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Makonde
20th December 2010, 11:06 AM
I see that my E-5 records distance to subject in the EXIF. This is very useful information in many shots! (especially correlating with aperture to think about how DOF might have been different). My E520 didn't do that - how about the E3? Or is this a new feature unannounced?!

Bo_Nydahl
20th December 2010, 07:55 PM
Just checked an E3 shot and I cannot see any distance information.

Mike

Ulfric M Douglas
20th December 2010, 08:58 PM
The first time I noticed that info in an EXIF was yesterday : viewing a blog with great photos from a "Russia for the Russians" demo in Red Square, Moscow, linked from a TP forum thread.
The very excellent pictures were taken with a Canon5D2&Fast lens.

I'm guessing the "distance" EXIF stuff is inserted by "professional" cameras ...

Nick Temple-Fry
20th December 2010, 09:36 PM
The E-3 certainly includes this, click to the gallery and see

http://e-group.uk.net/gallery/data/506/P2100147_DxO_raw.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/21298).

It is upto the raw engine whether this is shown (DxO does, Master didn't, nor does Viewer 2 for the E-3)

Nick

fitheach
20th December 2010, 09:48 PM
My E520 didn't do that - how about the E3?

I think your E520 did - as mine does!

When looking at the full EXIF output of my files there is a MakerNote for "Focus Distance". See this page for more info EXIV2 (http://www.exiv2.org/tags-olympus.html)

Looking at some of my recent shots I see figures reported such as "915/10". Judging from my shots this figure seems to be mm/10. I would have to conduct a test to confirm this hypothesis. I also looked at a shot I took with a manual focus OM macro lens and the distance was reported as "0/10" - no surprise there!

I suspect that many of the 4/3 cameras have this info but some image software progams don't bother providing it.

Makonde
20th December 2010, 10:48 PM
Thanks for the replies. Interesting. As the info is rather useful for post-mortems I'm a bit surprised to learn that it's there but not always extracted! I'm using ACR/Photoshop for both cameras...

theMusicMan
20th December 2010, 10:50 PM
I am assuming Lightroom doesn't show this...?

OlyPaul
20th December 2010, 10:59 PM
That would be correct John.

peak4
21st December 2010, 12:29 AM
Well worth having a look at Phil Harvey's ExifTool (http://www.sno.phy.queensu.ca/~phil/exiftool/) or a development which uses it in a graphical user interface ExifToolGUI (http://freeweb.siol.net/hrastni3/foto/exif/exiftoolgui.htm)
It seeks to find all the hidden information that there is to be read, and then display it in an accessible format.
The accuracy of the focus distance information embedded is a bit iffy sometimes though.

Ross the fiddler
21st December 2010, 02:27 AM
The E-3 certainly includes this, click to the gallery and see

http://e-group.uk.net/gallery/data/506/P2100147_DxO_raw.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/21298).

It is upto the raw engine whether this is shown (DxO does, Master didn't, nor does Viewer 2 for the E-3)

Nick

Kuso Exif Viewer V3.0 tells me its 4.44 m.

photo_owl
21st December 2010, 11:47 AM
The accuracy of the focus distance information embedded is a bit iffy sometimes though.

indeed - very iffy!

fitheach
21st December 2010, 11:58 AM
information embedded is a bit iffy sometimes though.

Really? Are you sure?

I think there would be two possibilities:

1. the EXIF "Focus Distance" is taken from the calculation used to determine the Autofocus or Manual focus point.

OR

2. the EXIF "Focus Distance" is taken from some other arbitrary measurement/calculation.

If the EXIF "Focus Distance" is taken from 1. then data presented should be accurate otherwise our photos would all be out of focus.

If the EXIF information is taken from some other source then I could see it could be inaccurate but why would Olympus do it that way? The calculation is already done by the camera no need to do it again.

A quick analysis of my previous indoor shots suggests the distance is reported correctly (but that isn't definitive).

Jim Ford
21st December 2010, 07:30 PM
The accuracy of the focus distance information embedded is a bit iffy sometimes though.

'Jeffrey's EXIF Viewer' says:

"At 4.4m
Warning: Olympus camera focus-distance data is often erroneous"

Jim

Nick Temple-Fry
21st December 2010, 09:48 PM
14 and a half foot, seems like an overestimate to me of a couple of feet.

Nick

photo_owl
22nd December 2010, 01:20 PM
Really? Are you sure?

I think there would be two possibilities:

1. the EXIF "Focus Distance" is taken from the calculation used to determine the Autofocus or Manual focus point.

OR

2. the EXIF "Focus Distance" is taken from some other arbitrary measurement/calculation.

If the EXIF "Focus Distance" is taken from 1. then data presented should be accurate otherwise our photos would all be out of focus.

If the EXIF information is taken from some other source then I could see it could be inaccurate but why would Olympus do it that way? The calculation is already done by the camera no need to do it again.

A quick analysis of my previous indoor shots suggests the distance is reported correctly (but that isn't definitive).

I think you may be missing the bigger picture

All exif data representations involve third parties establishing the meaning of the manufacturers meta data, and then representing it as results for the user. Olympus, in line with other manufacturers, doesn't provide an instruction book!

To see just how one EXIF viewer developer worked with some early Oly users to work out what was where and how it might be decoded - including the AF distance - you can look at this old thread

http://forums.dpreview.com/forums/readflat.asp?forum=1022&thread=12748188&page=1

so there is some art in the science as well.

fitheach
22nd December 2010, 04:56 PM
Just to clarify the discussion above there seems to be two EXIF fields in use "Focus Distance" which is used in the E-520 (and possibly other E series cameras) which is a proprietary Olympus field and "Subject Distance" (used in the E-3 and E-5) which is part of the EXIF specification 2.2 (http://www.exif.org/specifications.html). Subject Distance is not used in the E-520 and Focus Distance is not used in the E-3 (I don't have an E-5 image to check). Perhaps this means Olympus are dropping use of their proprietary tag.

I actually prefer the Olympus' terminology as it is presumptuous for the camera to assume it knows what your subject was ;)



All exif data representations involve third parties establishing the meaning of the manufacturers meta data, and then representing it as results for the user. Olympus, in line with other manufacturers, doesn't provide an instruction book!

That is not true for "Subject Distance" as it is part of the EXIF specification (see above). Whether Olympus (or any other manufacturer) abide by the specification is another matter. Focus Distance is proprietary to Olympus and they are free to do with it what they want. I would suspect that Olympus (and other manufacturers) probably do provide an "instruction book" to special partners and/or those willing to pay. It may also be the case that Olympus aren't being intentionally secretive it is just that they don't consider it something the "average" user would be interested in.

However, from a user perspective (at least this user and probably some others on this forum) the Subject Distance/Focus Distance would be useful information to have. I have written to Olympus' technical support asking them to clarify some of the questions raised in this thread. If I get a response I will report back.