Some may recall that I made a very successful in-camera
double-exposure of a moon into a mountainous landscape a couple of
months back. In retrospect, it seems that more luck than knowledge was
involved. By a factor of ten, at least.
A recent adventure with a poppy demonstrated that luck doesn't help
much in the long run. :-)
Today i did a series of double-exposures, similar to the one of the
poppy, but under more controlled conditions. One part-exposure in
focus (IF), and one part out of focus (OOF). I varied the relative
exposures of each part between -0 and -2 stops.
http://www.oksne.net/tests/dbls/index.html
The lens was FA 100/2.8 macro. The IF exposures were done at f/32, the
OOF at f/2.8. White balance was set to auto, and ISO at 200. I worked
with a tripod this time. The raw conversion is done with the
QuickProof function of PhaseOne C1 Raw v3.6, and no attempts were made
to change any parameters from the camera. The background is dark grey
to the eye, and the light was clear blue evening sky.
There are a few conclusions and at least a few oddities.
One conclusion is that the multi-exposure function in *istD does not
recalculate exposure based on the number of part-exposures involved.
Cameras like the Z-1/Z-1p subtracted a certain EV value to each
exposure based on the total number. The *istD, however, does not.
The EXIF data recorded are only from the last part-exposure.
One oddity is the IF: -1 OOF: -2 picture, that has a colour balance
noticeably different from all the others, even though the whitebalance
reports to the same number as do all the other shots. Light was almost
constant during my session, too, so this one beats me...
This test is probably only scratching the surface of a big issue.
Maybe it's easier to control it in Photoshop after all...:-)
Jostein
