A photo shot with an 1:1.8 lens contains the following exif data:
ApertureValue: 1695994/1000000
MaxApertureValue: 16/10
How is this possible? Both values are <1.8.
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Sign up to join this communityYou are confused because ApertureValue and MaxApertureValue are APEX values, not F-stops.
An F-stop of 1.8 is equivalent to an APEX aperture value of about 1.695994. (The formula is Av=log₂A², where Av is ApertureValue and A is f-number. See the Wikipedia APEX system page for a full explanation.)
Some exif readers (like ExifTool) convert these to F-stops for the user, but others do not.
FNumber
and ExposureTime
correspond to the values we're used to working with, and ApertureValue
and ShutterSpeedValue
are the APEX values.
– mattdm
Mar 12 '15 at 19:00
ApertueValue
to f/number for display (in this case, f/2.4), but if I look at the raw values, Fnumber
is set to 240/100 and ApertureValue
to 252/100 — the corresponding APEX value. Hmmm. I'm not sure if these tools are making it more or less confusing by converting.
– mattdm
Mar 12 '15 at 19:10