I need some help over barlows !

[beamish]

I've reached the point now where I feel I need to own a quality 2" Barlow.

Firstly I'd love the 4x Nagler P/mate but for now I think the 2x would probably get more use.

So the question I'd like some advice over is :-

Big Barlow 2x 2" or 2x 2" Powermate ?? given the fact that I don't own any Nagler EP's am I likely to get the full benefit of the P/mate over the BB ?

To throw another spanner in - I've come across a superb price for a Meade 5000 2x 2" barlow, BNIB for around 100.00 ,how might this compare to the BB (as this is likely to be a contemporary EP)

Many thanks,

Karlo

[FLO]

I've come across a superb price for a Meade 5000 2x 2" barlow, BNIB for around 100.00

That is a very good price for an excellent barlow! I'd buy it.

[johninderby]

The Meade 5000 2" barlow is probably about 95% as good as the Televue BB so at £100.00 it's the better deal.

John

[beamish]

I thought as much ! cheers chaps !

[Starflyer]

Is it for visual or imaging Karlo?

[beamish]

Imaging !

Don't confuse the Meade Series 5000 Ultra 2X TeleXtender as a camera adapter... and don't confuse it as a barlow! The Meade 07672 TeleXtender is an image amplifier which incorporates an advanced four-element optical design that delivers a flatter field-of-view with sharper field edges... Better than even the best three-element apochromatic barlow lens! What's more, color fringing in the 2" Meade Tele Extender is virtually non-existent...

Thanks to the included 1.25" adapter, you'll get twice the magnifying power of all your eyepieces without sacrificing the wide field or the long eye relief. The Meade 2X Ultra TeleXtender outperforms conventional barlows with super sharpness at the edge of the field and outstanding clarity. All air-to-glass surfaces of 2" Utra TeleXtender's four premium optical glass lenses are fully coated with multiple layers of individually tuned ion-deposited anti-reflection materials for maximum light transmission and contrast. The lens edges and all internal metal surfaces are blackened to maximize the image contrast. Extra features of the Meade 07672 “TeleXtender" include non-marring clamp rings that won’t damage your good eyepieces and a machined safety groove in the 2X Ultra's barrel to ensure it won't fall out of the focuser by accident. The Meade Series 5000 TeleXtenders are the finest power multipliers sold today!

Karlo

[brianb]

Can't see the point of 2" barlows myself. Pointless for imaging as a 1.25" barlow gives more than adequate coverage at least up to APS-C size, and pointless visually as medium power EPs (20mm & shorter) are usually 1.25" fitting & there's no point in barlowing a huge heavy 2" EP to get the same performance as a good simple 1.25" EP which weighs less, has plenty of eye relief and probably performs better through having much less glass in it than the 2" combination.

If you want a 4x "barlow" see if you can find the 1.25" AE Imagemate. I have one of these & it's a cracker.

[beamish]

Hya Brian,

not quite sure what you mean by APS-C, but I'm looking to use my DSLR. Would you recommend that a 1 1/4" would still be adequate ?

I assumed that a 2" would reduce any possible vignetting.

Karlo

PS I have the AE 4x I/mate and agree that it's fantastic for the money.

[brianb]

not quite sure what you mean by APS-C, but I'm looking to use my DSLR. Would you recommend that a 1 1/4" would still be adequate ?

APS-C (22mm x 15mm) is the sensor size of most DSLRs. The other sizes are full frame (36mm x 24mm) and four thirds (18mm x 13.5mm).

If you want to use a focus extender with a SLR type camera, you'd be far better off getting a tele-extender (teleconverter) designed for photographic use - these are (at least) 7 element, highly corrected for all aberrations and give a flat field.

So far as illuminating the field with a barlow is concerned, don't forget that a 2x barlow magnifies the focal plane, so that a 1 cm image circle is magnified to 2 cm.

I've had nothing but Bad News with 2" barlows - either they don't fit far enough into the focuser to achieve focus (because the nose of the barlow hits the light baffles at the far end of the focuser) or they smash into the mirror if you try to get round that by fitting them in a diagonal. You might like to consider those practical issues before parting with money.