Originally posted by normhead It's much easier to keep more of the subject in focus and I get more enlargement of the subject.
It is just as easy to get as much of the subject in focus using a larger format, simply by stopping down one more stop. The larger f-stop on a larger format does not translate into a noisier image because the total amount of light is the same (as you know, if you understand equivalence between formats).
You only get more enlargement of the subject, if your pixel pitch is higher. Nothing to do with format size. You get as much enlargement out of a D800 as you get out of a K-5.
It is true that there is currently no FF camera that gives you as much (digital zoom) enlargement as a 24MP APS-C camera, but it is also true that the APS-C format is rather "resolution hungry" as a smaller part of the image is enlarged to the same size as an FF image, thus establishing higher requirements regarding lens sharpness and AF accuracy.
Once you take the different enlargement factors into account, some IQ concerns are seen in a different light. For instance, the myth that FF corners are weak has been dispelled by falconeye. Since FF requires less enlargement the aberrations in the FF corners are less visible than you probably expect.
BTW, there are further advantages to FF which have been discussed at length elsewhere. It is tiring to see FF proponents being reduced to "shallow DOF" aficionados time and again.
Originally posted by normhead shoot lots of landscapes macros and wildlife images, and look more to have everything in focus. I don't shoot portraits very often, so for me, giving up the extra DoF of APS-c to get the narrow DoF of FF, is pretty much a bad idea.
You don't have to give up any extra DOF when switching to FF. Just stop down a stop more.
It is true that you won't get f/32 (the equivalent of f/22 on APS-C) on an FF camera because many lenses do not stop down further than f/22, but they don't for good reason: Already at f/22 you get so much blur through diffraction that IQ suffers badly. Effective resolution drops down to ~2MP. Such high f-stops don't make sense on these format sizes. If you need the DOF, either get a view camera or perform focus stacking. Stopping down to f/32 is not a good solution.