Eyepiece & Filter Questions

[Zaine UK]

Hi all,

I have some questions i'd like to ask about my Celestron CPC 800 & Celestron Eyepieces and Filters.

1) When using the x2 Barlow do i attach the Barlow too the Star Diagonal then attach whatever eyepiece into the back of the Barlow?

2) Where do you put Filters? At the top of the eyepiece, the bottom, or at the end of the Star Diagonal. (Inbetween the Barlow an the eyepiece).

I want to get a good idea of how everything fits now in my house rather than out in some dark field.

Thanks... Martin

[LukeSkywatcher]

Hi Martin.

1) When using the x2 Barlow do i attach the Barlow too the Star Diagonal then attach whatever eyepiece into the back of the Barlow?

Yes.

2) Where do you put Filters? At the top of the eyepiece, the bottom, or at the end of the Star Diagonal. (Inbetween the Barlow an the eyepiece).

It really doesnt matter. They can be attached to the end of either the EP or the diagonal.

Probably best to put them on the end of the EP. If it is a Moon filter or light pollution filter then it would be fine to screw it to the end of the diagonal that goes into the scope because you will be using it for a while. Colour filters (different ones for different planets) i think are best on the end of the EP.

[AstroMum]

Regarding your first question, yes the barlow goes between the diagonal and your eyepiece. I believe (though I may be completely wrong here) that you can also put the barlow between the diagonal and the focusser which will halve the power of the barlow.

Never used filters I'm afraid, so can't help there.

Oops, too slow, Paul beat me to it.

[LukeSkywatcher]

Regarding your first question, yes the barlow goes between the diagonal and your eyepiece. I believe (though I may be completely wrong here) that you can also put the barlow between the diagonal and the focusser which will halve the power of the barlow.

Never used filters I'm afraid, so can't help there.

Oops, too slow, Paul beat me to it.

Thats an interesting point you mention. It was brought up here by someone a few weeks ago. I thought they said they tried it and it increased the power of the barlow (dont qoute me). I haven't really tried it fully yet but initial experimenting seems to be sound. So by doing this, the train of light would be:

focuser>barlow>diagonal>EP

[barkis]

Diagonal into focuser, Barlow into diagonal, Eyepiece into Barlow, is the way I would combine them.

Ron.

[Zaine UK]

I've noticed that my filters don't want to screw into the rubber bit at the end of the eyepiece. Am i doing something wrong?

[182570]

try the other end of the eyepiece

[LukeSkywatcher]

Diagonal into focuser, Barlow into diagonal, Eyepiece into Barlow, is the way I would combine them.

Ron.

That is the "Norm", but with some setups, it is possible to put the barlow into the focuser and then the diagonal into the barlow and then the EP into the diagonal.

I think how successful this is all depends on the F/L of the scope though.

I dont know to be honest because i have not experimented under the right conditions.

[Zaine UK]

try the other end of the eyepiece

Got it. Thanks everyone.

[AstroMum]

Thats an interesting point you mention. It was brought up here by someone a few weeks ago. I thought they said they tried it and it increased the power of the barlow (dont qoute me). I haven't really tried it fully yet but initial experimenting seems to be sound. So by doing this, the train of light would be:

focuser>barlow>diagonal>EP

You could well be right. I keep meaning to try it, but always forget!

Either way, by putting it between the focusser and diagonal, one effectively gets an extra magnification for all their eyepieces.

[barkis]

Refractors are noted for plenty of leeway when it comes to focus travel. Hopefully, there would be no light loss by having to rack in the Barlow too into the beam, in order for the light to reach the field lens of the eyepiece, having also to traverse the length of the diagonal.

Also, the weight of the eyepiece plus diagonal, will be amplified by the length of the Barlow. A possibility of distorting the focuser, if there is play in it to start with. A bit pedantic perhaps, but in some circumstances, valid I think.

Ron.

[glowjet]

If you put the barlow ahead of the diagonal you will increase you mag by 50%, especially effective with refractors 500mm to 1200 F, never tried it myself, but referred to in The Backyard Astronomers Guide

[Zaine UK]

If you put the barlow ahead of the diagonal you will increase you mag by 50%, especially effective with refractors 500mm to 1200 F, never tried it myself, but referred to in The Backyard Astronomers Guide

Thanks for the tip.