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07-04-2009, 05:50 AM   #1
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K 20D Exif Shake Reduction Info

I have a Pentax K20D , a Sigma 28/1.8 EX DG Macro and a Tamron 28-200 XR DII . I feel happy with the camera and the Sigma. The Tamron I'm just testing. I have just a little question about the Shake Reduction info in the EXIF. For the Sigma in this section the SRFocalLength is always 58. This value does not corresponds to the real focal length of the lens, that otherwise is correctly recorded in the focal length of the EXIF. When I'm using the Tamron the situation is similar, and in fact the the SRfocalength is always two times the real focallength. That explains the value of 58 obtained with 28 mm lens. But at 200 mm the SRFocalLength makes an exception and it takes always a 51 value.... and as a matter of fact all the pictures at this 200 mm focal length presents a certain quantity of motion even when they were taken at a reasonable shutter speed. Something is going wrong in the lens? or in the camera?

07-04-2009, 11:01 AM   #2
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bump (ten character rule)
07-04-2009, 01:45 PM   #3
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Original Poster
Sorry, I'm new in the forum...(I'm also new with Pentax, in fact) What do you mean with "bump (ten character rule)"?
07-04-2009, 02:16 PM   #4
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Try PhotoME...

Welcome and there is nothing to worry, it is all OK. I guess You use some generic EXIF viewer which is unable to decode SR focal length correctly :-( Try installing PhotoMe and You get real data. It is not a straightforward coding- as I recall less than 127mm is multiplied by 2 and some weird math was done with longer ones- You can figure this math out yourself if curious :-) And Your Sigma says 29mm because it reports so in Pentax mount I guess (third party thingies are the result of reverse engineering sometimes I guess).
Best and happy shooting, JR


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