Wetpixel

Field Review of Nikon D700 in Subal ND700

by Alex Mustard

RECTILINEAR CORNER SHARPNESS
The Red Sea trip also gave me the chance to shoot the rectilinear 17-35mm in some more detailed field tests. As I elaborated in my D3 review, one of the potential downsides of FX is the blurred corners of wide rectilinear lenses, which have the potential to be more prevalent on the larger format.

With the D3 I was satisfied with the corner sharpness with this lens when shooting the great white sharks in Guadalupe. But I would be the first to admit that images with blue ocean in the corners is hardly a challenging test. Red Sea reefs would be a tougher proposition with plenty of detail that needed to be retained in the corners. I used the 17-35mm with a +4 dioptre behind a Subal FE2 dome and a port extension ring and shot several scenes at a range of apertures using the widest end of the zoom (17mm).

These test shots were taken at a range of apertures. While these are not the greatest photos and I can only show you them small, I think that you will agree that the corner sharpness is impressive, and I would consider all the images at F8 and greater to be entirely useable and better than I have seen on many tests with full frame cameras and wide angle zooms. Nikon D700, Subal ND700. Nikon 17-35mm +4 dioptre @ 17mm. 2x Subtronic Alphas. ISO 200.

Crops (50%) from bottom left corner:

These are 50% crops of the lower left corner of same images (100% crops did not show enough of the image within the page size restrictions of Wetpixel page templates to be useful). Detail is recorded well from F8 or higher. At F5.6 detail is lost in the corners (note the anthias here are closer to the lens so out of focus). Chromatic aberration, seen as fringing, is present in all the images, particularly noticeable on the white tips of the fire coral. Nikon D700, Subal ND700. Nikon 17-35mm +4 dioptre @ 17mm. 2x Subtronic Alphas. ISO 200.

The corner sharpness results from the 17-35mm are better than I had expected. I shot subjects that I thought would highlight corner sharpness problems. I using the lens at the widest zoom setting, choosing subject matter close to the camera and lighting the entire frame, to reveal detail in the corner of the frame. I find these results completely useable at apertures of F8 and above and they even stand up well to a pixel peeping examination. As I found in my D3 review, this lens (or at least my port setup for it) is prone to chromatic aberrations on areas of high contrast (in this case tips of the fire coral). When I get a FX camera of my own I intend to experiment with my port setup and would expect to improve this performance further.

I also had another chance to experiment using the auto focus fine-tine feature to apply a focus offset, closer to the camera, for the 17-35mm in an attempt to improve corner sharpness. Frustratingly, the results were inconclusive really because the corner sharpness was so decent in the first place. In the end I could not tell any difference between the before images and the after ones, which suggests that first the effect is not very large and second I need some more controlled conditions to observe it. I’ll try and get the 17-35mm and a D700 or D3 in the pool soon.

 

These two images show the same reef taken with different values of the auto-focus fine tuning for the 17-35mm lens. I had hoped that by setting the fine tune closer to the camera it would improve corner sharpness. I was not able to detect any difference between these shots regarding corner sharpness. Nikon D700, Subal ND700. Nikon 17-35mm +4 dioptre @ 22mm. 2x Subtronic Alphas. ISO 200.