

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6 hours ago, DaveS said:

Has anyone else had an ASCOM Gain / Offset window pop up in their capture software? i have it in Maxim and posted a thread about it.

No, not had this with APT. I did get a full run last night of 4 hours with no issues though. imaged heart nebula under the full moon. There are minor bugs in APT like if I disconnect camera to go into settings the cooling values are not recognised and need to close the cooling window. Also histogram in APT does not play well at all with the camera images, keeps changing and never gets it right unless I manually set it. I am getting 50mb fits images from camera, I am not 100% sure if the heart nebula images are binned 1x1 as when I opened the ascom settings today is was set at 2x2. Can anyone confirm the sizes of their images from the camera in both bin modes?

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9 hours ago, Deeko said:

No, not had this with APT. I did get a full run last night of 4 hours with no issues though. imaged heart nebula under the full moon. There are minor bugs in APT like if I disconnect camera to go into settings the cooling values are not recognised and need to close the cooling window. Also histogram in APT does not play well at all with the camera images, keeps changing and never gets it right unless I manually set it. I am getting 50mb fits images from camera, I am not 100% sure if the heart nebula images are binned 1x1 as when I opened the ascom settings today is was set at 2x2. Can anyone confirm the sizes of their images from the camera in both bin modes?

My images in bin 1x1 are 51000kb. I am yet to use bin 2x2 and don't ever see myself using it to be honest

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First light with Heart Nebula, 4 hours of SHO with  80mm TS scope and flattener. The full moon did not help at all but at least I got to image something and check guiding etc. (camera is seriously heavy!). I need to adjust the back focus, currently at 55mm. Though setup is getting stripped down again to fit a 115mm apo sometime next week. Happy with the results so  far and look forward to trying more targets without the moon. Some images attached. Roughly processed image in Photoshop and stacked and stretched Ha image.

v2.png

heart-Hydrogen-alpha-St.png

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Hard to believe, but two clear nights in a row in UK, of course with an obligatory full moon 😕 I managed another 4 hours, this time on the soul nebula. Always struggle with processing this target. Safe to say, aside from some minor glitches (setting up, before starting an image plan) the camera seems to be able to do a full image run in APT without any issues. probably be next year again before we get another clear night in the UK, will buy whatever new camera is available at the time for the occasion :)

v1.png

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5 hours ago, teoria_del_big_bang said:

Another nice image, but I really like the heart image. I always struggles with getting anything worthwhile on SII or OII with that target but yours has grat colours.

Steve 

There a are a few tips I have picked up along the way, first one is here for applying selective colour in Photoshop: http://bf-astro.com/hubblep.htm. The other is here is you use Pixinsight (for reducing green and bringing out the cyan/gold): https://www.youtube.com/watch?v=v6GHqYyyHg8&ab_channel=Chuck'sAstrophotography I am a big fan of quick wins/fixes, barely have any time for astro so what time I do have needs to be spent wisely and not wading through massive tutorials :)

 

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