- [Update 2013-10-13] On second (third? fourth?) thought, I don't think this works like that. The Barlow lens would need to be before the secondary to recover lost aperture.
If you use an Barlow with these scopes, then more of the primary becomes visible.
The closer the Barlow's lens is to the secondary, the more pronounced the effect is – so a "Shorty" Barlow is not as good as one with a long barrel. (Though the optimum for spherical mirrors would be a good "Bird-Jones" corrector.)
And one needs to make sure that the Barlow itself does not introduce vignetting itself…
No comments:
Post a Comment