Autofocus, teleconverters and built-in processing

(1) Autofocus.

The D800 utilizes a very similar Autofocus (AF) system to that reviewed in-depth in Alex Mustard’s review of the D4’s AF published earlier. To avoid duplication, I would suggest referring to it before reading my observations below.

Nikon’s designation is nominally the same as that of the D3 and D700, the 51-point Multi-CAM 3500FX AF. As Alex found, this belies what seems to be a significant performance improvement. Coming from the D7000, which features a pretty competent AF system too, the D800 definitely can be viewed as a “pro” version. The camera’s additional processor power, combined with its use of data from both the Multi-CAM and Nikon’s Advanced Scene Recognition System, makes for fast and accurate AF performance even in low light levels. My experience is similar to Alex’s, with auto area mode in Continuos AF (AF-C) working well even with rectilinear wide-angle lenses. Again similarly, I found that despite it having face detection priority, it seemed not to ignore foreground sharpness in favor a face further away.

I am also a fan of the 3D AF mode for shooting macro. The ability to hold focus even when in water that is moving, or on a subject that is moving across the frame is very useful. I find the mode excellent for fish portraits too. I think this mode seemed to work very well on the D7000, and I am pleased to report that this is carried forward into the D800.

Focus in Live view mode is available in AF-S (Single servo) or AF-F (Full-time servo). Both modes utilise contrast detection, which takes focus information directly off the sensor. This limits both the speed and accuracy of the AF. Whilst Live View mode will give a full screen image preview even when the camera is in DX mode (as opposed to a limited view through the viewfinder in this mode) this will be at the expense of some AF performance.

I deliberately shot in low light and on a site with a great deal of surge in order to test the AF. There is no doubt that it is far superior to that of the D2Xs, and significantly better than the D7000.

The D800 does not have the Focus + release or vertical and horizontal focus point memory options that are on the D4.

(2) Using teleconverters.

There is a school of thought that using a DX fisheye lens with a teleconverter produces a rectilinear image, avoiding the need to purchase a dedicated rectilinear wide-angle lens.

I tested the D800 with a Tokina 10-17mm fisheye and a Kenko 1.4 x teleplus Pro 300 teleconverter. The combination produced vignetting, and image quality was significantly degraded.

Rectilinear wide-angle lenses, like the Nikon 16-35mm produce fantastic results with the correct port extensions and big (9”) domes. I do not think that the DX fisheye + teleconverter approach has much merit with this camera.

The tested combination also did not seem to meter correctly, with it giving inaccurate exposure readings. This may be due to the actual units used, so may not be a generic problem. If you plan to use the camera with a teleconverter, further testing is necessary to ensure that it works.

By contrast, 15 of the camera’s 51 AF points are even sensitive down to f/8, of great benefit when using teleconverters with macro lenses. To quote Roger Gailbraith:

“The D800 can autofocus properly to f/8, as long as your composition keeps the subject within a subset of the AF array’s 51 points.

If the maximum aperture of the lens or combo is between f/5.6 and f/8, the number of AF points that retain their cross-type performance drops to nine, while six others, left and right of centre, operate with single line sensitivity only. The remaining 37 AF points in the array may function, but may not detect focus distance properly if they do.

If the maximum aperture of the lens or combo is f/8, the total number of properly-operating points is 11, with the centre-most AF point retaining its cross-type sensitivity. Again, other points might function, but might not function well.”*

Essentially, this means that using that AF with macro lenses and teleconverters should give significantly better AF performance.

(3) In-camera processing modes.

The D800 has an expended repertoire of in-camera modes, including time-lapse, HDR and RAW processing.

Nikon cameras have offered a built-in intervalometer for some time. This provides a means of capturing a series of images that can be post-processed into a time-lapse sequence. The D800 has taken this ability one step further, with an in-camera time-lapse mode. The user inputs the time interval between shots and the total time that the camera will shoot and the camera will then calculate the total length of the resulting film. Once the setting are confirmed, the camera will shoot the sequence and then develop it into a self-contained .mov file on the card. This is also capable of being reviewed on the camera’s LCD screen.

In addition, the D800 has an HDR mode, which allows the in-camera blending of two differently exposed versions of the same image. It is important to note that this is not available while shooting in RAW, but only in TIF or JPEG quality modes.

Lastly, 2 RAW images can be overlaid and saved as a new RAW file. RAW images can be edited for size, white balance, exposure, D lighting and vignette control and then saved as JPEG files in-camera. If the camera is shooting in JPEG or RAW + JPEG modes, a wide variety of in-camera effects can be used to enhance images.

1. Introduction.
2. The Nikon D800 body, controls and overview.
3. Resolution, ISO and tonal range.
4. Image size and “shooting to crop”.
5. Autofocus, teleconverters and built-in processing
6. Conclusion.