15-85 to 24-105L

If going from crop (60D) to full frame (5D2) and 15-85 to 24-105L what kind of a difference will I notice? I'm very happy with everything about the 15-85.

I'm already not happy with how fast the 15-85 is but the constant F4 of the 24-105 will probably make it faster overall.

Anyone do this transition and can provide any insight?

I'm still debating if I would sell the 24-105 or keep it. Seems very versatile (similar to 15-85).

24-105 on FF is an incredible lens. Use it for a lot of stuff. The ONLY thing that bothers me about it, is that the barrel extends when zooming, leading to lens creep when walking around with it. Optically though, that focal length on FF versus crop is extremely more useful.

It's either keep the 24-105 or trade for a prime and use my 50 and whatever I trade for.

The 24-105 is really only a stop faster at the most than your current 15-85 so you're not going to notice a big difference in shutter speeds in similar situations but f4 will allow you a little more DOF control on FF than it does on crop. Also, the IS is better on the 15-85.

On the same format, the 15-85 and 24-105 (both on crop) are actually very similar in the IQ department, however you'll likely see better IQ on FF with the 24-105 due to the characteristics of the 5D mkII.

I have both lenses and I can tell you that you won't be disappointed with 15-85mm. It's the lens that I now recommend to my friends. When you can only one lens, no other lens, even the 17-55/2.8, will beat it.

I just went to Sammy's camera and got a 17-40 to try out. WhileI was there some guy maybe in his mid 20's was getting a 5D which is mommy was buying him. Ahhh...sweet. Anyway, The guy I talk to all the time there told me that 24-105 is a great lens, but that a lot of people are returing it to get teh 24-70 which is a bit more expensive and is limited in focal range. The only benefit I see is the 2.8. If that is improtant to you at that point you may as well go for a good prime 50mm 1.2 and have far better IQ for a couple hunddred more than the 24-70.

the 24-105 is a great lens on a crop or FF. I've had no lens creep issues with mine, but, obviously, your mileage may very.