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Maximum useful barlow magnification

Started by ddoctor, 08/30/2005 08:29AM
Posted 08/30/2005 08:29AM Opening Post
Hi group,

I'm using a 10" f/7 newtonian. No problem with a 3x barlow, but what about a 5x powermate? Let's assume superb seeing and everything else. I can't remember the calculation for the maximum useful increase. I don't use eyepiece projection. I know a lot of folks routinely image in the f/35 range. Is it too much for this set-up?
Posted 08/30/2005 09:30AM #1
David -

It should be just fine - especially so for the planets in good seeing.


Alan Friedman
Posted 08/30/2005 10:51AM | Edited 08/30/2005 10:51AM #2

I have used a 5x powermate with my 10" F/12 Mewlon and it has worked quite nicely. Even with projection tubes behind my 3x barlow producing F/40 I get nice images. But mostly it depends on seeing.


Paul Maxson
Moderator - CCD Imaging and Processing/Solar System
Celestron C14, Mewlon 250, Orion EON120, ASI120MM, Flea3.