Re: Nikkor - overview?

Geoffrey S. Mendelson wrote:

I just answered this last week. I won't repost it as it was very long and
there were some minor corrections and it would be best if you looked up both
my original article and the corrections in an archive.

Here is my original post with the corrections. Hopefully I've gotten
the attributions correct, I appreciate their taking the time to
correct it.

Re: Nikkor - overview? (long)
from [Geoffrey S. Mendelson]
Subject: Re: Nikkor - overview? (long)
From: gsm@xxxxxxxxxxxxx (Geoffrey S. Mendelson)
Date: Thu, 26 Jan 2006 21:30:02 +0000 (UTC)
Newsgroups: rec.photo.equipment.35mm

David Dyer-Bennet wrote:

There are not quality differences between those. And I don't think
there is an AF-G designation; I believe there's a separate G
designation. Those are all *feature* distinctions.

Exactly.

There are different quality lenses in all of them.

The original Nikon F slr light meter (Photomic F) used a coupling fork
and pin mechanism to determine what F stop the lens was set to. The photomic
F meter did NOT measure light through the lens.

When the second meter (Photomic Ft) was designed it had a problem as it
was supposed to meter with the lens open, but there was no way for it to
tell what it was measuring. It averaged expsoure across the full frame.

The third meter (Photomic FTn) used "center weighted" exposure measurement,
60% of the light used to calculate exposure came from a central circle.

In order to calculate epxosures properly, the light meter had to be
"indexed", i.e. set to the maximum apeture of the lens. Some early
cameras did this by setting a dial, Nikon engineers figured out how
to do it by mounting the lens at F5.6, racking it to minimum apeture
and back to maximum. Quite ingeneous.

Lenses at that time were called Nikor-x, where the x was the first letter
of the latin number of elements, e.g. Nikor-H was a five element lens,
Nikor-Q was a four.

The original 1959 design was unable to accomodate these meters and the
mirror box was enlarged in 1964. There is AFIK no way of telling these
cameras from the earlier ones, except by serial number and visual inspection.

The original system was an analog system, the resitance element to measure
lens apeture was a continuous carbon resistor and the meter would measure
at any setting of the F stop ring.

In 1977, Nikon went from an analog system to what they called a "digital"
system. It was still analog, but instead of having a continous strip
resistor, the meter went to a set of switch contacts one for each
setting of the F stop ring. This used much cheaper single resistors for
each settings and a worn switch contact could be cleaned instead of
having to have the whole switch replaced.

This system first appeared on the standard F2 photomic finder. Those finders
are rare and can be identified by the "long tail" a small extension to the
exposure window on top of the prism on the underexposure (left side).

In mid 1977 Nikon changed to the autoindex (AI) system. The new meters really
had no need to be set to the maximum apeture of the lens. To make a proper
calculation all the needed to be known was the proportion of light the
lens would transmit closed down. The AI system used a cut in the apeture
ring and a probe that pushed against it instead of a pin in the fork.

For compatbility reasons, the AI lenses also came with a fork and the new
finders could move the probe out of the way for the old lenses. Since the
meter prism had no indication of the actual F stop in use, AI lenses had
a small scale with the F stops on it reflected by a mirror to the user's
eye.

Nikon converted pre-AI lenses to AI by replacing the apeture (F-stop)
ring with an AI one. You can tell these lenses by their metal barrel grip.
Nikon went to a rubber barrel grip just before they went to AI.

Non Nikon conversion of lenses was done by many people by removing the
metal on apeture ring. Some of these were crude, leaving the metal exposed,
some repainted it and placed scales with little numbers on them.

When Nikon came out with the EM (around 1981-82, I'm not sure), they came
out with a low price line of lenses called "series E". I hesitate to call them
cheap, opticaly they were excelent, some have been the best lenses Nikon made
in that apeture/focal length combination. Series E lenses used some external
plastic parts and did not have a fork.

The EM was improved to the FG which was Nikon's first camera with
"programed" exposure, meaning it could set the F stop and shutter
speed for you. The FG used a very complicated system of determining
the exposure with the lens wide open, and then closing it to where the
lens should be and recalulating expsoure based upon the actual apeture
set.

With the release of the FA, a programed exposure version of the FE, Nikon
standardized the postition of the stop down lever in relation to the
closure of the lens. The allowed the FA to react much faster as it did
not need to recalculate the exposure when after a delay for the diaphragm
to "settle".

These lenses were called AIs. Externaly an AIs lens has a small bit of
metal scooped out on it's back, which allows the camera to detect it.
With out it the FA and later cameras will not go into programed
exposure.

Any lens can have the metal removed with a dremel tool, but this will
not convert an AI lens into an AIs lens. It will fool the camera,
exposures will be eratic. If you look at an AIs lens, you will see the
scooped out area and being a specific size and shape, it's easy to tell
if you have a counterfit.

Nikon's first camera was the F3AF, Very rare, it had a huge prism with the
extra autofocusing electronics in it. The lenses (there were three) had
motors in them. In order to focus the lenses, electrical contacts were
added to the camera and the lens inside the top left corner of the lens
mount.

The AF lenses from the F3AF are AIs lenses and can be used manualy on
any camera that accepts AIs lenses. They will only focus on the F3AF and
F4.

The second generation of AF lenses, the common AF-Nikors, were AIs lenses
with some significant changes. The AF lenses indicated maximum apeture,
and current apeture through the electrical contacts. They also could be
set to a particular apeture through the electrical contacts.

Nikon elected to put their autofocus motors in the camera and so the
lenes where changed to a rack and pinion focusing mechanism from the
helicoid one used before. This cut the size and weight of the lenses
and more significant the manufacturing cost and therefore the price
went down by almost a third.

The early AF lenses were look alikes of the Minolta Maxxum lenses and
had the distance scale in a window and a small manual focusing ring at
the front of the lens.

They were however, standard AIs lenses and could be used on nonautofocus
lenses with full function. They included dimples in the apeture rings so
that it was easy to (add a) "fork" the lenses for pre-AI cameras.

Later improvements to AF lenses included ergonomics of the old style
lenses (external distance scales and wider focusing rings).

Nikon later added the electronics to measure the focus distance the lens
was set to, these lenses are designated AF-D.

Since all cameras since the 8008 (late 1980's) set the apetrure
electronicaly, the aperture rings were an expensive compatiblity feature
not needed by most users. Nikon now produces a line of lenses that have
no apeture ring at all called the "G" series. Some of the "G" lenses
have mostly plastic body parts, and are therefore much cheaper. Opticaly
they are excelent.

There are designations for various other features, such as "ED" (extended
definition (low dispersion) glass), IF (internal focus, where lens elements
in the middle of the lens move instead of the ones at the end), VR (vibration
reduction, i.e. image stabilized).

There also is a line of lenses specialy designed for the needs of the smaller
sensors Nikon uses in their digital cameras, but I'm not familure with it.

Geoff.

--


Re: Nikkor - overview? (long)
from [Philip Homburg] [Permanent Link][Original]
Subject: Re: Nikkor - overview? (long)
From: philip@xxxxxxxxxxxxxxxxx (Philip Homburg)
Date: Thu, 26 Jan 2006 23:10:01 +0100
Newsgroups: rec.photo.equipment.35mm

In article <slrndtiff7.naf.gsm@xxxxxxxxxxxxxxxxxxx>,
Geoffrey S. Mendelson <gsm@xxxxxxxxxxxxx> wrote:
In order to calculate epxosures properly, the light meter had to be
"indexed", i.e. set to the maximum apeture of the lens. Some early
cameras did this by setting a dial, Nikon engineers figured out how
to do it by mounting the lens at F5.6, racking it to minimum apeture
and back to maximum. Quite ingeneous.

Small correction: the Nikkormat needs the lens to be set at f/5.6. The
FTN finder is far more flexible in this respect.

Nikon converted pre-AI lenses to AI by replacing the apeture (F-stop)
ring with an AI one. You can tell these lenses by their metal barrel grip.
Nikon went to a rubber barrel grip just before they went to AI.

Of course the last sentence implies that you can really tell whether a
late non-Ai lens (with a rubber focus ring) has been converted to Ai
or whether it was Ai from the start. Not that it would matter much.

When Nikon came out with the EM (around 1981-82, I'm not sure), they came
out with a low price line of lenses called "series E". I hesitate to call them
cheap, opticaly they were excelent, some have been the best lenses Nikon made
in that apeture/focal length combination. Series E lenses used some external
plastic parts and did not have a fork.

I think the E series didn't have multi-coating as well.

With the release of the FA, a programed exposure version of the FE, Nikon
standardized the postition of the stop down lever in relation to the
closure of the lens. The allowed the FA to react much faster as it did
not need to recalculate the exposure when after a delay for the diaphragm
to "settle".

But the FA still retains that feature to be able to handle non-Ais lenses
as well.

These lenses were called AIs. Externaly an AIs lens has a small bit of
metal scooped out on it's back, which allows the camera to detect it.
With out it the FA and later cameras will not go into programed
exposure.

The FA does support Program mode with non-Ais lenses.

Any lens can have the metal removed with a dremel tool, but this will
not convert an AI lens into an AIs lens. It will fool the camera,
exposures will be eratic. If you look at an AIs lens, you will see the
scooped out area and being a specific size and shape, it's easy to tell
if you have a counterfit.

The scooped out area is needed to provide the camera with the focal
length. (To avoid slow shutter speeds on tele lenses).

--
Re: Nikkor - overview? (long)
from [Rob Novak] [Permanent Link][Original]
Subject: Re: Nikkor - overview? (long)
From: Rob Novak <yermama@xxxxxxxxxx>
Date: Fri, 27 Jan 2006 13:40:17 -0500
Newsgroups: rec.photo.equipment.35mm

On Thu, 26 Jan 2006 23:10:01 +0100, philip@xxxxxxxxxxxxxxxxx (Philip
Homburg) wrote:

The FA does support Program mode with non-Ais lenses.

Correct. The FA will not, however, switch between its internal
Program-highspeed and Program-lowspeed exposure curves with a non-"s"
AI lens. Series-E lenses are, for all practical purposes, AI-s as
well.


--



--
Geoffrey S. Mendelson, Jerusalem, Israel gsm@xxxxxxxxxxxxx N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/
.

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