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07-15-2010, 06:48 PM   #31
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QuoteOriginally posted by Laurentiu Cristofor Quote
Strange - the note and the second list you provided seem to contradict each other. In the list, if I am reading it right, there are several HSM lenses that are marked as working on Pentax. It's true that the 70-200 MACRO HSM is marked as not working, but other HSM lenses are shown to keep AF with the teleconverters.

Looks like their guidance is a mess anyway.
That list is indeed confusing to read, now that you mention it. I believe the ones listed as "EX DG / HSM" in the table only had HSM in other mounts besides Pentax. For example, the "APO 100-300mm F4 EX DG / HSM".

I have the 1.4x matched converter and there's no way it would work with HSM/SDM as it lacks the PZ contacts.

07-16-2010, 04:58 AM   #32
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QuoteOriginally posted by Pentaxor Quote
I think it would just be a matter of time where slow lenses would be as capable as fast lenses in such demanding situations.....
Not trying to pick a fight here, but I think we are not all that far away from theoretical limits. Last time I looked, sensors were about a factor of three below theoretical quantum efficiency limits - I think that included the Bayer filter strategy.

At the quantum efficiency limit, only software tricks can further improve S/N ratios (like an algorithm that decides "this area is sky & the sky has no noise"..etc..)

I suspect it may not be long before the remaining 2 stops sensitivity are picked up by sensor and software design, but there are practical limits not far away.

07-16-2010, 02:34 PM   #33
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the 55-300 is probably the best value for the money. It can have slow focus, but anything better, like the sigma 2.8s, come with a significant higher price and weight.
I have the DAL version and bought a cheap copy hood. Couldn't be happier.
07-17-2010, 06:48 AM   #34
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I've a copy of the Tamron 70-300 LD on my Sony. Images are nice but its relative focus speed put it on the shelf. The K-7 is faster to focus overall than my A200 so hard to say how a Tamron would compare to 55-300 in speed.. but it was the slowest-focus lens in my Sony bag so I usually grabbed my 100-200 instead.

I now have the DAL version of 55-300; its range wins, IQ is great but I don't need 1:2 'macro' which might be of interest to some buyers. It's definitely smaller than the Tamron, weight is similar. I would say the focus is a bit .. whiny .. with the DAL, a bit more annoying than the DA 16-45. The bokeh has not been as nice as the Tamron either, but I've only had a few days with the 55-300 so am still learning its highs & lows. I expect I'll miss the manual-focus override at times that the DA models have, but otherwise it's quite nice - and I found a good price for a new copy. For lo-light tele I've a man-focus 135/2.8, as bpjod notes a prime like that is nice to have at times.

Last edited by jimr-pdx; 07-17-2010 at 06:50 AM. Reason: it's better now

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