Recently, I read a review of the Nikon D800 indicating that the “best” lenses are essential for this camera. Another article made the same comment about the Canon EOS 5D Mk III. So, I guess that any camera with a full-frame (36 x 24 mm) sensor should be used only with pro-calibre lenses. Is it true, and if so, why?
You may be thinking of the D800/D800E Review by the folks at DP Review, Jeanne; and yes, they make a valid point that applies to other full-frame DSLRs too. “Can the D800 make good on its pixel count and provide a level of fine detail that trumps its DSLR rivals? It can. We emphasize the word can, because if you’re truly after 36-MP performance, be prepared to do some work. Flawless technique and top-shelf equipment (particularly lenses and a tripod) along with a low ISO are requirements not options.” Of course, the value of a tripod applies to any camera if you want the absolutely best possible image quality.
While any DSLR provides optimal results with a superior lens, this is particularly important with a high-resolution 24 x 36 mm sensor which tends to emphasize the effect of any optical aberrations. The reviewers at SLRgear.com mention another important aspect: “We generally caution readers considering making the move to full-frame that it really brings with it a hidden commitment to excellent glass, because full-frame is so unforgiving of cheap optics in the corners.”
For a specific example, here’s a comment from that site about an affordable wide-angle zoom tested on both a large- and small-sensor EOS camera: “The lens loses its sharpness fairly quickly in the corners with the full-frame body; darkening at the corners is also much more pronounced.” Remember, a 24 x 36 mm chip captures light across the entire image circle projected by a lens. If it cannot provide optimal brightness and resolution around the edges, the overall image quality will be less impressive. That’s less of an issue when a multi-platform (FX, EF, etc.) lens is used on a DSLR with the typical smaller sensor because only the central area of the lens’ image circle is actually used to make the image.
Many reviews of multi-format lenses are completed with only the small-sensor camera that the reviewer actually owns. If you are a full-frame DSLR user, it’s worth searching for test reports that provide an evaluation of a multi-platform lens with the same body that you own (or a similar one). Use a rigid tripod and also follow the reviewer’s advice about using the optimal apertures – such as f/5.6 to f/8 – and you’ll get images with the best possible resolution and brightness across the entire 36 x 24 mm frame.