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Old 20-08-2015, 02:32 PM
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Shiraz (Ray)
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Join Date: Apr 2010
Location: ardrossan south australia
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if you haven't already come across it, this gives a good summary of the various types of Barlows and some of the things that you could consider when using them. http://www.brayebrookobservatory.org...BarlowLens.pdf

re quality etc, the GSO 2" that Glen mentions is worth a look - mine is almost as good all round as the much more expensive TV Big Barlow.

Powermates are just another Barlow, but they have extra lenses to turn them in telecentric systems - for your application, that means no extra field curvature. That might be worth having if you can find a way to control coma.

Last edited by Shiraz; 20-08-2015 at 02:44 PM.
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