One of the exercises I give students is to shoot something moving on 3
successive shots. Then take the red channel from the first, the green
channel from the 2nd and paste them into the third (Blue) Thus the
Photoshop image has one colour channel from each image.
You get the same result as using 3 filters and mutiple exposure. The
moving stuff (Clouds and water are popular) become "Rainbow" because the
primary colours are out of register. The stationery stuff is not affected.
Herschel
Don Roberts wrote:
But, in Photoshop, do you really need to make the exposure compensations
in camera? You can adjust density and transparency in PS. I also tried
the channel procedure and didn't get the right effect either.
With the drop shutter, you take one exposure and have to use manual
settings. But since you will be shooting digital you can see your
results right away and adjust exposure as necessary. For instance, with
ISO 100 film I would get a shutter speed of maybe 1/30 sec. or so.
Changing the aperture made the difference. It would seem that there are
a couple of approaches that would bear trying and would not require a
camera that made double or triple exposures.
Don
PhotoRoy6@xxxxxxx wrote:
Don, I have taken three normal slide shots, pulled out the red
channel from one , the green channel from another and the blue
channel from a third and was unable to get the results I wanted. With
the drop shutter did you get a normal tones for the areas that were
not moving?
In regards to shooting in film the camera TTL takes into account
the different filter factors and equalizes them so each separate color
exposure are a third of the exposure. The different filter factors for
example might produce one exposure at 1/60 and the other two
exposures at 1/180 and all exposure would be at equivalent to 1/3 of
the final exposure. The cameras' meter would calculate this for you
automatically. You don't get this computation using a film camera or
an digital camera on manual. Though I see that you could obtain the
automatic calculations on a digital camera (since you can't fool the
camera by changing the ISO like on a film camera) by using the minus
three stops on the exposure compensation function button.
Roy
In a message dated 4/30/2009 7:01:54 P.M. Eastern Daylight Time,
droberts@xxxxxxxxxx writes:
I know what you are after since I have done that myself. It seems
that if you took 3 separate exposures through red, blue and green
filters, it would be very easy to combine them in Photoshop
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