So Daniel, I would say ZWO highly recommends an offset for your camera of 50 and Gain settings of, 0 for bright objects, 100 for most objects and from my experience I can tell you that use of a filter requires a gain of al least 100 and often much much higher.
Also set your sensor cooling to -10 and leave it there year round.
Yes, I use gain 100, and I use an IDAS LPS D3 with that gain. The offset I showed you from value 1 is that one that NINA put on its own. I haven't configured anything but gain (for the very first time and I don't touch it anymore) and temperature, always set it to -10ºC.
But there's a lot of people giving comments on the pictures, trying to see histograms, telling I don't know what kind of technical things that newbies like me with that camera need to ask for the parameters in order to know if I was doing any kind of sacrilege.
I just configure the exposition time, and usually I'm in most cases in 300 seconds with the filter. And the histogram is not clipped as I showed you in the first post of this thread.
So, I'll llet all in gain 100, offset 1 (NINA gave that value) and -10ºC. And then just I'll decide the exposure time for each deep space object.
Thanks and clear skies!
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Rick Veregin:
Just to add one point to this discussion. In setting offset you want to set it so that you are not clipping your DARKS, not your lights. If you clip your darks then you will not properly subtract the noise from your lights. ZWO uses offset 50 (which actually gives you 500 adu offset) with gain 100. For higher gain you must increase the offset--for example I use offset 150 (gives 1500 adu offset) for 350 gain, which doesn't substantially clip my darks. Note in setting the offset on your dark there may possibly be dead pixels that register zero no matter what, so don't kill yourself with huge offsets to try to get rid of 0.2% dark pixels.
Hi @Rick Veregin,
That's a new point for me. I thought that clipped histogram was in lights cause in darks always were in the Y axis. So, my thoughts were wrong, isn't it?
I've opened a dark frame with ASIFitsViewer and the histrogram is clipped. Here yes it is.
Now, what I've to do? Essay to find a value in which the histogram were not clipped but just begin to jump very close to the Y axis? Maybe the values of 18 or 20 or may that 50 that ASIAIR seems to set as default value.
Thank you I was convinced that the histogram were in lights  |
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Thanks for raising this @Daniel Arenas. It has made me analyse my camera a little more closely. I have been using my 2600 with a bias of 50 - I think because I read a few posts recommending that value. But I have now investigated more thoroughly to see what the offset actually should be.
Set to offset 0 the camera reports a minimum pixel value of 0
So I then shot 20 bias frames at gradually increasing offset settings and integrated them using a minimum value method and measured their lowest pixel value.
What I found is that an offset of 5 produces a min pixel value of 0.0006 (which is >0) so it's actually not necessary to go to any higher offset.
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Stuart Taylor:
Set to offset 0 the camera reports a minimum pixel value of 0
So I then shot 20 bias frames at gradually increasing offset settings and integrated them using a minimum value method and measured their lowest pixel value.
What I found is that an offset of 5 produces a min pixel value of 0.0006 (which is >0) so it's actually not necessary to go to any higher offset.
Oh! Excellent @Stuart Taylor !
That's the test I wanted to do next days. But maybe I can use your value to see if, for me, it's OK too. I say that because I've read that it doesn't matter if the model and make of a camera is the same, it depends on the sensor and there aren't two sensors identical.
PD: I'm not any kind of expert, I just reproduce what I've read in forums, or I've seen in videos.
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Daniel Arenas:
Stuart Taylor:
Set to offset 0 the camera reports a minimum pixel value of 0
So I then shot 20 bias frames at gradually increasing offset settings and integrated them using a minimum value method and measured their lowest pixel value.
What I found is that an offset of 5 produces a min pixel value of 0.0006 (which is >0) so it's actually not necessary to go to any higher offset.
Oh! Excellent @Stuart Taylor !
That's the test I wanted to do next days. But maybe I can use your value to see if, for me, it's OK too. I say that because I've read that it doesn't matter if the model and make of a camera is the same, it depends on the sensor and there aren't two sensors identical.
PD: I'm not any kind of expert, I just reproduce what I've read in forums, or I've seen in videos.
I was surprised that only an offset of 5 makes a measurable difference to the min pixel value. So I have been using far too high a value for quite a long time. For me it only needs to be 5
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I typically us a gain of 100 and an offset of 20. Temp of 20f. Simply a beautiful camera.
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Daniel Arenas:
Rick Veregin:
Just to add one point to this discussion. In setting offset you want to set it so that you are not clipping your DARKS, not your lights. If you clip your darks then you will not properly subtract the noise from your lights. ZWO uses offset 50 (which actually gives you 500 adu offset) with gain 100. For higher gain you must increase the offset--for example I use offset 150 (gives 1500 adu offset) for 350 gain, which doesn't substantially clip my darks. Note in setting the offset on your dark there may possibly be dead pixels that register zero no matter what, so don't kill yourself with huge offsets to try to get rid of 0.2% dark pixels.
Hi @Rick Veregin,
That's a new point for me. I thought that clipped histogram was in lights cause in darks always were in the Y axis. So, my thoughts were wrong, isn't it?
I've opened a dark frame with ASIFitsViewer and the histrogram is clipped. Here yes it is.
Now, what I've to do? Essay to find a value in which the histogram were not clipped but just begin to jump very close to the Y axis? Maybe the values of 18 or 20 or may that 50 that ASIAIR seems to set as default value.
Thank you I was convinced that the histogram were in lights
Assuming you are at gain 100, bias 50 is fine. But no need to take me word for it, and for dim targets or with a narrow band filter, you will want to run your gain as high as possible, do good to know how to set things up properly.
All you need to do is run your dark at higher offset and see where you move away from zero on the X axis. One thing to note, it is a problem if your offset is set too low. It is not a big deal if your offset is set a little too high. The only thing you lose with a higher offset is dynamic range. However, even when I need to set offset to 150 for a 350 gain, that is only 1500 ADU actual offset. So by setting the offset this high I loose about 1500 adu from my total dynamic range, but since it is a 16 bit capture, that is only 1500 out of 65,535 adu total, which is negligble. So just experiment with a few darks at different offset and choose something that is away from the left side, so that there is little if any Y value at X=0.
Rick
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Hi Daniel,
I use gain 100 offset 50. Temp at -5C in the summer, in North Carolina it struggles to get below that and -10 to -20 C in the winter,
Binning 1 X 1.
Steve A.
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Hi all,
Newish to the 2600 MC Pro, but had great success with it. I set the gain to 100 and offset 50. Temp is -10 in summer and -15 in winter. As I understand it the main thing with temp is to keep it low and consistent from sub to sub, so I try and keep it away from having to operate the cooling at max, and maybe having some over temps. I hear the discussion about setting the gain to zero for bright objects but for me noise is generally most obvious in the darker areas of the frame, away from the target, so I will generally go for the gain that gives me the best trade off between Dynamic Range and noise.
If anyone is interested in a full discussion of all these parameters and the issues there is a great series of articles on cloudbreakoptics.com. First article in the series here:
https://cloudbreakoptics.com/blogs/news/astrophotography-pixel-by-pixel-part-1
Cheers
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Rick Veregin:
All you need to do is run your dark at higher offset and see where you move away from zero on the X axis. One thing to note, it is a problem if your offset is set too low. It is not a big deal if your offset is set a little too high. The only thing you lose with a higher offset is dynamic range. However, even when I need to set offset to 150 for a 350 gain, that is only 1500 ADU actual offset. So by setting the offset this high I loose about 1500 adu from my total dynamic range, but since it is a 16 bit capture, that is only 1500 out of 65,535 adu total, which is negligble. So just experiment with a few darks at different offset and choose something that is away from the left side, so that there is little if any Y value at X=0.
Rick
But yo do that with darks or with bias frames? @Rick Veregin did it with bias frames (if I'm not wrong). I've read in the Net that if bias frames are well "exposed" with offset value in order not to clip the histogram, then the darks histograms will be not clipped to. That's a thing to test next days.
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Asiair user here so no offset setting available. Always use gain 100, -10 deg in summer, -15 rest of year. Had to clean cooler pad oil off my sensor soon after I first got camera but its been fine since then, and was easy to clean since I'd successfully cleaned other sensors before. I'm imaging right now here in New Zealand. Target is GUM 39 nebula in the southern sky, with a C11 Edge HD /reducer at f/7 and 1960 mm focal length, Optolong L-Extreme dual band narrow band filter as it's almost a full moon tonight, 3 min unguided exposures on a 10Micron GM100 HPS mount. Capturing with Asiair Plus and watching the captures from warmth of house on a winter night.
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Daniel Arenas:
Stuart Taylor:
Set to offset 0 the camera reports a minimum pixel value of 0
So I then shot 20 bias frames at gradually increasing offset settings and integrated them using a minimum value method and measured their lowest pixel value.
What I found is that an offset of 5 produces a min pixel value of 0.0006 (which is >0) so it's actually not necessary to go to any higher offset.
Oh! Excellent @Stuart Taylor !
That's the test I wanted to do next days. But maybe I can use your value to see if, for me, it's OK too. I say that because I've read that it doesn't matter if the model and make of a camera is the same, it depends on the sensor and there aren't two sensors identical.
PD: I'm not any kind of expert, I just reproduce what I've read in forums, or I've seen in videos.
I ran the test at offset values of 0, 5, 10, 20 and 30
Daniel Arenas:
Rick Veregin:
All you need to do is run your dark at higher offset and see where you move away from zero on the X axis. One thing to note, it is a problem if your offset is set too low. It is not a big deal if your offset is set a little too high. The only thing you lose with a higher offset is dynamic range. However, even when I need to set offset to 150 for a 350 gain, that is only 1500 ADU actual offset. So by setting the offset this high I loose about 1500 adu from my total dynamic range, but since it is a 16 bit capture, that is only 1500 out of 65,535 adu total, which is negligble. So just experiment with a few darks at different offset and choose something that is away from the left side, so that there is little if any Y value at X=0.
Rick
But yo do that with darks or with bias frames? @Rick Veregin did it with bias frames (if I'm not wrong). I've read in the Net that if bias frames are well "exposed" with offset value in order not to clip the histogram, then the darks histograms will be not clipped to. That's a thing to test next days.
I used bias frames
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a very good dicussion here and very informative.
My experience with the 2600MC is very positive regarding the setting which is not very critical in a wide range.
Normally I run my scopes with the AsiAir Pro so no way to influnce the offset value.
Regarding the gain I guess the DR must be considered in context of stacking.
It's true that the DR is lower at Gain 100 but doesn't really effect the stacked image since the DR increases with the number of stacked images.
Background limitation and
So for me is no need to change the gain. A comparison between different settings (gain 0/100 - cooling 0..-20°C) on the same target and almost same conditions shows no visible difference in the DR or details of the final image. Image processing might be the bigger problem  |
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I used to do gain 0 for broadband and 100 for narrowband but for the last year or so I've just stuck with 100/40 at all times. HGC lowers read noise with very little penalty to DR and since my subs never exceed 180s the loss in FWC is irrelevant.
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Daniel Arenas:
Rick Veregin:
All you need to do is run your dark at higher offset and see where you move away from zero on the X axis. One thing to note, it is a problem if your offset is set too low. It is not a big deal if your offset is set a little too high. The only thing you lose with a higher offset is dynamic range. However, even when I need to set offset to 150 for a 350 gain, that is only 1500 ADU actual offset. So by setting the offset this high I loose about 1500 adu from my total dynamic range, but since it is a 16 bit capture, that is only 1500 out of 65,535 adu total, which is negligble. So just experiment with a few darks at different offset and choose something that is away from the left side, so that there is little if any Y value at X=0.
Rick
But yo do that with darks or with bias frames? @Rick Veregin did it with bias frames (if I'm not wrong). I've read in the Net that if bias frames are well "exposed" with offset value in order not to clip the histogram, then the darks histograms will be not clipped to. That's a thing to test next days.
For a CMOS camera from my experience I recommend using dark frames for the lights and dark flats with the flats--so everything matches. If you do this do not use a bias as well. The dark includes the bias already. If you want to use just a bias for lights and flats that is your choice, a bit easier, but my experience is your flats will not work as well, and you won't do as good a job as darks for both lights and flats in reducing noise. So whatever you use bias, flat darks, or darks, ensure you are not clipping, very few pixecl counts on the Y axis at X = 0 on the left of the histogram.
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Daniel Arenas:
Rick Veregin:
All you need to do is run your dark at higher offset and see where you move away from zero on the X axis. One thing to note, it is a problem if your offset is set too low. It is not a big deal if your offset is set a little too high. The only thing you lose with a higher offset is dynamic range. However, even when I need to set offset to 150 for a 350 gain, that is only 1500 ADU actual offset. So by setting the offset this high I loose about 1500 adu from my total dynamic range, but since it is a 16 bit capture, that is only 1500 out of 65,535 adu total, which is negligble. So just experiment with a few darks at different offset and choose something that is away from the left side, so that there is little if any Y value at X=0.
Rick
But yo do that with darks or with bias frames? @Rick Veregin did it with bias frames (if I'm not wrong). I've read in the Net that if bias frames are well "exposed" with offset value in order not to clip the histogram, then the darks histograms will be not clipped to. That's a thing to test next days.
Curious do you use Bias or Dark Flats. I read somewhere that ZWO recommends Dark Flats with their cameras, so I have switched to Dark Flats.
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James R Potts:
Daniel Arenas:
Rick Veregin:
All you need to do is run your dark at higher offset and see where you move away from zero on the X axis. One thing to note, it is a problem if your offset is set too low. It is not a big deal if your offset is set a little too high. The only thing you lose with a higher offset is dynamic range. However, even when I need to set offset to 150 for a 350 gain, that is only 1500 ADU actual offset. So by setting the offset this high I loose about 1500 adu from my total dynamic range, but since it is a 16 bit capture, that is only 1500 out of 65,535 adu total, which is negligble. So just experiment with a few darks at different offset and choose something that is away from the left side, so that there is little if any Y value at X=0.
Rick
But yo do that with darks or with bias frames? @Rick Veregin did it with bias frames (if I'm not wrong). I've read in the Net that if bias frames are well "exposed" with offset value in order not to clip the histogram, then the darks histograms will be not clipped to. That's a thing to test next days.
Curious do you use Bias or Dark Flats. I read somewhere that ZWO recommends Dark Flats with their cameras, so I have switched to Dark Flats.
I use dark flats. The only time I use a master bias now is if my master dark doesn't match the exposure time of the lights. The master bias can then be used to 'optimise' the master dark to match the lights. Saves having to shoot a pile more darks on the occasions when you use an exposure time not in your library
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I set my camera at gain 100 and temperature at 0C most of the time and it works fine. It doesn't drain my field battery.
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Franz:
A comparison between different settings (gain 0/100 - cooling 0..-20°C) on the same target and almost same conditions shows no visible difference in the DR or details of the final image. Image processing might be the bigger problem
This kind of says it all for me and why I am fine with not messing with my settings. However, next time I shoot a galaxy, I may try 0 gain and 100 gain to see if I notice any difference.
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Group:
Just adding my 2-cents worth. When I first started using my 2600MC Pro last fall, I used the ZWO menu selection of "Lowest Read Noise" which resulted in a gain of 100. My images looked great. However, after several months, I came across an interesting comment on one of the various astro-imaging groups that recommended using gain Zero. I tried this, and like most of the above comments said, I didn't notice that much of a difference. However, after several more months using this setting, I have noticed ONE thing: with gain zero, the stars don't seem to be as over-saturated, and I am getting better, richer star colors.
I should mention that I image from a Bortle 3 site that averaged 21.4 or better with a SQM-L meter, and my subs usually run from 120 seconds to 240 seconds. As far as noise, in my experience there is no difference between the "Lowest Read Noise" setting and the "Highest Dynamic Range" (or Zero gain) setting.
I should also mention that I don't use darks, flats, or bias frames. This camera is so "quiet" that the extra fuss of doing this seem superflous.
Stargazer66207
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James R Potts:
Curious do you use Bias or Dark Flats. I read somewhere that ZWO recommends Dark Flats with their cameras, so I have switched to Dark Flats.
I use dark-flats, no bias, just because in my beginnings someone recommends me do in that way with the ASI2600MC Pro. I do not have any kind of objective information with charts and other data to sustain that.
Kind regards.
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I should also mention that I don't use darks, flats, or bias frames. This camera is so "quiet" that the extra fuss of doing this seem superflous.
But how do you do if you have dust motes in the sensor? Flat frames also have this purpose.
Greetings.
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Hi everyone,
Dark flats are most of the time useless.
I suggest to read the paper that Siril staff wrote on this
(Sorry this is the french page, I guess the english translation is somewhere in their website)
https://siril.org/fr/2021/12/stop-%C3%A0-la-mode-des-dark-flats/
In a nutshell, they only recommend darkflats for very long flats (over 10s) or for cameras with very strong ampglow.
So most of the time, a masterbias is suffiscient enough and you save a bit of processing time if you had produced one with your dark librairy.
Edit: Here is the english translation :
https://siril.org/2021/12/enough-with-dark-flats/ |
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Daniel Arenas:
But how do you do if you have dust motes in the sensor? Flat frames also have this purpose.
So far, I have been lucky. My sensor has no dust motes, or any other problems. Keeping my fingers crossed!!!
Stargazer66207
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I have both the ASI2600MC & the ASI6200MM and I use a gain of 100 and an offset of 50 with a temperature of -6. This seems to work well in all UK conditions that I experience.
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1.43
4.69
2.10
6.76
4.21
0.00
1.51
0.00
8.52
3.00
1.20
1.81
2.41
