stacking with slow change in image scale?

[Forum_2014]

Hello,

I have taken a series of 100 images of comet Lovejoy with STATIONARY camera.
As the optics cooled during the series, the images not only show shift and rotation but also a slow change of image scale.
Now i want to stack all these with AstroArt. How to do this?

How can i automatically equalize the image-scale for the series of images?
Rotation and Shift could then be done through the preprocessing menu and after that i could also stack while centering on the comet, but how to do the scaling?

Best regards,
Martin

[Forum_2014]

Hello Martin,
the option "Star Pattern, align and rotate" is able to scale images, but it's limited to +- 2% to make it more robust and fast.
It seems that in your images you have a change of scale of 4/5 %.
Maybe you could solve this way:
In Preprocessing place as the first image the number #50 (of 100), then place the others. Doing so the scaling of every image may fall in the range +- 2%.

If this does not suffice, you may try to remove the first 10 and the last 10 images, or just write me for a personalized build without that limitation(!)
(yes of course a "Scale" parameter would have been better).

[Forum_2014]

Hello,
Yes i think the software should learn that capability, which i have even found with some freeware tools (which also lack in convenience).
Regards, Mart