EXIF info question...

[Cadwell]

I've been looking at EXIF info for some of my shots and I'm a bit confused about something. Here is a sample...

Make - Canon
Model - Canon EOS 10D
Orientation - 1 (top left)
YCbCrPositioning - 1 (center of pixel array)
ExifOffset - 196
ExposureTime - 1/350 seconds
FNumber - 4.5000
ISOSpeedRatings - 100
ExifVersion - 220
ComponentsConfiguration - 1 2 3 (YCbCr)
CompressedBitsPerPixel - 3 (average)
ShutterSpeedValue - 1/250 seconds
ApertureValue - F 4.50
ExposureBiasValue - 0.0000
MaxApertureValue - F 4.00
MeteringMode - 5 (multi-segment)
Flash - 0 (no flash)
FocalLength - 420 mm

What I don't understand are the two values ExposureTime and ShutterSpeedValue. Shouldn't these be the same? They are on many shots but not on all...

I know this is probably an incredibly stupid question... but it's bugging me ;)

[RichardtheSane]

1st, this is a TOTAL guess, but it is my idea of what may happen.
Is the exposure time always higher than the shutter speed value?
IIRC then the sensor is not powered all the time, and needs to be powered for a set period of time to take the shot, in a smaller digicam then the time the sensor is powered is all that controls the TV value during exposure.
In an SLR the shutter is a far more pricise way of measuring exposure, but the sensor still needs to be powered, so what could happen is the exposure time refers to the time the sensor is charged and the shutter value is your true shutter speed.

Just a theory though, anyone got a definitive answer?

[Cadwell]

Is the exposure time always higher than the shutter speed value?

I have examples where the ExposureTime is longer than the ShutterSpeedValue and others where it is shorter. There are many where it is the same. There does not appear to be a consistent pattern.

[jkelley]

I'm curious as to what program you are using to read/extract the EXIF info. I looked at a couple of raw images that I have using the Canon FVU and BreezeBrowser. I only saw 1 value shown for shutter speed.

[Cadwell]

I was using a freeware image viewer called Irfanview. I've used it for years.

You can also get the same information using windows explorer if you're using Windoze XP. (Right click on the image and select "properties", select the "summary" tab and click on "advanced". That brings up the EXIF info)

The images were JPEG straight out of the camera... don't know if that makes a difference to the EXIF info stored or not.

[jkelley]

I also use Irfanview. Great free program, but I'm not sure/convinced that the EXIF info that it provides for the 10D is reliable. I wonder if Canon has deviated from the EXIF standard that was used/incorporated in the Irfanview program. I hope you get an answer to your original question but I have concluded that the best way for me to get the EXIF info for the 10D is to use one of the two utilities that I previously mentioned. Good luck :wink:

[evilenglishman]

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[RichardtheSane]

I thought I was speaking rubbish :D :D :D