Small, Medium, Large?

Ok I've got a 5D coming in the mail. With the MP being so big, I was wondering if the filesizes could be dumbed down a bit by using smaller Resolutions. If I use Small instead of Large or Medium, will I still retain all the details the camera would have captured if I had shot at a larger format or no? I don't print my pictures, and even if I did, they'd be 5x7s or 8x10s. So do I need to shoot at L or M? Or will S be the same thing just smaller in size?

If you use Small or Medium resolution, then you are throwing away data - effectively turning your 12(?) megapixel camera into something like an 8Mp or 6Mp camera. I must admit it's not obvious to me why you would want to do that...

Why not simply get another couple of CF cards (they're cheap enough) and stay with the highest resolution?

I would not do that, as Stewart said, your losing out on the essence of the 5D

Why are you even considering dropping data
It's like buying a Ferarri and only driving in first gear.

I have to admit, this is sometimes tempting. My pc is barely able to manage the larger file sizes. So far I have been able to resist dumbing them down though.

Use Large or get a 30D. You are paying serious money for the sensor in a 5D , you might as well get the benefit.

august23,
I suggest you shoot Large.
It can be like this, you are going to lunch and the meal costs $18 so do you bring $18, or more? What if the price went up, or you decided to get a large drink with your meal (it raises the cost). You would be better off bringing more!
I look at photos the same, take the largest I can get and if I need more its available. It also gives much more cropping options for prints. The one or many times you want to print larger its no problem with large. Like others have said a CF card is cheap now, so space is available. You can burn all photos on CD's or DVD's so it doesn't take up drive space.
However if your shooting RAW you will only affect the size of the jpeg file, not the RAW file.
But its your camera (going to be your camera), so do what you want and enjoy it.

That's why I asked lol. I didn't know if it would come at a loss of detail or not. Now that I know it will, I'll shoot at Large.

Can anyone tell me the average filesize of a Large Jpeg shot from the 5d? I'll see if it's time to invest in some new harddrives lol.

The file from a large jpeg will be about 7mb.

The average size of large jpeg from my 5D varies from 2mg to 7mg. It depends how complex the photo is, ex. a photo with a lot of sky or water in it tends to be smaller.

Always shoot at maximum resolution - take full advantage opf all those MP - as everyone says you never know when you'll regret throwing data away.

Have you shot in RAW? It's perfectly reasonable to shoot in RAw + small JPEG as you still have all the original data.

But if you can afford a 5D surely you can afford storage?

Sounds to me like you would be "dumbing it down" to a 30D or and XT...

Man you got the Ferarri...put the peddle to the mettal!