Nikon 50/1.2 AI metering errors

[dave_cheney]

Hi,

 

I have an interesting problem with my 50/1.2. On two camera body's

I have tried it on (F3 and F4) the lens seams to give 1 to 2 stop

under exposure. This has happened regardless of backlighting,

sidelighting or anything else that would fool a meter. Has anyone

experienced this before?

 

When I use an external meter the exposures are perfect so I am

assuming that there is some misalignment of the meter coupling pin.

 

I like using this lens, it has a great feel and the images are

superb, would you suggest anything besides altering the exposure

compensation to compensate for the lens. If so, does anyone have an

idea how much. I did read a while ago that lenses like the 50/1.2 and

1.4 have a slightly different AI cam which nobody is sure why.

 

Any suggestions?

 

Cheers

 

Dave

[lex_jenkins]

Hmm...I'm not familiar with any of the f/1.2 Nikkors - was this lens designed as an AI type or was it AI'd later? It's possible to mess up on the conversion. However the only non-AI f/1.2 Nikkors I've seen were the 55mm variation.

[dave_cheney]

Hi Lex,

 

My lens is 183795 Nikkor 50/1.2. Although I can't prove it at the moment I do not think this lens is a pre Ai conversion. A lot of 55/1.2's were produced and converted to AI, but these are pretty easy to spot as they have the older style scholoped barrel. Mine (from a web page I once found) appears to be the second version of the AI series, which has the rubber focus ring.

 

Cheers

 

Dave

[constance_cook]

Hi Dave:

 

According to Peter Braczko in his book The Complete Nikon System, this lens was introduced in July, 1978 with the beginning serial number 177051 as a non-AI. Given your number, it is not likely one of the later versions that were AI or AIS.

 

Conni

[kelly_flanigan1]

The last 50mm F1.2 Nikkor I used was in 1976; and it had a prong that mated well with my Nikkormat Ftn's meter. One had to place the lense on F5.6; to align the prong on the meter pin. <BR><BR>The AI cam surface is different for each F stop of lens. This lets the camera's meter know what the maximum aperture is of a lens in useage. By cam surface; I mean the notch feature on the lenses aperture ring; that contacts the spring loaded feature of post AI cameras.

[dave_cheney]

Hi Connie,

 

I'm pretty sure that Nikkon did not make the 50/1.2 in a pre AI from. From this web page

 

http://www.cs.kau.se/~nicke/private/photo/misc/lensspec.html

 

I've seen that my lens is one of the early AI 50/1.2's

 

From that page there is a jpeg of a sample AI 50/1.2

 

http://home.aut.ac.nz/staff/rvink/ai5012.jpg

 

Which is identical to my lens and also bears a serial number before my lens.

 

Besides, if my lens was an AI conversion it would be using a factory AI ring (non factory conversions are easy to spot) so the AI poisition would be correct.

 

Cheers

 

Dave

[david_tolcher]

I have a 50 F1.2 and on one of my bodies the tab that couples with the AI ridge did not follow as it should passed about F2. Check on F1.2 if there is a gap between the coupling ridge and the little tab on the mount. A service sorted it out for me.

 

Best regards

 

Dave

[kelly_flanigan1]

Dave and the Group; Nikon had the 55mm F1.2 out in the December of 1965; it is shown in my oldest white cover Nikon Nikkormat handbook c1968; plus I saw the lens at Nikon dealer befrore man landed on the moon. These were all pre AI; since AI arrived roughly a decade later.<BR><BR> <a href="http://www.geocities.com/amadeusgould/Nikon_Club_Ned/Nikkor_1-2_55_mm_Eng_01.html"> There were FIVE versions of the 55mm F1.2 before the SIXTH version came with AI.</a> Serial number of the lens in the Nikon handbook is 970103 ; a Nikkor-S Auto lens; which was the prototype's photo for the datasheets..

[kelly_flanigan1]

The lens I used in 1976 was probably a 55mm instead of a 55mm F1.2 ; we used it for meteor photography; and the owner got it when recently in Japan in 1976.

[kelly_flanigan1]

<b><a href="http://home.aut.ac.nz/staff/rvink/nikon3.html">Roland Vink's Nikon Lens Serial Numbers List</a></b> The 50mm F1.2 arrived in the March of 1978.

[kelly_flanigan1]

Rolands Serial number link above is real nice. It lists the number of screws in the lens mount. A - minus; is used for a slotted screw; and a +; plus used for a Phillips screw. When I did Engineering worked for the Japanese; they used the terms plus and minus for the type of screws; and NEVER use the term "Phillips". Many of their plus screws did NOT have the same head as an actual Phillips head screw. We had special Japanese screw drivers on the assembly lines for the plus screws; where a Phillips screwdriver did not work well. I showed them an OLD pre WW2 Sears screwdriver witht the Phillips patent number on the shaft.

[dave_cheney]

Hi Kelly,

 

Thanks for the link, but just to reitterate, my lens is the 50/1.2 Nikkor, not the 55.

 

Thanks for the suggestion above, I've checked the AI linkage and on my bodies the AI tab on the lens stays mated with the camera through the full travel of the camera.

 

I have seen it reported here

 

http://www.zi.ku.dk/personal/lhhansen/photo/mcr.htm

 

That fast nikkors, ie 1.8, 1.4, 1.2 have a different placement of the AI coupling ridge to f2 and slower nikkors. Maybe this is why my lens causes the meter to underexpose.

 

Cheers

 

Dave

[kelly_flanigan1]

The AI coupling ridge should vary for different fstops; that is waht they are suppose to do. This tells the camera what maximum fstop the lens is on the camera. All F2 AI lenses should have the same type notch. All F2.8 AI lenses should have the same type notch. Either the AI notch is wrong; or the spring AI mechanism feature in the camera is goofed up.

[kelly_flanigan1]

Dave; see if the coupling ring is somehow getting hung up when the 50mm F1.2 is on a camera body; compare what is happening versus when another AI lens is on the camera...Some non factory AI conversions have known problems; and tend to hang up on the mechanism.