I' still trying to find a way of establishing the actual camera to subect distance from the EXIF data in a NEF or camera JPEG.
I've tried various EXIF viewers including ExiftoolGUI, Opanda PowerExif, PhotoMe and Kuso but no luck. Some of these programs give a 'Focus Distance' which is usually wrong and some give a 'Subject Distance' which is always shown as 'unkown'.
Sun 01-Apr-12 03:10 PM | edited Sun 01-Apr-12 03:11 PM by gpoole
"Focus distance" in the "Lens data" block of the "Manufacturer notes" (address 0098 for D300) appears to be the best you can do. This is probably the value provided by the D feature of AF-D and AF-S lenses. It looks to me that these values are divided into steps and don't provide a continuous measurement of the actual distance. The size of the steps probably is designed to satisfy the distance parameter in 3D Matrix metering. There is no reason to have the lens supply distance numbers to higher resolution than is needed for the 3D matrix computations.
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Sun 01-Apr-12 03:27 PM | edited Sun 01-Apr-12 03:27 PM by Gromit44
>"Focus distance" in the "Lens data" block of the "Manufacturer notes"
With a 24-70mm f/2.8 that reading seems to be completely useless regardless of the actual subject distance. For instance, in PhotoMe 'Focus Distance' says 6.68m on a shot of a building which I know was at least 30 metres away. With another much closer shot (which I know as only 4 metres away) it still says 6.68m.
Hovering over the reading line produces a popup info window which says: "The focus distance is approximate and not very accurate for some lenses".
Yes. Looking at the exif in three images below, two makes sense -- the third is questionable:
Subject distance: 1.5m (OK)
Subject distance: 2.5m (OK)
Subject distance: 1.5m (not sure; I don't have the NEF file here, so I'll have to check the focus point later. The wall is about 5.8m away, but I think the focus was on the driver's mirror -- which would make the distance OK)
I use KUSO (not often) and (from my memory) any time I looked at the focus distance field it seemed to be correct. However, to me it is not a very important bit of info after-the-fact so I can't vouch for accuracy or repeatability.
More often, for critical DOF situations I use a Simmons range finder or a Lieca architectural distance meter and ExpoAperture DOF calculators before selecting f-stop.
I tried Kuso and it's wildly inaccurate with the 24-70. For the shot of the building mentioned above, it gave Focus Distance as 6.68m again (the actual distance was over 30m) and Subject Distance as 'unknown'.
I've got the ExpoAperture2 discs but I find them fairly useless without an accurate method of assessing distances. Which Simmons / Leica models have you got?
Wed 04-Apr-12 09:32 AM | edited Wed 04-Apr-12 09:39 AM by barrywesthead
> >I've got the ExpoAperture2 discs but I find them fairly >useless without an accurate method of assessing distances. >Which Simmons / Leica models have you got?
I started with Leica Disto products which are accurate to millimeters but hard to aim and use – still best for short range accurate work but priced in the $500-1000 range. I have them for industrial uses and would not recommend them as an investment for photography other than for precise still work.
The Simmons LRF 600 rangefinder is a little over $100 at Bass Pro, specced down to 10 yards but works perfectly for me down to 5 yards and out to 400 yards. There isn’t even an off-on switch. Just pop it out of your pocket (I keep it in a photography vest pocket – no case) look through it like a telescope, click the button and the distance in yards is right in the viewfinder. This combined with the ExpoAperture2 Discs is a great tool for DOF control.
I have checked it at shorter distances and it's pretty much spot on and it's still running on the original battery after a year.