Digital Camera Dilema - Depth of field - NOT

Ron Gatrelle gatrelle at
Fri Sep 28 13:47:41 EDT 2001

----- Original Message -----
From: " Clay Taylor" <CTaylor at>
To: <birdcr at>; <leps-l at>
Sent: Friday, September 28, 2001 9:51 AM
Subject: Re: Digital Camera Dilema - Depth of field - NOT

> Hi all -
>     I am only jumping in here to dispel the depth of field myth - the
> digital discussion is VERY fascinating.


>     My own messing around with digital cameras has been limited to field
> work, but those of you shooting controlled setups should use a Kodak 18%
> Gray Card either as a full background or positioned somewhere in the
> If the color balance varies between photo sessions (shooting with natural
> light at two different times of the day will do it) at a later time, you
> should be able to use your photoshop system to change the gray card tones
> the correct 18% gray, and the entire picture will now be correctly color
> balanced.  Studio photographers use that system for matching colors
> different film emulsions, and the digital world is no different.
> Clay Taylor
> Moodus, CT
> ctaylor at

Clay has injected another very important element of digital photography  -
computer editing.  Then when you get and become familiar with an editing
program ( I use Paint Shop Pro) you need to fight with  paper and printers.
All of these things need to work together.  Camera, editing software,
printer, paper -- a weak link along the way can and will alter the best
equipment around it.   For those who will not be printing their work the
first two the main concern -- plus the very simple step of going into your
computers "setting" and setting the color at 24 bit (or higher) color
resolution.  The bottom line is that there are MANY different way to get
basically the same results.  What will work for one may not work for

As I said before, I don't know nuttin bout no photo- graphy.  I do know a
little about computer editing of pictures as I do all that for our
publication.  In all this I see that a person's ability to get good results
is not based nearly so much on the kind of equipment one has - but how well
one knows how to use it.

The gray card reminds me of this.  A while back Joe and I were taking some
pictures in the back yard.  For some reason the camera wanted to focus on
the black writing on the white specimen label.  To sure this I picked up my
grandsons yellow sand shovel and put the edge of it in the cameras field of
view on the same plain as the specimen.  This worked to fix the focus.
However, when I went to crop the picture (which eliminated the shovel edge
from the picture)  I noted that the entire left half of the picture had a
yellow hue to it.  The sun light reflecting off the shovel had bounced down
to the white pinning surface and flooded the left half the picture with
yellow color.   I could not adjust this with the computer for if I got the
left half "right" then the unaffected right side lost the yellow it needed.
So we re-shot.  Now, this translates to outdoor shots of specimens on
yellow, red and blue flowers -- the reflected light from the flower can
alter the natural hues of the specimen.  This is another reason I like to
shots in indirect sun light - slightly in shadows - at a different exposure
rate.  etc.
Ron Gatrelle


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