Nikon F Photomic FTn questions

I got an F (69XXXXX serial number) with an FTn finder recently and have a few questions. I've put a few rolls through it already, and it seems to work reasonably well, but I'm curious about a few things:

1) Should the needle be perfectly centered when doing a battery check? How far off should it be when using alkaline batteries? Mine came with PX625A cells, and when I do a battery check, the needle is currently either right on the left side of the O, or just a hair inside; I'm not sure how drained they may be. Actually, at the moment, it is almost perfectly centered in the O. Is that typical? I'm trying to figure out if perhaps the meter has been adjusted to use 1.5V batteries.

2) Assuming it hasn't been adjusted to use 1.5V batteries, recommendations on solutions? The options I've seen have been the Wein MRB625 zinc air cells and adapters for silver oxide cells, including the CRISCAM MR-9 adapter. Thoughts? How long do the Wein cells last once opened? Presumably silver oxide cells with adapters last...a long time?

3) I've noticed some odd behavior if I haven't used the meter for a while: the batter check barely registers and the meter clearly isn't responding properly. I'm not 100% sure on the "fix", but it seems that if I turn the meter on and point the camera at a relatively bright source things start working fine after maybe 10 seconds. Has anyone run into this? At this point it's just a minor annoyance, thankfully.

I'm leaning towards getting the battery adapters, but I don't want to pop them in only to find out somebody recalibrated it for alkaline cells. The exposures I've been getting seem pretty good, or at least in the working range of Ilford HP5.

As an aside, this has been my first foray into film since I got my D200 in 2006, and the first time I've had an all manual camera (started on an EM, moved to an N70, and also used an FG a bit). Here's one photo from the first roll I shot:

It's an old camera and I wouldn't be surprised if it hasn't been serviced in quite some time so if it has a few quirks that's not a shocker. All of my F2 bodies center the needle if the battery is good. I doubt it's been adjusted for 1.5 batteries but can't say for certain. Honestly I'd shoot it for a month or so and see if it continues to work properly. If it ain't broke....

Rick H

If the battery check is centered, it is almost certainly using the cells it's calibrated for. If it was calibrated for mercury cells the battery check will be out of the notch.Back when things were new and mercury batteries were common, that battery check should have been right in the middle of the notch, but as I recall, it was permissible anywhere within the notch (the notch in the viewfinder or the O on top).

Alkaline batteries do settle down later in their life to about 1.35 volts, and may stay there for a while. So it's possible that you have a mercury-adjusted meter that is working well enough with aged alkalines. But the voltage of the batteries is not very consistent, so you must keep an eye on it. Chances are that if the needle is centered, it's OK for the moment.

Silver oxides should last a couple of years, and if you can afford the adapters it's probably the easiest solution. Hearing aid batteries in my experience have gone a couple of months, but die pretty abruptly when they do. They might do better in the FTn than they did in my old Konicas, which had sensitive on/off switches and often turned themselves on.

As I've mentioned in other threads, one other pretty foolproof way to fix the problem is to recalibrate the meter, but this is not for everyone, I think. It's not too hard to do, but it does require opening it up and having another reliable meter to compare to.

I wouldn't worry about the battery check. I would rather check the meter and see if it's accurate and later on and see if it changes when the battery goes low.

I've done a few fairly casual comparisons between the FTn and my D7200, and they seem pretty close. Are there particular conditions where 1.5V cells would cause a larger error?

I assume the 625A you talk about is an alkaline battery. As an alkaline battery is used, it's voltage drops. A standard AA battery starts brand new at about 1.65 volts, and most devices that use them (like the mouse on this computer) will quit working when the voltage has dropped to less than 0.7 volts. Devices that use alkalines are designed to cope with the decreasing voltage and still function as intended.

Mercury batteries produced constant voltage, which is why they were so popular among camera manufacturers. Using an alkaline in place of a mercury battery in a light meter will cause constantly changing voltage and therefore constantly changing inaccuracies. You can do a quality control check in open sunshine - the sunny-16 rule would let you set the aperture at f16 and see if the meter indicates a shutter speed equal to the ISO setting.

Zinc-air hearing aid batteries (Wein batteries) also produce constant voltage. I used them in my Nikkormats before I went digital, and I got anywhere from 1 to 3 months from each battery, depending on my camera use. A package of 5-6 of the hearing aid batteries cost me $4.95US back them, so the battery expense was negligible. The bonus is that hearing aid batteries are available in just about every pharmacy everywhere. They are generally smaller in diameter than the mercury battery they replace. I found an O-ring in a local hardware store's assortment of O-rings that was a great fit in the battery compartment to keep the hearing aid battery centered.

I assume the 625A you talk about is an alkaline battery. As an alkaline battery is used, it's voltage drops. A standard AA battery starts brand new at about 1.65 volts, and most devices that use them (like the mouse on this computer) will quit working when the voltage has dropped to less than 0.7 volts. Devices that use alkalines are designed to cope with the decreasing voltage and still function as intended.

Yes, it is currently using alkaline cells as noted. However, alkaline cells start at 1.5V, not 1.65V.

I'm aware of all of the noted differences in battery chemistry. I'm more curious about the specific questions I had regarding the FTn and its behavior with alkaline batteries. I.e., whether what I'm seeing is typical, or if perhaps mine was modified at some point. Or perhaps drifted from spec somehow.

That is to say, I'm reluctant to spend $80 on adapters if it turns out the meter would actually be less accurate when fed the proper voltage.

However, alkaline cells start at 1.5V, not 1.65V.

1.5V is the "broken in, under load" voltage of an alkaline cell. The new open circuit voltage of an alkaline cell is generally in the 1.6-1.65V range.

I too use type 675 hearing aid batteries in all of my F finders(from original Photomics to FTNs) with good results.

All of my F2 bodies center the needle if the battery is good. I doubt it's been adjusted for 1.5 batteries but can't say for certain.

Rick,

I THINK the F2 has a bridge circuit that makes it relatively insensitive to voltage variation. I've at least never seen anything in the manual cautioning to use a specific battery chemistry. The F meters are different, as they are specifically made for a type 625 mercury.

With that said, the two common LR44/SR76 chemistries are alkaline and silver oxide, and they actually have a fairly similar voltage. Silver is a stable 1.55, while alkalines start out at 1.65V and drop as the battery is depleted. I've not noticed any differences between silver and alkaline on my F2s, although I generally prefer silver. Unless you leave the meter on, the batteries in an F2 are more likely to die from age that from being depleted, and silver cells last longer.

I have alkaline cells in all my older cameras, especially the ones I paid $10 for.

For most, it is close enough for black and white, and probably for color negatives.

Lately, I have only had slide film in cameras too old to have a meter.

(Specifically, a Canon IID2.)

I have a Vivitar light meter with CdS cell, also with an alkaline cell.

I use both the battery check, and compare to sunny 16, to see how well it is doing.

The F2 asks for silver oxide batteries:

Nikon F2 photomic instruction manual, user manual, PDF manual, free manuals

as above, I have alkaline in mine. I suppose I could put the right ones in, though.

I also have alkalines in my FT3 and EL2.

I've done a few fairly casual comparisons between the FTn and my D7200, and they seem pretty close. Are there particular conditions where 1.5V cells would cause a larger error?

I don't think so. I don't even think the right battery would make any more accurate that what you have.

The F2 asks for silver oxide batteries:

 

Nikon F2 photomic instruction manual, user manual, PDF manual, free manuals

 

as above, I have alkaline in mine. I suppose I could put the right ones in, though.

 

I also have alkalines in my FT3 and EL2.

Alkalines should be fine for F2 though. They just die quicker that's all. The F3 in the other hand doesn't have battery check. It simply quit working when the voltage is below 2.4V.

Yes, the FM also stops working, no LEDs, when the voltage is too low.

Favorite for the FM is the DL1/3N 3 volt lithium cell.

The F2S, F2SB, and F2AS also lack a battery check. They work the same way as the FM-if you flip them on and something lights up, they are good to go.

I think the little 1/3N battery(and to get overly pendantic, it is a battery and not a cell-unlike the LR44, etc) works in the F2 also. I should get some of them-I have enough FM-type cameras and they are handy for those.

I've noticed some odd behavior if I haven't used the meter for a while: the batter check barely registers and the meter clearly isn't responding properly. I'm not 100% sure on the "fix", but it seems that if I turn the meter on and point the camera at a relatively bright source things start working fine after maybe 10 seconds. Has anyone run into this?

This on again, off again syndrome is fairly common with the old F Photomic meter heads. And yes, it is extremely annoying- especially when you just bought it and are trying to decide whether its OK or you should return it for refund. If it only exhibits this behavior occasionally, its tolerable, but if it pulls this nonsense every second or third time you pick up the camera, it gets real old real fast. The Nikon F body itself is a wonderful, enduring classic but the prisms have increasingly become untenable as the decades fly by: the metered ones usually have dead or dying meters, the plain prisms are plagued by de-silvering issues. The later F2 and FM variants are easier to find in fully usable condition, and probably more practical long term. But the lure of the original F is hard to resist...

Re the battery questions: as it happens I've gone thru close to a dozen FTn meter prisms in the past few months, trying to find a couple that were fully operational. Most were not, and the two I kept can be moody. They don't like alkalines much: the battery check is more erratic with alkalines, and they're more likely to trigger the above "works today, plays dead tomorrow" syndrome. For the short term, you can probably get away with using alkaliness until you're quite certain this FTn will be your everyday film camera (and you're absolutely out of your mind in love with it). Then, and only then, would I consider the ridiculously overpriced silver oxide voltage adapters (for not much more than two CRIS adapters cost, you could pay a tech to adjust the meter internally for silver oxide voltage). I prefer to buy dirt-cheap 675 zinc-air hearing aid batteries: the 675s give consistent readings with the FTn until they suddenly drop dead after two or three months, and you can use simple passive home-made size adapters to make them fit snugly. Others here report success recycling the bases from a pair of Wein cells, which are nothing more than 675 batteries set in a passive base to make them look like the old mercury cells. Use the Weins until they die, pry out the dead batteries, then use the leftover bases as re-loadable adapters to hold your own (much cheaper) 675s.

This on again, off again syndrome is fairly common with the old F Photomic meter heads.

Thankfully (fingers crossed) to this point it seems like once it's "on", it's on, and that the startup issue is just that. Hopefully that continues to be the case.

Thanks for the battery advice. Maybe I'll start with a pack of Weins and see how it goes. At this point I'm still debating how much film I'm going to be shooting, period, especially since I've been having huge headaches with dirty negatives, which is another story.

Metering accuracy, what accuracy!?

We're talking about reflective metering here - TTL or otherwise. And wide-area reflective metering at that.

Unless your subject is a grey card filling the frame, or is guaranteed to have an integrated reflectance of 18%, you really have no idea how accurate the metering is going to be.

The battery voltage is totally moot in practical use. It's like someone completely adrift in a rubber dinghy wondering if oars or an outboard motor would have been the better option.

Metering accuracy, what accuracy!?

 

We're talking about reflective metering here - TTL or otherwise. And wide-area reflective metering at that.

 

Unless your subject is a grey card filling the frame, or is guaranteed to have an integrated reflectance of 18%, you really have no idea how accurate the metering is going to be.

 

The battery voltage is completely moot in practical use. It's like someone completely adrift in a rubber dinghy wondering if oars or an outboard motor would have been the better option.

So...camera makers have been building useless components for the past 50+ years? And we're all just lucky that our photos turn out at all?

Metering accuracy, what accuracy!?

 

We're talking about reflective metering here - TTL or otherwise. And wide-area reflective metering at that.

 

Unless your subject is a grey card filling the frame, or is guaranteed to have an integrated reflectance of 18%, you really have no idea how accurate the metering is going to be.

 

The battery voltage is totally moot in practical use. It's like someone completely adrift in a rubber dinghy wondering if oars or an outboard motor would have been the better option.

I do test the meter of my cameras for accuracy (and I do know an accurate meter doesn't mean good exposure) and it can be done. I do found cameras that use mercury cells read differently with different batteries but they are about similar inaccuracy either way so yeah I agree with you that battery voltage is moot.

The battery question is only "moot" if you don't care whether your meter is reading even remotely within design specifications: and if thats the case, why bother having a built-in meter at all? Reflective vs incident vs channeling the ghost of Ansel Adams isn't the point: this thread is about getting the decrepit old Nikon F meter prisms to give readings somewhere in the neighborhood of other typical TTL meters. Whether TTL meters are worthwhile to begin with is a different subject.

The old hand-held and TTL meters that were designed for mercury batteries vary wildly in their reaction to alkaline or silver oxide substitutes. The few with bridge circuits are completely unaffected: no issues at all. The rest are all over the map (just ask Konica and Olympus fans). Bodies differ even within the same brands. The Nikkormat FT and FTn cameras that were contemporary with the F meter prisms are much less flaky with alkaline or silver oxide than the F prisms. I go thru Nikkormat bodies like Kleenex, buying them for the attached lenses and stowing the bodies in an ever-growing pile (they have almost no resale value anymore, but I hate to just discard them). I test the meters in Nikkormats with a single alkaline cell, and their response has been totally uniform: if the meters work properly, they're spot-on with a 675 zinc battery and exactly one stop off with alkaline (compared to readings of the same scene made by other cameras at the same ISO). Its pretty easy to compensate for one stop with the film speed setting, so no big deal using alkalines with a Nikkormat. Silver oxide will also work in a pinch, but the readings are a tad further off from alkalines.

The F meter prisms are a whole other ballgame: they react to alkalines unpredictably, and go way off with silver oxide. Best case scenario the meter is out by two-three stops, depending on light levels, the discharge state of the battery, and whether the F meter prism is copping an attitude that day. They seem most comfortable with zinc-air hearing aid batteries today, in lieu of mercury, but they can still be flaky. Lets just say the aging F meters are no picnic period, even if you could lay hands on a stash of new mercury batteries. If you want a mechanical shutter F body with decent metering, forget the F and opt for an F2SB or F2AS with silicon blue cells and silver oxide power.

So...camera makers have been building useless components for the past 50+ years? And we're all just lucky that our photos turn out at all?

- Yep. That about sums it up. Why else do you think matrix metering was invented? It wasn't just for fun; it was an attempt to rectify the shortcomings of simple averaging or centre-weighted reflective metering, which admittedly was good enough for the sloppy exposure latitude of negative film.

One correction - not for the past 50+ years. Only before around 1990.

In 1965, I bought a Nikon F Photomic T when I was in Japan in the USAF. A few years later I lost it on a NYC subway. I wonder if you have my camera? :)

In 1977 I bought my first camera a black Nikon F2AS and someone stole from me when I had it at the 1 hour processing lab that I managed at the time. I wonder if you have it?