Barlow

[JackieStar]

I forgot to ask in my last post: When I use a 2X barlow(no manuf. name on the barrel) with my EP, the view gets much+++darker!!

Is this due to the fact that the FOV is smaller and thus less light entering the EP?

Confused because I don't get same reaction with a 10mm EP when used alone!

[ibase]

The view is expected to grow darker because the magnification is increased when using a barlow so it's nothing to worry about. Less magnification = brighter image because the exit pupil of the eyepiece (that tubular ray of light coming out from the eyepiece) becomes smaller as the magnification increases, thus less light is hitting the eye and makes for a darker view. More important is if the image is not blurry, if it is, then the power may be too high for the given scope or seeing conditions.

Best,

Hernando