The camera uses the code recorded in the data chip in the lens. Having
partially disassembled an FA and an F lens I can say with relative
assurance that that focal length is reported by several conductive
strips that are sampled differently as the zoom ring is turned. I
expect that the reported focal length is most likely correct. The
Acontacts tell the camera the absolute maximum and minimum apertures the
lens is capable of, (as per Boz K mount description page). Now I don't
know how the following is done, but based on behavior I'd say the lens'
on board chip sends a modification signal to the camera body based on
the focal length selected so the camera will display and record the
correct f stop. This doesn't happen with A zoom lenses since they have
no chip.
On 5/25/2012 2:30 PM, John Sessoms wrote:
From: Darren Addy
I'm curious... if it shows up in Photoshop as a Pentax-F 35-105mm,
does that mean that it is also misreading the focal length that this
lens is set at (when doing image stabilization)?
If it is doing image stabilization for a 105mm focal length when the
lens is set to 200mm, that could definitely lead to some lack of
sharpness. I think I will see if I get better results with Image
Stabilization off and tripod mount it (which I guess I should be doing
to test for sharpness anyway!).
I don't know.
I think the camera just has to have some kind of a code to bury in the
EXIF to identify the lens & it uses the code that PhotoShop thinks is
the Pentax-F 35-105.
I don't know why it wouldn't use the code for the FA* 80-200/2.8 ED
[IF]? But it apparently doesn't
I just did a quick test on mine with the K20D & when you press the
INFO button, it shows the correct focal length - 80 = 80, 200 = 200
and in between shows proportional focal lengths in between.
--
Don't lose heart! They might want to cut it out, and they'll want to avoid a
lengthily search.
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