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07-28-2011, 01:20 PM   #31
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I did some more testing and have more extensive results. I got the kit lens (WR version) focused correctly and added in the DA 16-45/4. New composite images are labelled.

It's newspaper taped to my garage wall, camera on a tripod about 7 feet away. K-7, ISO 100, 2 second delay, all lenses at f2.8 or wide open. I focused manually, checked in live view, used contrast-detect AF for the Pentax zooms, and chose the best out of three images. I used the Sigma's hood for all the primes and the standard hood for each Pentax zoom. Exposures all used the same shutter speed. I set the white balance to the same number for each of these shots in ACR. (I keep forgetting to set a custom WB in advance.)

Lenses were:
DA 18-55mm f3.5-5.6 WR
Sigma 24mm f2.8 Superwide II in PK-A mount
Vivitar (Komine) 24mm f2.0 in PK-A mount
DA 16-45mm f4.0
Kiron 24mm f2.0 in PK mount

These composites are done in CS5. I open all the images in ACR, match the WB, open them in CS5, take crops at 100%, stick them into one file, label, change into 8 bit and save as a JPG.





Other comments: The Vivitar is hard to focus accurately, probably related to the lack of sharpness wide open. The Kiron is a little more difficult than the others but the other 4 are workable. I was most consistent with the Sigma, which might mean good things for the AF version. The Sigma is smallest.

I might have the chance to add more to this comparison later. I took shots at apertures from wide open through f11 for all lenses.


Last edited by Just1MoreDave; 07-28-2011 at 01:30 PM.
07-28-2011, 09:33 PM   #32
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Amazing work Just 1 More. Thanks so much. Looks like the kit fares fairly well (even compared to the 16-45).

Looks like the sigma is the one to look out for. And it comes in AF, too!
07-28-2011, 11:33 PM   #33
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QuoteOriginally posted by Just1MoreDave Quote
I might have the chance to add more to this comparison later. I took shots at apertures from wide open through f11 for all lenses.
Thanks for this comparison. Can you add a similar set of images, but with results at f/4? I am curious how the primes improve when stopped down.
07-29-2011, 05:07 AM   #34
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QuoteOriginally posted by Laurentiu Cristofor Quote
Thanks for this comparison. Can you add a similar set of images, but with results at f/4? I am curious how the primes improve when stopped down.
Yes, comparing lenses at different apertures isn't really optimal, especially with varied exposures (which may be caused by different coatings).

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