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04-18-2011, 12:50 PM   #46
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QuoteOriginally posted by GeneV Quote
Ivor, just so we know how to evaluate the resolution numbers and the images together, would you mind letting us know the focal length and aperture information for those excellent images?
Gene

The exif information is embedded with the photos.

Peter

04-18-2011, 02:54 PM   #47
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QuoteOriginally posted by GeneV Quote
Maybe, but it is not a point of reference for most Pentax users to use in comparing resolution figures from one Pentax lens that one owns (tested on a K10) to another that has been recently tested on a K5.
Well, I think the thing that you can compare is the center to border resolution for both lenses. In the Pentax's case, the border resolution drops off considerably at longer focal lengths (and never really sharpens up, even stopped down), while with the Nikon, the borders drop off compared to the center, but do sharpen up nicely when stopped down.

Exact numbers do not transmit across brands or even cameras.
04-18-2011, 03:29 PM   #48
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QuoteOriginally posted by Ivor K Ecks Quote
Gene

The exif information is embedded with the photos.

Peter
So, is the pelican shot a crop, or is the lower left corner the lower left corner of the frame? If it is not cropped, I'd say that corner is a good deal better than I would expect at 110mm from the test data, and a lot better than the example at that FL.
04-18-2011, 07:07 PM   #49
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QuoteOriginally posted by GeneV Quote
So, is the pelican shot a crop, or is the lower left corner the lower left corner of the frame? If it is not cropped, I'd say that corner is a good deal better than I would expect at 110mm from the test data, and a lot better than the example at that FL.
Gene

None of the shots are cropped. Most are straight out of the camera JPEGS with maybe a slight levels adjustment.

Larger sizes can be seen on my Zenfolio pages.

Peter

04-19-2011, 03:03 AM   #50
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QuoteOriginally posted by Ivor K Ecks Quote
I simply cannot agree with Klaus's evaluation of this lens
[...]
And for those who want a full size image
http://PDIphotos.zenfolio.com/img/s3/v26/p447878257.jpg
Thanks for the full size image (35mm f/6.7). The 0.5 MPx thumbnails in your post can't support a quality argument though.

As for the full size image: it looks good indeed.

But keep in mind that according to PZ, 35mm is this lens' sweet spot (24mm and 50mm at f/8 both have very good corner resolution in the PZ test. So, your sample selection actually supports Klaus evaluation.

btw, 35mm seems to be the sweet spot of all 18-135 designs (Canon, Nikon, Pentax).

QuoteOriginally posted by GeneV Quote
On the point of reference, perhaps the FA31 should be included as well because of its excellent performance, but for most of the users of a review, the most frequently owned lens, i.e. the kit lens, would be most useful.
I didn't mean the FA31 retest on the K-5 to be a user-level point of reference.

It serves as entry point into a mathematical model to map K10D figures onto K-5 figures. This model can only be constructed from lens data which is clearly sensor-limited. FA 31 Ltd. does this. The kit lens not. My "Understanding Image Sharpness White Paper" contains information how such a mapping can be done. Note that high K10D resolution figures would be even higher on the K-5 while low K10D resolution figures can be higher or lower on the K-5 (I cannot know without a good point of reference).
04-19-2011, 06:39 AM   #51
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QuoteOriginally posted by falconeye Quote
I didn't mean the FA31 retest on the K-5 to be a user-level point of reference.

It serves as entry point into a mathematical model to map K10D figures onto K-5 figures. This model can only be constructed from lens data which is clearly sensor-limited. FA 31 Ltd. does this. The kit lens not. My "Understanding Image Sharpness White Paper" contains information how such a mapping can be done. Note that high K10D resolution figures would be even higher on the K-5 while low K10D resolution figures can be higher or lower on the K-5 (I cannot know without a good point of reference).
You are, of course, absolutely right from an engineering standpoint. However from the standpoint of user-friendliness, making calculations is not as simple as just comparing the new lens to something you have used.
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