Which Barlow?

I now have an 8" f/5 newtonian. I have an Ultima 2x barlow that I used to use for my SCTs, but there's just not enough focal length (2000mm) with this combo.

I am interested in perhaps a 3-5x barlow. Any suggestions? I have been looking at the Powermate barlows. The 4x 2" barlow looks nice, but is pricey. The 5x 1.25 barlow is about a hundred dollars cheaper. With my system, which would you get?

I will use it for visual and webcam.

Thanks and Clear Skies,
Brock

Hello Brock! 8)

IMHO, and because I own 2" eyepieces, and I suppose you do too, I would purchase the 2" 4x Powermate. Yes, they are pricey, but you don't get any better than that!

Just make sure you get/have the 2"/1.25" adapter, so that you can use your webcam and your 1.25" eyepieces with it... 8)


Clear skies!

I like the 4x 2" alot. Got one at NEAF couple years back and
the optics are superb in it. It is impossible to tell
any change in the image quality. I tried a couple of the 5x 1.25"
over the years (bought on Astromart, also a TV "loaner" at
WSP), and it seemed to me the optics were not of the same
quality; image quality was noticeably changed. Maybe I just
had bad luck with the 5x, but I like my 4x alot.

That said, the 4x is alot heavier than the 5x, so you need to
think if you might run into balance problems. The 4x 2" + a
2" eyepiece is heavier still.

I now have an 8" f/5 newtonian. I have an Ultima 2x barlow that I used to use for my SCTs, but there's just not enough focal length (2000mm) with this combo.
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What eyepieces are you using? I also have an 8 inch F5 Newt and find that a 2x barlow is enough. I use a Paracorr which adds 15% to the focal length. An Ultima without the Paracorr and a 9 mm gives about 244x, with a 7mm it gives 314x.

jon

Thanks for the responses everyone!

The barlow would be primarily used for webcam. My lowest focal lenght eyepiece right now is a UO 7mm ortho that gives me 143 power, which is not too bad.

I should have known that everyone would pick the most expensive alternative!

Thanks
Brock

Hello:
I have a 12.5" f/15 cassegrain I use for visual observing. WIth such a long focal length (about 5m), wide field 2" eyepieces are just about the only thing I use. But, when it comes to high magnification planetary observing, I'll use a simple 1.25" plossl, sometimes even with a barlow. Planetary observing, like webcam imaging, doesn't require the wide field capability of a 2" eyepiece. In such a case, you're only interested in the very center of the focal plane. So, I'll go against the trend and recommend the 1.25" barlow. It's cheaper, and you don't need the extra glass anyway. By the way, my barlow has a 1.25" barrel as well, for the reasons I just mentioned. I use a barlow even though the focal length of the scope is very long so that I can use long focal length eyepieces for high power observing in order to enjoy thier better eye relief.

Cheers
Mike Connelley