24mm camera lens shootout, on the Sony a7R: first round

Finding a clean 24mm prime camera lens that won’t cost you an arm and a leg is difficult, but finding one that works well on the Sony a7R camera can be a real battle.

That’s due in part to the demands that the 36mp sensor in the a7R places on things like field curvature of the lens. A 24mm lens on the full-frame sensor in the a7R is roughly comparable to a 15mm lens on an APS-C crop sensor camera, so it’s a pretty wide view.

This 24mm lens shootout will give you a good idea of what 24mm glass works best on the a7R, and to some extent, even how those lenses will work on DSLR or mirrorless camera bodies. This first test session covers the Canon FDn 24mm f/2.8, the Sigma 24mm f/2.8, and the smc Pentax 24mm f/2.8(K-mount). The test image is a group of medium distance landscape shots, because landscape shots are helpful for evaluating how flat the lens image field is, at infinity focus. All shots were taken at f/8, with the obvious question being, why not follow conventional wisdom for landscape shooting, and use f/11, f/16, or even f/22? The answer is that previous testing with 24mm DSLR lenses on the a7R didn’t always show enough image improvement on the sides, at smaller apertures, to make the tradeoff in center resolution loss worthwhile: Wide angle lenses on the Sony a7R¬†However, since this should be evaluated for each lens design, some of the lenses that lose because of lens curvature issues will get re-tested in a consolation round.

Ease of focus at long distances: Pentax 24mm(3 points) wins by a landslide, it’s a dream to handle, followed by the Sigma 24mm(2 points), with the Canon FDn 24mm(2 points) slightly behind, but close enough to call it a tie. The Sigma 24mm being tested is an autofocus lens, which is difficult to manually focus, but the contrast is perhaps higher, so it’s slightly easier to get focused at long distances.

Lens contrast: look at how dark and contrasted the “5610” number is on the side of the building, dead center of each image: Pentax 24mm(3 points), Sigma 24mm(2 points), Canon FDn 24mm(1 point). Exposures varied in these images, even though they were all shot at “0” on the in-camera exposure meter. Download the jpegs from the link, make your own determination.

Sides of the images: On the left side, compare the text in the street signs, hanging from the traffic lights. The right side has several areas to compare. Canon FDn(3 points) wins on one side, Sigma 24mm(3 points) wins on the other side, while the Pentax 24mm(disqualified) simply fails in a blurry haze.

Center of the images: They all look good, take your pick. Keep in mind that what the Sony a7R giveth, it also taketh away. Resolution testing at lensrentals.com shows that the a7R sensor increases resolution in the center of a lens, in a manner that is probably unmatched by any other camera on the market. The flip side is that these test images show how tough the a7R can be on glass that doesn’t have a flat image field, like the Pentax 24mm lens.

Summary: ¬†Sigma 24mm(7 points) and Canon FDn 24mm(6 points) both advance to the next round, due to possible slight sample variation issues on the sides, that needs to be investigated further. The smc Pentax 24mm lens would be fun to use on a crop sensor camera, and it might even be worth looking at for a 24mp full-frame sensor, as long as you don’t expect too much from the sides. The smc Pentax 24mm will get re-tested at other apertures in the consolation round.

Here is the test image, it’s nearly 20mb in size, **be sure and view it at 100% size**:

http://www.codectest.com/images/24mmfdnsigmapentax.jpg

Dan Euritt

24mm camera lens shootout, on the Sony a7R: second round

24mm camera lens shootout on the Sony a7R: third round, Konica 24mm

24mm SLR prime lens test, fourth round, shot on the Sony a7R

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