Author Topic: Minor problem with ImageSolver 3.5.1  (Read 1060 times)

Offline cfranks

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Minor problem with ImageSolver 3.5.1
« on: 2015 April 24 21:17:19 »
Solving an image created with DrizzleIntegration, PI 01.08.03.1123, Win 7 x64, the image solves very well but the Focal Length stored in the Fits header has been multiplied by the DI output scale.

Charles

Offline Andres.Pozo

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Re: Minor problem with ImageSolver 3.5.1
« Reply #1 on: 2015 April 25 04:11:55 »
That is the expected behavior. The script calculates the resolution of the image and using the resolution and the pixel size it calculates the effective focal length.
When you drizzle an image is as if you used a tube with a longer focal length or if you used a camera with smaller pixels. If you set the real pixel size of the camera, the focal length will be multiplied by the drizzle factor. If you divide the pixel size by the drizzle factor the focal will be the original value.

Offline cfranks

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Re: Minor problem with ImageSolver 3.5.1
« Reply #2 on: 2015 April 25 05:24:08 »
Thanks Andres but that means, on my image, that the FOV calculates as ~ 1.75 degrees wide whereas it is actually 3.5 degrees.  The pixel size listed is the same as the camera and the image has the same number of pixels as the camera but the focal length of the optics is twice what it should be.  I don't have the knowledge to understand, that's all.  :-[

Charles