Putting a real CPU in the Nikkor 35/1.4 Ai-S

[Bjørn Rørslett]

See this thread http://nikongear.net/revival/index.php/topic,276.0.html to get an idea of the difficulties entailed. You don't enter such projects with a guarantee of the lens surviving the surgery.

I can discuss with Erik the possibility of doing an "internal Dandelion" like he did with my 50/1.2. Probably the 55/1.2 is trickier, but the questions remains open for the time being.

[the solitaire]

Ok,no need to worry.Ialready figured the 55 f1,2 should be tricky because, aswith the Noct and 50mmf1,2 the rear element is already cut by the factory to accomodate the aperture lever.

In that case I should maybe pick some other easier candidates to chip instead and leave the 55mm f1,2 in the non-CPU register. Since it is however one of th elenses I use most, I also forget to set the correct non-CPU settings more often.

[Bjørn Rørslett]

I have a similar yet not entirely compatible situation. One of my Noct-Nikkors is CPU-modified, the other not. All other Nikkors are CPU-modified. Thus the default lens for all cameras is set to 58/1.2.

[the solitaire]

I must admit that the 55mm f1,2 is to dear to risk splitting the rear element while shaving something off the element and I do use the lens wide open enough to not risk changing how it draws OoF lightsources in any way. Your solution seems the safer approach.

I must admit that I never liked the dandelion chips but your solution seems to be far more durable so I am quite impressed and willing to try converting a few easy lenses this way myself.

I do have another nerdy project planned for which I also play with the idea of using a chip to get focal length and aperture information on the camera

[stenrasmussen]

Ok, here is a series of photos illustrating the modification process. First I had to modify the contact block so that Bjørn's CPU would fit. This involves removing some of the contact pins (the small metal parts in the photo) and remove some of the small plastic ridges left between the removed contact pins.  I also shaved some of the metal off the back of the contact block in order to minimize the amount of grinding of the rear lens cell. This lens is particularly tricky since the CRC (close range correction) rotates the rear cell when focusing is carried out.

[stenrasmussen]

Next step is to fit the contact block to the bayonet. I'm using dental drill bits in the initial phase of the drilling process. When a precise location for the screw is made I switch to a 1.5mm drill bit which will take me through the rest of the flange of the bayonet.

[stenrasmussen]

Then the light baffle stands trial and will have to be 50%'ed. The large notch in the left piece in the photo contains the remains of a Dandelion CPU...'nuff said.

[stenrasmussen]

Quite a lot of material had to come off...
(this is just before the final result and before I painted the exposed aluminium barrel).
I later had to clean out some dust that managed to get trapped inside the rear lens. This involved removing the lens cells from the focusing helicoid. ...and that's when patience and trial and error starts...