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Archive 2013 · Mount ID and Metering

  
 
rjb6893
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p.1 #1 · p.1 #1 · Mount ID and Metering


I unearthed my brother's old Vivitar Series 1 70-210 just for fun despite its age and weight. However, I've not been able to determine the mount (see below) even with some serial number sleuthing (22705070). I'm guessing early 1970's, so probably pre-AI or K. It mounts fine on my D7000 and is very sharp using "guess-by-histogram" metering. I thought that if you could mount a lens safely, one could use the "non-CPU" feature, but I can't get it to recognize the lens. Time to get a conversion kit from Mr. White?
Regards,
Ron





Vivitar S1 mount close-up




Jul 29, 2013 at 08:31 AM
mikerfns
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p.1 #2 · p.1 #2 · Mount ID and Metering


No need to do any serial number sleuthing.

The lens is definitely pre-AI. There is no AI coupling ridge on the back surface of the aperture ring (http://www.zi.ku.dk/personal/lhhansen/photo/mcr.htm), and no EE post (http://www.zi.ku.dk/personal/lhhansen/photo/EE.htm).

That is why the camera doesn't "recognize the lens" when you change the aperture ring setting with the non-CPU lens data entered. There is no coupling ridge to engage the AI coupling tab on your D7000, and the lens needs to engage and move that tab in order for the camera to recognize that you have moved the aperture ring. Normally pre-AI lenses should not be mounted on a D7000, as the extended rear skirt of the aperture ring on some of them can jam onto and potentially break the AI coupling tab, but that doesn't appear to be the case with this one. There is almost none if any material extending beyond the face of the mount flange, and in fact it appears to be flush and level with the mount flange surface. That is apparently quite common on third party pre-Ai lenses like the Vivitar above.

That means an AI conversion will require *adding* material to the back of the aperture ring to create a coupling ridge, as there is nothing there to mill away to create a ridge to engage the camera metering tab. I don't know if John White will do that type of conversion, but you can email him and ask. I do know that William Sampson does that type of conversion ... on a part time occasional basis. (http://www.aimodification.com - go the bottom of page and click on "unusual modifications" link)

No need to use "guess-by-histogram" metering though. The camera will still give you an accurate meter reading at maximum aperture for this lens if you enter the maximum aperture into the non-CPU lens data. So you can take a meter reading (in M mode), and then adjust your shutter speed setting (slower) by the number of f/stops you are set from wide open on the aperture ring. Not as fast as aperture priority (which won't work), but it only requires some simple on the fly arithmetic.

Mike



Edited on Jul 29, 2013 at 07:22 PM · View previous versions



Jul 29, 2013 at 07:05 PM
EB-1
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p.1 #3 · p.1 #3 · Mount ID and Metering


I have one of those lenses from 1976. (Back then the Nikon 80-200/4.5 was too pricey for me.) I would not bother with an AI conversion on that lens due to the very high flare and significant CA. There are better choices from that era or a bit later.

EBH



Jul 29, 2013 at 07:20 PM





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