Am I the only one who feels like Canon is hindering the practicality of upgrading?

There are actually many lenses to chose from and the 24-105 really shines on FF...

You should not discard the new Tamron 24-70. Photozone review is stellar:

"obviously the best standard zoom for Canon EOS at this stage - at least till the Canon EF 24-70mm f/2.8 USM L II enters the scene."
http://www.photozone.d​e …amron2470f28eos​ff?start=2

The IS on it is good for 3 stops and build quality is better than the other Tamron lenses that are more budget oriented.

RobDickinson wrote in post #14909908
f4 on a FF body is easily equivalent to f2.8 on a crop.

No it isn't. You think when you put that f/4 lens on a full frame camera the bokeh will suddenly change shape or size? The lens aperture will somehow get wider and let in more light? It will suddenly work with f/2.8 cross type focus points?

It's still f/4 no matter what camera you put it on.

bokeh shape or size? the plane of focus for similar framing on ff at f4 vs crop at f2.8 the ff body will have shallower DOF and more OOF blur.

And yes the 24-105 does actually work with some f2.8 sensors as per the manuals of the bodies.

But I was speaking in practical terms that the 24-105 is pretty much a direct equivalent to the 17-55.

mannetti21 wrote in post #14909891
I've been considering selling my 7D and moving to the 5D3, primarily for the improved ISO performance, among some other less significant reasons. If I were to do this, I would sell the 7D, the 17-55, and maybe even the 28mm. Problem is, I feel limited as far as lens selection, in a such a way that I'm wondering if I'm actually better off with my current setup.

High ISO won't do you much good if you don't have any lenses to take pictures.

There is no direct replacement. Might as well accept that now. The 24-105 is a nice lens, but you are correct - it's not f/2.8. I kept my 50D & 17-55 f/2.8 after buying a 5D II just so I could continue using the lens.

There's only one 24-70 with image stabilization - the Tamron 24-70 f/2.8 Di VC USD. I don't know how it is in terms of image quality. Price tag is $1300.

RobDickinson wrote in post #14910346
But I was speaking in practical terms that the 24-105 is pretty much a direct equivalent to the 17-55.

...except you are forced to give up a whole stop of ISO to compensate. So take the 24-105 and stick it on another old full frame that isn't as low-light friendly as the 5D3, maybe something like the 1Ds (to serve as an extreme example to illustrate the point). Now the difference is obvious and not simply masked by superior sensor technology.

Yes, I advise not using archaic bodies out of the stone age, given the OP was specifically talking about a 5d3.

And according to the 5d3 manual the only thing you loose with the 24-105f4 lens with focus points is the dual cross type ability, all the cross type points work fine.

You're right though mannetti, Canon does heavily encourage( or force, depending on your needs) upgrading and spending more. That's good business sense, and most companies do this with their different product lines.

A full frame zoom will cost more because it needs more glass.

Theres plenty of alternatives if you want to save money. A 50f1.8 is cheap and a nice focal length on a FF body, theres also the 40/2.8

Thanks for the discussion guys. I know myself well enough to realize that sometime in the next few months I will have ordered the 5D3. As mentioned before, the 24-105 seems to be the closest replacement to my favorite lens, the 17-55.

Having the extra ISO capability will help compensate for the f/4, and in reality, if I'm serious about getting shots in dim lighting beyond the scope of the 5D3's ability to compensate, then I probably should be using the Speedlite or switching to a fast prime anyways, rather than going all the way to f/2.8

Like others have said, 24-105 is better than 17-55 + crop in every possible way.

Longer range, thinner dof (if desired), better build and with IS just like the 17-55.

mannetti21 wrote in post #14910574
.. the 24-105 seems to be the closest replacement to my favorite lens, the 17-55.
...

I swear by this lens as my walkabout lens on my 5D2 .. it really does shine on a FF body. I actually like the 17-40 F4 as well

JeffreyG wrote in post #14909940
What RobDickenson said is correct. The 24-105L on a 5D3 will be like having an EF-S 15-65 f/2.5 on the 7D in terms of range, DOF and low light capability.

But he already has 17mm f2.8. That's a lot of money to gain 1/3 a stop, when for any other lens option he will gain 1.5.

I've gone from a film Eos-3, to a crop 30D and back to a full frame 5D2 without any need to switch lenses. I have used a 24-70L as my mainstay, with a 70-200L for all my "normal stuff".

This does raise an interesting question, a lens with a max aperture of say f4, will it in fact be faster on a crop body. When you consider that actual aperture size is related to focal length, then logically it follows that say a 1/2" diameter (or whatever the max is) iris on a crop camera is greater in relation to the focal length and hence faster. Or is the fact that it is designed to spread that light beyond the confines of a crop sensor mean that as some of the light is wasted it pulls it back to f4.

Please discuss