Luminous Landscape Forum

Raw & Post Processing, Printing => Adobe Lightroom Q&A => Topic started by: AFairley on July 29, 2014, 06:50:50 pm

Title: Why do aperture values in user created lens profiles not match as-shot aperture?
Post by: AFairley on July 29, 2014, 06:50:50 pm
I have a question for those of you familiar with Adobe's Lens Profile creator application and the lens profiles it generates.

I just created a lens profile for the Nikkor 28mm f3.5 AIS lens on the D800E.  I shot image sets at f 4, 5.6, 8, 11, 16 and 22, and those aperture values appear in the image EXIF data and were reported in the Lens Profile Creator application.  However, if I look at the XML of the generated lens profile, it identifies the apertures as 4, 4.97 (I am rounding the value showing in the profile to two decimal places), 6.00, 6.92, 8, 8.92.

In other words,
f4 = 4.00 in the profile
5.6 = 4.97
8 = 6.00
11 = 6.92
16 = 8.00
22 = 8.92

Can anyone explain why this apparent mismatch is occurring?  I have downloaded and looked inside profiles for other lenses and camera manufacturers created by others and see the same phenomenon in them too.

Thanks,
Alan Fairley