40D vs. 30D Raw Image Files

Raw files from my 30D (8.1MP) range from about 6.7 mp to about 9 mp.

Although the 40D(10.1MP) is only 2 MP more than the 30D the raw files range from 13 mp to over 15 mp.

What causes the much larger raw files? Is it lower or possibly no compression of the file?

Thanks for your answer.

I believe the much larger file size is caused by the 14 bit A/D converter of the 40D. The 30D has a 12 bit A/D converter.

Most of my CR2s from my 40D range between 9-12 Mb. I've only had one that thats been in the 13s. I wonder if it has much to do with the ISO, most of mine are taken in the 200-400 range. BTW isn't the 40D fantastic ??
Andy

Thanks Paul I'm sure you hit the nail right on the head.

Andy, coming from a 30D I am more than pleased with the 40D. It is a major upgrade vs. the 30D. Many of the smaller nits have been resolved with this camera. Things like overexposure flashing in full size image. Much improved menu selection. Changeable focus screens. I also like that the same grip and batteries and cards still work with this camera. Everything I have from 10D days still works. The best upgrade so far!

The same grip for the 10D works for the 30 and 40d's? I thought it changed with the 20d. Maybe I will have to pull mine out and see if it works.