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Old 18-08-2015, 09:48 AM
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rustigsmed (Russell)
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Join Date: Mar 2012
Location: Mornington Peninsula, Australia
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Question 1.25 or 2" barlow/powermate for dslr?

Hi IIS'ers,

I've been thinking I might try and make use of the resolution of my scope and nab some extra focal length, i want to make planetary nebulas a bit larger. the scope is 12" f4 so am thinking I wouldn't want to push it past f8 which means pretty much a 2x barlow or powermate? I have a televue 5x which the quality is quite impressive but then it has to be for 5x the focal length.

my first question is in regard to whether I should be going for a 1.25" or 2" - will the 1.25 result in excessive vignetting on the dslr?

the second question is really relating if the answer is 2" whether something like the Televue big 2x barlow is good enough (or overkill) or should I really be going for a powermate? (~$460)

Pretty much a 1.25" powermate is the same price as 2" barlow, and then a 2" powermate is becoming more than I want to spend... unless its really going to make a significant difference.

In summary,
1. 1.25" too much vignetting?
2. balancing pricing options up 2" gso ed $89; 2" televue barlow $300, 1.25 tv powermate $300, 2" powermate $460 eeek!

thoughts and experiences or even other brands welcome. obviously it needs to be able to thread into oag/dslr somehow. I am thinking 2" is probably a better option.

cheers

Rusty
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