Question on Exposure, same settings, different results

[txbit]

Hi, I did search one this without any results. Please let me know if you have seen this before.

I've just started testing my new 300D with 18-55mm EFS lens. Firmware rev is t 1.1.1. I'm using 256MB of Kingston Elite Pro.

I like the consecutive shooting ability and have found inconsistencies with some exposures. Checking the exposure information for each shot, they appear identical but the results are not.

File Name
IMG_0402.JPG
Camera Model Name
Canon EOS DIGITAL REBEL
Shooting Date/Time
6/25/2004 11:16:21 AM
Shooting Mode
Program AE
Tv( Shutter Speed )
1/60
Av( Aperture Value )
5.0
Metering Mode
Evaluative
Exposure Compensation
0
ISO Speed
100
Lens
18.0 - 55.0mm
Focal Length
42.0mm
Image Size
2048x3072
Image Quality
Fine
Flash
On
Flash Type
Built-In Flash
Flash Exposure Compensation
0
Red-eye Reduction
Off
Shutter curtain sync
1st-curtain sync
White Balance
Auto
AF Mode
AI Focus AF
Parameters
Contrast +1
Sharpness +1
Color saturation +1
Color tone Normal
Color Space
sRGB
File Size
2094KB
Drive Mode
Single-frame shooting
Owner's Name
Camera Body No.

File Name
IMG_0403.JPG
Camera Model Name
Canon EOS DIGITAL REBEL
Shooting Date/Time
6/25/2004 11:16:22 AM
Shooting Mode
Program AE
Tv( Shutter Speed )
1/60
Av( Aperture Value )
5.0
Metering Mode
Evaluative
Exposure Compensation
0
ISO Speed
100
Lens
18.0 - 55.0mm
Focal Length
42.0mm
Image Size
2048x3072
Image Quality
Fine
Flash
On
Flash Type
Built-In Flash
Flash Exposure Compensation
0
Red-eye Reduction
Off
Shutter curtain sync
1st-curtain sync
White Balance
Auto
AF Mode
AI Focus AF
Parameters
Contrast +1
Sharpness +1
Color saturation +1
Color tone Normal
Color Space
sRGB
File Size
2281KB
Drive Mode
Single-frame shooting
Owner's Name
Camera Body No.


Any help would be appreciated,

Thanks,

Mark

[maderito]

Well, your file sizes changed ( 2984KB vs. 2281KB ) so clearly you have 2 different image captures. We'd have to see the pics to judge what is actually different in the 2 shots - and why. Can you post the shots? See the FAQ (http://photography-on-the.net/forum/faq.php#24) on posting images to the forum.

[Steveo31]

Was it on a tripod? Subject matter the same, etc etc. Lotta variables come into play.

[robertwgross]

Built-in flash was on. I find if you take two shots in quick succession, the flash might be right for the first one and not fully recycled for the second shot. That results in a weaker exposure for the second one, darker, and completely different results. But that is just a wild guess.

You could run a test using daylight or a studio light to rule this out.

---Bob Gross---

[Tom W]

By George, Bob, I think you may be on to something. They were shot in fairly short succession, based on the times indicated in the data.

I know that I've short-cycled my shoe-mount flash a few times with predictably dark results, and I can only guess that the recycle time of the built-in might be a bit longer that a 380EX with fresh batteries.

[txbit]

Built-in flash was on. I find if you take two shots in quick succession, the flash might be right for the first one and not fully recycled for the second shot. That results in a weaker exposure for the second one, darker, and completely different results. But that is just a wild guess.

You could run a test using daylight or a studio light to rule this out.

---Bob Gross---




You are correct, I've also posted the previous image (also a normal exposure). These three shots were in very close succession.


http://www.nollners.com/images/IMG_0401.jpg

401 (previous)

http://www.nollners.com/images/IMG_0402.jpg

402

http://www.nollners.com/images/IMG_0403.jpg

403

Thanks for the help, wonder why it will let you take the shot if the flash is not fully recycled?

Mark

[Tom W]

Thanks for the help, wonder why it will let you take the shot if the flash is not fully recycled?

Mark

I think it depends on what mode you're in, but I'm not certain. A guess would be that Canon was thinking that one might prefer a somewhat underexposed shot to no shot at all. The second shot looks like it might be easily recoverable with a little levels adjustment in Photoshop Elements.