Barlows and Focal Length on fast scopes

[Nick P]

I have been reading on various threads here and on other forums (fora?) that a barlow will increase the focal length of the scope.

The question is, would this affect the quality of the image on a fast (say 4.5f) scope making it better for planetary viewing?, or is the effect limited to magnifying the image without improving quality?

Any information will be appreciated

Nick

[Peter Drew]

A good Barlow does'nt exactly improve the optical quality of the telescope, however, the effective narrowing of the focal plane angle does tend to make the eyepiece a little more forgiving. You also retain the apparent field of view and the eye lens diameter of the eyepiece which can be beneficial.

[Nick P]

Thanks for the response Peter, would this mean then that a mediocre eyepiece would improve its performance in a fast scope with a good barlow (or any barlow for that matter)?

[Peter Drew]

I don't think a Barlow lens, however good, would significantly improve a mediocre eyepiece, it depends on what you mean by mediocre. What I really maent was that, due to the Barlow creating a longer effective focal length, less sophisticated and hence less expensive eyepieces can still work well with short focal length objectives which normally require the more expensive types.