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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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What is writing that value? EXIF data is just metadata appended to an image file, and is editable by many programs and devices. – drewbenn Jan 13 '12 at 17:46
1  
I wouldn't sweat it - there's loads of stuff in EXIF data that either makes no sense or is plainly incorrect, my 1D4 EXIF files report the camera has a CCD sensor (it's actually CMOS) that measures 32.77mm x 21.23mm (it's actually 27.9mm x 18.6mm according to Canon!) I'm pretty sure if your lens was f/1.6 it would be marketed as such! – Matt Grum Jan 13 '12 at 17:49
OT, but I was curious so I just looked it up: I now believe that the proper capitalization is "Exif" which is how it is used throughout the standard. – drewbenn Jan 13 '12 at 18:29

1 Answer

up vote 1 down vote accepted

I have seen that exact value (16/10) on a Nikon before. It may just be an incorrect value as Matt says. It could also be a calculated value adjusted for:

  • focus distance info from the lens, which affects the apparent aperture
  • adjustment for low ISO (i.e L.03 or L.07)
  • adjustment for exposure compensation
  • FX lens on a DX body

For example if you had ISO set on Nikon to L.03 the EXIF data might report ISO 200 and the aperture open a stop wider than it can actually go.

If you can share more information about which camera and lens, and other EXIF data we might be able to make a better guess, but the main point is you can't completely trust EXIF data.

You can also get different results using different EXIF readers. What reader are you using, and what value is reported by your processing software (Lightroom or Aperture or whatever)?

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As pointed out here, viewers might report different values than from the processing software. – Johan Karlsson Jan 13 '12 at 20:14
It's a nikon camera (D7000 i think) with a 50mm 1,8 lens – ThiefMaster Jan 13 '12 at 22:44

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