Effect of a coma corrector on focal length (Paracorr 2)

[SkyHiker]

I have trouble plate solving with my ASI2600MC while it goes smoothly with my QHY5 guide scope. One possible cause is that the focal length of 1200 mm has changed to something else by the use of the Paracorr 2. Entering a wrong focal length can definitely mess up plate solving - well at least if the difference is between the primary scope and the guide scope, that I have experienced.

Does anyone know if this is could be the cause or is it more likely an issue with index files, and do I just have to wait longer because of the longer focal length (1200 mm for the 12" vs. 162 mm for the guide scope)?

I could point the scope at a remote hillside and test for focus with and without the CC, add the 55 mm for the rings to the difference. It should not be a whole lot more, maybe 100 to 150 mm. If it behaves like an ideal lens, that is. Perhaps enough to mess things up.

[Piet Le Roux]

Good day Henk,
Your focal length with the Paracorr II should be 1200 X 1.15 = 1380mm, Are you using the "turntable" with the Paracorr or a spacer?

[BABOafrica]

I'm especially interested to know how this works out since I'm in the process of making an f/4 8in astrograph, which will need a coma corrector.

BABO

[notFritzArgelander]

Good day Henk,
Your focal length with the Paracorr II should be 1200 X 1.15 = 1380mm, Are you using the "turntable" with the Paracorr or a spacer?

Yes, just so.

[SkyHiker]

Good day Henk,
Your focal length with the Paracorr II should be 1200 X 1.15 = 1380mm, Are you using the "turntable" with the Paracorr or a spacer?

Thanks Piet I will try that.

I use a spacer, 2 rings of 55 mm total. The fancy turntable is just for visual.

[Piet Le Roux]

I loved the Paracor II with the 15" Obsession..it really made the wide angle views pop!