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Old Mar 15, 2008, 10:50 AM   #1
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One last tests of the lens, this time using the Pentax AF1.7 on the Sigma 300. I see the drawback with the Sigma over the Pentax FA* 300, in that the focus lock to lock on the Pentax is very short, but the Sigma is extremely long. Because of this using the AF1.7 you are limited to a very short in focus area and have to use the lens focus ring to reach out.

The AF1.7 has about 5 areas of focus with the Sigma where it has only 2 with the Pentax. But then the Sigma is a 2.8 and the Pentax is a 4.5.

On the plus side, I now have a 510mm f/4.8 auto focus lens to use.



Tom
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Old Mar 15, 2008, 2:08 PM   #2
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Hi Tom,

This looks very good, but after seeing how sharp the lens alone is wide open, I knew it would. I think that you'll grow to appreciate the extra speed that you get with this combo. I'm definitely a believer. . .

Scott
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Old Mar 15, 2008, 3:53 PM   #3
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ennacac wrote:
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One last tests of the lens, this time using the Pentax AF1.7 on the Sigma 300. I see the drawback with the Sigma over the Pentax FA* 300, in that the focus lock to lock on the Pentax is very short, but the Sigma is extremely long. Because of this using the AF1.7 you are limited to a very short in focus area and have to use the lens focus ring to reach out.

The AF1.7 has about 5 areas of focus with the Sigma where it has only 2 with the Pentax. But then the Sigma is a 2.8 and the Pentax is a 4.5.

On the plus side, I now have a 510mm f/4.8 auto focus lens to use.



Tom
And you are using it well Tom! Very sharp photos.

Dawg
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Old Mar 15, 2008, 10:26 PM   #4
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Looks like this lens is pretty good - very sharp picture considering the TC. It looks like a good alternative.
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Old Mar 16, 2008, 3:36 AM   #5
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Encouraging about the AF Conv, I'll have to use mine more. But then I'll have to get a 300mm, hmmm... Obviously going off brand isn't always a bad choice. Impressing photo, Tom. What does the combo weigh?

Kjell
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Old Mar 16, 2008, 9:33 AM   #6
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Kjell, the lens weighs 4lb 6oz which is about half of what my 500 4.5 weighs, the AF1.7 doesn't weigh enough to make any difference. It is heavy enough that you need some support, but it does work with a monopod, unlike the 500 that requires a tripod.

The joy of APSC sensors is that you use the very center of the lens, taking any fall off at the edges out consideration like it would be with a FF sensor.

I will have to try this lens on my MZ-S to see how it performs with full frame at the edges.

Tom
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Old Mar 17, 2008, 5:40 AM   #7
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Outstanding sharpness Tom. Boy I wish Pentax would decide to produce another run of these T/Cs.

Tim
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Old Mar 17, 2008, 6:08 AM   #8
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Whatever the set up, it sure looks like you know how to use it. Really nice shots!

Glenn
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