Nikon F Photomic Aperture Indexing

[ben_hutcherson]

Not too long ago, this dyed-in-the-wool Canon guy picked up a Nikon F with the original Photomic finder. It has the external CdS cell, but is the later "push button" version rather than the "flag" version.

 

In any case, the camera came with a 50mm 1.4, but I have a few other F-mount lenses. I'm a bit confused by the aperture indexing, though. Unlike my F2(DP-1) and Nikkormat FTn, the camera seems to just read the aperture correctly without having to twist the ring back and forth like I do on other cameras. I've checked it with a 55m f/3..5 and 28mm f/2.8, and it seems to read the apertures correctly on all of those lenses. In addition, the exposures are at least good enough on Tri-X.

 

Am I missing something here? It seems strange that this earliest finder can read the aperture correctly without having to be "taught" while the later ones require it. The only real limitation I can find is that it won't go down to f/32 with my 55mm Micro.

[jim_bielecki1]

I believe that "indexing" the lens tells the camera's meter what the maximum aperture is. If not indexed, it may meter correctly at other apertures, but not wide-open.

[ben_hutcherson]

Jim,

 

What I'm referring to is the fact that the Photomic finder seems to correctly index the maximum aperture without having to do the aperture ring dance.

 

My best direct comparison of stuff I own is on the F2 DP1, where twisting the lens to the maximum and minimum aperture activates a sort of spring loaded mechanism and the maximum aperture then shows through a window in the front of the prism and(presumably) it meters correctly.

 

The original Photomic doesn't seem to require this-it just reads the maximum aperture correctly regardless of the lens installed. I'm wondering if there's a step I'm missing in this, as it seems strange that the earliest metered camera could accomplish this while later cameras required "teaching" the camera the maximum aperture. I've read the manual and it makes no mention other than installing the lens and setting the lens speed(plus a page of doing exposure compensations through the ASA dial depending on the filter factor and/or whether or not one of the metering attachments is installed).

[JDMvW]

Here is a pdf file for instructions on Nikon Photomic.

 

http://www.mir.com.my/rb/photography/hardwares/manuals/nikonf/FTn.pdf

 

There are different models, so you might have to google farther.

[Matthew Currie]

On the pre-FTn finders, the meter is manually indexed and stays set to whatever you have set it to. For any maximum aperture change, you must re-index using the ASA dial. On the top of the shutter speed dial you will see a set of little numbers on the side, corresponding to the max apertures, and you should match that to whatever your film ASA is. For normal metering, you'd use the black arrow. and a colored arrow for the telephoto tube. On the original Photomic and the early T, you turn the top ASA dial to match the desired aperture. On the later T and Tn, you lift the outer ring and turn it.

 

The original Photomic finder also has extra marks to allow it to compensate for filter factors and the like.On the T and Tn there are no extra marks, since filters and telephoto etc. are read through the lens. It's been almost 40 years since I had one of these, but as I recall it also had an incident light disk hiding under the telephoto tube, and you could put that in, and stand at the subject, point at the light source, and set it that way.

[ben_hutcherson]

On the pre-FTn finders, the meter is manually indexed and stays set to whatever you have set it to. For any maximum aperture change, you must re-index using the ASA dial. On the top of the shutter speed dial you will see a set of little numbers on the side, corresponding to the max apertures, and you should match that to whatever your film ASA is. For normal metering, you'd use the black arrow. and a colored arrow for the telephoto tube. On the original Photomic and the early T, you turn the top ASA dial to match the desired aperture. On the later T and Tn, you lift the outer ring and turn it.

 

The original Photomic finder also has extra marks to allow it to compensate for filter factors and the like.On the T and Tn there are no extra marks, since filters and telephoto etc. are read through the lens. It's been almost 40 years since I had one of these, but as I recall it also had an incident light disk hiding under the telephoto tube, and you could put that in, and stand at the subject, point at the light source, and set it that way.

 

I've read the thing online about setting the maximum aperture on the ASA dial, but again I can't find anything in the manual about it

 

First Edition Nikon F Photomic Instruction Manual – 1962

 

Mine does have the additional numbers on the ASA dial, but page 10 of the above manual indicates that those are used to set the filter factor, not the maximum aperture of the lens.

 

I do have the incident and tele/spot attachment.

 

I guess maybe I'm overthinking it.

[glen_h]

For a through the lens meter, it needs to know how far down you are from maximum (and metering) aperture.

 

For non-TTL, it needs to know the actual aperture, not how for down it is from maximum.

 

For some cameras, you are supposed to always mount and dismount at f/5.6.

[ben_hutcherson]

For a through the lens meter, it needs to know how far down you are from maximum (and metering) aperture.

 

For non-TTL, it needs to know the actual aperture, not how for down it is from maximum.

 

For some cameras, you are supposed to always mount and dismount at f/5.6.

 

That makes sense-thanks. Like I said, the rear window on the back of the prism DOES correctly register the aperture regardless unless it's set to something smaller than f/22. I'm guessing that when these prisms came out, none of the lenses made in the mount went that far down.

[Matthew Currie]

I guess it's been so long since I had the old Photomic that I forgot one does not have to index to the lens aperture. On the original meter coupling system, the fork is always at F 5.6, so the actual aperture is always correctly indicated, and for a plain lens without the tele adapter, you just set the ASA to the black arrow. I traded in my original Photomic for an FTn, as I recall, in 1978.

 

As I recall, it was usually possible to mount a lens without presetting the aperture, but it engaged more easily if you preset it to 5.6.

[ben_hutcherson]

I guess it's been so long since I had the old Photomic that I forgot one does not have to index to the lens aperture. On the original meter coupling system, the fork is always at F 5.6, so the actual aperture is always correctly indicated, and for a plain lens without the tele adapter, you just set the ASA to the black arrow. I traded in my original Photomic for an FTn, as I recall, in 1978.

 

As I recall, it was usually possible to mount a lens without presetting the aperture, but it engaged more easily if you preset it to 5.6.

 

That's been my experience as well. You can slide the prong to any position via the slider on the front(in fact the manual tells you to do this to meter for lenses without a coupling prong) but if you slide it all the way over with the lens set to 5.6 it clicks into place pretty easily. I just wish that I could keep all of these things straight :) . My F2/DP-1 does need it at 5.6, while on my Nikkormat FTn I have to remember to push the prong all the way over and I think it wants the lens at 5.6 for mounting.

 

BTW, I did have to do a bit of light service on mine as I found that follower would pop out of the prong at either end as it was a bit sluggish to move up and down. I ended up giving it a good cleaning a small amount of grease(I used the same Moebius grease I use on watch mainsprings and keyless works) and it works perfectly now. I know the non-TTL meter has its limitations, but it's accurate enough at least for Tri-X and the camera is certainly a talking point. I may even brave a roll of slide film in it. From what I've seen, a nice pre-AI 50mm 1.4 seems to run $75-125 depending on condition, so I think I did alright at $175 for the full kit.

 

I've never been a Nikon guy(I'm still an ardent Canon FD user for 35mm), but went on a bit of a binge not too long ago with the F-series bodies, as I've always liked them. I now have all up through an F4, and am debating about an F5. I feel like the F4 and earlier are better for MF lenses, though, and if I'm going to buy some AF lenses I'd rather put the money toward the EOS mount. All of that aside, I've always admired these older F-series bodies and I'm glad to finally get a chance to play with them.

[fwstutterheim]

The original Photomic: has it "open-aperture" metering or "stop-down" metering? With open-aperture metering you have to index, to know what "open" is and how many steps from "open" the aperture ring is set in order to simulate the working aperture. With stop-down metering this is not needed because you meter using the actual aperture, not a simulated aperture. You write it has an external CdS-cell. External cells usually meant stop-down metering, IIRC.

Ferdi.

[ben_hutcherson]

The original Photomic: has it "open-aperture" metering or "stop-down" metering? With open-aperture metering you have to index, to know what "open" is and how many steps from "open" the aperture ring is set in order to simulate the working aperture. With stop-down metering this is not needed because you meter using the actual aperture, not a simulated aperture. You write it has an external CdS-cell. External cells usually meant stop-down metering, IIRC.

Ferdi.

 

The metering is external, not TTL. It meters via a CdS cell above the lens and facing out, not inside the prism as in later meters.

 

Focusing and composing are done at full aperture-the lens uses the metering prong to tell the meter where the aperture is set.