Nikon F Photomic Meter way off (i think?) with 1.5v batteries

shootfilmto · Oct 8, 2017

Does anyone have any experience with Nikon F Photomic meters? Particularly when using 1.5v Alkaline batteries (not ideal, I know).

I shot a couple of rolls of tri-x a few days ago, and am expecting the shots to be pretty cool - definitely caught some good moments on a good lighting day.

Last night, I thought I would compare the meter to my Canon EF (which has a voltage regulator, so using 1.5v batteries is no problem), and to a light meter app on my phone (which has proven to be quite useful, in a pinch.)

Using Kodak Gold 200 as a test roll, it gave me some interesting readings, compared to the iPhone app... I ended up having to dial in ISO2400 (!!!) on the ISO ring, in order for it to match what the phone read, which, in my opinion, is an absurd difference. It's like 3 1/3 stops off...

Something here is fishy, I've read that people have had no problems using their Nikon F with modern 1.5v batteries, and now that I've found such an inconsistency in metering, I'm reluctant to develop these rolls (without knowing how much to compensate)

Any insight on this would be appreciated.

Chan Tran · Oct 8, 2017

I don't think the voltage difference caused that much of an error. Something else is also wrong.

shutterfinger · Oct 8, 2017

Test the Photomic in bright sunlight, open shade, deep shade, and indoors. You may find the exposure error different in each lighting type. The selenium cell is likely going bad and will respond to lower light levels less than higher light levels.

John Koehrer · Oct 8, 2017

Selenium?

shutterfinger · Oct 8, 2017

John Koehrer said:
Selenium?

https://www.cameraquest.com/nfinder.htm Selenium.

Test using an 18% gray card or similar even tone for the best results.

jimjm · Oct 8, 2017

Actually, just the first clip-on meters for the Nikon F were selenium. All Photomic head meters were CdS (batteries required), although the earlier models didn't meter TTL.

The metering difference the OP is seeing is not unusual when these Photomic heads age, due to internal corrosion. I recently bought a mint '72 body with an FTN head. Probably only had a few rolls thru it and was stored away for over 40 years. Mechanically, the body is 100%, but the meter was also reading 3 to 4 stops off. Camera Clinic in Seattle overhauled and calibrated the meter, and converted it to take current 1.5v silver oxide batteries.

wiltw · Oct 8, 2017

Chan Tran said:
I don't think the voltage difference caused that much of an error. Something else is also wrong.

shutterfinger said:
Test the Photomic in bright sunlight, open shade, deep shade, and indoors. You may find the exposure error different in each lighting type.

Years ago I have tested an Olympus OM-1 with genuine 1.35v mercuric oxide cell (I still have one!) and with the 1.5v alkaline cell in various lighting, to determine how much error can result. In the case of the OM-1, the error quantity is actually dependent upon the STRENGTH of the ambient light. At low light level was maybe 1/2 EV off, while at bright light levels it might be about 1.5EV off! So 0.15v difference can make a HUGE difference!

shutterfinger · Oct 8, 2017

jimjm said:
Camera Clinic in Seattle overhauled and calibrated the meter, and converted it to take current 1.5v silver oxide batteries.

CdS cells go bad also. Did Camera Clinic replace it(any) in yours? Thanks for the correction.

When outdoors in bright light I check my reading against Sunny 16 equivalent and disregard the difference if its less than a stop or so, 3 to 4 stops difference would make me suspicious.

I use a Gossen Ultra Spot as my reference when meter testing.

BrianVS · Oct 8, 2017

My Selenium meter is still accurate...

I've used 1.5v batteries with the CDS based Photomic heads- usually the reading is off by 2/3rds of a stop compared with 1.35v batteries. I shoot ISO 400 film set to ~ISO 250 on the selector.

Chan Tran · Oct 8, 2017

wiltw said:
Years ago I have tested an Olympus OM-1 with genuine 1.35v mercuric oxide cell (I still have one!) and with the 1.5v alkaline cell in various lighting, to determine how much error can result. In the case of the OM-1, the error quantity is actually dependent upon the STRENGTH of the ambient light. At low light level was maybe 1/2 EV off, while at bright light levels it might be about 1.5EV off! So 0.15v difference can make a HUGE difference!

Yeah you call it 1.5EV off but the OP experienced 3.5EV off. And with that can not be accounted for the difference in voltage alone.

BrianVS · Oct 8, 2017

There is a good chance that the CDS cells have lost sensitivity- usually the high-end and low-end of the range goes first. There are other things that can go bad. These meters are pushing 45 to 55 years old.

blockend · Oct 9, 2017

Old Nikon and Nikkormat meters are generally unreliable. None of mine have metered accurately whether the camera was mint or beaten, that's about 8 cameras. Assume a meter repair fee in your budget, or don't worry and meter externally (phone app, sunny 16, whatever). Old Nikons are mechanical wonders but electrical dinosaurs.

E. von Hoegh · Oct 10, 2017

BrianVS said:
There is a good chance that the CDS cells have lost sensitivity- usually the high-end and low-end of the range goes first. There are other things that can go bad. These meters are pushing 45 to 55 years old.

Sometimes the potentiometers give trouble; the wiper after sitting in one position for decades will oxidise at the point of contact; the fix can be as simple as moving the wiper and returning to original setting.
As for the meters being unreliable: Nikkormat FT 1966: Meter is accurate, ring resistor smooth. Nikkormat Ftn 1970 with signs of very extensive use: After cleaning ring resistor, meter is accurate. Nikon FTN: meter recalibrated for silver oxide cells, accurate. Nikon F2 (1972 with later DP11); accurate but camera and finder were overhauled before I got it. Nikon F2A 1979: Meter was apparently recalibrated for Beattie Intenscreen, it reads approx 2/3 to 1 stop low with Nikon screens or it just happened to drift into matching the intenscreen perfectly.
So they're not as bad as all that, after 38 to 51 years.

Fin · Oct 10, 2017

shootfilmto said:
Does anyone have any experience with Nikon F Photomic meters?

Yes... Buy a decent handheld meter.

Honestly, I have several different heads and parts including Tn and FTn bits. I managed to get an FTn working briefly, 6 months later it claims to be seeing light even though the lens cap is on, and I'm an ex electronics engineer! Buy a nice old working Lunasix or Sekonic, and save yourself some pain!

cooltouch · Oct 14, 2017

I don't trust phone apps. They often provide absurd readings. As for your Photomic head, which is it? Dunno if it matters that much, but generally speaking the newer the head, the better chance it has of being accurate. However, I have an F with the original non-TTL metered finder and it is dead-on accurate when I use 1.4v hearing aid batteries in it.

What I would do first, to determine just how far off it is would be to use a hearing aid battery or a considerably more expensive Wein cell. Either way, the voltage is close enough to 1.35v. If you use a hearing aid battery you might have to use an adapter if the + voltage is picked up from the side of the battery compartment and not from the cap.

Once the battery is installed and providing current to the meter, check it against a good meter that's known to be reliable. I like to use an evenly lit surface or area for this. Green grass or the blue sky away from the sun both meter as 18% gray. So start here and see how far off you are. If not all that far, you can use the ASA dial to compensate.

Smudger · Oct 17, 2017

my understanding - all the Photomic F -series finders were designed for 1.35v mercury cells.Even with good circuitry, they won't respond well to 1.55v cells. Buy hearing aid zinc/air #625 (1.4v) , for the several times a decade you are going to bring out and use the camera.

E. von Hoegh · Oct 17, 2017

Several times a decade?? An F usually with FTN finder is my main walk-around slr, the meter has worked fine since I recalibrated it for AgO cells in 1998.

blockend · Oct 17, 2017

E. von Hoegh said:
So they're not as bad as all that, after 38 to 51 years.

You have mentioned electrical intervention on almost every camera. Most people assume a camera will meter properly when switched on. Not with the base plate or top off, or with battery testers. Old Nikons are certainly fixable, but are less likely to work out of the box than more modern metering systems, at least in my experience.

puderse · Oct 17, 2017

I bought my first F when Ektachrome was only 3 and a Luna Pro not long after. If you want to use the meter, send it to:drwyn@aol.com for a CLA and calibration for modern batteries.

Alternatively, use it as a prism and buy a good hand held meter. Luna Pro's can be had for a song and instructions for tweeking the internals for modern batteries are several places on the internet.

Throw away your phone and get a life.

E. von Hoegh · Oct 17, 2017

blockend said:
You have mentioned electrical intervention on almost every camera. Most people assume a camera will meter properly when switched on. Not with the base plate or top off, or with battery testers. Old Nikons are certainly fixable, but are less likely to work out of the box than more modern metering systems, at least in my experience.

Every camera was decades old, I don't expect things to work without maintenance. Anyone who does is in for an unpleasant surprise.
The interventions were all pretty minor, well within the realm of normal maintenance.
The meter on my '69 Kiev 4 worked from the get-go, and allowing a slight (10%) difference between GOST and ISO it's accurate. Go figure.

blockend · Oct 17, 2017

E. von Hoegh said:
Every camera was decades old, I don't expect things to work without maintenance. Anyone who does is in for an unpleasant surprise.
The interventions were all pretty minor, well within the realm of normal maintenance.
The meter on my '69 Kiev 4 worked from the get-go, and allowing a slight (10%) difference between GOST and ISO it's accurate. Go figure.

I can only speak from personal experience. None of my Canon light meters have failed, including an FTb (mercury cell), 5 A-series and 2 T-Series bodies (CR123 cells), ditto a Yashica of 1970s vintage. OTOH my six Nikkormats and two F2 meters have all been way off or dead.

That doesn't make vintage Nikons bad cameras, on the contrary, but it does suggest mercury cell cameras and Nikons in particular will probably/almost certainly require surgery to get the meters working. I haven't cared to fix mine because I'm used to working with meter-less cameras, but I wouldn't want a newbie to think a Nikkormat, Photomic F or F2 meter is likely to work, unless the seller explicitly says it will.

E. von Hoegh · Oct 17, 2017

blockend said:
I can only speak from personal experience. None of my Canon light meters have failed, including an FTb (mercury cell), 5 A-series and 2 T-Series bodies (CR123 cells), ditto a Yashica of 1970s vintage. OTOH my six Nikkormats and two F2 meters have all been way off or dead.

That doesn't make vintage Nikons bad cameras, on the contrary, but it does suggest mercury cell cameras and Nikons in particular will probably/almost certainly require surgery to get the meters working. I haven't cared to fix mine because I'm used to working with meter-less cameras, but I wouldn't want a newbie to think a Nikkormat, Photomic F or F2 meter is likely to work, unless the seller explicitly says it will.

Canon FTb, good meter; Canonet QL19, good meter, Minolta Maxxum 7000, good (very) meter; OM-3, unused, meter is accurate but eats cells; Mamiya 1000DTL, meter accurate in both ranges(!), Pentaxen SP-F and SP1000: meters accurate after cleaning cell contacts on SP-F; all of these cameras except the Maxxum and the OM-3 were suffering from various levels of dust and/or neglect, the SP-F was the filthiest camera I've ever seen - but the meters came alive - which I consider a bonus, I've a few other bodies with meters DOA that I haven't looked into. Over the years I've had three metered Nikon Fs, all the meters worked acceptably right off the bat, but that was 20+ years ago. I expect any old camera I get to have issues, that way I'm never disappointed and often pleasantly surprised. Quite a lot of the sellers on feepay and other sites have no clue, so it's safe to ignore what they say as to function unless they specialise in photo gear.

I really like that Canon FTb...

cooltouch · Oct 17, 2017

Smudger said:
my understanding - all the Photomic F -series finders were designed for 1.35v mercury cells.Even with good circuitry, they won't respond well to 1.55v cells. Buy hearing aid zinc/air #625 (1.4v) , for the several times a decade you are going to bring out and use the camera.

Hearing aid batteries are what I always recommend for the old cameras that used the old mercury cells. Be advised, though, that the hearing aid battery number is 675, not 625. 625 is the number for the old mercury batteries and/or their 1.5v replacements.

I have found that a 675 battery will typically last for about 6 months before it's exhausted. But they are so cheap that this is no big deal. If it's been a while since I've used a camera that takes these batteries, I always just pop in a new one.

BrianVS · Oct 17, 2017

I used to clean the resistor rings of the Photomic Finders with TV Tuner Cleaner. A good cleaner for tape heads would probably work. Most of my Photomic Meters are still working, F "Bullseye", "T", "Tn", and a couple of "FTn"s. I bought several of these used, some 40 years ago.

Exopix · Nov 23, 2017

Just got a 1969 F with Ftn meter. Have not tested it yet and I will use silver oxide 1.55V batteries. How much compensation will I need to do in ASA-steps to compensate for the higher voltage?

Nikon F Photomic Meter way off (i think?) with 1.5v batteries

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