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01-15-2011, 06:30 PM   #1
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645D sample with FA 35mm

There's been some interest in the forum about how well the FA 35mm f/3.5 works on the 645D. I got a new copy of the lens quite awhile back for use on my Canon digital bodies with a Zoerk PSA adapter. I haven't shot the lens much on my 645D yet, since ironically it has been a bit wider field of view than I've usually needed in what I've been photographing so far.

I did get a chance to use it a little bit last weekend out in the Canadian Rockies. Attached here is a down-sampled frame from several I took. If anyone is interested in seeing the full size image, please email or PM me and I will provide you a link to a full resolution JPEG, for personal use only. (Please no reproduction.) It's sizable, so I'm not posting the link for the entire world, lest my bandwidth be crushed.

Details of the shot: Mt. Michener, David Thompson Country, Alberta, Canada. Photographed with Pentax 645D, FA 645 35mm f/3.5, f/11, ISO 100, tripod, cable release, manual exposure, autofocus on distant mountain peak. Converted from DNG with Adobe Camera Raw 6.3, no sharpening, linear curve, all exposure settings neutralized except for slight recovery slider for highlights.

Since I haven't processed the image, it looks quite flat, and the midtones are underexposed since I was preserving the distant snow highlights. Detail is good in general, however, and the image processes up very nicely and looks great for the most part. (I did sharpen the small image for posting here, but the full resolution image is unsharpened.)

However there is one significant negative characteristic that I'm seeing in the few files I shot -- some mustache pattern distortion equally spaced towards the outer edges on the left and right. I'll need to do a few more controlled test shots to confirm whether that's really what's going on, but if it is then it's quite problematic since that kind of thing is very difficult to compensate for. There are many situations where it wouldn't be a factor, but in landscapes it would be troublesome.

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01-15-2011, 06:50 PM   #2
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Further to my note on the mustache distortion, I just did some playing around with the lens distortion correction feature found in Adobe Camera Raw. ACR 6.3 supports a lot of the Pentax FA 645 lenses, including the 35mm. Flicking the distortion setting on & off, there is a clear inflection point in the image where opposite-direction corrections are being applied. This inflection point corresponds on both left & right sides to where I'm seeing some inexplicable fuzziness in the image.

This unfortunately supports the possible conclusion that there is an optical mustache distortion effect going on with this lens...
01-15-2011, 07:19 PM   #3
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Thanks for sharing this with us Royce! I just sent you an e-mail re getting a full size jpg. Look forward to seeing it.

Gary
01-15-2011, 08:15 PM   #4
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Thanks for sharing the full res image Royce....the detail is very impressive! The more I see of the 645D, the more I'd like to have one (unfortunately!). I'll have to keep looking for a 35mm lens now too.

Gary

01-16-2011, 12:46 PM   #5
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Here is a small version showing the direction of the final image. Toning, sharpening and so on produce excellent clarity and detail. I also do a lot of HDR work, and this is a blend of 3 frames exposed at -1, 0 and +1 EV. (The color sample posted above is the -1 EV image, exposed for the extreme highlights.)

The only flaw in the source is in the areas where the distortion is fuzzing things out a bit. (Not visible at this down-sampled resolution.) Everywhere else the FA 35mm is very crisp.
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01-16-2011, 11:46 PM   #6
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Very nice looking B&W conversion Royce! I haven't explored the possibilities of HDR myself, but your use of the technique to blend exposures in a high contrast image like this one intrigues me, so I may give it a try. Sure looks good here.
01-17-2011, 08:10 AM   #7
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nicely done...I definitely like the B&W better :-)
01-17-2011, 08:33 AM   #8
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The tonal range advantage of the 645D compared to my Canon 35mm digital cameras is a very real step forward. I've seen some criticisms of Pentax for "only" having 14-bit which is likewise claimed by Canon, but the Pentax files are much better regardless of the numbers. I've been very impressed by how a single exposure on the Pentax will work up. Even so, the best single exposure can use some help now and then , hence the HDR work in post...

01-21-2011, 06:52 PM   #9
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Nice shot Royce. I like your B&W conversion. I noticed your photos on display at the Camera Store today. Very nice!
01-21-2011, 10:04 PM   #10
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Thanks. That reminds me I should take in a few more prints for them.
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