barlow lenses vs powermates

[denis0007dl]

....one more thing I did not mentioned, TMB 1.8x barlow little extended to 2x  seems have little sharper image and little

more light transmittion than Zeiss 2x barlow!

It is also built like a tank.

I like it more than Zeiss barlow.

It give me magnifications 1.8x-2.2x while extended, while APM ED barlow provide me 2.7x-3.2x magnifications

without break images.

They are all I need.

[rowan46]

It seems to me that the main difference is what you use them for if its just to amplify  I found my bresser telextender edged any of the barlows I had tried at that price point. If however you are using them to improve eye relief the barlow is definitely the one to go for. I have to say I have never tried the best barlows they are well out of my price range. My bresser cost me £80 new and it was much better than any £80 barlow I had tried.

[denis0007dl]

It seems to me that the main difference is what you use them for if its just to amplify  I found my bresser telextender edged any of the barlows I had tried at that price point. If however you are using them to improve eye relief the barlow is definitely the one to go for. I have to say I have never tried the best barlows they are well out of my price range. My bresser cost me £80 new and it was much better than any £80 barlow I had tried.

Yup, these barlows are expensive, especially TMB and Zeiss, and they worth money if you need 

ultimate images.

APM barlow is not expensive, it is 140 euros, and I am sure price of it will go up and up

through years, so everyone who look ultimate barlow at 2.7-3x magnifications, do not miss it for that

price.

I also have GSO 2" 2x barlow but with TS logo, and it produce very noticable less quality images comparing it

vs Zeiss, TMB, APM or AP.

But it is also cheapest of all.

[russ.will]

I'm interested in the coma correcting claim - I thought all barlows/Focal multipliers did that, because they double the focal length of the scope, not half the focal length of the EP. If you're making your F5 Newt into an F10, of course you'll get less coma and sharper stars to the edge. For that matter, a 2.7x barlow should be better than a 2x for the same reason.

I'm also slightly dubious that you can nail colour accuracy down to the optical topology, as opposed to the manufacturer. I've often seen it said that TV glass seems to have a warmer tint. 

That doesn't mean the APM stuff doesn't look lovely though and less air glass surfaces (all other things being equal) means light scatter should be improved.

Russell

[RikM]

I'm interested in the coma correcting claim - I though all barlows/Focal multipliers did that, because they double the focal length of the scope, not half the focal length of the EP. If you're making your F5 Newt into an F10, of course you'll get less coma?

Russell

You are also seeing less of the field area due to the increase in magnification.

[Merlin66]

Hmm.

I have and use the TV Powermates....excellent performance - love them!

But I also find the TMB Barlow (followed by the Orion ED Shorty+) to give very good (well...ok, also excellent) results.

I keep hearing about the great performance of the new Baader Hyperion Barlow...but haven't had the chance to test one.

[HumptyMoo]

I really want to contribute here as I have a TV powermate 2.5x. I have nothing to compare it to though which is the problem. If I use the powermate and 13mm nagler on a planet (well Jupiter, I am yet to see anything else) it is a really crisp and clear view (on the one occasion I had clear enough skies, not a scientific method of repeatable results I know).

I don't notice I have added the PM optically except for maybe a more pronounced colour trace at the edge of the planetary disc as Jupiter moves through the eyepiece (again hold no worth in my observation as I really have no comparison and I am not convinced I have perfect collimation).

For stars like Sirius, I get a lot of flaring when the PM is introduced, although again that is probably seeing conditions mostly, I have been plagued by high atmosphere haze and general cloud for months now.

It is also worth noting that John suggested the amount of glass the EP and PM introduce can have an affect on flare.

Hey, when these clouds clear I will make an effort to substantiate my very limited evidence, what I have, I throw out there for at least some "additional guff" to the topic

[michael.h.f.wilkinson]

A classic  Barlow lens can be made to excellent specifications and is not necessarily worse than a telecentric Barlow (TV Powermate, Meade TeleXtender, Bresser SA Barlow), Siebert Telecentric Barlow). The disadvantage of a telecentric Barlow  is that it has more lens groups (two vs one in the classic Barlow). This can introduce extra reflections, flare, etc. Where the telecentric design can be decidedly better is in super or ultra wide-angle EPs. The field widening inherent in the classic Barlow design can cause vignetting in these design. I have a hunch dennis0007dl's comparison may have been done with the supermonocentric EPs or similar EPs (Zeiss orthoscopics ??) with small (or even tiny) AFOV. In these designs a top-quality Barlow may be better (effectively using the Barlow as a Smyth lens and the SM 16 as the rear lens set of a long eye-relief planetary design). Using the same type of Barlow on a Nagler or Ethos might show up the shortcomings of the classic Barlow design.

[AlexB67]

it was my understanding too that the reason a decent triplet barlow gives better correction across the FOV to a doublet say,  so there is that side of the coin as well to consider, but I perhaps need to be corrected on that.

I've never owned a  quality barlow, it is just a basic very cheap skywatcher I own, not even the deluxe, it came with my first scope. What I can say I do not find it vey good  at all in some cases with some eyepiece combos I own in how it affects consistency across the FOV, and nothing I own even goes greater than 68 degrees.

[denis0007dl]

A classic  Barlow lens can be made to excellent specifications and is not necessarily worse than a telecentric Barlow (TV Powermate, Meade TeleXtender, Bresser SA Barlow), Siebert Telecentric Barlow). The disadvantage of a telecentric Barlow  is that it has more lens groups (two vs one in the classic Barlow). This can introduce extra reflections, flare, etc. Where the telecentric design can be decidedly better is in super or ultra wide-angle EPs. The field widening inherent in the classic Barlow design can cause vignetting in these design. I have a hunch dennis0007dl's comparison may have been done with the supermonocentric EPs or similar EPs (Zeiss orthoscopics ??) with small (or even tiny) AFOV. In these designs a top-quality Barlow may be better (effectively using the Barlow as a Smyth lens and the SM 16 as the rear lens set of a long eye-relief planetary design). Using the same type of Barlow on a Nagler or Ethos might show up the shortcomings of the classic Barlow design.

Yes, we made test with high quality Zeiss ortho and TMB supermonocentric eyepieces!

[denis0007dl]

Here are some of my beauties, and you can see comparation 

I have two APM and TMB barlows....

[Jannis]

I'll buy a new barlow this year to replace that toy-quality 1-lens plastic-glass barlow i have that came with the Skywatcher Capricorn 70, but i can't really decide on what to get. I was sure to get a PM, but then i started reading this thread...

I'll use it pretty much only for lunar and planetary imaging, but i don't know how far i can push the explorer 200 scope anyway?

Have anyone tried these lenses under same condition for imaging so one can see the actual difference? I belive i saw a thread here earlier comparing a few of them, but i can't find it..

[catman161]

I use the the Skywatcher 200P (not the PDS) on an NEQ6 and do planetary and have had good results with both the 2x and the 4x powermates. Below are comparison shots of Jupiter-1st one is with 2x and second with 4x. Both captured with an ASI120MC. Hope it helps.

Sent from my iPhone using Tapatalk

[Alkaid]

Very interesting discussion, thanks all for sharing.

[John]

I use a 2" "x Powermate for visual observing and it's superb - you would not even know it was in the optical path apart from the magnification boost.

A lower cost but still excellent alternative is the Explore Scientific Focal Extender.