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07-15-2009, 05:53 PM   #1
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Do you think lens brand can affect WB on the K-7

I noticed something I thought was interesting today. Shooting outdoors at 50 mm I compared my Pentax glass to my Tamron 17-50. Camera settings were identical. Whenever I looked at the shots from the 17-50 the WB seemed a bit "off." Sort of yellow. None of the Pentax glass did this. When I developed the files from RAW with APE using "daylight" for all the files, the pictures looked almost identical.

Do you think it is possible that the K-7 uses information from Pentax lenses in order to set the camera WB? I know that the K-7 has a more advanced WB algorithm.

07-15-2009, 05:57 PM   #2
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Or could it be the coating?
07-15-2009, 05:58 PM   #3
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It's more likely that the Tamron has a warmish colour transmission.
07-15-2009, 06:08 PM   #4
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QuoteOriginally posted by Wheatfield Quote
It's more likely that the Tamron has a warmish colour transmission.
Wheat, but then why would it be the same as the Pentax when I develop from raw using daylight wb?


Edit: Well my Tamron 90 doesn't do that. Just the 17-50. Very interesting.

07-15-2009, 06:11 PM   #5
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QuoteOriginally posted by PentaxPoke Quote
Wheat, but then why would it be the same as the Pentax when I develop from raw using daylight wb?
The K-7 has an "auto-fine tune even when a preset WB is selected" option. Try setting custom setting 11. "WB adjustable range" to "Fixed".
07-15-2009, 08:43 PM   #6
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The Tammy 17-50's colour rendition is much warmer... not just on a K7.
07-15-2009, 08:50 PM   #7
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QuoteOriginally posted by bentax Quote
The Tammy 17-50's colour rendition is much warmer... not just on a K7.
Sorry but I don't understand what you mean. If I develop from RAW using daylight WB, the Pentax and Tammy look the same. If the tammy had a warmer rendition, wouldn't it be so in the RAW as well? It is only the in-camera jpeg that is warmer on the tammy. As if the WB used by the camera is different for that lens.

Maybe it is the lens coating, or "warmth" of that particular lens, that throws off the WB sensor on the K-7 a bit? This is not a major thing. I just find it interesting.
07-15-2009, 09:01 PM   #8
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QuoteOriginally posted by PentaxPoke Quote
.. Shooting outdoors at 50 mm I compared my Pentax glass to my Tamron 17-50. Camera settings were identical. Whenever I looked at the shots from the 17-50 the WB seemed a bit "off." Sort of yellow. None of the Pentax glass did this. ......
There's a fair bit of on-line comment that the Tamron 17-50mm has a warm cast.
This lens has a big user community because its also used on Canon/Nikon/ Olympus etc.

I have a Tamron 28-75 and it also has a bit warmer tone than Pentax glass. Likely related to the different coatings used. My guess is its too subtle to see anything in RAW, but it confuses the AWB for JPEG.
Haven't used it on the K-7 yet, probably try it over the weekend...

So far, I'm aware the K-7 makes use of Pentax lens-embedded data to optimise for Program line (if you use P-mode in MTF), Autofocus, Distortion/CA correction (if you turn it on). Haven't seen anything on AWB. These cameras may be getting "too clever" by a bit - doing things without your realising it.....

07-15-2009, 10:20 PM   #9
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QuoteOriginally posted by kittykat46 Quote
My guess is its too subtle to see anything in RAW, but it confuses the AWB for JPEG.
Thanks Kitty. That makes sense to me. I also notice that it focuses just a bit differently than it did on the k20d. I believe I read that the K-7 uses the color wavelength of light to improve AF. I wonder if the coatings fool that a bit as well. Presumably Pentax cameras are calibrated best for Pentax glass.

This is a subtle thing that I thought was interesting. Thanks for the opinions.
07-15-2009, 10:27 PM   #10
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fwiw, my 77ltd looked very different on the K7 than on the K20d. My other FA ltds looked about the same. There certainly is some different processing going on, but not sure about the artifacts.
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