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Advice on Barlow lens?


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A barlow lens multipies the magnification given by an eyepiece by a factor, usually 2x or 3x. So a 10mm eyepiece that will give 120x in your scope on it's own will give 240x when used with a 2x barlow lens.

You put the barlow lens into the scope then the eyepiece into the barlow lens.

Decent ones start at around £35 (the TAL 2x is the one usually recommended).

240x would be about the maximum usuable power under usual UK observing conditions. Often it's less to be honest !.

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Hi.

As a complete newbie I`m proberbly not the best to comment just yet, but from what I have read on here there are differing opions on Barlows. Some say if you get a good one then great, they double the ammount of ep's you have, other say it is just more glass between your eye and the object you are trying to view, so you are better off with multiple ep's.

I only have the stock 2 ep's that came with my scope so I am yet to decide on what to get next, a barlow or 2 more ep's.........:(

Edited by Daz Type-R
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A barlow will make the view dimmer because of the magnification. A good barlow will be no worse than using a higher mag eyepiece, for example; a 10mm eyepiece in a 2x barlow will give a simular view as a 5mm eyepiece without barlow.

The barlow will increase your range without having to buy many eyepieces. I am sure someone here could suggest a good range of eyepieces coupled with a barlow.

Just remember, the higher the mag, the dimmer the view and the faster the the object viewed will move across the FOV.

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Sometimes I prefer the view on a barlowed ep the the equivalent focal length ep without the barlow. Not sure why.

They're useful little beasties though. They can double as an extension tube and are helpful if you intend to get into planetary imaging.

I don't notice much light loss or loss of contrast with mine.

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It's the planetary imaging that's attracting me to a barlow at the moment. I have a choice of DSLR or CCD imaging and I know a barlow would almost be essential for CCD imaging, so my initial though is to get a 2x barlow. This will give me some magnification for CCDing and also expand my current EP catalog.

In terms of "decent" there will not be a whole lot of difference in quality at a 2x scale I would guess, but as you go up to to a 3x or a 5x I think quality will be exponentially more important.

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....Sometimes I prefer the view on a barlowed ep the the equivalent focal length ep without the barlow. Not sure why.....

That might be because a barlow preserves, or even increases, the eye relief of the eyepiece that it's being used with. With short focal length plossls and orthos the eye relief can be rather "tight".

Good quality barlows simply seem to "get out of the way" seemingly delivering nothing other than additional magnification. Barlows that I have used that fall into this category would be:

- Celestron Ultima 2x

- Tele Vue 2x barlow

- Antares 1.6x 2" barlow

- Tele Vue Powermate 2.5x

Edited by John
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