hilltime
Well-known
I have these two Zeiss meters probably not far apart in age. Just took them out and inserted a fresh 9v battery and was checking their reliability as I haven't tested in a number of years. The white meter reads accurately outside in bright light 1/250@F5.6 ASA 100 and in a testing area (white wall) inside, 1/50@F4. Both are correct, confirmed with a more modern known value meter. The black version reads the same outside, close to 1/250@F5.6 ASA 100, but inside reading is remarkably different,
1/15@F1.4. Any reasoning behind this that anyone might know or guess? Would it be the failure of the CDS cell in a lower light condition or some other condition?
An inquiring mind would like to know......
1/15@F1.4. Any reasoning behind this that anyone might know or guess? Would it be the failure of the CDS cell in a lower light condition or some other condition?
An inquiring mind would like to know......
Attachments
KoNickon
Nick Merritt
The cell may just be losing its sensitivity in lower light as it ages. How old are these anyway -- 60+ years? These take a 9V battery?!
Glenn2
Well-known
I have an Ikophot CD from the sixties which uses a mercury coin cell. I liked it a lot, but it’s lost accuracy so now sits on a shelf, replaced by a Sekonic L-308S.
For checking meters I made a Jpg file that’s pure white and matched to the resolution of my monitor. When this is viewed on a monitor it makes an evenly lit reproducible target to aim meters at for comparison.
Glenn
For checking meters I made a Jpg file that’s pure white and matched to the resolution of my monitor. When this is viewed on a monitor it makes an evenly lit reproducible target to aim meters at for comparison.
Glenn
Chriscrawfordphoto
Real Men Shoot Film.
When metering cells go bad, they become non-linear. That means they may be accurate at one light level and off at a different light level. Very few old light meters are truly accurate or reliable anymore. For actual use in making photographs, a modern digital meter really is best.
hilltime
Well-known
Mid to late 60’s vintage as the white/ brown meter is a combo Zeiss/ Voigtlander product. The last production of Ikophot meters and using a common 9v battery. I have a few of the much more ubiquitous selenium meters with the leather case and gold foil logo which are accurate and working just fine. As a matter of fact, have probably 50 different meters from the 40’s thru the decades culminating with a Pentax spot meter. Never thought I’d develop a “collection “ of meters, but couldn’t resist the varied “coolness” of design.
Cascadilla
Well-known
The community college where I teach has 20+ Pentax K 1000s that have CdS light meters. What I have seen many times as they age is under exposed negatives. I have frequently had students set the ASA at 200 or even 100 to deal with this problem and that usually works well enough for a beginning photo class. I know that Chris Crawford is right that these cells go non linear before they die completely, but the lower ASA settings have usually worked for my students. I do have reasonably accurate selenium cell meters from the 1950's--a couple of Zeiss Ikophots among them. They would not be my first choice for low light work, however.
KoNickon
Nick Merritt
I should have been more specific -- which 9 volt battery does it take? I think of the large rectangular ones with both terminals on one end. Are there others out there?
hilltime
Well-known
That's the one you have described.
