Master Dark won’t add to lights. Version 56

Hi Miquel (@mcbbcn),

Thank you for your question and welcome to the forum.

If the Master Dark won't be added to the light, then the masterdark doesn't match the light frames for either ISO/gain and/or exposure time. This is currently a requirement in APP. (Which I will remove soon in upgrading the calibration engine). The reason is that currently, APP doesn't yet support dark frame scaling. (Which will come in the future upgrade)

What ISO/gain and exposure time do your light frames and your dark frames have? Is it the same or not?

Kind regards,

Mabula

Hi Mabula,

I’m using a QHY8L Color CCD and the lights are 300 seconds and the darks are 150 seconds. I had not issues calibrating these darks with these lights in other software programs.  Regarding ISO/Gain, I can’t tell but I will look into it. I basically took my darks and lights I had used to process the image in other software packages and use it with this one to see how it compared. If I can find gain values, I will share them.

Best

@mcbbcn,

Yes, okay, the exposures don't match for your lights and darks so that's the reason the masterdark isn't added to the lights. In a future version it will, but for now, this is a restriction in APP because it doesn't do Dark frame scaling yet .

But having said that, If you need to calibrate data it's always best to match the calibration frames as good as you can to the frames to be calibrated off course (practical issues aside) 😉

I intend to upgrade APP's calibration engine in APP 1.060 so then it should be possible I think...

Cheers,

Mabula

Posted by: Mabula Haverkamp - Admin

@mcbbcn,

Yes, okay, the exposures don't match for your lights and darks so that's the reason the masterdark isn't added to the lights. In a future version it will, but for now, this is a restriction in APP because it doesn't do Dark frame scaling yet .

But having said that, If you need to calibrate data it's always best to match the calibration frames as good as you can to the frames to be calibrated off course (practical issues aside) 😉

I intend to upgrade APP's calibration engine in APP 1.060 so then it should be possible I think...

Cheers,

Mabula

Hi, I saw you are preparing for version 1.60.  Will this version include Dark scaling?

Indeed, I am working now on a big upgrade for the calirbation engine to make calibration simpler for the user by making APP smarter 😉

Dark scaling is indeed part of that.

Cheers,

Mabula

Hi Mabula,

Thanks for validation. I’m not sure it’s possible to get a trial extension as I have not been able to successfully process an image with my data but it sounds like version 60 should allow for that. My trial expires in 4 days. Do you think I will be able to extend the trial so I can test version 60 when it comes out?

best,

I have read on other forums that you should not use dark scaling for this camera. The amount of amp glow is fixed, not proportional to the duration of the image taken.
Because of this, you can not use dark scaling.  However, if you don't have darks and lights that match, you can try testing APP without darks but make a Bad Pixel Map and use that instead. Should be good for a test and let you get a feel for this system. 

If the version of APP that has dark scaling included allows you to turn off dark scaling but still use mismatched darks and lights that will work for you as the thermal noise is so low with this camera it hardly matters if the times don't match. Just don't use dark scaling.

Posted by: mcbbcn

Hi Mabula,

Thanks for validation. I’m not sure it’s possible to get a trial extension as I have not been able to successfully process an image with my data but it sounds like version 60 should allow for that. My trial expires in 4 days. Do you think I will be able to extend the trial so I can test version 60 when it comes out?

 

best,

Hi @mcbbcn,

Sure, no problem 😉 just contact me using e-mail (support@astropixelprocessor.com) or with private messaging about this when you want to restart the trial. APP 1.060 is in the making, but it will take a week or 2 at least before it will be released.

Cheers,

Mabula

Posted by: Tim

I have read on other forums that you should not use dark scaling for this camera. The amount of amp glow is fixed, not proportional to the duration of the image taken.
Because of this, you can not use dark scaling.  However, if you don't have darks and lights that match, you can try testing APP without darks but make a Bad Pixel Map and use that instead. Should be good for a test and let you get a feel for this system. 

If the version of APP that has dark scaling included allows you to turn off dark scaling but still use mismatched darks and lights that will work for you as the thermal noise is so low with this camera it hardly matters if the times don't match. Just don't use dark scaling.

Excellent, thanks for the information @tim 😉

What I will do, in APP 1.060, you will be able to just apply a masterdark of not-matching ISO and/or exposure time (unlike currently) and choose to use dark scaling or not.

Dark scaling makes life easier, but an issue like strong amp glow is indeed something that is very hard to fix. Scaling assumes that different signals in the darks still behave linearly, and some signals, like amp glow tend to follow other rules 😐 So if you have such a camera, making accurate darks that match for temperature and exposure is rather important if you want to achieve optimal calibration. The short cut that dark scaling gives is not always an optimal option for this reason. It really depends on the camera's sensor characteristics and the quality and complexity of a dark scaling algorithm.

Mabula

Hi @Mabula,

Thank you, I appreciate the direction.

Best,

Miquel

😉