On Jul 14, 2005, at 5:34 AM, Dave Kennedy wrote:
Had a lightning storm
...
Never really trying to shoot lightning before, I basically went on the
following theory:
Set camera to Av, set to a small aperature (essentially to extend the
shutter speed - I believe it was 20s), press the shutter and wait for
lightning.
The way I have shot lightning successfully is after sunset. I use all
manual settings:
- ISO 200, sometimes with an ND filter
- minimum aperture (f/22)
- Bulb
Just "hold and hope" once you know about where the lightning is going
to be happening.
On another (kinda) unrelated topic, I found that the DS seemed to take
forever to process the image after the longer shutter speed elapsed.
Probably like 15-20s before it actually started writing to the disk.
Is this normal?
This is called "dark frame subtraction" a form of noise reduction.
The DS has NR of this sort turned on by default, it goes into
operation at about 1/25 second. You can turn it off using a custom
function (I think it's on the first page of the Custom Settings menu).
The only theory I could come up with, is that the body reads
continually from the sensor during the exposure, and then when the
shutter closes, the body compiles the image from memory. (I was
shooting in Jpeg). Would Raw have been quicker?
This has nothing to do with it.
To give you an idea of how effective the DS' noise reduction can be,
here are test shots from the DS, one made with NR off and another
with NR on, both processed with identical settings in Vuescan and
Photoshop+ACR 3.1, respectively:
http://homepage.mac.com/godders/straight-NR-comp.jpg
I chose to use two different RAW conversion programs for this example
as Vuescan does not do hot pixel removal where ACR does. Normally I
process with ACR.
Some folks have found that having NR on can influence sharpness at
short shutter times, so I normally have it switched off.
Godfrey
