Meter challange for M5 owners

[awilder]

For those of you that own both an M5 and hand held spot meter or a modern cameara with an inboard TTL meter like an M6 or SLR, please let me know if there is any significant difference in meter reading or linearity of accuracy throghout the f stop range for the M5 compared to the other meters when metering a nice deep blue sky (i.e. not overcast or cloudy). Many fans of the M5 say that it's meter accurately matches the hand held spot meters but found on the last two samples I've tried that they tend to overexpose by about a stop and can be non-linear over the f stop range when metering solid blue subjects. The deeper the blue, the greater the error. These cameras were supposedly calibrated and used the correct mercury cells. Metering subjects that weren't at either end of the color spectrum produced accurate measrements compared to known accurate meters usung modern silicon cells. My guess is that with 40 year old age, these CdS cells loose accuracy in their spectral sensitivity at the short end but it's just a guess.

 

[sepiareverb]

...when metering a nice deep blue sky (i.e. not overcast or cloudy)....

Oh a clear blue sky. Someday maybe.

My weather looked like this all last week too.

 

[Chriscrawfordphoto]

CdS Cells have a strange spectral sensitivity that is way too red/yellow sensitive and not enough blue. Silicon cells do too, but with them manufacturers put a blue correction filter over the cell to make it respond like human vision....this was never done with CdS cells, which simply are not capable of matching modern meters on deep colored subjects. They also underexpose in Tungsten light cause the warm light looks brighter to the CdS cell than to film.

 

[venchka]

I own multiple hand meters. As you know, I used to own two M5s. Now one. Whenever I was using the M5s, I just metered with the cameras. I never compared them to the Luna-Pro, Luna-Pro sbc, Minolta Auto-Meter IV or Weston Master V or any of the Canon cameras with meters.

Bottom line: I have said it over and over: The M5 meter is the best meter I've used.

Clear blue unfiltered sky. Kodachrome. Home scanned.

The Kodachrome album in my LUG Gallery is all M5. The welder shots in the Houston Album are all M5.

 

[payasam]

I would not worry unless results on film are objectionable.

 

[venchka]

ps: Both cameras calibrated for and using mercury cells.

 

[awilder]

My M5 results were just as Christopher Crawford said, underexposed for subjects primarily at the red end of the spectrum (especially in tungsten lighting) and overexposed at the blue end of the spectrum, compared to my MP and modern Sekonic spot meter. I wasn't aware that this is a common characteristic with CdS cells, so now I know it's not an age issue with the M5. Normally, I would never spot meter a straight blue sky (unless shooting an air show), so shooting everyday subjects like people, landscapes, etc. would not produce any significant exposure error on the M5 as the spectral range of these subjects would not fall at the the spectral extremes of red and deep blue. There is also the exposure error with the M5 induced when aiming the camera up or down such as aiming the camera towards the top of a high building or down to the ground, something acknowledged by Leica in their instruction manual but I found that error from extreme tilt to be no more than +/- 0.5 stop.

 

[venchka]

Primary light: Arc welding. Secondary: Sodium vapor. An ugly, sickly orange light for sure.
Long past due Fuji 800. Saved by the Nikkor 8.5cm lens and M5.

 

[awilder]

When I refer to under and over exposure at visible spectrum extremes, I'm simply testing the meter on a uniform patch of color and comparing it to a meter of known accuracy, that way other factors don't affect the reading. Since I primarily shoot slides with little tolerance to exposure error (especially for overexposure), sample shots like the nice one posted don't tell that much especially with negative film that has greater lattitude than slides. Most of my slides were properly exposed with my M5 but with the M6 or MP, every one was dead on except in cases of stupid metering errors on my part.