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03-08-2009, 01:09 PM   #16
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Thanks! The sun was almost directly in front of me and just above the treeline. Obviously the snow blew out badly but the targets came out OK partly due to big enough lens hood.

03-08-2009, 03:47 PM   #17
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QuoteOriginally posted by Maffer Quote
At relatively close distances (2.5m) the lens seems to give very mixed up results:

-50mm @ 2.8 needs -6 AF adjustement
-70mm @ 2.8 needs -9 AF adjustement
-100mm @ 2.8 needs -6 AF adjustement
-150mm @ 2.8 needs -3 AF adjustement

Shooting out there at longer distances the adjustements above seem to screw up the focusing. AF if very fast with K20D. The lens is very quit during the time it takes to lock focus. When the focus is just right the lens is very sharp even wide open.
I had the same exact situation with the Sigma 70-200 EX HSM II, just as dpreview had reported in it's review of the lens.

I love the Bison shots btw


John
03-08-2009, 04:11 PM   #18
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Great shots Gus, and I really like that Bison shot Maffer =) I'm guessing close focus problem in different zoom range is more common with third party lenses? My 28-75 Tammy exhibits this to some degree when close focusing as wall.

And I can tell that Gus lost his pentax color in those shots
03-20-2009, 02:25 AM   #19
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Hmph, this lens is really a mixed bag of pros and cons. Yesterday I wandering in the forest with this lens attached to k20d. Took some shots of rock formations and trees etc. the usual stuff by focusing manually. Everything did look pin sharp in the viewfinder and I made the mistake of not checking the shots afterwards from the LCD only to find all of my manually focused shots being horribly FFed when checked on my PC later. Using AF from the same distances gives sharp results but then I cannot rely on what I see on the viewfinder, just have to trust the AF system.

Go figure I just ruined many nice shots by using MF. Sigma 70mm macro and the other lenses I own seem to give perfect results when focusing manually using the viewfinder.

03-28-2009, 05:03 AM   #20
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Some notes of shooting our doggie in very bright daylight conditions:

1) AF is instant at all focal lenghts. Squeeze the trigger - BAM! Right there. This is with stationary target.
2) If the target is moving, the system fails however. If the dog was running towards me or away from me what happened was a funky machine gun effect with bad results unfortunately. In AF-C mode with center AF point fully centered on the dog the camera was trying to update the focus but was constantly one of two steps beyond the target. The focusing action is very silent but you can hear a faint click when focus locks. So with moving dog I got: tick - tick - tick - tick - tick (repeat like 50 times in rapid fashion) but the focus was always few steps behind the dog. Result was usually blurred shot. With shutter speed of 1/2000 sec I should be able to freeze the moment so I don't think that's the problem here. Going to try catch-focus next with moving stuff.
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