400mm F5 (i.e. 2000mm) dob and a 2" 40mm 52 deg ep

[moriniboy]

Its for our Astro Society truss dob.

Just wondering if the ep would vignette, looks ok through the FOV calculator, is there anything I should be concerned about?

Looking at the ES one for £86 that FLO have in stock.

[Ricochet]

You would have to measure the secondary size and position to work it out. If the dob was designed with a 2" focuser you will be fine. If it started with a 1.25" focuser there might be slight vignetting but I wouldn't worry about it. 

[Rick_It]

The eyepiece is only 52°, very far from maximum TFOV for a 2". So if you have a 2" focuser and a normally designed telescope, there should be no problem.

Why your society got this eyepiece, and not a 40mm 62° or a 40mm 68°?

[moriniboy]

All we can afford I'm afraid.

[Louis D]

Then I would get a 30mm 80 degree eyepiece from ebay like this one for £63.59 shipped to the UK.  It will max out your field of view in a 2" focuser and yield a much more reasonable exit pupil of 6mm versus 8mm for the 40mm.  The outer 50% will have increasing field curvature and astigmatism that mostly provides context, but the central 50% of the view is very sharp.

[moriniboy]

Thanks for all the replies.