Filters and barlows

[Sheap]

my parents got me a few things for my telescope for christmas (and my birthday which is technically tomorow, but it all came in the same box), including a skyglow filter and a barlow, does it matter whether the filter goes before or after the barlow in the optical chain?

[rmcpb (Rob)]

I will hazard a guess that it does not matter, the light is filtered once either way so pick your poison.

OTOH give it a go either way and report back so we can all learn.

Cheers

[matt]

I always screw the filter into the base of the eyepiece and then put that combined unit into the barlow.

Although I don't think it matters?

I take it your barlow has a thread for screwing a filter on? If not, it's a moot point

As Rob says, give both a go

[janoskiss (Steve H)]

If you screw it on the EP, it will increase the magnification you get with the barlow slightly. More so if it's a shorty barlow.

[stephenmcnelley]

At any rate you will need to refocus with a filter in the optical chain, more so if the filter is srewed into the eyepiece, this is usually the case unless the EP's are crap or have no threads inside the eyepieces screw on barrel extensions that slide into the focuser.