ZM Meter and Gossen meter different readings

[matvogel]

Hello,

Maybe this topic has already been discussed. I'm wondering about different results when comparing the metering of the Zeiss Ikon ZM built-in meter and my external Gossen Lunasix F meter. I use both regularly and could not say that the one or the other is wrong. I get excellent results with the Zeiss meter, when shooting b/w and color slides. The external meter I use for my folders and for large format.

Yesterday I was shooting with the ZM color slides and in parallel also with my Bessa II also colors slides with the same ISO setting. When I made a side by side comparison with the ZM TTL metering using a 35 Biogon, I always got a full step slower result with the ZM than with my Gossen reflective light meter.

Today, I verified it with a grey card and second camera - a Nikon FM2 and the two TTL systems are always getting the same result.

Very strange because I get excellent slides out of my folder where I meter with the Gossen for years now. Am I just lucky due to increased exposure tolerance of modern films? Actually, I'm using E100G in 120 and Ektachrome 100 in 135 - should be the same emulsion.

Any idea? What could be the problem? Is my Gossen off?

Cheers
Matthias

 

[Neare]

The ZI's meter may simply have a smaller coverage of the scene, as to what your lens (taking into consideration its focal length too) is pointing at. Whereas the gossen is weighting much more of what is in front of you and will not have any effects a lens may give to the metering.

Or your gossen could be off. 🙂

 

[matvogel]

For the next verification I will use a spot meter.

 

[Richard G]

On a meter thread along similar lines someone quoted the old saw that the man with two watches does not know what time it is.

 

[matvogel]

On a meter thread along similar lines someone quoted the old saw that the man with two watches does not know what time it is.

Very good analogy! 🙂

 

[ferider]

If your Gossen meter behaves like mine, this difference will only show in normal daylight. When you go darker, say 1/15th, f2, 400 ASA or so, my TTL meters and Gossens are identical.

I've seen this behavior with 4 different digital Gossen meters that I tried. I am guessing they are calibrated for stronger contrast in daylight.

I wouldn't worry about it. Or account for the difference in use after some test shots with a given film.

Roland.

 

[Steve M.]

It's probably due to print film's tolerance. Two meters SHOULD give the same results if they're metering the same light value, but it can get tricky because the field of view is different from one meter to another. If you're comparing two cameras it's even trickier, as one camera's meter may not be exactly right, but it's shutter speed variable (could be running slow) may make up for it. Fortunately your cameras are exposing right so it's moot.

 

[pau3]

The metering pattern of the the ZM and the Lunasix are different, and, in the case
of the ZM also depends on the lens you're using. Do they agree when you meter
a grey card? The result should be independent of the pattern.

Best,
Pau