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05-22-2012, 08:30 PM   #1
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Sue from Seattle area

First I would like to thank Pentax Forums for this supportive website- It means so much to me when I am the only Pentax user in my camera club-
At this time I am researching teleconverters vs purchasing the 50-500 mm zoom by Sigma.
Just trying to find out how to ask about the Pentax F 1.7 Teleconverter- If anyone out there has used this - I own a Pentax K5 and was thinking about using a teleconverter with my Tamron 28-300mm lens as a less expensive alternative to an expensive 50-500mm which doesn't seem to have a good review-

Also are there any extension tubes made for Pentax cameras? Thanks for your help here

05-22-2012, 08:40 PM   #2
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Location: Perth Western Australia
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Welcome to the forum, in answer to your question, yes Kenko make extension tubes for Pentax and they have the contact points for the camera & lens. Remember, when using extension tubes you will lose a certain amount of light which you'll need to compensate for.
05-22-2012, 09:49 PM   #3
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Welcome to the funny farm! Don't mind the outpatients. For tips on extension for Pentax lenses, see:

Both extension (tubes, bellows, helicoids, etc) and rear-mounted teleconverters, eat light. And the less expensive sorts reduce lens functionality. Auto-aperture control depends on A-type contacts on both the lens, and extension or TC. The cheap trick for extension is to get used A-type TCs and remove the glass. Compared to A-type macro tubes, deglassed TCs are both less expensive and less flexible. Ain't no free lunch here.

For more reach, I prefer quality front-mounted adapters to rear-mounted TCs. These don't cut light, nor interfere with lens aperture|focus functions. I often use a Sony VCL-1546A screw-on 1.5x tele adapter on lenses with front threads up to 52mm. I see less loss of image quality than with midrange rear-mount TCs. And quality tele adapters from Sony, Canon, Olympus, Kowa etc are pretty cheap.

The best TCs are optically better than such tele adapters. But they cost much much more. I'd have to rob a minimart to buy a good one, but I'm too lazy for that, so I'll get by with the Sony.

Glad to have you with us. Have fun!

EDIT: For A-type tubes, here is your opportunity:

Last edited by RioRico; 05-22-2012 at 10:31 PM.
05-23-2012, 10:24 AM   #4

Join Date: Jul 2010
Location: Oregon
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On you len choices: neither. If you want high image quality, stay away from zooms with ultra-wide range. If you want 500mm cheap, get a mirror lens.


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