How do I check how many stops I over/under exposed on a previous sports photo?

[Strnge]

How do I check how many stops I over/under exposed on a previous sports photo? I know it was at 2.8, but I was adjusting for a cream uniform.

[dmwierz]

Strnge - this is kinda subjective and can get a little complicated. Let me tell you what I do, and let others smarter than me weigh in:

The best way I know of is by looking at the histogram. Even then, though, there is not hard and fast rule, since you'll need to take into account things like the dynamic range of the scene photographed, the camera's metering mode (how your camera interprets and displays the light it sees - ties directly into how the data are displayed in the histogram) and what the dynamic range of your sensor is, and a few other things.

Most digital cameras have a dynamic range of 5-7 stops (meaning the ability of the camera to capture the brightest and dimmest portions of a scene - anything lower or higher than this range is simply rendered as black or white, respectively), so you could roughly estimate that a photograph of an 18% reflective gray card with a histogram with no information at all on the right side would be roughly under-exposed by 2-3 stops. It's not precise, though.

Here's are a couple good tutorials on using the histogram:

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

http://www.luminous-landscape.com/tutorials/expose-right.shtml

Clear as mud? Anyone else wanna jump in?

[Strnge]

Thanks Again. I will try and decode what you said. I will also print and read the tutorials while on the way to the SF Gaints game today.

[BigBlueDodge]

Why not look in the EXIF of the photo to see what level of Exposure Compensation you had dialed in?

[tzalman]

For good exposure I'd want that cream uniform to be in the area of 245/238/230.

[neilwood32]

Why not look in the EXIF of the photo to see what level of Exposure Compensation you had dialed in?

If he was shooting manual, theres no way to tell other than the histogram and that would be an educated guess at best.

[Strnge]

I shot AV. I am trying to figure out what TZALMAN ment by 245/238/230?

[chauncey]

Those are RGB (red, green, blue) numbers, based on values between 0-255 for each.
If you have 255/255/255, it is pure white and 0/0/0 being pure black.