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Old Wednesday 23rd September 2009, 22:17   #1
DRodrigues
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A barlow that works with Pentax scopes

At http://www.pt-ducks.com/cr-telescope....5x_magnifiers I said that a barlow of 2x that would work in birding telescopes would be the best compromise. Meanwhile I found a modular barlow that could be even better since offered 1.6-2-2.5x http://www.bs-astro.com/index.php?pa...emart&Itemid=1 . As is not expensive I decided to try it. First contact at the store showed that it focused both at PF100 and Optolyth 100, in all 3 magnifications. I bought it and took it for a better contact on my field conditions. The result was not so good since it doesn't focus at the infinite with 2 and 2.5x magnifications. However the 1.6x works surprisingly well in terms of light and colour definition. Another good point is that using it in a Baader zoom, first version, it focus in the PF100!!! Like that I can have a very good 15-5mm zoom i.e. a 42-126x zoom which can be very useful on my cr-birding. Even more interesting is that I prefer the views through this barlow/Baader zoom combo than through the XFzoom (I use eye glasses), being that at both higher magnifications the combo seems to have more light than the XF! I have to do a more detailed test but the resolution test will take some weeks. I have to compare it to the XF and to the XW5mm.
For now I have 4 different zoom ranges for my Optolyth 100:
- Optolyth 20-60X - use it mostly for digiscopy;
- Baader zoom 25-75x - it focus on my telescope but can't be the case for other Optolyth models or older versions - don't use it since prefer the next for my cr-birding;
- Optolyth 30-90x (the 20-60x for the 80 models, it increases 50% more on the 100) - the higher magnifications allow more resolution so is better for cr-birding;
- Barlow 1.6x+Baader Zoom - results on the mentioned 42-126x - will see if it will replace my XW5 for higher distances resighting...

David
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Old Saturday 27th February 2010, 18:06   #2
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tried a barlow in a 65 and doesnt come to focus with the eps i have......may try with short plossl to see if it wroks
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Old Sunday 28th February 2010, 23:09   #3
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Try using the barlow element by itself (removed from short tube and screwed directly into eyepiece). This has worked for me with my diy 50mm refractor.

Rmel66.
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Old Sunday 28th February 2010, 23:54   #4
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Quote:
Originally Posted by woodhornbirder View Post
tried a barlow in a 65 and doesnt come to focus with the eps i have......may try with short plossl to see if it wroks
WHB, I've tried alot of different combo's, short barlow's long one's, etc. I could never find a combination that would work with the PF 65. You generally will be able to achieve some sort of focus but, to reach infinite focus is impossible the scope doesn't have enough focus travel. Bryce...
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Old Tuesday 2nd March 2010, 13:37   #5
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does that mean its doable witht he pf80 then?
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Old Sunday 4th July 2010, 03:46   #6
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It took a bit but I updated the info at cr-telescopes with a couple of photos http://www.pt-ducks.com/cr-telescope...1.6x_magnifier
I think it answers to some doubts and it should work in all PF models.
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Old Sunday 4th July 2010, 10:28   #7
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that would be great news!
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Old Thursday 4th November 2010, 19:16   #8
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bumping this....

has anyone found a similar piece that is available in the US to get the Baader Hyperion Zoom to reach focus? The store that David linked to is in Brazil! :)

Most barlows of course are long tubes and will not work... is there any such small adapter piece that can screw onto the front element of the Baader Zoom?

Last edited by eitanaltman : Thursday 4th November 2010 at 19:19.
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Old Sunday 7th November 2010, 13:44   #9
DRodrigues
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The store that David linked to is in Brazil! :)
It's in Portugal not Brazil... Just a few thousands km of distance... :-) Anyway not in North America.

Regarding your questions I remember to see a post on this forum of someone from USA that used a corrector for binoviewers and got focus with the baader zoom. However I didn't managed to find it now.
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Old Sunday 7th November 2010, 20:55   #10
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I finally had the time to do some testing with a Televue 2.5x Powermate in both a PF-80ED and a PF-65EDII with a variety of eyepieces. I didn't have a Baader zoom available but I did test it with the 8-24mm SMC Pentax zoom.

The Powermate is not a true Barlow, but acts like one when it comes magnification.

I had no convenient "infinity" object, so I used a tree at a range roughly 2000 feet, or 600 meters.

Without exception, when focused on the tree, every eyepiece had more focuser travel remaining with the Powermate than it had with the same eyepiece alone.

Near-focus with the Powermate was reduced just 2-3 feet on all eyepieces.

Now the bad news; average retail is around $180, so a short fixed focal length eyepiece may be a better alternative for times when you need more power unless you absolutely need to have a zoom.

Also, a PF-65EDII looks ridiculous when using a Powermate and an 8-24 SMC Pentax zoom eyepiece.

I also discovered that focus direction near to far is in the opposite direction between the 65 and the 80mm scopes.

FWIW,
Mike
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Old Tuesday 10th May 2016, 17:37   #11
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I'm really late to the party, but I was wondering if anyone else has been successful using a Teleuve 2.5x Powermate with the PF80ED-A?

Does it work without any of the tweaks required for other barlows, or are those tweaks always necessary?

Thanks!
Pedro
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