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04/05/2007 12:38:47 AM · #1 |
As I was going through some pics shot with my 50 1.8 at 1.8 tonight I was noticing how the degree of OOF of the background and bokeh quality changed substantially depending on the distance of the subject and the background objects.
I was also wondering how far I was from the subject and thought it would be cool if the camera would record the focus distance in the EXIF.
I really don't know what I would use this info for but figured it would at least be interesting.
Questions:
1) Is this type of info available from any camera/lens combo?
2) If so, what would this info be useful for?
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04/05/2007 12:49:07 AM · #2 |
I wish my camera/lenses recorded the distance. I would love to have access to that info!
And yes... distance makes as much of a difference as aperture to DOF. If you shoot macros, you'll find that f/11 is extremley shallow DOF, while for landscapes, f/11 is huge DOF.
Here's an online DOF calculator for you to play with. :-)
Message edited by author 2007-04-05 00:49:23.
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04/05/2007 01:01:44 AM · #3 |
I think IrfanView shows that information for my camera -- I've pasted complete EXIF from a picture below and highlighted what I think are the relevant fields. I just don't know what unit it's using!
File: - IMG_7307.JPG
Make - Canon
Model - Canon PowerShot S3 IS
Orientation - Left bottom
XResolution - 180
YResolution - 180
ResolutionUnit - Inch
DateTime - 2007:03:04 13:07:53
YCbCrPositioning - Centered
ExifOffset - 196
ExposureTime - 1/4 seconds
FNumber - 2.70
ExifVersion - 0220
DateTimeOriginal - 2007:03:04 13:07:53
DateTimeDigitized - 2007:03:04 13:07:53
ComponentsConfiguration - YCbCr
CompressedBitsPerPixel - 5 (bits/pixel)
ShutterSpeedValue - 1/4 seconds
ApertureValue - F 2.71
ExposureBiasValue - 0.00
MaxApertureValue - F 2.71
MeteringMode - Center weighted average
Flash -
FocalLength - 6.90 mm
UserComment -
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 2816
ExifImageHeight - 2112
InteroperabilityOffset - 2772
FocalPlaneXResolution - 12515.56
FocalPlaneYResolution - 12497.04
FocalPlaneResolutionUnit - Inch
SensingMethod - One-chip color area sensor
FileSource - DSC - Digital still camera
CustomRendered - Normal process
ExposureMode - Auto
WhiteBalance - Auto
DigitalZoomRatio - 1.00 x
SceneCaptureType - Standard
Maker Note (Vendor): -
Macro mode - Normal
Self timer - 20/10 sec
Quality - Superfine
Flash mode - Not fired
Sequence mode - Single or Timer
Focus mode - Single
Image size - Large
Easy shooting mode - Manual
Digital zoom - None
Contrast - Normal
Saturation - Normal
Sharpness - Normal
ISO Value - 16464 (other)
Metering mode - Center weighted
Focus type - Auto
AF point selected -
Exposure mode - Program
Focal length - 600 - 7200 mm (100 mm)
Flash activity -
Flash details -
Focus mode 2 - Single
White Balance - Auto
Sequence number - 0
Flash bias - 0.00 EV
Subject Distance - 73
Image Type - IMG:PowerShot S3 IS JPEG
Firmware Version - Firmware Version 1.00
Image Number - 1007307
Owner Name -
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04/05/2007 01:57:52 AM · #4 |
I googled this and found that my EXIF data should have the distance info in it.
People were claiming that with their D70, D70s, and D2X it was there.
I now wonder if ACDSee is stripping this out.
Will test it when I'm not falling asleep.
ETA, I found a good free EXIF viewer - EXIF Pro.
It showed me a value I've never seen before, lens!
How cool is that?
Too bad ACDSee doesn't show that.
I'd love to filter by lenses.
Message edited by author 2007-04-05 01:59:31.
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04/05/2007 02:12:15 AM · #5 |
| Different programs will show different information. The EXIF does capture the focal length. You might try Nikon Capture. |
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04/05/2007 02:17:20 AM · #6 |
Originally posted by Gringo:
Different programs will show different information. The EXIF does capture the focal length. You might try Nikon Capture. |
I'm not talking focal length.
Every piece of s/w I've used shows that.
I'm talking about the distance from cam to subject... I guess "focus distance".
Essentially what is shown analoguely (please excuse word creation after 4 IPAs) on the barrel of your lens.
Apparently it's in the last couple of EXIF specs so I don't know why every cam doesn't embed this.
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04/05/2007 02:33:10 AM · #7 |
The focal length of a lens is defined as the distance in mm from the optical center of the lens to the focal point.
:-/
Isn't that the same thing? |
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04/05/2007 02:37:03 AM · #8 |
Originally posted by Gringo:
The focal length of a lens is defined as the distance in mm from the optical center of the lens to the focal point.
:-/
Isn't that the same thing? |
He means like this.
Your using a 50 mm prime and the subject is 8 feet away. he wants the exif to tell the camera he focused 8 feet away, not that he used a 50 mm lens. :)
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04/05/2007 02:45:39 AM · #9 |
Oh....sorry (It's late).
:-/
You can pick up a laser distance device for about $300.00.
That won't help you with availability in the EXIF data. I wonder if there is a simple calculation you can build to multiply the field of view by the focal distance or something. (Sorry I'm not much help here).
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04/05/2007 07:19:45 AM · #10 |
| My thanks to dwterry for the link to the dof calculator - I know its shown on the sde of the lens sometimes but I've been trying to get used to my lenses and knowing by rukle of thumb whaqt aperture I need - this has involved taking loads of unecessary pictures at a range of settings - this calculator will give me a real head start |
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