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Old Dec 7, 2006, 2:13 AM   #1
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Just wondering if anybody has tried using a 1.4x teleconverter with the sigma 70-300 apo dg lens. How bad is the image degradation? Will the autofocus still work? What will my wide open apeture be then?

Also, can the K100d operate lens with HSM such as the sigma 50-500?

Thanks.
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Old Dec 7, 2006, 11:50 AM   #2
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What I know is that there is a significant difference between converters and converters. The Pentax converters are very good, but also pretty expensive compared to other brands. They are also manual focus. I use a Pentax 2XS with my 600 mm lens, and thanks to the smaller sensor on digital the problems that should show (vignetting) are absent. I'm very satisfied, there is very little degradation. I'm at work now, but will post a picture when I get home later tonight.

Cheaper third party converters may be good or may not be good, you'll have to test or ask around to know.

Kjell

Edit: I forgot to mention the Pentax AF 1.7. Gives autofocus even to manual focus lenses. For some reason it's a lot cheaper than the manual ones, and is still sold new. I think Roy has one, and the pics Ihave seenwas HQ.

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Old Dec 7, 2006, 12:52 PM   #3
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bilybianca wrote:
Quote:
Edit: I forgot to mention the Pentax AF 1.7. Gives autofocus even to manual focus lenses.
Just out of curiosity... How is this achieved?
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Old Dec 7, 2006, 2:23 PM   #4
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The 1.7 has moving elements which is how it does AF, but it can not cover the entire range of most lenses, so most people focus the MF lens to infinity before using it.

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Old Dec 7, 2006, 3:49 PM   #5
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royca,

i've had a number of people recommend the tamron 1.4x.. 70usd at B&H. it's the least expensive there than anywhere else. i've never had much luck with 2x TCs but i've got the tamron 2x and i'm fairly pleased with it. people have also said to stay away from the sigmas.

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Old Dec 7, 2006, 4:15 PM   #6
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This was taken with the 600 mm lens + Pentax Rear Converter 2XS. The picture is cropped, the bird was pretty far away. I think the converter defends itself.

Kjell
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Old Dec 7, 2006, 4:42 PM   #7
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luck??? wow
this was also taken with one of the best lenses pentax ever produced also. and on a prime.

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Old Dec 7, 2006, 5:26 PM   #8
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A couple more, same combo. Point: converters can be OK.

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Old Dec 7, 2006, 5:27 PM   #9
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Second, slightly cropped:
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Old Dec 7, 2006, 5:39 PM   #10
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kjell,
the raptor shot-- were you panning??

roy
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