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Pentax scope Barlow lens problem

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Pentax scope Barlow lens problem

Postby mikalmmd on Sat Jun 02, 2007 11:31 pm

I have a Pentax PF-65ED-A Angled 65mm ED Spotting Scope and I just purchased a Celestron Ultima 2x Barlow lens. With both of my eyepieces, a Hyperion 13mm, and a Pentax 20x-60x zoom, I am unable to achieve focus at infinity. There is not enough focus travel in the scope. Is this a problem with the scope or with the particular Barlow lens? Would a different Barlow lens work better? Is there another way to solve this problem?
Thanks for your help.
Michael Kalm
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Postby opticsplanet.com on Mon Jun 04, 2007 7:51 am

Hi

Although the Pentax can use standard 1.25" telescope eyepieces, it cannot use most 1.25" telescope accessories, such as barlows and photo adapters - for the very reason you mentioned. Sorry, I don't know of a barlow that will solve your problem. If you want more magnification, you are going to have to go to a different eyepiece.
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Re:

Postby Guest on Sun Apr 17, 2011 4:11 pm

opticsplanet.com wrote:Hi

Although the Pentax can use standard 1.25" telescope eyepieces, it cannot use most 1.25" telescope accessories, such as barlows and photo adapters - for the very reason you mentioned. Sorry, I don't know of a barlow that will solve your problem. If you want more magnification, you are going to have to go to a different eyepiece.


So Barlows, powermates and etc... don´t work with the Pentax PF??

Not even in the PF-80ED?


The Pentax, in the paper seemed so versatile to me... exactly because of the possibility of the XW+powermate(barlow).

I would love more insights on this... because I was thinking about the Pentax PF-80ED as the best scope available... considering the possibility of the 20-60 + XW20 + 2/2.5/3 magnifiers.

It would be Digiscoping, Birding and Astronomy in only one item. Insights and help, plz... is that right?
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Re: Pentax scope Barlow lens problem

Postby Jne_K on Mon Apr 18, 2011 9:51 am

Hi

Sorry, same answer. Other than the ability to use standard 1,25" telescope eyepieces, the PF series, including the PF80, uses a conventional spotting scope focusing design. This means a short focus travel and that, unfortunately, means no telescope accessories, such as conventional telescope camera adapters and barlows. If you want the capability to use a barlow with a spotting scope, you are going to have to try a more typical telescope design, such as a Mak in the Celestron C90, an SCT, as in the Celestron C5 or a refractor, such as a Televue.
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Re: Pentax scope Barlow lens problem

Postby Guest on Mon Apr 18, 2011 10:58 am

Jne_K wrote:Hi

Sorry, same answer. Other than the ability to use standard 1,25" telescope eyepieces, the PF series, including the PF80, uses a conventional spotting scope focusing design. This means a short focus travel and that, unfortunately, means no telescope accessories, such as conventional telescope camera adapters and barlows. If you want the capability to use a barlow with a spotting scope, you are going to have to try a more typical telescope design, such as a Mak in the Celestron C90, an SCT, as in the Celestron C5 or a refractor, such as a Televue.


You just made the Nikon fieldcope ED far more interesting for me now... and I was about to buy the pentax in the hope of using barlow =/

What is the point of the Pentax then?? What is the point to use all 1.25 when the only and best 1.25 there for it are its own zoom and the XW. It just seems versatile... but in the end it is as versatile as the Nikon (that also have the a similar set of wide view eyepieces...).
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Re: Pentax scope Barlow lens problem

Postby Guest on Mon Apr 18, 2011 11:00 am

Guest wrote:
Jne_K wrote:Hi

Sorry, same answer. Other than the ability to use standard 1,25" telescope eyepieces, the PF series, including the PF80, uses a conventional spotting scope focusing design. This means a short focus travel and that, unfortunately, means no telescope accessories, such as conventional telescope camera adapters and barlows. If you want the capability to use a barlow with a spotting scope, you are going to have to try a more typical telescope design, such as a Mak in the Celestron C90, an SCT, as in the Celestron C5 or a refractor, such as a Televue.


But not even those shorty barlows??

You just made the Nikon fieldcope ED far more interesting for me now... and I was about to buy the pentax in the hope of using barlow =/

What is the point of the Pentax then?? What is the point to use all 1.25 when the only and best 1.25 there for it are its own zoom and the XW. It just seems versatile... but in the end it is as versatile as the Nikon (that also have the a similar set of wide view eyepieces...).
Guest
 

Re: Pentax scope Barlow lens problem

Postby Jne_K on Tue Apr 19, 2011 10:01 am

Hi

The big advantage of the Pentax is being able to use any brand of 1.25" telescope eyepiece, not just Pentax and any focal length 1.25" telescope eyepiece. This is a huge advantage in a spotting scope you want to also use for astronomy.

For instance, if you want more magnification from a Pentax PF80, just skip the barlow idea and go directly to a shorter focal length eyepiece to get the magnification you want. Just divide the focal length of the Pentax PF80 (500m) by the focal length of the eyepiece in question and you can get any magnification you want that is reasonable for an 80mm scope, especially a scope mounted on a photo tripod. A Pentax XW in a 3.5 mm focal length, for instance, gets you 142x. Same for a similar focal length Televue eyepiece, Vixen eyepiece and so on. That's twice as much as the maximum 75x you can squeeze out of a Nikon Fieldscope and, even then, it's only possible with one specific Nikon Fieldscope eyepiece.
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Re: Pentax scope Barlow lens problem

Postby Guest on Tue Apr 19, 2011 10:09 am

Jne_K wrote:Hi

The big advantage of the Pentax is being able to use any brand of 1.25" telescope eyepiece, not just Pentax and any focal length 1.25" telescope eyepiece. This is a huge advantage in a spotting scope you want to also use for astronomy.

For instance, if you want more magnification from a Pentax PF80, just skip the barlow idea and go directly to a shorter focal length eyepiece to get the magnification you want. Just divide the focal length of the Pentax PF80 (500m) by the focal length of the eyepiece in question and you can get any magnification you want that is reasonable for an 80mm scope, especially a scope mounted on a photo tripod. A Pentax XW in a 3.5 mm focal length, for instance, gets you 142x. Same for a similar focal length Televue eyepiece, Vixen eyepiece and so on. That's twice as much as the maximum 75x you can squeeze out of a Nikon Fieldscope and, even then, it's only possible with one specific Nikon Fieldscope eyepiece.


But Jne_K, I rather buy just XW20 and a powermate than to buy a WX20 + XW10... and I saw people saying on internet that the televue powermate 2.5 actually do work with the Pentax PF-80ED.

Can optic planet test this? I really can´t myself there is no such items available for me here...
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Re: Pentax scope Barlow lens problem

Postby Jne_K on Wed Apr 20, 2011 12:31 pm

Hi

Personally, I see no advantage to going the barlow route, but If that's the route you want to go, by all means give it a try. I have not used the specific combination, though, so I cannot verify it will work. Sorry.
Thanks for posting with us
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