Hi,

Cannot figure out the meaning of this tip:

 

Why the "effective" FL does not match my real one?

m

Do you use a focal reducer? If yes then you need to configure your telescope to have the focal length after applying the focal reducer.

Thanks for the reply. I don't use any focal reducer

You apparently configured the telescope to have a focal length of 714 mm and plate solving report 548 mm which is suspiciously close to 0.75 x 714 so I suspect that your flattener isn't a flattener but a flattener/reducer. So, what telescope and flattener do you use?

I don't use any flattener nor reducer, only a cls filter right now. But that should not change anything.
Yes, I thought those 548mm was reported by plate solving, but don't know why.
Thanks for your tips, by the way!

What is the telescope you are using?

TS102, 714mm FL (f7)

Is the camera pixel size entered correctly?

I faced the same situation. My presumably focal length was 360mm, but the plate solving was constantly saying it is 375. I found out that plate solving is correct (by cross-matching from astrometry.net), and I was able to correct the focal length by adjusting (in my case reducing) the distance between the flattened and the camera sensor.

If you believe that there is no FR or flattened that can reduce your focal length, I suggest trying to ADD some spacer between your camera and the scope, and test again (plate solving) till you reach the accurate number (or close to it).

 

hey! you nailed it! don't know why but was wrong! Was set to 3um but my dslr has a pixel size of 3.89. Just made some calculations and it makes sense the FL that ekos was reporting. Thanks for the clue!

m