RE: Filter/Speed/Meter & DON'T meter using a Nikon Camera

["Charles Jay Pilzer" <cjp@xxxxxxxxxx>]

In the F5, the prism is removable to change the focusing screen.  It is the
metering mechanism in the prism?  Could one have the IR blocking removed
from a prism dedicated to IR and have another prism for regular use?

cj

-----Original Message-----
From: owner-infrared@xxxxx [mailto:owner-infrared@xxxxx]On Behalf Of Rolland
Elliott
Sent: Thursday, October 05, 2000 11:31 AM
To: infrared@xxxxx
Subject: Re: Filter/Speed/Meter & DON'T meter using a Nikon Camera

Re: Filter/Speed/Meter & DON'T meter using a Nikon Camera
"try just shooting some HIE as described in the inserted literature
nice bright day w/ puffy clouds and sun behind you (some time other than
high-noon) "

BORING! I totally agree that the above method will work. I also think too
many IR photographers use it as a crutch and restrict their creative
potential because they only know how to meter under one lighting condition.

By making a corrected IR light meter one can avoid the cliché by being
confident with their exposures under different lighting conditions. That's
why I took off the IR block filter to my Nikon N90s a couple of months ago.
It's IR exposure accuracy is now something I rely on instead of half
trusting.

Also, For the person who tested the Nikon F1 nad F2's meters to try to prove
they are sensitive to IR light you may very well be correct, however, I
would like to point out the following:

1) The F1 uses CDS metering cells not SPD like you claim. The two different
metering cells have very different light sensitivities and characteristics.
The first two Prisims for the F2 also used CDS cells; it was not until the
DP3 that Nikon switched to SPD cells. It should also be noted that all the
Nikkormats used CDS cells.

2) The F1 is about 40 years old, and the F2 is about 30 years old.
Technology has come a long way since then.  If you ever have the opportunity
to look at a modern IR block filter under IR illumination, it is virtually
black and very effcient at blocking IR light.

All the Nikon N series(N50-N90s), FM/FE series and F100, F3-F5 cameras use
SPD cells which require IR block filters for correct visible light metering.
Actually there are a couple of exceptions, the F5 uses a 1005 pixel CCD, but
this metering system also requires a IR block filter.  The FM uses some sort
of Gallium diode. Don't know if the FM uses an IR block filter.

3) Your tests were rather unscientific. You didn't take apart the prisims to
see if they actually had an IR block filter and you didn't even know what
kind of metering system they used.  I think CDS's are less sensitive to IR
light so the F1 and F2 may very well not even have an IR block filter, I'm
not sure since I've never used a camera with a CDS. Hardly anyone uses these
cameras so it's a rather mute point. The only one's I've seen are on
collector's shelves.

Basically it boils down to this. You can try to meter IR light though a
filter that blocks IR light, but it is not very logical to do so. I've been
doing it for the past several years and it seems to work well for bright
sunny conditions. However, for anything but bright sunny conditions removing
the IR blocking filter from your Nikon will give you much more accurate
exposures. However this basiclaly requires dedicating a camera to IR
photography which most people probably don't want to do.

Peace, Rolland



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