Fits Header Focallen doesn't agree with my scope specs.

[Seldom]

I'm imaging with an NP101is.  Sometimes with a .8x Televue field FL reducer.  Specs say the base focal length is 540mm and the reduced focal length should be 432 mm.

I'm trying to recall if I used the focal length reducer on an image I took with a Canon60Da but after I run a Photometric Color Cal on the original image FitsHeader reports a focal length of 480mm.

When I'm imaging with an ASI1600MMC FitsHeader reports a Focallen of 443mm when I use the .8x focal length reducer.

Thoughts on how to interpret the 60Da focallen would be appreciated.

[Andres.Pozo]

There are at least two possible problems: You could be setting a wrong value for the pixel size of the camera or the focal reducer is not at the right distance.

[Seldom]

Thanks, Andres.  I know I had the focal reducer located wrong back then.