File Size as a Measure of Optical Performance

2012-06-09 • SEND FEEDBACK |
Related: Nikon, Nikon D800, Nikon D800E, Nikon DSLR, Zeiss, Zeiss 100mm f/2 Makro-Planar, Zeiss DSLR Lenses, Zeiss Lenses

File sizes across aperture for
D800 + Zeiss 100/2 Makro-Planar

RAW file size (lossless-compressed variants) for the same scene across apertures is an excellent measure of the total detail recorded, which includes the effects of depth of field, diffraction, and lens performance.

With a planar scene (which eliminates depth of field as a variable), file sizes can tell you exactly where peak lens performance is reached in terms of recorded detail.

For the example at right, the scene is not strictly planar; there is some foreground and some background and the camera is tilted up slightly. Still, it’s mostly planar.

Observe that the peak file size is reached at f/4, indicating that the maximum amount of detail is being recorded.

Aperture f/5.6 maintains this file size, but diffraction begins to soften detail at f/8, which thus drops the file size.