Help with file size

[alloyd1170]

Ok I think I know the answer to this, but want others' thoughts. I have been consistently using my Canon 7D with a 100-400 f/4.5-5.6 lens. Set on AV, ISO of 100, variable focal lengths. On some days, my file size (which is always on the largest L setting) is 10, 12+ MP and on other days it's 3-5 mps. What is up with that? Sunny days, & shooting soccer games. I changed cards to see if that was the problem, but no change. I'm hoping it's not an issue with the camera.

Thanks for your help!

 

[Cafeen]

Assuming you're talking Megabytes (MB, file size) and not Megapixels (image size), it's a perfectly normal thing with the files.

The MB is a measure of how much data is stored within the file, in this case, an image. Less data = smaller filesize. Not 100% sure on the details of the image data and what trends larger vs smaller filesizes, but suffice to say that it's perfectly normal.

As a note, one day of Disney shooting, my RAW files ranged from ~15MB to ~25MB on my 15.1MP Canon T1i. The JPGs (I shoot RAW+JPG) ranged from ~1.7MB to ~9.5MB.

 

[alloyd1170]

Thank you. That's what I figured. I just never had anything to compare it to like taking similar soccer shots every weekend. When I saw the difference in the mps, I got worried.

 

[Bstanley]

It is not an issue with the camera. Nothing is wrong.

The pictures are saved in a '.JPG' file format. It is a compressed format - which means that it is not untouched binary data (Zeros and Ones). Without getting all geeky about it the .JPG format examines the picture and removes duplicate data, or data that is imperceptible to the eye. NOTE: Camera RAW is compressed also - it is just lossless.

So for example if you looked at the file size of a soccer photo (say 35% sky) where it was one of those perfect 'Chamber of Commerce' kind of days without a cloud in the sky the file size would be smaller that the same photo where the sky was full of clouds (or where the picture was mostly of the field).

For homework - take a picture with the lens cap on - look at the file size - if I'm not pouring cider in your ear it will be significantly smaller than a 'normal' picture.