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12-07-2009, 05:21 PM   #1
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Refraction Lens

Hi there everyone, I have a question about refraction lenses. So I saw on Ebay a refraction lens with the zoom range of 650-1300mm, expensive of course but I was wondering, how do these refraction lens work? Are they Worth while? The Brand didn't seem too good but it was mostly out of curiosity. I couldn't find really good info around the net so I was wondering if you guys had any info on these Lenses?
Thank you!

12-07-2009, 06:13 PM   #2
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Is it possible this term was mistranslated? I'm not aware of any common uses of the term "refraction lens", although of course all lenses by definition refract light. I'm assuming you mean either the very simple lenses whose focal length is their actual length - hollow tubes with glass at either end - or else you mean mirror lenses. Neither are usually expensive, though - in fact they are often extremely cheap compared to "regular" telephoto lenses of the same focal length. Naybe there is another kind of lens I'm not aware of? Or some expensive versions of the simple "hollow tube" lenses?
12-07-2009, 07:10 PM   #3
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QuoteOriginally posted by Andrezao Quote
Hi there everyone, I have a question about refraction lenses. So I saw on Ebay a refraction lens with the zoom range of 650-1300mm, expensive of course but I was wondering, how do these refraction lens work? Are they Worth while? The Brand didn't seem too good but it was mostly out of curiosity. I couldn't find really good info around the net so I was wondering if you guys had any info on these Lenses?
Thank you!
If you're talking about the Phoenix or Opteka fixed 650mm lenses that come with a 2X teleconveter for 100 bucks... or worse, are a tube that you zoom out by simply extending the tube... don't bother they're crap.

There are decent quality mirror lenses with 500mm and 800mm focal lenghts though... But these are reflective, not refractive, optics. Still won't win you any National Geographic covers though.
12-07-2009, 11:51 PM   #4
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Those kinds of lenses are garbage for still shots, but they actually might be quite useful for video if you have a camera that does video, and are into that kind of thing. Poor quality lenses aren't as obviously bad in video, and the zoom range would be fun to play around with.

12-08-2009, 02:47 AM   #5
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Correct me if I'm wrong but don't all lenses work my refraction (apart from mirror and diffraction lenses)?
12-08-2009, 02:50 AM   #6
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QuoteOriginally posted by Dom Quote
Correct me if I'm wrong but don't all lenses work my refraction (apart from mirror and diffraction lenses)?
You have successfully echoed previous posts made in this very thread, right above you
12-08-2009, 03:01 AM   #7
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QuoteOriginally posted by Andrezao Quote
Hi there everyone, I have a question about refraction lenses. So I saw on Ebay a refraction lens with the zoom range of 650-1300mm, expensive of course but I was wondering, how do these refraction lens work? Are they Worth while? The Brand didn't seem too good but it was mostly out of curiosity. I couldn't find really good info around the net so I was wondering if you guys had any info on these Lenses?
Thank you!
I think, the seller simply meant, that it is a lens, built with lenses, not mirrors. A mirror lens is "reflective" and all usual lenses are "refractive", be it the humble 18-55 kit lens or the latest and best 600mm/4.0. The 650-1300mm is a zoom lens, using "lenses" and as such is a "refractive" lens, too.

Have a look at the technical data and you will recognize, that the zoom might work in thoery, but is extraordinarily slow and hardly useable. For a lens of that focal length, you would need a very sturdy tripod, which will be much more expensive than the zoom!

Ben
12-10-2009, 04:42 AM   #8
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Hmmm on Ebay they guy put as Refraction Lens but I went more into it and it's a mirror lens, so Reflective. Are they good? I don't intend to buy it, but out of curiosity.

12-10-2009, 09:28 AM   #9
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QuoteOriginally posted by Andrezao Quote
Hmmm on Ebay they guy put as Refraction Lens but I went more into it and it's a mirror lens, so Reflective. Are they good? I don't intend to buy it, but out of curiosity.
the zoom 650-1300 is no mirror lens. I don't know, whether there exiasts a 650mm mirror, that would be doubled with a 2x tele converter to 1300mm - but in any way this is a low value, low quality proposition.

It would be easier to comment, if you could post the link - than we know for certain.

Ben
12-10-2009, 09:48 AM   #10
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QuoteOriginally posted by Ben_Edict Quote
the zoom 650-1300 is no mirror lens. I don't know, whether there exiasts a 650mm mirror, that would be doubled with a 2x tele converter to 1300mm - but in any way this is a low value, low quality proposition.

It would be easier to comment, if you could post the link - than we know for certain.

Ben
Well Penax did make a zoom mirror lens, not in that range however. The Penax was a 400-600 zoom mirror lens.
12-10-2009, 12:01 PM   #11
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QuoteOriginally posted by Andrezao Quote
Hmmm on Ebay they guy put as Refraction Lens but I went more into it and it's a mirror lens, so Reflective. Are they good? I don't intend to buy it, but out of curiosity.
They are fine for what they are. Google the term and you'll find hundreds of references to people discussing the pros and cons. Or just visit the Mirror Lens Club thread in this forum.

Although as another poster said, I doubt it really is a mirror lens - there are very few mirror zooms. Although I suppose it could be a regular mirror lens (prime) that comes with a matched teleconverter - that's pretty common. But why would he call it a refraction lens? most likely, it's the "telescope" type of lens I described. In general, not good lenses at all, although they do at least have better bokeh than mirrors.
12-10-2009, 12:24 PM   #12
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QuoteOriginally posted by MikePerham Quote
Well Penax did make a zoom mirror lens, not in that range however. The Penax was a 400-600 zoom mirror lens.
I know that lens. I nearly bought it, but found it too slow for my taste. The only advantage being its really diminutive size, especially compared to the 500/4.5 or 1000/8...

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12-13-2009, 05:21 AM   #13
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The brand of this lens is Opteka, Japanese Apprently. Any good? They're cheap as, prob terrible quality but I could be wrong perhaps?
Here's the Link By the way: http://cgi.ebay.com.au/650-1300mm-Lens-for-Pentax-K10D-K20D-K100D-K110D-K200...item2c5229a3c5
12-13-2009, 05:58 AM   #14
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QuoteOriginally posted by Andrezao Quote
The brand of this lens is Opteka, Japanese Apprently. Any good? They're cheap as, prob terrible quality but I could be wrong perhaps?
Here's the Link By the way: 650-1300mm Lens for Pentax K10D K20D K100D K110D K200D - eBay Digital Camera Lenses, Lenses, Photographic Accessories, Cameras. (end time 20-Dec-09 23:06:26 AEDST)
Well, good luck. A quick google searched turned this up: Opteka 650-1300mm - Opinions? - DPChallenge Forums

On the other hand, there are mirror lenses that forum members (including myself) have used and got decent results with. A 500mm f/6.3 mirror is US$159 on ebay and a 800mm f/8 is US$ 189. These are not only cheaper than what you posted but much easier to handle being smaller and lighter.

The reviews for the 500mm f/6.3 are here: PentaxForums.com Third-Party Pentax Lens Review Database - 500mm F/6.3 DX

Also: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/71775-mirror-lens-club.html

Last edited by kristoffon; 12-13-2009 at 06:06 AM.
12-13-2009, 06:39 AM   #15
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Hmm so the brand itself is bad? Would you advise me to buy a Teleconverter or a Mirror lens if I wanted an extra reach? I have a Sigma AF 100-300, a Tamron 70-210, and a Sigma 70-200. All 3 are quality lens and work very well for me so far. Like I can reach this far:

But the shots I saw in that mirror lens thread certainly makes it a bit more interesting. So down to it, what would be better a Teleconverter 2x or a 500mm Mirror lens? They cost about the same from what I've seen...
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