Kodak DCS Pro 14n Digital SLR Kodak's latest digital SLR brings full-frame, 13.7 megapixel resolution to market for under $5,000. (Review first posted 3/23/2003)

Page: "Wide Angle" Analysis

Wide angle shots - 14mm f/2.8 Sigma lens (same lens on both cameras).

I'd heard that the 1Ds had some problems with very wide-angle lenses, perhaps a result of its use of microlenses on its CCD array. (The theory being that the microlenses themselves produce refractive effects at more shallow angles of incidence, in the corners of the frame.)

To test this, and compare the behavior of the 1Ds and the 14n in this important area, I called up Sigma and arranged to borrow a pair of their (excellent) 14mm f/2.8 ultra-wide angle lenses, one each in Nikon and Canon mounts. This is an impressive lens, claimed by Sigma to be the widest-angle non-fisheye lens on the market. The shot at right of the lens mounted on the 1Ds gives you some idea of what the huge curved front element looks like. (Special and sincere thanks to Tom Sobey of Sigma Corporation, who's really gone above and beyond the call to get me lenses I've needed for testing on very short notice. He's really set a benchmark for responsiveness by corporate PR folks that others will have a hard time attaining to. - Thanks, Tom!)

This would be a truly controlled test of the cameras themselves, in that I'd be using the identical optics on both cameras. To avoid as much as possible any aberration from the lenses themselves, I generally shot with them stopped pretty far down. I also tried to frame the shots as close to identical as possible, but didn't have my laptop along in the field with me to double-check the fine framing. (I was really pressed for time when I did this shooting, needing to get the 14n back to Kodak posthaste.)

The results were interesting. I really didn't feel that I saw any increase in chromatic aberration with the 1Ds over the 14n, but there did seem to be an increased softness in the corners of its photos. Both cameras performed well, and the lens was a joy to work with. - I've never had the budget to afford a super-wide lens like this for my own personal use, and it was a real revelation to spend a little time with an ultra-wide optic like this one. The lens showed amazingly little distortion of any sort, even barrel distortion: Its field of view is almost perfectly rectilinear. Chromatic aberration is surprisingly low (at least at the small apertures where I was doing my shooting), and the sharpness is excellent as well. Very cool...

Well, my salivating over the lens aside, I felt both cameras did a commendable job with the ultra-wide shots, really demonstrating that there are some times when you really want a full-frame sensor on a digicam. Here's a sampling of ultra-wide shots snapped under identical conditions with the two cameras:

Pro 14n EOS-1Ds
This is a shot where I was deliberately trying for worst-case flare, to see if there were any oddball optical effects in the corners of the frame with an overwhelming highlight. I did see a bit of a "tail" on the image of the sun in another shot taken with a very short shutter time with the 14n, but not anything that looked like it could be chromatic aberration with either camera.
The Bradford Pears were blooming abundantly, thanks to a very wet spring. I shot this beneath a pair of them, looking straight up.
This is a detail, cropped from the extreme upper righthand corner of the shots snapped with both cameras. (Any distortion problems, whether due to the camera lens or to the microlenses over the 1Ds' sensor pixels should be worst in the extreme corners of the image.) The image from the 1Ds is a bit softer, but they both show the same degree of chromatic aberration.
This is actually a shot taken looking along the limbs of one of the trees, horizontally, then turned on edge. I didn't get the framing really nailed on this one, as the shot with the 14n is aimed a bit more up and to the left than the one from the 1Ds. Cool playing with the ultra-wide lens though: It clearly takes some getting used to, takes an entirely different visualization than you'd get just walking around normally.
I thought I'd give the res target a try, figuring that was about as definitive test as one could ask for: The target elements are of course perfectly crisp, so there can be no question of whether you're really looking at the same thing with both cameras.
Aha! While I don't really see any more chromatic aberration in the 1Ds shot, it's clear that the image is much softer in the corners. The 1Ds' images are a bit softer overall, due to the antialiasing filter, but the center of this shot is a good deal sharper than what we see here at the edges.

Based on these admittedly limited tests, I have to say that the microlenses on the 1Ds' sensor really don't seem to have much impact on chromatic aberration (CA) with ultra-wide lenses. They do appear to result in a slightly greater softness in the corners of the image, blurring the edges of the target elements, and what CA coloration is present along with them. I've seen this very often in the corners of images from consumer-level digicams, where the radial blurring of sharp contrast edges makes what chromatic aberration there is seem that much more apparent. - The stretching of the tonal transitions at the edges of objects smears the color produced by the CA out across a broader area. This leads many to say that the lens exhibits more CA, when I think it would be more correct to say that it shows more coma (if that's indeed the correct name for this), which makes the CA more evident.

Bottom line though, I have to say that this is an area where there's a clear difference in favor of the 14n, albeit only affecting the corners of the frame, and then only with very wide-angle lenses.

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