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lukebl

5x barlow review

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I thought I'd share my recent experience of some 5x barlow/telextenders in their application with my SPC900 webcam, as there are often queries here about the best barlows to use.

Basically I recently sold my brilliant 3x Televue Barlow to someone on this forum (you know who you are!), as I wanted to get a greater magnification without having to use extension tubes. Although the Televue was great, and the optics were superb, it was a bit unweildy with the extension tubes so I thought I should replace it with a 5x one.

So, I bought an Astro Engineering Supreme 5x photovisual Barlow lens (c. £90), after reading the superlative hype on a certain website. I have to say, it really was complete rubbish! The image was simply not sharp with truly awful chromatic aberration.

I then bought a Meade 5x Telextender (c. £104), as I'd had one before and thought it was pretty good. That, however, was still nowhere near as good as my original 3x Televue barlow, and also didn't provide as much magnification as claimed. In fact the image was smaller than the original Televue+extension setup. There was also a lot of chromatic aberration. That was kindly taken back by the supplier.

So, I then splashed out on a Televue 5x Powermate (£140), and that is simply the best one so far. Almost no chromatic aberration and a sharp well-magnified image. If seeing wasn't so bad right now I'd post an image (you guys in places like Hawaii and Australia really have NO idea what bad seeing is, unless you've experienced the atmosphere here in the UK!).

So, here is my rating of the 4 options:

Televue 3x Barlow + extension tube Score: 8/10

AE 5x photovisual Barlow Score 2/10

Meade 5x Telextender Score: 5/10

Televue 5x Powermate Score: 9/10

So, for value for money, the Televue 3x barlow with an extension tube is unbeatable (around £70), well out-performing the more expensive Meade, although the £140 5x Powermate has the edge. And don't even think about the AE Photovisual barlow. I think I could have saved myself a lot of aggravation and expense by keeping my original 3x Televue!

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Great review. Final outcome not too surprising, except perhaps the Meade. Thought it might be closer to the TV. But never used one to know.

As for the AE. Just goes to show that although something may tick all the boxes in terms of spec, doesn't mean the final product is any good.

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great review. almost makes me want to buy another Powermate!

I agree with your comments but will only buy a barlow/powermate for imaging which I have no intention of even thinking about currently :)

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Very interesting review Luke - thanks for posting it.

I've used a 2" 2x Meade TeleXtender and found it pretty good for visual use - obviously your 5x version (1.25" I think ?) was not so good which I'm slightly surprised about but there you go.

I've also used a Powermate 2.5x and that was superb so I'm not surprised that the 5x Powermate impressed so much - all the Powermates seem to get rave reviews !.

The AE "Supreme" seems to be an inappropriately named product - good to look at, but clearly not to look, or image, through .... and they are not exactly giving it away either :)

Thanks again for posting your experiences with these products.

Edited by John

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I wonder how they make the TV Barlows free from significant CA with two element lens. Powermates are different design, but TV Barlows use two elements only.

There is also GSO/Revelation 5x "APO Barlow". I had it long time ago for a f/5 Newtonian. Can't tell how good it was, but I didn't had any issues related to it (except of shaky mount that wasn't good for f/25 imaging).

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Mine (Power Mate) arrived today, Very nice piece of kit !

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I'm, betting my Revelation 5x model is awful then! lol

Not necessarily! Can't say I've ever used a Revelation.

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I wonder how they make the TV Barlows free from significant CA with two element lens.

They never add significant chromatic aberration because they have small aperture, fairly long focal length for their small aperture and are very close to the focal plane.

The "APO"ness of 3 element barlows is pure marketing fluff. they have three elements to make them short, out of cheaper glass and to reduce the curves needed. In other words, they have three elements because they're relatively cheap, short and still relatively good, not because "APO" barlows are superior (unless you're desperate for a short, good and relatively cheap barlow).

Roland Christen confirmed this, and you can't say hes biased agaist APOs :).

"Using the words "Apo Barlow" is strictly a marketing game. At normal powers all Barlows are essentially apochromatic, regardless if they are 2 element or have 3 or more elements. It's not until you get to very high magnifications, around 8x when you might get a bit of color using a normal Barlow."

The extra elements in the Powermate aren't to reduce chromatic aberration, it's to make them more telecentric, i.e. reduce the angle with which the light bundles cross the focal plane en route to the eyepiece, to reduce vignetting in the eyepiece, keep the eye relief of the eyepiece the same, make the magnification depend less on placement of the eyepiece with respect to the telextender, and possibly avoid issues with very narrow passband filters that would be downstream.

By the way, the 3-lens shorties are *not* telecentric, on the contrary. Their short focal length exacerbates the possible issue of "classic" barlows. Telecentric telextenders have two widely spaced groups.

Edited by sixela

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This is the first review i've read , i found it very informative , i'm sure many peeps will now save money and agro .

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Thanks for the info. I've been concidering a barlow for quite soem time now to have between my explorer 200 and eos 550d to get closer to planets and more details from the moon.

Now i know wich ones to buy at least! :D

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Hi Jannis,

I would add that you shouldn't even think about putting a 5x Barlow in front of a DSLR. It won't work! The review above was solely based on using the Barlow with a webcam which is a very different beast to a DSLR. the webcam is very small and lightweight and used to take 100s of frames over a short time frame.

Using a 5x Barlow with a DSLR would be pretty unwieldy, and would give such a magnification that every tiny vibration or poor tracking would show up (I know. I've tried it). DSLRs are much more suited to prime-focus long-exposure imaging of DSOs.

I know it's hard to believe that a £10 webcam can give better results than a £500 DSLR, but they do. MUCH better!

Edited by lukebl
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Nice review Luke.

It never ceases to amaze this non imager what can be achieved, planetary wise, with a humble webcam.

Andy.

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Good review Luke. Shame that you had to find out the hard and expensive way which was the better performer, but as you have so generously shared your experience, hopefully it will spare a few of us the same fate. :D

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Thanks a lot Luke, I have the SPC900nc so televue 5 powermate will be on my list to get.

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To be perfectly frank, with hindsight I don't think I've gained anything by replacing the 3x Barlow with the 5x Powermate! I've lost a perfectly good 3x Barlow for visual use (the 5x is too powerful for visual use), and the 3x with an extension tube produced an image comparable in size and quality to the Powermate.

Looks like I might revert back to a 3x Televue Barlow if anyone has one up for grabs!

Edited by lukebl

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Hi Luke, as others have said ,great review. :) I have alo been looking at a barlow, I had the Celestron Omni, the results using it put me off them so I thought I'd go for ep's only, however as I only have the 4 TV's I was thinking about buying the TV x2 but it seems for another £6.00 I could have the x3. Your review has been very informative.

Thanks for posting it

Edited by Nexus 6

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Nice review. I have the Meade TeleXtenders 2x and 3x and use both for planetary imaging. I have also barlowed my 14mm to 7mm, with no apparent loss of quality, I am really surprised the 5x performs badly (not that I need one for my F/10 scope). Maybe the Meades only perform well on slower scopes (like mine).

Maybe I should get a 2.5x PowerMate for those situations when 3x is too much and 2x too little magnification.

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Nice work on the review Luke, shame you ended up going through all those iterations to get there though. I have the Antares 5x barlow, and really have nothing to compare it to at that scale. I don't think it's as good as the Celestron Ultima x2, but from the small amount of use I've put it to, I think it's pretty good.

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Thanks for the review. From the sales blurb I was sold on the AE 5x barlow so you've saved me the expense and hassle of buying something that wouldn't have measured up. Great to have an opinion from someone who has owned and tried a variety of different kit.

Thanks Luke, and thanks SGL!

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Thanks for the comments.

I still wish I'd now stuck with the original 3x Televue Barlow. The 5x is a nice piece of optics, but I sometimes wish I had a little less magnification. A Televue 3x with/without an extension tube gives you the best of both worlds.

So, the tip is get a 3x Televue and an extension tube (I use a cheap old barlow with the lens removed). You get good value, great optics and an option of magnifications.

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I'm, betting my Revelation 5x model is awful then! lol

Seemed to work ok for this guy. Check out the 3rd pic from the top...

Stockport Binocular & Telescope Centre. Chris Hill's Astrophotography

I'm planning on a speedy purchase of this Barlow to mate with my Nikon D40, which is the same res as his Pentax, and my Skywatcher 200P.

Then I'm gonna pray for some clear nights...

If I can get even close to his I'll be happy! And if it doesn't come up to scratch it can always be returned :rolleyes: If it does I might get a 3x to compliment my set :icon_confused:

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