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06-24-2020, 10:00 AM   #1
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Input Focal Length 90mm

Just got my KP and its amazing!
I have an old Tamron SP 90mm 2.5 (52BB) lens. When I mount it to the KP I am asked to set the Input Focal Length.
The menu list has 85mm and 100mm. I am not able to choose 90mm.
What focal length should I choose?

06-24-2020, 10:05 AM   #2
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Common wisdom say 85mm. It will undercompensate slightly for your motion instead of overcompensating. I don't think there is actual proof but I follow this advice.
06-24-2020, 10:07 AM   #3
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QuoteOriginally posted by swanlefitte Quote
Common wisdom say 85mm. It will undercompensate slightly for your motion instead of overcompensating. I don't think there is actual proof but I follow this advice.
thanks that is what I have been using and it is what the camera displayed as first option.
06-24-2020, 02:54 PM   #4
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QuoteOriginally posted by 42datasquirrels Quote
Just got my KP and its amazing!
I have an old Tamron SP 90mm 2.5 (52BB) lens. When I mount it to the KP I am asked to set the Input Focal Length.
The menu list has 85mm and 100mm. I am not able to choose 90mm.
What focal length should I choose?
The KP manual seems to be a little vague on the issue - the K-5 manual is very much more explicit:

"If the focal length for your lens is not listed above, select the value closest to
the actual focal length (example: [18] for 17 mm and [100] for 105 mm).
When using a zoom lens, select the actual focal length at the zoom setting
being used in the same manner."

From this, the implication is that 85mm is "closer" than 100mm, so would be the best choice!

Enjoy your KP, it really is an amazingly competent camera, even if the documentation is a little "sparse" in places

06-24-2020, 04:25 PM   #5
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QuoteOriginally posted by 42datasquirrels Quote
The menu list has 85mm and 100mm. I am not able to choose 90mm.What focal length should I choose?
It will make very little difference. It is just to match the shake reduction reaction of the camera to the lens, and either 85 or 100 are only slightly off the optimum for 90. Shake reduction is not perfect anyway, and not long ago we didn't have any shake reduction but we were not kept awake at night over it!* Obviously 85 is nearest, so go for it

* OK, maybe some of us were.
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