Number of shots on 1 Gig card

Ok, I'm using a 1 gig card in a 30D, shooting in large jpeg.
When I put in a new card it says I can get 239 shots.
Yesterday I was shooting at an airshow and I had 466 shots on
one card with about 50 shots left. Why does it show 239 when I can get much more?

ISO settings will change it. It also on a constant change as all shots are different sizes. Sometimes significantly. What you see is an estimation. Try changing ISO settings and watch the # difference.

It's probably just a pessimistic estimation of how many shots will fit with jpeg. Because of jpeg compression, different shots compress better or worse than others. Busy scenes will tend to compress worse; quiet scenes will compress better.

I shot at iso 100 the whole time, but yea, I know about that.
I guess I figured it would be alot closer of an estimate.
Oh well, not complaining, just curious. Thanks.

The camera is just estimating how many shots you can get. In shooting an airshow, if there are large expanses of blue sky, jpeg can get pretty darn efficient at compression.

400? on all my 1GB cards I'm lucky to get 250 shots. Are you sure its not a 2GB card?

That's it exactly. I've gotten over 600 on a 1 GB card in a D60 under the same conditions.

Yep, I'm sure

Hi

My 20D estimates ~250 shots on a 1GB card, but I regularly get well over 400. However I am shotting motorsports so there tends to be a fair amount of green grass and grey tarmac in the shots which I suspect compress quite well.

All the best

Keith

I shoot RAW and mainly take photos of live bands using a 20D. I consistently get about 120 RAW images per 1GB card.

well, since you are complaining about getting too many shots in jpeg@iso100, shoot in raw@iso3200. i'de be suprised if you can get more than 80 shots in a 1gb card...

When shooting basketball, I get 122 shots (give or take one or two) on a 1 GB card with the 20D.

The number of shots on a card depend on the mode you use. RAW with Large fine JPG will use more space than a small coarse JPG. Shooting large coarse JPG (no raw) I have gotten several hundred shots on a card and small coarse jpg can get over 300 on a 1gig card. I never pay attention to the number of shots claimed on the LCD, I just shoot and change cards when I run out of room. Only happened once, when I shot a wedding. Oh, I lied, it happened when I spent a day at the zoo, shooting RAW/Large JPG. I've never paid any attention to what happens when I use high ISO.

Just get a spare card ( I have two 512 cards) and shoot away. Don't worry about the technicalities.

I get about the same result on average when shooting RAW. My images range from about 6.9 to 8.9 MB each.

but D60's are 6.3 to the 30D's 8.2.. there is a slight mp difference. but i guess your numbers make sense.. fewer mp's, more pictures. *shrug..

original question asked: many factors contribute to the size of an image file. ISO sensitivity setting, color/b&w, MP's, format, histogram readings, etc. i mean, unless you sat there and took the exact same picture over and over again, the counter would be correct, but since you don't do that, it's just an estimate based on the current settings/conditions.