Dark frames

[geordie85]

I've ordered a qhy183m to accompany my qhy183c and I'm wondering if I'd be able to use the same dark frames from the qhy183c for the qhy183m? 

Not that it'll make too much difference if I need to make a new darks library as we get plenty of cloudy nights here. 

[vlaiv]

No, unless you want to end up with messed up calibration.

Each sensor is different in terms of bias and dark current. In part these are based on manufacturing defects / quirks of each chip and are a bit like finger print.

Some things in darks are general feature of the sensor line - like position/shape of amp glow, but each of individual sensors will produce slight variations in intensity / shape and that will cause problems with calibration.

[MarsG76]

I second that... I'd say no... different sensor, different age, color and mono will result in a different Dark frame pattern.

 

[geordie85]

I thought as much. 

Thanks for the confirmation 

[Adam J]

On 29/05/2019 at 14:52, geordie85 said:

I thought as much. 

Thanks for the confirmation 

I agree with the above but it might be interesting to try it and see the result. 

[geordie85]

On 30/05/2019 at 20:03, Adam J said:

I agree with the above but it might be interesting to try it and see the result. 

Well my camera arrived yesterday whilst I was at work. I put it on my flt98 earlier today and if the forecast remains true I'll be able to test it tomorrow. 

I'm not holding much hope for the forecast though. 

[ollypenrice]

If you want to see what the wrong darks do to your calibration you can try just rotating a master dark by 180 degrees, saving it and then applying it to a set of lights. It will make a mess.

Olly

[Adam J]

10 hours ago, ollypenrice said:

If you want to see what the wrong darks do to your calibration you can try just rotating a master dark by 180 degrees, saving it and then applying it to a set of lights. It will make a mess.

Olly

I was more interested in if the amp glow was idenitcal, it's a given that hot pixels etc will be in the wrong place. Just curiosity as in theory hot pixels and minor defects will be removed by dithering but amp glow will not be.

Edited June 1, 2019 by Adam J

[geordie85]

1 hour ago, Adam J said:

I was more interested in if the amp glow was idenitcal, it's a given that hot pixels etc will be in the wrong place. Just curiosity as in theory hot pixels and minor defects will be removed by dithering but amp glow will not be.

I will give it a go once manage to get an imaging session in, just for fun. 

Last night I managed to polar align, focus and get my spacing (almost) right (which happened to be on my first attempt) and four 10 second subs before clouds stopped play. 

 

[Adam J]

2 hours ago, geordie85 said:

I will give it a go once manage to get an imaging session in, just for fun. 

Last night I managed to polar align, focus and get my spacing (almost) right (which happened to be on my first attempt) and four 10 second subs before clouds stopped play. 

 

No need for imaging, just subtract one dark from the other and see whats left using identical settings.

[geordie85]

1 hour ago, Adam J said:

No need for imaging, just subtract one dark from the other and see whats left using identical settings.

I haven't taken any darks with the qhy183m yet. Busy at work. 

I will do when I get the chance though

[kirkster501]

What laptop is that please?

[geordie85]

19 minutes ago, kirkster501 said:

What laptop is that please?

Alienware m17 r2

[Adam J]

9 hours ago, geordie85 said:

Alienware m17 r2

Expensive laptop to damage with dew...take care. 

[geordie85]

6 hours ago, Adam J said:

Expensive laptop to damage with dew...take care. 

I do cover it when it's cold or I'm out doing a long imaging session. 

[alan potts]

Thats a great shame, the best thing I have ever seen is from Backyard Astronomer, a large plastic storage box turned on its side with holes for the cables.

Alan

[geordie85]

For those who are interested, it didn't work. It didn't take out the amp glow, but left it looking really weird, noise everywhere along with hot pixels and the image was a complete mess. 

It was interesting to try though.