What exactly is a barlow nosepiece?

[AstroMum]

I'm just reading up on binoviewers and one which I particularly like (William Optics) comes with a 1.6x barlow nosepiece. Am I right in thinking this doesn't attach like a regular barlow and can therefore only be used with the BVs?

I was hoping to be able to use the barlow to increase the magnification of my existing EPs when not using the BVs.

[Paxo]

Hi Becky,

With some equipment, and most bino viewers come into this category, it is actually not possible to bring the image to focus in all types of scope combinations. You often need more in-focus i.e. you need to turn the focuser further in than you can to achieve focus (this is a common problem with newtonian scopes and cameras for example).

One very simple way around this is to use a barlow lens just before the viewer or camera, which pushes the focus point a bit further out into the range where you can focus. The upside, they come to focus, the downside is you get a small increase in magnification.

To summarise, the barlow nosepiece is a small accessory you attatch to the binoviewers to allow a good focus to be achieved.

Steve

[AstroMum]

Ahhhh.... so it's not to be confused with a regular barlow lens. Thanks for the clarification Steve.

[Paxo]

I might be wrong, looks like you might just need to unscrew the bino nosepiece and screw in the barlow nosepiece if you need it. It is exactly the same as a barlow lens, they've just removed the top half where you put the eyepiece in. Many of the barlows you buy actually screw apart anyway leaving a thread which you can screw accessories into.

Steve

[StevieDvd]

The barlow on the WO binoviewer is added to the nosepiece much like adding a filter. Never tried the end of a standard barlow on mine (yet - that's if the thread is the same of course.)

[brantuk]

Yup - my WO bv's have a nosepiece onto wich the 1.6 barlow is screwed. I can also use them without the 1.6x but in a 2x Powermate

[AstroMum]

Ok, so it works like a regular Barlow but doesn't have the part you would pop a single EP into, is that right?

I'm basically trying to keep costs down and hoped that by buying the WO binos I would effectively get a free Barlow I could use with my existing EPs.

[brantuk]

Yes - it's a specially threaded barlow designed for the BV's. Dunno if it's a filter thread that would enable you to screw it onto a regular eyepiece - but I'll just go check that and update here for you

Welll - that was easy - good news - it is in fact a filter thread and I just screwed it onto a Celestron 32mm Plossl - so your idea is fabulous. Dunno how well it works though on normal eyepieces but I'll try and remember to give it a go next time I'm out observing

[acey]

A Barlow is a negative lens (i.e. has concave surfaces so if you were to look straight through it you see an upright, smaller image). Put in front of an eyepiece, it has the effect of shortening the overall focal length, i.e. it increases the magnification seen througth the eyepiece.

As has been said, binoviewers often need more focuser travel than scopes allow, so the focal length needs shortening. The screw-in negative lens (Barlow) does this - and also increases the magnification of the binoviewer.

The effect of a barlow depends on how far in front of the eyepiece it is placed: moving it gives greater or lesser magnification. A "2x barlow" is a negative lens fixed in a tube that will place it at the required distance to give you double the magnification. Just change the length of the tube and it will be a different factor by which you increase (you could even make your own "zoom lens" this way - though it won't stay in focus as you vary the magnification).

If you're trying to keep costs to a minimum then think very carefully about whether you really need a binoviewer. Most people manage fine without one. Because of the focuser travel / barlow issue, magnification will be higher than you'd get with regular binoculars. Also remember that if you want to use other magnifications than the supplied eyepieces provide, you'll need to buy two eyepieces instead of one. And if you want to look at faint objects (DSOs) remember that the binoviewer splits the available light between two eyes, so the image in each eyepiece is fainter.

[AstroMum]

Yes - it's a specially threaded barlow designed for the BV's. Dunno if it's a filter thread that would enable you to screw it onto a regular eyepiece - but I'll just go check that and update here for you

Welll - that was easy - good news - it is in fact a filter thread and I just screwed it onto a Celestron 32mm Plossl - so your idea is fabulous. Dunno how well it works though on normal eyepieces but I'll try and remember to give it a go next time I'm out observing

Oooh, thank you for seeing if it works directly with an EP. I'd love to hear how you get on trying it out in the field.

A Barlow is a negative lens (i.e. has concave surfaces so if you were to look straight through it you see an upright, smaller image). Put in front of an eyepiece, it has the effect of shortening the overall focal length, i.e. it increases the magnification seen througth the eyepiece.

As has been said, binoviewers often need more focuser travel than scopes allow, so the focal length needs shortening. The screw-in negative lens (Barlow) does this - and also increases the magnification of the binoviewer.

The effect of a barlow depends on how far in front of the eyepiece it is placed: moving it gives greater or lesser magnification. A "2x barlow" is a negative lens fixed in a tube that will place it at the required distance to give you double the magnification. Just change the length of the tube and it will be a different factor by which you increase (you could even make your own "zoom lens" this way - though it won't stay in focus as you vary the magnification).

If you're trying to keep costs to a minimum then think very carefully about whether you really need a binoviewer. Most people manage fine without one. Because of the focuser travel / barlow issue, magnification will be higher than you'd get with regular binoculars. Also remember that if you want to use other magnifications than the supplied eyepieces provide, you'll need to buy two eyepieces instead of one. And if you want to look at faint objects (DSOs) remember that the binoviewer splits the available light between two eyes, so the image in each eyepiece is fainter.

Thank you for explaining how barlows work, it's easier to know what I'm asking now that I understand the mechanics a bit better.

I would definitely like some binos eventually, but I think they're low priority at the moment. I will keep a casual eye out for the WO ones secondhand perhaps.