Mark C wrote:
A couple things I learned about the K-1 and Pixel Shift Mode:
The banding I was experiencing is the result of the electronic shutter
and artificial light. It's just a rolling shutter effect. I saw it in
Pixel Shift mode since that uses the electronic shutter, but setting the
camera to use the electronic shutter in standard resolution / live view
mode will also produce the banding. With the incandescent bulbs I used
in the test, the banding was worse at higher shutter speeds but seemed
to disappear at speeds of 1/15th or slower. Here's an extreme example -
pointed the camera directly at a 30W mini flood light and shot at 1/8000
/ f2.8:
http://www.markcassino.com/b2evolution/index.php/pentax-k-1-banding?blog=9
<signal processing geek>
Mark, as an experiment, please try this at various multiples of 1/120
second (83mSec):
1/120, 2/120, 3/120, 4/120, 5/120 -> 1/120, 1/60, 1/40, 1/30, 1/24, 1/20
Since the light is effectively a rectified sine wave, any time you
integrate (expose) over a half power cycle (1/20), you should get
exactly a full cycle of the light, and it should come out even with no
banding.
If you do run an experiment where you just cycle through exposure times
from, for example, 1/500 down to 1/5, at 1/3 stop (1dB) and post the
results, that should be a very cool demonstration of aliasing/nyquist
rate etc. and I've got some science teacher friends who'd probably
really appreciate that gallery being up on the web.
</signal processing geek>
--
Larry Colen [email protected] (postbox on min4est) http://red4est.com/lrc
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