Esprit Focal Reducer and OAG star shapes

[tomato]

I've recently fitted the SW 0.77 Focal reducer/Flattener to an Esprit 150 and the star shapes on my OAG camera now resemble baked beans, they were much better with just the SW F/F installed. 

Given that I cannot easily relocate the OAG in the optical train I guess all I can do is move the prism in as far as I can, but this wont be much given that I am taking advantage of the increased FOV.

PHD seems to guide OK on a Bean Star so I can live with it, but it just looks terrible on the screen.

[Laurin Dave]

Hi Steve, So long as they don’t look like baked beans on the imaging camera and it guides ok it should be ok..  a bit surprising though as it’s supposed to have a 33mm flat field ..  What imaging camera are you using ? 

[tomato]

The imaging camera is a good old G2-8300, my QHY268c is on the other standard Esprit. The star shapes don't look too bad in the corners on the CCD but a bit of fine tuning on the spacing is still needed. I cobbled it all together in a bit of a hurry with the promise of a few clear (moonlit) nights, so I should try adjusting the prism.

[Laurin Dave]

Good plan.. if you didn’t know take flats as you adjust it as you’ll see the shadow .. move it in so you can see it then move out until it disappears ..  will be well within the corrected circle.. enjoy the clear skies

Dave

[tomato]

Thanks Dave, will give your method a try.

The Horsehead is about to dip below the lip of my dome aperture for the second night in row, strange times...

[Laurin Dave]

It was obscured by power lines here an hour ago.. they disappear so fast at this time but at least it’s clear for a change!