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02-22-2007, 08:01 AM   #16
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QuoteOriginally posted by FotoPete Quote
Wow that's great! Thanks for the link! Haha I can't believe all hype surrounding the APO status. I looked at the MTF's before and they looked exactly the same.
There's more to image quality than MTF charts... What APO (supposedly) gives you is better control over chromatic aberration.

DISCLAIMER: I own neither of these Sigma lens. After trying the non-APO version and the Pentax DA50-200, I chose the latter. So maybe I know nothing at all :-)

03-01-2007, 08:44 PM   #17
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QuoteOriginally posted by srej Quote
For a K100D should I buy a SIGMA 70-300 DG or the Pentax 50-200.
With the rebate the SIGMA is only slightly cheaper.
I'd like the extra telephoto but not at the price of quality or functionality.


I have the Sigma DG APO Macro and the Pentax.

I'm not enthusiastic about the Sigma, especially beyond 200mm. Contrast goes down toward the wide end, and I never have gotten a really sharp shot on the long end either.

The Sigma has about twice the bulk of the Pentax, but of course has the macro capability (in the 200-300mm range) and extra 100mm's. It is over 10" long with hood when at 300mm and closely focused.

I have the Sigma 18-50 which is very sharp, so perhaps there is something to the hit-and-miss aspect of Sigma lens - though the 70-300 was $219 and the 18-50 was $375.

I'm currently looking for long lens alternative to the Sigma (actually, I ordered an "ugly" 300mm f4 for the heck of it.) I use the Pentax unless I really need the extra length. I often say "eh..." when viewing my Sigma images (at the long focal lengths), but rarely if ever with the Pentax.

I did an informal test of the Pentax vs Sigma at 100mm and 200mm (I could not set the FL exactly however, but close enough). I give the Pentax the slightly better grade in both cases. Pentax on left, Sigma on right.

I did not use a tripod but probably should have to eliminate that variable, However, I shot a couple with the Pentax and 6 or so with the Sigma and used the best one.

And, there may be a difference in performance stopped down a couple more stops.

Hope it helps.



Last edited by SpecialK; 03-01-2007 at 08:51 PM.
03-01-2007, 09:03 PM   #18
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You better post some pics of the 300mm lens itself haha!
03-03-2007, 10:00 AM   #19
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QuoteOriginally posted by FotoPete Quote
You better post some pics of the 300mm lens itself haha!
Absolutely. But it takes about a week in shipping.. and it hasn't shipped yet :-(


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