To Paracorr or not to Paracorr

[Glenn Dawes]

Hi guys,

I have a 16" LB and am thinking of buying a Paracorr but don't know anyone who has one. Does anybody have any experience with this combination (or I suppose any f4.5 system). My 2 workhorse ep. are a 9mm Nagler and 16mm Series 5000 (Ultra WF) Meade. I'm interested in:

- effectiveness in wide angle ep (such as the Nagler) compared to wide field (low power) ep?

- effect on balance on the LB, afterall the Paracorr is close to 500g in weight!

- How noticeable is the 15% barlow effect?

- does it change the eye relief?

- anything else?

THanks

Glenn

[dannat]

Glen, can i suggest you read this article http://www.astromart.com/articles/article.asp?article_id=50
I found it very interesting

[Glenn Dawes]

Thanks Daniel,

That's very interesting! A lot of food for thought.

Glenn

[tnott]

I have tried various televue eyepieces in an 18 inch F4.5 and found that the paracorr made a big difference to the sharpness at the edge of the field in all of them. Stars were much more pinpoint at the edge and more stars were visible due to their light not being spread out as much.

It won't help the astigmatism you get from cheaper wide fields not handling the wider cone of light in a faster scope much (ie seagulls), just coma (ie comets).

I obviously keep it in the focuser of my 22 inch 3.6 scope the whole time.

It also flattens the field, which is good for eyepieces with some field curvature like the 28mm UWAN.

I notice less difference in an F5 scope, but the new owner of the 16" F4.9 scope I built now uses one and likes it.

The 15% reduction of the true field seems trivial to me compared to the improvement of the view. It is fairly heavy though, so may require counterweight on a LB with its small diameter side bearings.