Rol_Lei Nut wrote:
That's SOP on non-AI Photomics and is called indexing: Nothing at all to
do with the prong being "in the wrong position" (or with the fork
actually engaging the prong - it "informed" the Photomic of the maximum
aperture of the lens being used).

First ALL Nikon F finders with meters were called Photomic, it was a brand
name. It was first used with the 1964 Photomic F finder, which was coupled
to the apeture ring via a "fork" and shutter speed dial.

AFAIK the name persisted until the end of the F2, as the F3 did not have
a light meter in the finder, it was in the camera body.

At least of the very early Nikon F series cameras had to have the F stop
set at 5.6 when you put it on the camera. Once you mounted the lens on
the camera, you twisited the apeture ring to "index" the meter.

I think later cameras did not require you to have the lens set at f5.6 when
you put them on the camera.

All of the pre-AI F2 finders required indexing.

That was the whole point of the AI (auto indexing) system of 1977.

Note that there were two style of pre-AI meters. The first used an analog
device (resistor strip) to determine the F stop. They are impossible to
replace, no parts have been available for almost 30 years.

The later ones made in mid 1977 and then all of the AI ones used a digtial
system to determine the F stop. This consisted of a set of discrete contacts
and individual resistors for each F stop. They can be rebuilt.

You can tell the difference by looking at the little meter needle on the top.
If it has an exta little window on the negative side (aka long tail), it has
the digital strip.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM