How does an old needle light meter work? (Canon FX)

[peter_kim2]

I found my dads old Canon FX (circa 1964) in the basement. I got a

replacement battery for it, its a mercury replacement battery.

 

Do I just set the shutter speed and manualy set the apreture on the

lens (its a FL lens)? I guess that part is easy enough. But there is

a swith on the side that selects between L and H, which I assume is

high and low and the light meter itself has two sets of number

consecutivly, fstops 1.4-16 in orange then after that 1.4-16 again

in white. Do I use the orange for L and white for H?

 

I was using the meter and it responds and all but it seems to tell

me to set the exposure a little underexposed. Im by no means a good

eyeball light reader but, for instance I was shooting on a bright

day but in the shade (with 400asa) so I kinda guesstimated 1/500 at

8 but the light meter told me to set it to 1/500 and 16+.

 

Anyways I dont know if Im using it right, can anyone shed some light

on this for me? (haha sorry for the bad pun!)

[ricekrispiesc]

I think that the meter is calibrated to use a mercury battery of a diffrent voltage, so you may need to find an appropriate voltage converter. Also with age light meters can deteriorate, so it might need to be checked.

[peter_kim2]

Hi well I got the Wein 625 battery, I looked around online and found this was a battery specficly made to replace the mercury batteries. This is the same battery that is used in the Leica M5 so I dont think the meter is off because of the battery...but perhaps the meter is just old as you suggested?

 

I was more curious about how to use it. Specificlly the H and L setting and what they mean and all...

[alan_swartz]

Peter,

 

You do choose shutter speed and set the aperture according to the meter reading.

 

You've noticed that there's an orange dot near the "H" mark on top, and a black dot near the "L" mark. When set to high sensitivity, use the orange scale, and use the white scale for low sensitivity. All the H-L switch does is move a baffle in front of the photocell. The baffle has a pinhole that reduces the sensitivity of the cell for use in bright conditions.

 

Note that the two meter scales overlap, where the f-numbers 1 and 16 occupy the same position. The scale slides when you change shutter speed, so that no matter what speed you select, the proper aperture will be indicated by the needle. The fixed index with all the diagonal marks helps to align the needle with the scale and compensates for linearity issues with the meter.

 

If the battery voltage is correct, there could still be resistance in the on-off switch, resistance in 40-year-old solder connections, dirt in the meter window or on the photocell. . .all could cause readings in error--but all these things should make it read low. It sounds like the voltage is too high, 1.5V instead of the 1.35 of the mercury cells. The FTb may be recalibrated, and I assume this camera also, but I don't know for sure.

 

I grew up with my dad's Konica with external meter. It was an ungainly affair that slipped onto and coupled with the shutter speed dial. The FX is a slick arrangement by comparison. I remember how inconsistent the exposures were. It's hard to be sure that the photocell window is aimed at the same spot the lens is! He usually took a substitute reading from his hand. He liked his slides a bit underexposed, so this worked well for him without adjustment. The Konica meter was sluggish and inaccurate at low light levels, where the resistance of its cadmium sulfide photocell was high.

 

Beyond the huge improvement in lens performance, I remember being astonished at the extremely consistent TTL exposure I got with my first Canon, an AE-1 Program. It was a huge leap forward.

 

Enjoy! I bought my old FX for almost nothing, and look forward to the day I can relive a bit of photographic nostalgia using it.

[peter_kim2]

Alan, thank you for that insightful explaination. I guess it doesnt really matter if I use H or L, just adjust for how dark or bright the light is? That sounds simple enough. The odd thing is this...I shot a roll using the meter of my Canon A-1 as reference then using the meter on the FX and they seem to be off when I compared the two...It almost seems as if my A-1 is overexposing by a stop and the FX is pretty much accurate in exposure! The horror! :)

 

But this Canon FX has a lot of nostalgia for me because it was my dads and a lot of the pictures, in fact all of them, of my pictures of myself as a baby were made with this camera. It never ceases to amaze me. The fact that I can use a camera today that was used to photograpgh me as a baby and it gives such good results!

 

Im finding a new found appreciation for 'old' cameras!

 

Happy shooting!

[alan_swartz]

Yes, just use the range that works! If the meter reads at the bottom of the scale (needle barely moves) on the low sensitivity setting, try high instead. I remember some instances where the light level was borderline. . .it wouldn't read on the low scale but was very high on the high scale. The FX is better equipped to deal with this than the Konica was, since the scales overlap.

 

As to the discrepancy in readings, are both cameras set to the same film speed? Is the A-1 set for some amount of exposure compensation? I'd be interested to check each camera against a handheld meter.

[richard_keistler]

Peter-

At the time the FX was produced, cadmium sulfide was replacing selenium in photo cells. Its sensitivity was so much greater than selenium that people didn't mind buying batteries. The greatest drawback for CdS cells is that they have some 'memory'. For example, if you're shooting outside in bright light, then walk into a fairly dim room, you need to wait a couple of minutes or so for the meter to 'forget' the bright light. This is true of all CdS meters. It was one of the reasons these were replaced by silicon blue meters and gallium arsenide in the late 70's. More often than CdS true deterioration will be the mechanical problems with the meter. They get dirty, the contacts get dirty. So often, a decent cleaning by a competent person is all that's required to get them back working fine. Of course, if any parts are required that can be a block. Nikon's FTn meters died by the thousands in the 80's and 90's and there was no fix--it happened to my FTn! Apparently now there are a few repair people who can get them going again. You have 2 options on these cameras that used mercury batteries: 1) have the meter recalibrated for the equivalent alkaline cell; 2) buy the MR9 voltage converter to go with the alkaline cell. The original advantage of mercury cells was that their power output was quite constant over their entire life, then they'd die quickly. Alkaline cells don't have a constant power output, and our cameras made for modern batteries have circuitry to take care of this. CdS is still an excellent workable meter, though; I have a couple that are nearly 40 years old and working perfectly. Hope this helps--

[carmen_craps]

<p>I have a question also about the Canon FX. I have just acquired one and the film is not advancing when I pull the lever for it to. It's like, the gears are stuck or something. I have a battery in it, there's film, it's on...I'm just frustrated and ready to use this camera. If anyone could help me with troubleshooting or advice or anything, really, that would be great (:</p>