Re: [MaxImDL] Question about Master Flats, Darks and Biases


Aug 18, 2004

 


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#13350 Aug 18, 2004

Hi All,

I am running Maxim DL 4.0 and would like to go the old fashioned way

of taking a bunch of Flats Darks and Biases and making masters which

I will use for calibration.

If I do this, can I simply put them in a file and then use set

calibration to select them?

It seems to me this would be faster and for the ST-11000 it would

take up less disk space.

I found that a few nights ago I took 1GB of images alone and when I

start processing everything my 1gb of RAM starts to choke.

I suspect that having one flat for each color, one dark for each

integration time and one Bias would not only take up less space, but

would process faster.

For example, if I want to calibrate each image as it downloads, it

should be faster that if I have 10 darks and flats sitting in the

file. Am I wrong here?

I would welcome any comments and thoughts on this question.

Thanks,

Jim Scala



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#13353 Aug 18, 2004

Jim Scala wrote:

> Hi All,

> I am running Maxim DL 4.0 and would like to go the old fashioned way

> of taking a bunch of Flats Darks and Biases and making masters which

> I will use for calibration.

> If I do this, can I simply put them in a file and then use set

> calibration to select them?



Yes. Note: if you use dark scaling, use Sum combine mode; otherwise it

will scale wrong (unless you manually change the exposure time in the

FITS header). That will be fixed in the next update.

> It seems to me this would be faster and for the ST-11000 it would

> take up less disk space.



My recommended alternative: Enter the frames normally into the Set

Calibration tool. Click OK. At this point you could just calibrate

images, but instead:



Click Process menu Create Master Frames. Save the master frames.

Re-open Set Calibration, clear the old stuff, and load up the Master

Frames.



Now, next time you go to calibrate, it will load those master frames.

You won't have to wait while it loads up all those files.

> I found that a few nights ago I took 1GB of images alone and when I

> start processing everything my 1gb of RAM starts to choke.

> I suspect that having one flat for each color, one dark for each

> integration time and one Bias would not only take up less space, but

> would process faster.



Actually, MaxIm DL only stores just ONE image internally per calibration

group. When you do the combine function, it reads them in just one at a

time. That way the system doesn't choke with excessive memory use.

> For example, if I want to calibrate each image as it downloads, it

> should be faster that if I have 10 darks and flats sitting in the

> file. Am I wrong here?



It shouldn't matter either way; both situations use the same amount of

memory. It will take longer on the FIRST calibration as it has to load

up all 10 frames -- one at a time -- and distill them down into the

internal master frame. After that the amount of memory used will be the

same as if you used just one frame.



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



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