While going through my mothers house, I found an old Nikkor-Q 250 telephoto lens and the reflex housing that was used with it with old Nikon rangefinder bodies. I dont have a rangefinder, but plan to get one someday. However, I do have an EM, you know, the one with the automatic aperture priority metering, and in the meantime, would like to try to use this old telephoto on the EM. I know that Nikon made the N-F tube (adapter) which allowed the use of these old lenses on F-mount bodies, which I believe is the same as the EM. Has anyone ever tried this N-F tube with an EM. If so, will the EM's auto metering work the way it normally does? Does it not work at all? DO you need to make some kind of adjustment? Also, exactly what does "stop-down metering" mean?

Thanks

-- Jeremy Mahnke (NCRAJM@aol.com), February 01, 2002

Answers

I know of these items, Jeremy, but I've never used them myself and there is one critical factor I cannot tell without having the N-F tube in my hands.

If you look at the back of a lens for your Nikon EM, you'll see the "meter coupling ridge" round part of the edge, just underneath the larger aperture numbers. OK? Now, if you mount the lens, lining up the dots, pushing the lens into the mount, and turning it anti-clockwise slowly ... you'll see the ridge making contact with a tab on the mount in the camera body and pulling it round. This is what Nikon calls "Automatic Indexing" or AI, and which it introduced to the F-mount in 1977.

Before 1977, the ridge was a complete circle, going right round the back of the lens like a skirt. If you try to put such a lens on an EM, you will likely break the tab. Bad idea. So when the AI lenses came in, Nikon sold new aperture rings for old lenses, where the skirt was cut back to just a meter coupling ridge. Even now, it is no trouble to find a repairer who can machine away the skirt to leave just a meter coupling ridge. Lenses modified like this -- known as "AI'd" lenses by the Nikon community -- are what you have to use on an EM if you want to use pre-1977 lenses.

The thing I don't know, Jeremy, is whether the N-F tube has a full skirt in the same way as a pre-1977 lens has. And I guess you don't know either, if I'm right in inferring from your note that you have not yet bought an N-F tube. When you go looking for a tube, take your EM with you, and try mounting the tube slowly and watching very carefully to see whether to fouls the tab. If it does, you'll have to get the skirt machined away to use the tube on your EM.

An alternative would be to get one of the handful of Nikon bodies that have a tab which can be folded back out of the way of the skirt: FM, FE (not FM2 or FE2), F3, F4, or a specially modified F5.

Once you've got the tube mounted on the camera, the rest is plain sailing. The lens should mount on the front of the tube just as it used to do on the old reflex housing. The EM's auto metering will work just fine, but you will have to use stop down metering.

There are two sorts of Nikkor-Q 25cm (Q just means four elements, by the way), so I'll give instructions for each.

The first sort has a single aperture ring at the front of the lens, completely unconnected to the camera -- no meter connections, no diapragm connections. Set the aperture ring to wide open; focus in the usual way; stop down the aperture ring to the aperture you want; press the shutter.

The second sort has two rings at the front of the lens, connected together but, again, completely connected to the camera. Try these out. One of them should have f/stops marked on it: this is the "pre-set" ring. When you rotate it, nothing should happen to the iris inside the lens. Park it at f/22. The other ring is the "aperture ring": when you rotate it back and forth the iris should open and close. Open the iris fully and move the pre-set ring to f/8. You should find that the aperture ring now works as before, except that it won't close the iris past f/8, the setting on the pre-set ring.

Now go for a cup of coffee, then try that paragraph again. It makes more sense if you have the lens in your hands!

Now, choose the aperture you want for your photograph; set that on the pre-set ring; and open the iris wide open with the aperture ring. Frame and focus in the usual way; spin the aperture ring as far as it will go (to stop the lens down to the setting on the pre-set ring); and press the shutter.

This second sort of lens is quicker to use once you're accustomed to it: you don't have to take the camera away from your eye to stop down.

Later,

Dr Owl

-- John Owlett (owl@postmaster.co.uk), February 02, 2002.

I bought an old F mount Nikkor-P 300mm f/4.5 lens, once upon a time.
It was, without doubt, on of the worst telephoto lenses I have ever owned or used. So, just because it has Nikkor stamped on it, it doesn't mean that it'll give you great results. It may not be worth the search for an adapter and the cost of it.
OTOH, there are probably plenty of camera collectors that wouldn't know good image quality if it bit them, and they'd pay dearly for that sort of RF Nikon gear.

-- Pete Andrews (p.l.andrews@bham.ac.uk), February 04, 2002.