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  #1  
Old 30-04-2017, 01:05 PM
glend (Glen)
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Best Barlow for Planetary Imaging?

I am just getting the gear together to have a go at planetary imaging. I need a barlow for my Edge HD8 (f10 fl of 2032mm). My planetary camera is the ASI224MC. I am looking at 2X barlows to get over 4000mm focal length. What are the best choices currently available? The barlow will probably only be used for imaging with this scope, but might be used visually occasionally with my other scopes. Looking around on the Net i am leaning towards the Televue Powermate 2X, but are there better choices, or just as good at lower price, etc?

Opinions?
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  #2  
Old 30-04-2017, 03:54 PM
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Shiraz (Ray)
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think that 2x is ideal for your scope Glen. TV is really good quality. For small field of view, field curvature will not matter much and a Barlow will be as good as a Powermate.

FWIW, I have both a 2x big Barlow (TV) and a GSO 2x 2" - both appear to be effectively the same for image quality, but the TV AR coatings seem to be a little bit better.

Last edited by Shiraz; 30-04-2017 at 05:15 PM.
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  #3  
Old 30-04-2017, 05:25 PM
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Camelopardalis (Dunk)
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Glen, I use a Powermate for (most of) my planetary imaging. I have the 2.5x as it is smaller and lighter. With the ASI224 with its 1.25" nosepiece, I've measured it coming in at f/21-22, correlating with TVs specs on surface to sensor distance.

I've also tried a Bintel ED Barlow, and can't say that I can tell the difference with such a small sensor.
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  #4  
Old 30-04-2017, 10:14 PM
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Atmos (Colin)
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I'd personally go Powermate for the piece of mind and as Ray mentions... the AR coatings
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  #5  
Old 02-05-2017, 10:33 AM
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sil (Steve)
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Quote:
Originally Posted by Atmos View Post
I'd personally go Powermate for the piece of mind and as Ray mentions... the AR coatings
I agree
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  #6  
Old 02-05-2017, 10:42 AM
glend (Glen)
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Thanks everyone for your advice. I bought the Televue 2X, 1&1/4" barlow, not the Powermate version. With the ASI224 sensor i think it will be fine.
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  #7  
Old 02-05-2017, 02:59 PM
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graham.hobart (Graham stevens)
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planetary

I was thinking about doing this with my Tak 8inch Newt f4 - so about 800mm focal length.
Would a 5x barlow or power mate be needed?
Graz
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  #8  
Old 02-05-2017, 03:32 PM
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Merlin66 (Ken)
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Graham,
To get into the "sweet spot" of f25 to f30 (rule of thumb f ratio=x5 the camera pixel size) the x5PM would work well.
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  #9  
Old 02-05-2017, 04:03 PM
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Glen,

either a 2x, or even a 2.5x will serve you well. I generally use a 2x for general seeing on Jupiter but will use up to a 3x on Saturn in good seeing. I generally go with a focal length of between 10-12 meters with a C14. You should be able to get away with around 4-9 meters with a C8.
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