NikonGear'23
Gear Talk => What the Nerds Do => Topic started by: stenrasmussen on April 28, 2016, 12:06:37
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Upon living on the cpu-edge with a Dandelion installed in my 35/1.4Ai-S an attempt at mounting it on my D5300 caused one of the pins to become skewed and break off. So from now on I will NEVER use those fragile things again. I have a CPU on the way from Mr. Bear and here's a donor contact block waiting on the host lens.
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Sorry to hear about the mishap with the Dandelion. However, this incident only confirms what I learned myself and heard from others. The Dandelions indeed are lacking the tenacity and vigour of their botanical counterparts... Besides the contact pins stick out too far and are very vulnerable as you already have experienced.
Your CPU replacement currently is on its way through the Norwegian snail-mail system. Hang in there.
Meanwhile, start a slimming process of your new contact block.
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Slimming process, rear lens cell and contact block.
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Sten, a while ago I picked up a number of the 10-pin "wide" block contacts on Ebay. What I found when I measured them all was that there was quite a variation in their thickness - up to around one third of a mm.
A third of a mm could be really handy if you are squeezing a contact block into a confined gap between the rear lens cell and the lens mount.
Much of the variation seemed to be due to the metal backing plates being inconsistent in their curvatures.
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Bjørn, have we issued a certificate to Sten for being an NG Nerd of High Order ;D
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The "inconsistency" of the long blocks vanishes when it is realised there are two distinct types. One for mounting in plastic casings, which requires longer screws with wider head and coarser thread and has the rear platforms for the screws raised above the metal backing plate; the other for mounting in metal casings and needing shorter screws as the mounting brackets are flush to the rear surface. Only the second type should be used when space is at a premium. The problem in general with the first type, often scavenged from damaged cheap "kit" zooms, is the need for non-standard screws with wide heads, and these can be tricky to make flush to the surface of the bayonet unless you trim the heads. Plus the curvature of the block is stronger than of the second type.
I always order type 2 contact blocks to avoid these issues.
If Sten gets into troubles with the required slimming, I can provide him with the correct block.
CPU-modifying of the 35/1.4 is 'easy' in the sense that one does not need to cut into the rear glass elements, only the wall of the retaining cell. Due to the presence of CRC, the wall needs to be slimmed over a fairly wide area. This is in contrast to the Fisheye 16/3.5 where the removal of material is more concentrated as the rear part of that lens, unlike the 35/1.4, does not rotate on its own.
Sten passes all tests as an NG Super nerd, no problem in that area :D
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Mmm...
Bjørn, the blocks that I was referring to sound like what you call Type 2, in that they take an M1.4 short screw of 3mm overall length and the metal backing plate is folded into a step near where each screw passes through the backing plate, so as to minimise the length of the required screw. And yes, I still encountered a ~1/3mm variation in their thickness near the middle of the block. It was also worse away from the outer/outside edge of the block.
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Perhaps they occur a little differently between various lenses? I order a specific spare part and they are all identical. Same as used in the 24-70 AFS, by the way.
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I think it was pretty difficult to chip this lens,,, So well done Sten!
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To be fair, Sten only has shown the opening moves as it were. Hopefully the new CPU has arrived. That is if the Norwegian Mail hasn't sent it to the Arctic North for sorting, then dispatching it back. Such things do happen in the name of "efficiency", that outdated buzzword.
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You guys certainly has guts. I usually keep heavy machinery and optical instruments separate. Off topic: B&H New York to my door, 2-3 days, Posten from Oslo to my mailbox . Maybe 5 days before I receive a pick up note ::) Snail mail, is no understatement.
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There is a mutual relationship and friendly understanding between a lens and a Dremel.
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...as long as risk is appropiately assessed 😉
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Nothing ventured nothing gained.
Been through the 35/1.4 modification a few times myself, and unlike Erik et al. I am no expert on these matters. Persistence and patience are key ingredients. Plus willing to take a risk, like I did when I asked Erik to modify my 58 Noct.
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How difficult is it to chip a 55mm f1,2? It is one of my most used lenses and I am considering chipping a few of my lenses (20mm UD Nikkor, 55 f1,2 and 135 f2,8) to save the hassle of constantly correcting the EXIF data in lightroom after I forgot to change the camera setting ;)
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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.
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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. :)
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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.
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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
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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.
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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.
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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.
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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...