SoCalTiger wrote in post #15393616
Gear Acquisition Syndrome? As the above poster mentions, it would be helpful to know why you want to upgrade in the first place. A lot of people get really caught up in just buying more stuff when they don't really need it.
Sounds like a bad case of G.A.S.!
5DIII is a great camera....
All your lenses will perform differently, which can be good or bad depending upon your point of view and what you need/want to shoot.
Your 24-70 will suddenly be nice and wide! However, for portraiture I find the 24-70 more useful on a crop camera than on FF.
However, you will no longer enjoy the same "reach" with your longer lens(es).
Crop cameras can use both crop lenses and full frame lenses. Full frame cameras can only use full frame lenses, for all practical purposes. In general, a kit of lenses for full frame tends to be bigger, heavier and more expensive. An extreme example: I use a 300/4 IS as my longest handheld lens, often on crop sensor cameras, with and without a 1.4X teleconverter. It's a very hand-holdable lens, not too terribly expensive. In order to enjoy the same "reach" with a full frame camera, I'd have to switch to my 500/4 IS - much bigger, heavier and more expensive... and, for the large part, a tripod-only lens (I wouldn't want to handhold it for more than a few minutes!)
So someone who uses mostly wide lenses might be quite happy with a full frame camera, while someone whose emphasis requires long telephotos may be better served with a crop camera.
FF are also preferred for greater control over depth of field... Format doesn't actually change depth of field, only aperture, focal length and working distance do.... But with a FF camera we work closer to get the same framing, all other factors being the same. And a FF camera's viewfinder gives a more accurate rendition of DOF. Plus, a FF camera's less crowded sensor allows for lenses to be stopped down more, such as for landscapes or macro work, before diffraction becomes an issue.
In general, FF is also preferrable for low light work... the less crowded sensors are more resistant to high ISO noise.
I use both formats... a couple 7D plus a 5DII. Best of both worlds. This is sort of like the old days of film, when we used 35mm, medium format and large format cameras for different purposes. However, the neat thing about today's DSLRs is that you can have a couple different formats available that for large part share the same lens kit (and possibly some other accessories)... saving a lot of money and stuff to haul around! In fact, having two formats to use with them sort of leverages or extends the capabilities of your lens kit. Even after three years using my mix of 7D and 5DII, and having taken some 200,000 images with the three cameras, I don't feel any real urgency to upgrade.
