Jpeg size in camera vs. Raw to Jpeg in DPP

I just noticed that when I convert raw pictures to large Jpegs in DPP the file size is approximately 7-8 megs. When I shoot large Jpegs on my 30D they are 3-4 megs in size. Why the difference? Is is more beneficial to shoot all raw then convert to Jpeg through DPP? In other words, will the larger Jpeg file from DPP give you more lattitude in post-processing?

Set the DPP converter to about 6-8, which is about the equivalent to what the camera is doing and you'll notice similar file sizes.

In other words, the camera is compressing more (throwing away more data) than the RAW converter does when set to max.

John E wrote in post #5139256
In other words, will the larger Jpeg file from DPP give you more lattitude in post-processing?

Preferably, do all the adjustments in DPP before converting to jpeg to minimize data loss.

The fine jpg on the xti is equivalent to 8 in DPP. I verified using a program - I can't think of the name and its on my home computer. Anyway, the output was 98 (fine jpg) and 97 (8 in DPP). Thats as close as I could get it. The size is around the same although DPP is a little larger file due to the extra noise (in camera uses noise reduction).

Oh and the larger size will only assure you will not have compression artifacts. It should be said that I have yet to see compression artifacts using fine jpg in camera. So just set DPP to 8 and save (after you make all of your adjustments).

Oh, I found it. The tool is JPEG quality estimator

http://www.mediachance​.com/digicam/jpgq.htm