Upgrade comment needed

I know this topic has probably been beaten to dead. Here is what I am thinking about to do:

I currently own 30D, 40D, 17-55IS + a few other lens. I am thinking of selling 40D+17-55IS and get 5D+24-105 kit. The money required for this upgrade is about $1000 which I can manage.

The only thing that is keep me from doing it is versatility and image quality of the 17-55IS. I want some input from people who make this upgrade. What is your experience? I used to own 24-105 and used it on 30D, I was NOT happy. I wonder if 5D will make a difference. Also how about DOF? Do I lose much by having F4 on 5D vs F2.8 on 40D?

eel

What do you shoot and why do you want to "upgrade"?

f/4 vs. f/2.8 means half the shutter speed in low light situations...but there is always the 24-70 to consider.

Switch the 24-105 to the 24-70. A bit heavier than the 17-55 but covers the same range on a 5D as the 17-55 on a crop. Optically they are so close you cant tell the differance between the two. Lacks IS though.

Also depending on how lucky you are, the 24-70 may not be as sharp at 2.8 as your 17-55. I would keep the camra you have and when you can swing it, get the 5d as a 2nd option, depending on your picture needs.

The 5D is the "camera of choice" for certain types of photography, but for others the 40D (or the big brother 1D Mk III) excel. Don't switch mindlessly. Why do you want to ditch the 40D, especially in combination with the unique 17-55 f/2.8 IS? That combination will give you shots that you could not get with the 5D+25-105.

If, though, you are withing the focal range of the 5D and the lenses that you have, the full frame has its advantages. Just don't do a "knee jerk" thing.

I couldn't be happier with the 5D + 24-105 the 17-40 is even more fun but the 24-105 stays on,I can't see having two crop bodies keep the better of the two and get the 5D
JMHO