D750: highlight-weighted metering with Zeiss-/ Voigtländer lenses

[Danulon]

Hi there,
 
this is something I already posted over at fotozones, but I feel that it fits better to this forum.

I recently bought the Nikon D750 and thoroughly enjoyed using it during my 3 week vacation trip to Canada last month.
During that trip I used Nikon G-type lenses. After the trip I used instead my Voigtländer-SLII and Zeiss-ZF.2 lenses on several occasions.

I soon realized that the new highlight-weighted metering didn't work with the Zeiss lenses. A quick look into the user manual provided the following information:
 

Center-weighted metering will be used if highlight-weighted metering is selected with non-CPU lenses or if matrix metering is selected with non-CPU lenses for which lens data have not been supplied. Note that center-weighted metering may also be used if highlight-weighted metering is selected with certain CPU lenses (AI-P NIKKOR lenses and AF lenses that are not of type G, E, or D).

(underlined by me)
 
So far, so bad. I didn't use the new metering method that often, but it was quite useful with situations of high contrast.
I could live without this new feature when using 3rd party manual lenses. But then the odd thing occured: ONE of the lenses did provide highlight-weighted metering: My trusty Voigtländer 40 mm Ultron SL II (the one receiving a quick fix by Bjørn at his Germany workshop - involving a match for the loosened chip).

So I tested all my manual glass: Zeiss 21 mm 2.8, Zeiss 25 mm 2.8, Voigtländer 90 mm 3.5, and Zeiss 135 mm 2.0.
The result stayed the same. All of these lenses did NOT support highlight-weighted metering.

This increased my curiousity. I wrote an e-mail to Zeiss customer support in Germany. Mere 30 minutes later I received an answer!
From that information I gleaned as much (my interpretation!) that Zeiss lenses delivery a code to the camera. For some unknown reason the most recent Nikon cameras apparently refuse to interprete these codes for highlight-weighted metering.

My first guess was that the 40 mm Voigtländer hid its "identity" by pretending to be a Nikon lense. But then my raw converter clearly identifies this lense as a Voigtländer 40 mm lense and this information stems from the lense chip. So this guess is obviously wrong.

As written above I can live with the fact that these lenses are not completely supported by Nikon cameras. But I am still curious about the reasons for the one exception from the "rule"...

Cheers,
Günther

[Bjørn Rørslett]

The lenses you list are "Ai-P" type equivalents. All modern Nikon cameras support the basic A, M, P, and S exposure modes plus matrix  metering for the "P" type chips.  As they are not "D", the 3-D matrix metering mode is unsupported and the same applies to the new derivative, highlight weighted matrix metering.

I don't think your 40/2 tries to pose as a Nikkor to the camera. Why it still responds to highlight metering I cannot explain at present, unless the lens by chance sends a micro code that the camera accepts.

From the quoted Nikon description, your third-party CPU lenses might have been set to centre-weighted matrix metering by the camera.

[Danulon]

Hello Bjørn,

I omitted that part: yes, the lenses - except the 40 mm - automatically switch to centre-weighted metering.
Then I'll accept the oddity of the 40 mm supporting all metering modes as a miraculous gift. :-)

Cheers!