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Hi, I have a zwo 482 camera which is only camera I can afford at the moment I use it with the asiair, could I create a library of darks with this camera and also can the temperature be a few degrees?
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A couple of degrees shouldn't matter too much.
You can create a library, but you may have to create several master darks to match different temperatures, it depends on how stable the ambient temps are in your location.
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Jan Erik Vallestad:
A couple of degrees shouldn't matter too much.
You can create a library, but you may have to create several master darks to match different temperatures, it depends on how stable the ambient temps are in your location.
Do I just take darks like what I do normally to create a library? Just stacking several sets of darks in master frames?
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Yes, do one set and if the temperature changes more than a few degrees from one night to another, make a new one. Chances are you will be covered before too long. The camera still record temps, so should be easy enough to keep track 
Then you just pick the one that is within a couple degrees when you need them.
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Jan Erik Vallestad:
Yes, do one set and if the temperature changes more than a few degrees from one night to another, make a new one. Chances are you will be covered before too long. The camera still record temps, so should be easy enough to keep track
Then you just pick the one that is within a couple degrees when you need them.
Would u say whatever darks or master darks I take do not delete them? Keep them if I need to shoot new darks then keep doing it till I get atleast about 10 different temperatures or something?
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Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
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Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
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True, I have none so from May to September there's no activity here. The past week temps have been shifting from -15 to +6 degrees as well.
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Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
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I was never able to calibrate properly with that camera, incidentally. I think it was due to the bonding wires reflecting too much light pollution.
I am not saying it's a general problem, because I have seen great pictures taken by others. Perhaps just my location. But it was a very real problem for me, that I didn't have with the 178MC or the (Omegon) 533.
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Arun H:
Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
Does temperature of darks matter for eaa? If you're just live stacking and not bothering processing or restacking the data?
Arun H:
Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
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Connor Bradley:
Arun H:
Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
Does temperature of darks matter for eaa? If you're just live stacking and not bothering processing or restacking the data?
Arun H:
Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
Would dark frames matter if you done short 30 minutes sessions on just say double stars or star clusters? Since the temperature not change much in 30 minutes plus star clusters don't need long periods of long intergration time anyway.
Connor Bradley:
Arun H:
Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
Does temperature of darks matter for eaa? If you're just live stacking and not bothering processing or restacking the data?
Arun H:
Connor Bradley:
Jan Erik Vallestad:
Something along those lines. Delete the dark single exposures and keep the master file, then make new ones if the read temp suggests so. I think 1-2 degrees is neglible at least. Maybe even more. But yeah, if ambient temps are stable you should be covered relatively quickly.
The way I see it is the only time darks is big issue is theirs a huge difference in temperature between summer and winter in the UK so I may need new darks for summer anyway, not like I do much imaging in summer anyway as theirs only like 2 hours of true darkness anyway.
Keep in mind that dark current varies exponentially with temperature. So, for example for the 2600 MC Pro, a 5 C temperature difference doubles the dark current. The purpose of dark frame subtraction is to eliminate mean/baseline dark current response differences between pixels that are additive in nature. And dark frame subtraction actually increases random noise, though this is a small contribution compared to other sources of noise and benefits of mean dark current subtraction usually outweigh the downsides of the addition of a small amount of random noise. But this is only true if the darks match lights in time and temperature.
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Those cameras record sensor temperature so it is not so difficult to create dark library with master darks for every 5 degrees or whatever granularity you are happy with and then match them with your lights. Just tedious.
In EAA you cannot do that and in my opinion it would be completely pointless. You are not after faint detail there. You are after things at least ten times brighter than whatever noise is there. And subs are short, meaning dark current does not reach significant levels.
It is more akin to planetary (where the camera excels). And dark current is almost never considered there.
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Those cameras record sensor temperature so it is not so difficult to create dark library with master darks for every 5 degrees or whatever granularity you are happy with and then match them with your lights. Just tedious.
In EAA you cannot do that and in my opinion it would be completely pointless. You are not after faint detail there. You are after things at least ten times brighter than whatever noise is there. And subs are short, meaning dark current does not reach significant levels.
It is more akin to planetary (where the camera excels). And dark current is almost never considered there.
Yeah I mainly do eaa rather than serious astrophotography so I should be fine getting darks close as I can? I keep my sessions short anyway.
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I think the point being made is that you don't need darks at all for EAA.
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