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Chipped T-mounts? Any good? And how do they work?


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9 replies to this topic

#1
Marcus Rowland

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My longest lens is an old T-mount 500mm f8; I also test T-mount lenses fairly often, since I buy and sell them on eBay. One of the problems with them is that my D50 doesn't meter or confirm focus unless the lens has a chip, which really slows things down if I'm trying to get a picture of a bird or something.

 

Various vendors offer T-mounts with the chip, but they look a bit fragile and home-made; I'm a little worried that the chip might break off and damage the camera. I'm also unclear as to how the chips actually work - do they have to be programmed for the individual lens, or is it more a generic "this is a manual lens, just return a speed for the light that's coming in and don't worry about anything else" sort of thing?

 

Has anyone tried them, and what were the results like? Can you recommend a particular supplier?

 

I'm also looking at getting a chipped adapter for using M42 screw lenses, since I probably sell more of them than any other fitting and it would be useful for testing them. Again, has anyone tried them?



#2
Merco_61

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The dandelion chips are on the fragile side, but they work as long as you keep an eye on them. Here are the programming instructions.



#3
Marcus Rowland

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OK - that makes it a bit clearer. It's the fragile part I'm really worried about - I get the impression that nobody is actually manufacturing a purpose-built T-mount containing a chip, they're gluing the chips onto ordinary T-mounts. And that doesn't give me a lot of confidence in their strength etc.!



#4
Marcus Rowland

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Well, I've sort of tried this now - I got a chipped M42 adapter for my Canon 300D, since I've started using that for lens tests, and tried the 500mm lens on that with an M42 mount fitted. Results were mixed - exposure was dead on, focus confirmation was lousy. Is that fairly typical given the lens aperture (f8), or are Canon poorer than Nikon in this respect? I think I'll be getting a chipped T-mount for Nikon anyway, the exposure part makes it worthwhile. Although this does mean that my (originally £10) 500mm lens will now have cost about £40 - £10 for the lens, about £12 for a canvas carrying case (a Velbron tripod case), skylight filter, cap and long hood, and circa £18 for the chipped T-mount...

 

Oh well, it's only money (he said, banging his head against the wall)...

 

One thing I definitely noticed about this - chipped adapters for Canon are a LOT cheaper and seem to be better made, with less chance of the chip getting damaged because of its design. I got the M42 adapter for £5.39 and I'm waiting on a Pentax K adapter for £7.39, there's also someone selling chipped T-mounts for £7.45 though they don't look so well made. The ones sold for Nikon cost a lot more and don't look nearly so robust.

 

I suppose that part of this must be that the chips are more expensive, but I'm willing to bet that there's also some "he's got a Nikon, he can afford to pay more" thinking in there. But I mustn't be bitter (he said bitterly)...



#5
Marcus Rowland

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Tried the 500mm on a really bright day and focus confirmation worked much better, which I suppose makes sense.

 

Meanwhile I've twice failed to get a chipped Nikon T-mount in auctions, and the prices seem to have gone up across the board (or rather the pound has gone down) while the Nikon-fit ones still look a bit amateurish compared to the ones for Canon. Can anyone recommend a source other than eBay that won't charge an arm and a leg? Preferably in the UK or Europe, unless they ship very cheaply.

 

Very tempted to check for minimum order quantities on AliBaba and buy a job lot, sell the rest on. But I suspect it isn't entirely easy to get started in that game without falling foul of customs etc. And on a quick check nobody is selling them ready-made anyway!



#6
Dogbytes

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Nikon-fit ones still look a bit amateurish compared to the ones for Canon.

 

And on a quick check nobody is selling them ready-made anyway!

I've never seen one, what sort of a job would it be to make them? Is it machining up a T-mount and affixing a chip, or what?

Might be an interesting project...



#7
Marcus Rowland

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The ones I see on ebay seem to be an ordinary T-mounts with the chip glued to the metal at the edge of the bayonet with a teeny amount of glue. Since the metal at that point is about a millimeter thick it looks distinctly fragile, which is why I'm concerned about damage if the chip comes loose. What I think I'll do if I buy one is put some epoxy resin underneath the chip inside the throat of the T-mount, so that it has more support. I'm only going to be using it with a very long lens so I don't have to worry about the rear element of the lens being obstructed by anything. The Canon ones are either made with a metal support for the chip or have a little support bracket screwed to the mount.



#8
Dogbytes

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Might have to look at a couple - just out of interest...



#9
Merco_61

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It might be possible to use the better chips sold by Bjørn Rørslett and use an original Nikon contact block for a sturdier T-mount. Bjørn and some of the people who use his chips can be found over at Nikongear.net.



#10
Marcus Rowland

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Yes, the idea had crossed my mind - before I realized that the lens connectors aren't chipped in the same way, I wondered if it would be possible to cannibalize something like a Nikon Pronea lens and use the "chip" from that. But obviously it isn't that simple.