Re: Do you set your camera at high resolution?

Randy Berbaum offered these thoughts for the group's
consideration of the matter at hand:

Looking at the focus ring of most lenses I notice that the
further the subject is from the camera the more distance
covered by the same degree of rotation. So 1 degree may make a
change of 5' at the lower end while at the upper end the same
degree of rotation of the focus ring may cover a change of 30
or 50'. So I suspect the accuracy of "range finder" duty on a
camera lens is more a function of a percentage of the
distance. So at 3' the accuracy may be plus or minus 3" (a
total deviation of 16%). Then at 50' the same 16% would be
plus or minus 4'3".

Yes.

Camera lenses make poor distance measurement devices. Thus
any distance reported in the EXIF would be highly variable and
its accuracy would be dependant on the lens itself, the
accuracy of the encoder that senses the position of the focus
ring, and the actual distance. All of which would make such a
number so imprecise as to be almost useless.

They were pretty damn accurate in the 35mm film days when I
hauled around a Nikon Photomic FTN. Of course, once you got close
to infinity, it was totally inaccurate, but more than enough to
focus on a subject, look at the distance, then use the manual
flash of the day guide number gizmo to set the aperture. Worked
pretty well for me.

Now there is a solution. For relatively close objects you can
get a small handheld "laser tape measure" at a local home
repair or hardware store and take the measurement with much
better accuracy. Then if this measurement is important to your
photo you can add it to the comment section later. At least
until cameras come equipped with built in radar or laser range
finders this may be what you have to do. :)Who knows, with the
competition between P&S manufacturers to come up with a
"feature" that nobody else has, one manufacturer may actually
do something like this. ;)

I evaluated nearly a half-dozen of these things last year, having
the same idea you present. I found ALL of them useless in a
photographic environment primarily because they are designed to
measure square rooms and don't like it if the laser isn't aimed
at 90 degrees to some large, solid object like a wall. So, either
I got "error" messages meaning it just couldn't compute the
distance, or the reported distance was wildly inaccurate.

These days, in the increasingly rare instances when I really need
to know how far I am from a car I'm photographing, I just clip a
20' Stanley tape measure to my belt. That's generally enough for
my needs. The only issue is if a museum security guy sees me
trying to stick the tape past the barriers around the cars, so I
basically abandoned this idea. I also gave a run at measuring my
walking distance for each step and simply pacing off the
distance. That works reasonably well IF I can make it all the way
to the subject.

But, the whole question would be moot if the damn camera would
just show you in the blinking viewfinder! About every other
important aspect of the AF and AE lock things are there, why not
the distance the AF computed? Again, if the computer in the
camera didn't "know" the distance when you press the shutter down
half way to get an AF lock, it couldn't set the lens, right?

--
HP, aka Jerry
.

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