Old Nikon SLRs consistently overexposing, but only in strong light?

albireo · Wednesday at 10:29 AM

BrianShaw said:
I've paid attention over the years and never seen a hint of time-related inaccuracies other than light leaks and broken FREs. It's most likely not a generic issue and probably something you're not currently looking at regarding your technique. Give some consideration to the more recent suggestion of "light leak" through the viewfinder. The F3 addressed that issue with a viewfinder shutter built into the prism.

All the cameras were indoors, on a tripod, in a shaded room, pointing outside.

My eye was on the viewfinder during all measurements, for all cameras tested, so there was no light leak through the viewfinder.

I feel you're trying really hard to place the 'blame' on me and I understand you're passionate about these cameras, but I am not trying to diminish their value in any way.

I am just trying to understand if this has happened to anyone else and there's some sort of pattern, or if I've been twice unlucky and I should just send mine for service.

Chan Tran · Wednesday at 10:30 AM

BrianShaw said:
I've paid attention over the years and never seen a hint of time-related inaccuracies other than light leaks and broken FREs for that era of Nikon camera. It's most likely not a generic issue and probably something you're not currently looking at regarding your technique. Give some consideration to the more recent suggestion of "light leak" through the viewfinder. The F3 addressed that issue with a viewfinder shutter built into the prism.

This is what I found also. Besides from the F3 which had a bad amplifier chip that needed to be replaced my 2 FM and FM2n of different age read the same as the F5 and the same as the much newer digital Df and D850. Only selenium and Cds cells have the aging problem.

BrianShaw · Wednesday at 10:32 AM

Chan Tran said:
Only selenium and Cds cells have the aging problem.

And, interestingly, some of the aging problems in meters of those older technnologies isn't related just to the cell/cell type but to other parts of the meter design/implementation. But that's a topic for some other thread...

albireo · Wednesday at 10:32 AM

A bit of data I've forgotten to add before: my FG has SR44 (silver oxide) and not LR44 (alkaline) in.

Would this be likely to play a role?

4season · Wednesday at 10:33 AM

I'm no expert on the failure modes of photocells, but I have encountered CdS cells which developed partial short circuits. They still responded to light, but indicated exposures which were many stops off. But the error occurred under all lighting conditions.

BrianShaw · Wednesday at 10:38 AM

albireo said:
A bit of data I've forgotten to add before: my FG has SR44 (silver oxide) and not LR44 (alkaline) in.

Would this be likely to play a role?

Possibly. You should really put SR44 in both of those cameras. But since both were off significantly under the same conditions that difference isn't the explanation of the core concern.

4season · Wednesday at 10:40 AM

Oh, and what specific Nikon lens did you use for the tests? Obviously, the newer cameras can interface with lenses via electronic contacts, while the older cameras rely on the mechanical AI coupling.

albireo · Wednesday at 10:49 AM

4season said:
Oh, and what specific Nikon lens did you use for the tests? Obviously, the newer cameras can interface with lenses via electronic contacts, while the older cameras rely on the mechanical AI coupling.

50mm 1.8 Ai-S on FE,FG, Nikon F90X. Later tried a 50mm f/1.8 AF-D on all three.

50mm 1.8 STM EF on Canon EOS 3.

Same observed discrepancy sadly.

Chan Tran · Wednesday at 10:52 AM

albireo said:
A bit of data I've forgotten to add before: my FG has SR44 (silver oxide) and not LR44 (alkaline) in.

Would this be likely to play a role?

No! Cameras of the FE era and newer should work with battery voltage of 3.3V down to 2.5V without changing the reading.

chuckroast · Wednesday at 11:16 AM

albireo said:
I don't have many older SLRs as I tend to like using electronic SLRs from the 90s or newer. My Nikon F90X, Canon EOS3 etc are my favourite class of 35mm cameras.

On occasions I dust off a Nikon FG and a Nikon FE - both in great condition, visually mint, great mechanics etc etc.

My last two rolls with the FG and FE however produced extremely overexposed negatives. I was surprised, as I used film and developers I have standardised on, and I use the same film+dev combo with the F90X and EOS3 with spot on results every time.

I had never noticed dense negatives from the FG and FE before but interestingly I had mostly used them in Winter, with poor lighting, and never in full sun. This time, I was taking pictures in bright conditions and just shot away expecting good results.

The negatives are borderline unusable for my standards. I decided to make a quick check

-Same lens, tripod, swap lens between FE, FG and F90X - bright sunny day, measure bright walls, bright skies; exposure meter in the F90X set to centre-weighted.
-Repeat test against EOS3, set to centre weighted meter, and use a Canon EF prime lens of the same focal length as above. Same tripod.
-Compare FE and FG against 'sunny sixteen' guess in simple bright light frame, iso set to 250 (so expect 1/500 f/11). Same tripod position, same lens.

Results: Nikon F90X and EOS are in complete agreement with each other, and +/-1/3rd stop wrt sunny 16 guess (depending on scene, discrepancy ofc due to wrong guess on my side). FE overexposed by 1 and 1/3rd stop. FG overexposes by 2 stop.

I repeated the above test in an indoor setting. Same ISO setting. Overexposure error of the FE and FG reduces to 1/3rd stop.

So it would appear that the meters in these two cameras are not to be trusted anymore, which is a shame. What is even more worrying is that it seems they can kind of be trusted when the light is low, but become essentially useless with strong light?

My questions

Has anyone else encountered this kind non linear metering error in these Nikon cameras?

Any other checks you would recommend I should try to make sure I'm not wrongly interpreting what I'm seeing?

How common is it in similar photodiode cell meters of the same age?

Is it worth attempting to have them fixed?

I've only skimmed this thread, so forgive me if I am repeating already noted facts in evidence, but ...

Bright light typically demands faster shutter speeds. Shutters tend to get slow with age, especially noted in the higher speeds.

Being off by 1+ stop at 1/250 and shorter, is not unusual as the camera ages. If this is the problem, the only fix is to measure the speeds and correct at the time of exposure or CLA the camera.

I would say slow shutters are far more likely to be the culprit than a bad meter, though either is possible.

albireo · Wednesday at 11:22 AM

chuckroast said:
I've only skimmed this thread, so forgive me if I am repeating already noted facts in evidence, but ...

Bright light typically demands faster shutter speeds. Shutters tend to get slow with age, especially noted in the higher speeds.

Being off by 1+ stop at 1/250 and shorter, is not unusual as the camera ages. If this is the problem, the only fix is to measure the speeds and correct at the time of exposure or CLA the camera.

I would say slow shutters are far more likely to be the culprit than a bad meter, though either is possible.

Thanks. Honestly this makes a lot of sense to me. I wonder if I could use my old Raspberry Pi 3 cobbled together with a sensor of sorts to measure shutter speeds.

Actually - come to think of it. Are shutter speeds something that would be measurable via an iphone app?

chuckroast · Wednesday at 11:30 AM

albireo said:
Thanks. Honestly this makes a lot of sense to me. I wonder if I could use my old Raspberry Pi 3 cobbled together with a sensor of sorts to measure shutter speeds.

Actually - come to think of it. Are shutter speeds something that would be measurable via an iphone app?

You may be able to record the shutter opening and closing with your phone, just open the back and put the phone mic near the shutter curtain. Lock up the mirror when you do this to minimize extraneous noise for the measurement.

Then look at the waveform with something like Audacity to determine how long the shutter is open. So, 1/1000 should be ).001 sec or 1ms, 1/500 should be 0.002 sec or 2 ms and so on.

The error in f/stops is calculated like this

log(actual time / nominal time) / log 2

For example, if your are measuring 1/1000 of a second, it should be 1ms of open time. Say it is actually open 1.5ms - it's slow. Then the calculation is:

log (1.5/1) / log 2 = 0.585

It's overexposing 0.585 f/stops

It's not a perfectly precise measure but it will get you in the ballpark.

Chan Tran · Wednesday at 11:42 AM

albireo said:
Thanks. Honestly this makes a lot of sense to me. I wonder if I could use my old Raspberry Pi 3 cobbled together with a sensor of sorts to measure shutter speeds.

Actually - come to think of it. Are shutter speeds something that would be measurable via an iphone app?

If you try to measure shutter speed in auto mode is quite difficult. Older phone has a mic input and can be used to measure shutter speed. But manual shutter speed isn't the same as auto shutter speed. So if you shoot mostly in auto it's difficult as you have to measure the shutter speed in auto too.

250swb · Wednesday at 12:00 PM

albireo said:
I had never noticed dense negatives from the FG and FE before but interestingly I had mostly used them in Winter, with poor lighting, and never in full sun. This time, I was taking pictures in bright conditions and just shot away expecting good results.
meters of the same age?

Obvious question but somebody else may have asked it already, is the exposure compensation set to a + figure given you last used them in poor lighting?

As to worth getting them fixed, an FG can be had on eBay for £50 ($67 ?), you'll spend far more than that fixing it. But before buying another just take it apart and see if the is any obvious corrosion on electrical contacts under the baseplate etc. you can't do anything wrong, it's bust as it is.

Paul Howell · Wednesday at 12:18 PM

Mid day, sunny sky, compare to sunny 16, at 1/125 shutter speed you should be between a 1/2 stop of F 16. The FG has a backlight button, is it perhaps stuck?

Disappointed_Horse · Wednesday at 1:02 PM

chuckroast said:
I've only skimmed this thread, so forgive me if I am repeating already noted facts in evidence, but ...

Bright light typically demands faster shutter speeds. Shutters tend to get slow with age, especially noted in the higher speeds.

Being off by 1+ stop at 1/250 and shorter, is not unusual as the camera ages. If this is the problem, the only fix is to measure the speeds and correct at the time of exposure or CLA the camera.

I would say slow shutters are far more likely to be the culprit than a bad meter, though either is possible.

Since the FE has an electronically controlled shutter, I would not think the shutter speeds would be off by more than one stop. (I'm not familiar with the FG.)

One other point: I'm a big proponent of the Sunny 16 rule but it is not always 100% accurate. I am in Florida and with shutter speed set at 1/ISO at this latitude, outdoors on a clear, bright, sunny day meters at f/22, not f/16.

ic-racer · Wednesday at 1:14 PM

albireo said:
Has anyone else encountered this kind non linear metering error in these Nikon cameras?

Any other checks you would recommend I should try to make sure I'm not wrongly interpreting what I'm seeing?

How common is it in similar photodiode cell meters of the same age?

Is it worth attempting to have them fixed?

Adjustment or repair of meter should be part of any CLA. In my opinion the fully mechanical Nikons are more worthy of repair, but that is like only my opinion.

I had good results repairing many Nikon meters.

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albireo · Wednesday at 1:16 PM

250swb said:
Obvious question but somebody else may have asked it already, is the exposure compensation set to a + figure given you last used them in poor lighting?

Yeah good point but no it's set to zero compensation.

Of course as you say there might be a poor contact or the underlying circuit might be degraded leading to a permanent compensation. But that wouldn't explain why the meter of both cameras works fine when measuring less intense light.

koraks · Wednesday at 3:27 PM

chuckroast said:
Shutters tend to get slow with age, especially noted in the higher speeds.

albireo said:
Honestly this makes a lot of sense to me.

But it doesn't explain why the meter readings would be off. The explanation makes sense if the actual exposures on film are off, but your post #1 suggests things are already inconsistent at the metering stage. Did you also assess actual exposures on film, or just meter readings?

albireo · Wednesday at 3:39 PM

koraks said:
But it doesn't explain why the meter readings would be off. The explanation makes sense if the actual exposures on film are off, but your post #1 suggests things are already inconsistent at the metering stage. Did you also assess actual exposures on film, or just meter readings?

Not as part of the same test, no, but my recently developed negatives being very off is what prompted me to do my little comparison above.

But you're right of course - it if was simply a matter of slow shutter, why would the viewfinder readings be off, too? I honestly don't know.

koraks · Wednesday at 3:43 PM

So it's not a slow shutter. Or, at least, not only a slow shutter. And I still have very serious doubts that the meter is actually defective in any way.

Do you get OK readings under less demanding conditions, but across the entire metering range? With 'less demanding' conditions, I mean no bright light sources in or near the frame and no strongly backlit scenes.

Chan Tran · Wednesday at 3:44 PM

albireo said:
Not as part of the same test, no, but my recently developed negatives being very off is what prompted me to do my little comparison above.

But you're right of course - it if was simply a matter of slow shutter, why would the viewfinder readings be off, too? I honestly don't know.

You could do a number of tests.
You can compare the meter reading as you already have.
You can shoot a new camera and an old camera side by side in manual mode using the same settings. This would determine if the shutter speeds are different.
You can shoot in auto mode but bias the meter via exposure comp or ISO to have the same reading as the new camera. This will determine if the auto shutter speed is correct.

My EM doesn't have manual mode so that doesn't count. The meter read low so if a scene that a good camera indicates 1/125 the meter on the EM shows 1/60 however when the meter on the EM shows 1/60 the actual shutter speed is 1/125 so it's fine as is but the reading is off.

albireo · Wednesday at 3:56 PM

koraks said:
Do you get OK readings under less demanding conditions, but across the entire metering range? With 'less demanding' conditions, I mean no bright light sources in or near the frame and no strongly backlit scenes.

Koraks, I am mainly a medium format user - I use TLRs with no batteries or integrated meter and I meter using Sekonic incident meters and Minolta Spot meters.

Exposure being correct is for me crucially important, I wasn't born yesterday as a photographer, and I know exactly what you mean when you talk of backlit scenes and 'bright light sources near the frame'.

The meters of my FM and my FG are not being fooled by 'demanding' light in the test scenes. There was no demanding light in the tests I did. Rather, uniform intense sunlight, so simple to interpret that the centre weighted measurements of my F90X and my EOS3 matched my Sunny 16 predictions within 1/3rd stop or less.

The issue here is not that these meters are being fooled by weird, complex light.

Anyway - thank you everyone for all the hints and tips. I will send the FE for a CLA and dump the FG.

albireo · Wednesday at 4:10 PM

Chan Tran said:
You could do a number of tests.
You can compare the meter reading as you already have.
You can shoot a new camera and an old camera side by side in manual mode using the same settings. This would determine if the shutter speeds are different.
You can shoot in auto mode but bias the meter via exposure comp or ISO to have the same reading as the new camera. This will determine if the auto shutter speed is correct.

My EM doesn't have manual mode so that doesn't count. The meter read low so if a scene that a good camera indicates 1/125 the meter on the EM shows 1/60 however when the meter on the EM shows 1/60 the actual shutter speed is 1/125 so it's fine as is but the reading is off.

Thanks. Some good hints there.

By the way earlier I replied to you or another member and said my images were 'backlit". I suspect I made a linguistic mistake here. I didn't mean the subject was backlit, but rather that the sun was behind *my* back. Not sure what's the correct English term for this. Plain, simple 11AM sun rising high behind me. Would that be "front lit"?

This clearly generated some confusion for which I apologise.

koraks · Wednesday at 4:21 PM

albireo said:
The issue here is not that these meters are being fooled by weird, complex light.

Okay, I misunderstood/misinterpreted your original question; my bad.
Can you confirm that the metering starts to get weird consistently beyond a certain EV level, regardless of what kind of lighting setup you're aiming the camera at (provided it's bright enough ofcourse)?

Old Nikon SLRs consistently overexposing, but only in strong light?

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