Baadars are bad at f4.7? So is there an alternative with t-ring adaptor?

[jjqpr]

Hi all,

to be specific I am reading baadars are bad on fast scopes so presumably my 250px at f4.7 is a no -go?? I do have the 5mm baadar because I loved the way it can screw into a t-ring for DSLR eyepiece projection photography... and I was all set to get another baadar for that reason until I read they aren't great on f5 or faster scopes!

So I wondered do any other brands make it so easy to screw on a DSLR to the eyepiece? i know you can buy tubes that the eyepice can sit in but I prefer the idea of screwing it directly into the eyepiece??

Thanks for any help.

[jjqpr]

Not answering my own question but I did find this and they say under the eyecup there is a thread for t-ring... so that would work, question is is it a good EP and will it be goiod at f4.7? What are the options if not?

[jjqpr]

http://www.amazon.co.uk/Celestron-1-25-inch-8-24mm-Eyepiece/dp/B0007UQNV8/ref=sr_1_2?ie=UTF8&qid=1390309176&sr=8-2&keywords=Celestron+93230#productDescription

forgot to post link above...

[glowjet]

Although I do not have a reflector I understand that the use of a Barlow is one way to overcome the problem of a fast scope with certain eye pieces. The Baader has, of course, the very useful eye piece threaded parts for attaching T rings for eye piece projection photography. Using one of the less high powered Baader eye pieces together with a Barlow, could achieve the results you are after. I am sure someone will have already tried this and will be able to comment

[jjqpr]

Thanks glowjet, that sounds very interesting! I am not sure how it works quite, I know the barlow increases the magnification but I am not sure why it would get round the problem of the eyepieces on a fast scope quite, so can anyone explain? Thanks again

[Peter Drew]

The faster the telescope the wider the angle of light from the objective, this makes correction more difficult for a given eyepiece, the Barlow lens alters this angle to match the angle from an objective of twice the focal length in the case of a 2X Barlow, making it easier for the eyepiece to deal with. 

[AlexB67]

A barlow can help with astigmatism, since this is worse in some eyepieces, especially cheaper ones. In effect the barlow will result in a scope with a slower effective focal ratio as far the eyepiece sees it.  Some of the premium eyepieces do have a barlow element build into the design already and work on that basis. Coma however will be unaffected, for that you would need a coma corrector, a barlow is not going to help. 

edit. sorry Peter was already there as I typed this, too late

[jjqpr]

OK thanks guys, that makes a lot of sense! ... just one thing, the baadar eyepieces you screw straight into a t-ring on a camera, where would a barlow fit into this setup? could it go on the other end of the eyepice and slot straight into the focusser tube?

and wow I didn't think these were cheap eyepieces either, I really have much to learn

[glowjet]

As is in normal practice, you fit the Barlow before the eye piece

[JamesF]

I'd guess you should make it a decent barlow if you're going that route though.  A lower quality one is possibly going to end up having some of the same problems as lower-end eyepieces.

James