barlows: TV powermate vs other barlows?

dew · Post by **dew** » Thu Oct 02, 2003 1:59 am

hi, im looking to get a good barlow. planning to get 1 or 2 premium eps but i want to get an excellent barlow that will not add any distortions or degrade the original image. i figure get 1 excellent barlow and i can save a whole lot of money getting different focal length eps..
now my question is about the televue powermate. if im not wrong its about s$300 is it really all that good and is it worth the money? whats the difference betwwen the powermate and a regular barlow?
thanks!

eu-wen

harlequin2902 · Post by **harlequin2902** » Thu Oct 02, 2003 3:10 am

Hi Eu-Wen,

The Powermate is an interesting 4-element amplifying lens system. According to TeleVue, they aren't really "barlow lenses" at all...hm...

This will help to explain everything you want to know about these innovations from TeleVue :
http://www.televue.com/engine/page.asp?ID=42

If you're thinking of getting a powermate, the one which is 'practically compatible' for your scope at the moment is the 2.5x (new ~ S$350 shipped) . The rest are in 2" format and will not fit the ETX, and the other 1.25" version they have is a 5x which is definately too much power for your ETX due to it's long focal length.

If you're looking for a proven barlow with a premium name and that has good re-sale value in the future, go for the TeleVue 2x Barlow (new ~ S$220 shipped). These babies are very highly sought after. Some of them do find their way into Astromart occasionally, and some of those that did couldn't even last a full minute before getting snapped up !

Post by **acc** » Thu Oct 02, 2003 8:59 am

TV Barlows (they are what they are, despite wat fancy name Nagler calls it) tends to be rather long, and may look out of place sitting on your ETX. IMHO, don't think they are worth the price. Can consider Celestron Ultima 2x barlows. Well-regarded and has a much smaller profile.

harlequin2902 · Post by **harlequin2902** » Thu Oct 02, 2003 11:24 am

Yes, the Ultima 2x is much shorter than the TeleVue 2x and will look "nicer" on the ETX if you are concerned about the overall setup appearance.

We do carry the Ultima-equivalent barlow -> Our Antares Ultima Barlow if you're interested. Short profile, 3 element design, with multi coatings on every air-glass surface for maximum light transmission. Made in Japan. We have some in stock right now, just in last week from the supplier

But if you really go technical ... simple physics laws and optical theory will tell you that the 3 element Ultima designed barlows will have a lower light transmission compared to other well made and well designed, 2 element barlows. Excellent coatings may sometimes overturn this argument, but I don't see why or how TeleVue grade coatings would be inferior to those on the Ultimas. They are at least on par or better.

Post by **VinSnr** » Thu Oct 02, 2003 12:23 pm

acc wrote:TV Barlows (they are what they are, despite wat fancy name Nagler calls it) tends to be rather long, and may look out of place sitting on your ETX. IMHO, don't think they are worth the price. Can consider Celestron Ultima 2x barlows. Well-regarded and has a much smaller profile.

As usual..TV eyepieces and accessories are overpriced

dew · Post by **dew** » Thu Oct 02, 2003 12:38 pm

hmm... from what i understand from the televue (correct me if i'm wrong) link that sam provided, the one major difference between powermates and barlows is that powemates do not extend the eye relief of the eyepieces, thus reducing any vignetting that might occur. is that correct?

my main concern in a barlow is that it will not introduce any distortions/optical defects. are all barlows created equal? or are there observable differences in image quality between them. (say the ultima vs tv barlow or tv barlow vs tv powermate?)

eu-wen

Post by **rcj** » Thu Oct 02, 2003 12:53 pm

Hi,
I will second the Ultima 2X barlow. Very good for the price.
Alernatively, TAKAHASHI has come out with a new barlow (at last!) complete with cool compression ring-styled visual adapter. It is a 1.25" 2X barlow version. You can refer to the crew at STARMATRIX (enquiries@star-matrix.com) for exact prices. It is short-styled.
Ray

Post by **VinSnr** » Thu Oct 02, 2003 12:53 pm

dew wrote:hmm... from what i understand from the televue (correct me if i'm wrong) link that sam provided, the one major difference between powermates and barlows is that powemates do not extend the eye relief of the eyepieces, thus reducing any vignetting that might occur. is that correct?

my main concern in a barlow is that it will not introduce any distortions/optical defects. are all barlows created equal? or are there observable differences in image quality between them. (say the ultima vs tv barlow or tv barlow vs tv powermate?)

eu-wen

I doubt you see any differences between an Ultima barlow and a TV barlow. Except differences in your wallet size when you purchase a TV barlow.

As for Powermate, I doubt much differences too. I have used all three types before....so just take my word and go buy a Ultima 2X barlow. if you have spare cash and must spend, just pass the cash to me.

Post by **Airconvent** » Fri Oct 03, 2003 12:07 am

Hi Euwen
I am using my ETX105 with a Televue x2.5 Barlow. The optics are great but as CC has pointed out, its a tad long and having x2.5 really wreck your brains trying to calculate the magnification! I have to print and paste out a look-up table on my eyepiece box to get a quick mag reference...
I would love to change to an Celestron ultima x2 but somehow, the TV's reputation makes me more shiok when I use it....

harlequin2902 · Post by **harlequin2902** » Fri Oct 03, 2003 1:02 am

I would love to change to an Celestron ultima x2 but somehow, the TV's reputation makes me more shiok when I use it....

I strongly agree

Eu-wen, whatever we say here, you are the one that's going to be using it in the end, so when faced with "paralysis by analysis", follow your heart if you must. That's usually the case when we are sometimes faced with decisions concerning (seemingly) overpriced premium stuff :roll: