EP unbarlowed vs barlowed

[Bart]

Hi All,

It might be my imagination, but when i use a 2x Barlow with my 15mm EP (x100mag) it appears much crisper than my 9mm EP without a Barlow (x83mag) and similarly, when the seeing allows, my barlowed 9mm seems clearer than my 4 mm. Now, they are relatively cheap Celestron EPS but did I read somewhere that the short focal lebgth of 750mm benefits from the use of a Barlow?

Thanks for any help

Bart

[russ]

but did I read somewhere that the short focal lebgth of 750mm benefits from the use of a Barlow?

Thanks for any help

Bart

Only as a tool to increase magnification (or focal length, however you want to look at it). The eyepieces should be marginally better without the barlow. Although a good barlow will have no noticeable effect on the image quality.

The barlow is a good tool to help avoid using small focal length eyepieces (<6mm Plossls/Orthos) which have very poor eye relief.

[Telrad]

If you use a Barlow you need to give some thought to a suitable choice of EP, for example, you have a x2 Barlow and a 25mm eyepiece, there is little point in acquiring a 12.5mm; it will mimic the 25mm + Barlow. A suitable choice might be 32mm, 18mm, 12mm instead..