Updated 2012-01-19 by Bill Claff (revised 2017-03-06)
The purpose of the collaboration is to collect photographic dynamic range information for a wide variety of cameras.
Any brand and model of camera can be used provided raw data can be captured.
The raw data must be in the form of a NEF file, NRW file, or
must be convertible to an uncompressed DNG.
(For Canon cameras this means a full resolution CR2, not a medium or small resolution.)
A rigorous approach requires pairs of exposures taken at
different light intensities.
However, this expedited procedure uses single exposures and a grid to produce very good results.
You should be able
to right-click and save from the following links as necessary.
Place these files all in the same directory.
Knowledgeable readers will know to put them in an appropriate directory on your DOS path but a new directory where you will perform the test is fine.
The target(s) for the required images is displayed using the following program:
Or you can use the following two static images instead of the DR_grid program:
Choose a fast lens
that can take images of your computer monitor at a comfortable distance.
I used a 50mm f/1.8D AF-Nikkor to collect my data.
Set all noise reduction settings to off (or a low as possible). In particular do not use long exposure noise reduction.
Do not use ISO Auto.
Remember to take RAW images.
If your camera does both 14‑bit and 12‑bit then it is preferable to use 14‑bit.
If your camera supports electronic and mechanical shutter then use the mechanical shutter.
You will be using Manual mode and Manual focus. Make sure Exposure Compensation is 0.
Run DR_Grid or put DR-Flat.jpg on your computer screen.
Resize the window so it’s somewhat larger than you can view in the viewfinder at closest focus and in focus.
At this first screen
adjust your monitor brightness so you are properly exposed at 1/30s with the
lens at f/4 and at your native ISO (the lowest numbered ISO for your camera).
1/30s is ideal but if you cannot achieve 1/30s or don't want to adjust your monitor do not worry.
Switch the exposure
from 1/30s to 1/250s and press ‘G’ on your keyboard to proceed to the grid or
put DR_Grid.jpg on your computer screen in place of DR_Flag.jpg.
If you did not achieve 1/30s in the preceding step then choose a shutter speed that is 3 stops faster than the shutter speed you can achieve.
So if proper exposure is 1/15s then switch the exposure to 1/125s.
Take a slightly out
of focus image of the grid. The image must be enough out of focus that no
screen detail is visible at 100%
It's a common mistake to make the images too out of focus!
Don't crop off the upper left of the grid. It is particularly important.
For all cameras that
vary amplification when ISO is changed (most cameras except for almost all
Take an image at each ISO such as 100, 125, 160, 200, etc.
Having data for intermediate ISO values is especially important for cameras with two-stage amplifiers.
Including any Lo or Hi (expanded) ISO that your camera may have such as Lo 1.0 or Hi 1.0.
For cameras that do
not vary amplification when ISO is changed (Sigma models except SD15, DP1x, and
Decrease exposure time another stop; for example from 1/250s to 1/500s.
Take either 5 (for EV steps of 1/2) or 7 (for EV steps of 1/3EV) images lengthening exposure with each image.
For example: 1/500s, 1/400s, 1/320s, 1/250s, 1/200s, 1/160s, 1/125s. (or 1/500s, 1/360s, 1/250s, 1/180s, 1/125s)
Transfer the images into a directory using your usual procedure (although a card reader is preferred to Nikon Transfer or any program that may modify the raw file).
Contact me at BClaff@post.harvard.edu to gain access to my Dropbox to transfer your files or to arrange for an alternate method.