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Chipping manual Nikkors / extension tubes / adapters
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PostPosted: Mon Feb 15, 2010 11:14 am    Post subject: Chipping manual Nikkors / extension tubes / adapters Reply with quote
Hi there!

Does anyone of you have experience with modifying Nikkor lenses with CPU chips?

I am planning to build such a CPU into my M645 => Nikon F-adapter in order to have exposure metering on my D50 with all M645 lenses I attach.

But I don´t have any experience with projects like this. Does anyone have some good tips?


Thanks in advance

Benedikt


PostPosted: Mon Feb 15, 2010 7:04 pm    Post subject: Re: Chipping manual Nikkors / extension tubes / adapters Reply with quote
BenediktW wrote:

Does anyone of you have experience with modifying Nikkor lenses with CPU chips?


A little. I've chipped an extension tube and a few lenses.

If you're modifying a plain F bayonet, you need to drill holes to and cut away bits of metal, so you'll need some tools for that, e.g. a Dremel. But finding tools should not be a problem.


Finding a chip, on the other hand, might be. One way to go about it is to look for cheap or wrecked lenses and extract the CPUs, as well as the contact blocks and the screws that hold the blocks in place, from those.

Note that if you find a chip for an AF lens (instead of an AI-P lens) your camera needs to be switched to manual focus, or it will futilely try to focus the lens.

Chips for zooms have a long strip of contacts attached. Against this strip moves a metal brush when the lens is zoomed; based on the position of the brush against the strip, some contacts are shorted and this is how the CPU will know the (approximate) focal length. You can experiment shorting the contacts in different positions in order to arrive to a specific fixed value.

Chips for D type lenses have another such a strip for focusing distance. I'm not familiar with what calculations happen with the exposure concerning the focusing distance, but you might want to try out e.g. infinity and see what happens.

These strips may be problematic when fitting the CPU inside the adapter, as they take up space.


Bjørn Rørslett has sometimes sold chips which have been programmed for specific lenses. In that case you don't need to fiddle with strips and the focal length/aperture values will be exactly correct. However, I don't know whether he does that anymore. Also, he doesn't supply the contact blocks or the screws, so you need to source those from somewhere else. (either wrecked lenses, again, or a repair shop that sells Nikon spare parts)


PostPosted: Mon Feb 15, 2010 7:34 pm    Post subject: Reply with quote
Thanks Smile

I´m trying to get a 18-55 AF-S, there are lots of these with broken ultrasonic drive, and they are an awful piece of rubbish anyway Twisted Evil
But perhaps there´s also a broken 35-70 somewhere, the other ones are sold too expensive.

So I´d have to short the zoom contact, this is a useful piece of information!

A chip from a prime lens would be more convenient so, but they are more expensive and difficult to find in defective state.


PostPosted: Mon Feb 15, 2010 8:07 pm    Post subject: Reply with quote
Bjoern Roerslet sells these chips programmed for a specific lens.
Contact him through www.nikongear.com he is "nfoto" there


PostPosted: Mon Feb 15, 2010 9:50 pm    Post subject: Reply with quote
Thanks! I talked to him, but I don´t need it for a specific lens, as I will eqip an adapter with it. His price is fair for what it does, but I don´t need this pricy solution. So I´ll go for the cheap DIY solution Very Happy


PostPosted: Tue Feb 16, 2010 8:10 pm    Post subject: Reply with quote
BenediktW wrote:

So I´d have to short the zoom contact, this is a useful piece of information!


If you want the CPU to report some particular value, yes. If you don't care, then you can just insulate the contact strip and stuff it somewhere inside the adapter -- it will still report something, but if you use only e.g. a 50mm lens with the adapter it might be advantageous to find the 50mm position of the strip.

A few years ago, when I had a Nikon D100, I chipped a Soligor tube and wrote a small page of the operation, see http://hannu.mallat.fi/accordion/accordion.html. The D100 didn't meter at all without a CPU, but I've since upgraded to D700 which does. Still I've added CPUs to manual lenses so I don't have to fiddle with the camera settings when changing lenses.


PostPosted: Wed Feb 17, 2010 12:27 am    Post subject: Reply with quote
For all the time & expense involved, I would just upgrade your camera to a D200 or better so that the camera can meter with the old lenses...


PostPosted: Wed Feb 17, 2010 9:25 pm    Post subject: Reply with quote
BenediktW wrote:
Thanks Smile
So I´d have to short the zoom contact, this is a useful piece of information!


If you don't short the strips, they will report whatever value corresponds to all zeroes.

if you do, its worth knowing that these strips use Gray code
http://en.wikipedia.org/wiki/Gray_code
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