Are superior lenses really necessary for full-frame DSLRs?

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October 1, 2012 at 1:51 pm  •  Posted in Q&A by  •  2 Comments

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?
—Jeanne J.

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.

In this small reproduction, it's impossible to evaluate the quality of this image, made with a full-frame high-resolution camera, and a pro-grade 70-200 mm f/2.8 lens on a hefty tripod. But the 24 x 36-inch print hanging on my wall is fabulous in all aspects, with incredible resolution of the most intricate detail even in the corners of the photo. (135 mm; f/8) © 2012 Peter K. Burian

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.

2 Comments

  1. Gregory Colvin / April 2, 2013 at 8:28 am / Reply

    Very informative article. You mention in the article that the optimal apertures are f5.6 to f/8 and I have seen that in another article. I now shoot with a D800 after using the D200 for many years. When using the D200, on landscape photos I would set the aperture at f22. So for best results I should use f8 with the D800? I want to get the best results. Thanks for the article.

  2. Peter K Burian / April 2, 2013 at 1:15 pm / Reply

    Thanks for your note, Greg. As a rule of thumb, you get the best optical quality a zoom lens can deliver at around f/56 – f/8. (Pro lenses might do so at wider apertures: smaller f/numbers).

    But sure, when you want maximum depth of field (a great range of acceptably sharp focus) you might need to use f/22 …..so the entire scene looks sharp. That is a creative decision, regardless of the camera/lens you use.

    While the optical quality may not be perfect at f/22, you may still use that for landscapes. A bit of sharpening in software can provide excellent results.

    But when you do not necessarily need the foreground and mid-ground and background to appear sharp in a photo, use f/5.6 or f/8.

    Optical quality is not the same as “sharpness from foreground to background”. This previous Q&A sheds some light on that topic: http://www.photolife.com/?p=12238

    Cheers! Peter
    http://www.peterkburian.com

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