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Old Mar 28, 2009, 5:11 PM   #1
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I've been thinking of teleconverters recently and would like some input.
1. What are my choices: I see Sigma, Tamron and Kenko advertized, but not Pentax. Do the non-Pentax brands preserve all automatic features?


2. What would you recommend in brand and magnification (1.4X vs 2) from the standpoint of image quality. I'd like to know if a t/c is an inexpensive yet worthwhile substitute for a longer lens. For instance 300 mm + 1.4 t/c vs. a Bigma (say).


Thanks.

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Old Mar 28, 2009, 6:27 PM   #2
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Generally speaking, the better the lens, the better the result. If the lens isn't good, no TC will give you usable pictures. And of course a TC slows down the lens, so to put a 2X TC on an f5.6 300 mm zoom will give you f11 as your largest aperture. But if you do have a reasonably fast prime lens, a worthy TC can give you a supertele with sufficient or even very good quality. Just look at Scott/Snostormsbirds with stacked TCs (I expect he'll chime in, he's the TC guru in this forum).

I have two Pentax converters.

The Rear Converter A 2XS, which has the electronic contacts but not AF. I use it mainly with my A*600 mm (requires very bright weather). I found mine on schreechbay before the prices skyrocketed, nowadays they seems to be very rare. But it's as good as it gets, optically.

The second one is the AF Converter 1.7, which I use with the A* 200mm and the A* 85mm. Besides maintaining all electronic communication between lens and body, it adds AF to these manual lenses. Not quite as good optically as the other one, but not lagging far behind.

I can't say anything about the quality of other brands, but I'd stay away from the cheapies of unknown makes.

Kjell
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Old Mar 28, 2009, 10:53 PM   #3
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bilybianca wrote:
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Generally speaking, the better the lens, the better the result. If the lens isn't good, no TC will give you usable pictures. And of course a TC slows down the lens, so to put a 2X TC on an f5.6 300 mm zoom will give you f11 as your largest aperture. But if you do have a reasonably fast prime lens, a worthy TC can give you a supertele with sufficient or even very good quality. Just look at Scott/Snostormsbirds with stacked TCs (I expect he'll chime in, he's the TC guru in this forum).

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I have two Pentax converters.
I can't say anything about the quality of other brands, but I'd stay away from the cheapies of unknown makes.

Kjell
Kjell, thanks for your input. Does Pentax make a converter presently...I do not see one in their product line up? If not, is used the only way to go?
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Old Mar 29, 2009, 4:03 AM   #4
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No Pentax TC in production, and the one on the "Lens Roadmap" has been removed.

The AF Converter could be bought new as recently as 11/2 year ago, but now I think it's only available on the second hand market. Maybe one still on the shelf in the local camera shop in Shuttahattaville or Ougadagolatown.

Kjell
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Old Mar 29, 2009, 10:40 AM   #5
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If you have the correct lens then the Sigma APO is a good one but it is a matched TC and will not work with all lenses. The Tamron and the Kenko will work with all lens. I use my Sigma sparingly and only When Really Needed. The more you put between you and the subject the more the quality will be degraded. For most photos in the digital realm you can get as good a photo from cropping as you can from a TC. But even here the base lens you use will dictate the quality of the image when you crop, just as it will dictate the quality when using a TC. A poor quality base lens will mean a poor quality photo no matter what. If you wish you can go here to see some crops with an all manual inexpensive 1976 era Vivitar lens.....
http://forums.steves-digicams.com/fo...mp;forum_id=94

And here is another comparison...original first and the crop second....

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Old Mar 29, 2009, 10:40 AM   #6
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And the crop. Straight from the camera with no PP.
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Old Mar 29, 2009, 3:25 PM   #7
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bigdawg wrote:
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If you have the correct lens then the Sigma APO is a good one but it is a matched TC and will not work with all lenses. The Tamron and the Kenko will work with all lens. ...
Actually, Kenko and Tamron both sell matched TCs too. The Kenko PRO 300 series and the Tamron SP series teleconverters are 'Matched' and only work with certain lenses. In fact, the Kenko PRO 300 series and the Tamron SP series teleconverters are identical. Tamron sells Kenko's teleconverters as its own. Even the 'Generic' Tamron TCs are made by Kenko. And the 'Generic' teleconverters fromKenko, Tamron and others are all Kenko, andwill work on all lenses.
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Old Mar 29, 2009, 4:53 PM   #8
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TCav wrote:
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bigdawg wrote:
Quote:
If you have the correct lens then the Sigma APO is a good one but it is a matched TC and will not work with all lenses. The Tamron and the Kenko will work with all lens. ...
Actually, Kenko and Tamron both sell matched TCs too. The Kenko PRO 300 series and the Tamron SP series teleconverters are 'Matched' and only work with certain lenses. In fact, the Kenko PRO 300 series and the Tamron SP series teleconverters are identical. Tamron sells Kenko's teleconverters as its own. Even the 'Generic' Tamron TCs are made by Kenko. And the 'Generic' teleconverters fromKenko, Tamron and others are all Kenko, andwill work on all lenses.
Glad to see you are alive and kickin'. LOL When can we see some photos from you?

Dawg
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Old Mar 29, 2009, 5:12 PM   #9
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bigdawg wrote
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Glad to see you are alive and kickin'. LOL When can we see some photos from you?

Dawg
Thanks, but I haven't had many opportunities for a while. I've lived in the Washington DC area long enough to know tostay clear of the city when the cherry blossoms start coming out.
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Old Mar 29, 2009, 6:37 PM   #10
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jelpee wrote:
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Kjell, thanks for your input.* Does Pentax make a converter presently...I do not see one in their product line up?* If not, is used the only way to go?
Pentax does have a couple of TC but so far they are discontinued - the AF 1.7x being the most reputable one indeed as Kjell said. There is one TC on the roadmap about to be released geared for the DA lenses with SDM motor.

What lenses you have or about to have? That is important for picking the right TC

Daniel
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