topic A77 EXIF info about focusing in Alpha & NEX interchangeable lens cameras

A77 EXIF info about focusing

mikeyp2000 — Fri, 06 Jan 2012 20:40:21 GMT

Hi,

Does anyone know how to get the following information out of the A77 EXIF files? I was wondering if the camera RAW or JPG files store details of which AF point was used and the focus distance.

I believe these might be tucked away in the Maker Notes of the EXIF but these are largely undocumented.

Can anyone at Sony point me in the right direction? I use the EXIFTOOL but the makernote is too hard to unscramble without technical support help. It would be great if someone at Sony could reveal the EXIF makernote specification.

Thanks

A77 EXIF info about focusing

Mick2011 — Mon, 09 Jan 2012 07:49:11 GMT

Hi mikeyp

Have you tried photoME? Sony makernotes are listed as supported and Jens, the software author, is very obliging with specific enquiries.

Cheers

Mick

A77 EXIF info about focusing

mikeyp2000 — Tue, 10 Jan 2012 22:38:12 GMT

As far as I know, Photome hasn't been updated for ages (2009 or so according to www.photome.de)

I also tried investigating with exiftool but it seems all the exif makernote decoding is carried out by enthusiastic users. I'm way out of my depth trying to decode undocumented exif makernote data. Surely someone at Sony wrote the code in the A77 that writes the metadata. Is there no way for the programmers to be contacted and asked (nicely!) to reveal their secrets?

Cheers

Michael

A77 EXIF info about focusing

Mick2011 — Wed, 11 Jan 2012 07:21:43 GMT

Ah that's a shame. I used it ages ago and it was very comprehensive. Hope he's ok

You answered your own question, really. For some reason Sony engineers are secretive about coding etc, where others are not. I have no idea why, but I can't see that long-standing position changing simply by asking nicely...

If I hear anything to the contrary I'll obviously let you know.

Cheers

Mick

A77 EXIF info about focusing

mikeyp2000 — Wed, 11 Jan 2012 14:17:26 GMT

I've been in touch with Phil Harvery, the author of exiftool He's asked me to email some sample exif info and he's confident he can decode the AF point data but probably not the AF Distance.

I'll update the forum once I get some news.

Cheers

Re: A77 EXIF info about focusing

mbiggs — Mon, 20 Feb 2017 10:41:54 GMT

if you run Phil Harvey's exiftool like this:

$ exiftool -u -U -V JPGFILENAME.JPG > exiftags.txt

...the resulting file will contain (depending on the camera model) maybe 29 tags called AFStatus*

In this extract, the first tag is called AFStatusActiveSensor and the value reported looks like this:

AFStatusActiveSensor = 18

Then come the (perhaps 29) actual sensor values. Here's a small sample:

This tells us a number f things:

By matching up the 18 value, the camera was using AF spot -> AFStatusBottomHorizontal

The -32768 values say these AF spots are all out of focus

A zero value means "In focus", so AFStatusBottomHorizontal was almost but not quite in focus

Hope this helps.