Dismantling the Micro-Nikkor 55mm f/2.8 Ai-S!

[richardHaw]

The Fast 50mm 1.2 has a medium long helicoil so yes: S5 - And yes a brand new, Nikon still make them, is kind of heavy in the focus feel.

I was referring to short f/2.8 3.5 lenses.

The 50mm 1.2 Ais is actually super nice to chip with a Dandelion CPU from within the mount itself since the 'light baffle' part protrudes and forms an outer metal shell exactly in the right position as a contact block.

why do some dandelion chips fail? i read some people in dpreview having trouble with them down the road 

[Erik Lund]

Because they are glued on and extremely fragile, they are glued together by two half's and the plastic is so thin due to the extremely tight design.

Is you are not careful when changing lenses you can easily bump it and it will break,,,

I have chipped a lot of lenses and extension rings with them, most of them still work,,,

Some are very easily broken just by touching them, since the design with the tiny golden coil spring fails, the spring is simply too weak or the is a problem inside the hollow pin design,  some have' fallen of' and got a re-glue.

Customers have often reported broken chips, most I see as rough handling when mounting,,,

The Nikon TC16A with AF has a similar design with coil springs inside the pins,,, A very different design of the whole contact block than to the rest of the Nikon Nikkor Af and AFS lenses and TC's

But for the 50mm 1.2 Ais and Noct-Nikkor and a few specialist applications like extension rings the Dandelions are nice enough

[Akira]

Rick, I'm impressed by this very thorough write up.  I wouldn't do this kind of restoration work myself, but it is still well worth reading through.  Thanks for sharing it here!

I'm just curious: how is the aperture lever of the 55/2.8 you restored?  I've heard that there are three different versions of Ais 55/2.8 according to the period of production.  If the lever consists of two separate parts, the 55/2.8 is a second version.  The first and the third have one-piece levers.

[arthurking83]

why do some dandelion chips fail? i read some people in dpreview having trouble with them down the road 

Could be the quality of a particular dandelion batch made at any one time?

Like Erik said, they are very fragile and break all too easily.
I got one as a test for the 500/8, as it's a simple matter of aligning it properly and gluing it to the rear filter.
Easy as using a good epoxy mix. Strong hold on the chip body itself, but having a strong grip on the chip body is futile when the body of the chip is easily broken!



CPU just fitted onto the filter.
Waited till it cured properly and it worked fine for all of about 2 months. I'm not 'rough' with my lens fitting/removal procedure, but at some point I could feel that it felt a bit weird/strange the way the lens mounted onto each camera.
The strange feeling wasn't that the lens fitting/removal procedure was rough, it was that the cheap thin weak plastic body of the CPU wasn't up to par, and that the design of the square holes with round pins poking through them wasn't ideal either.
After the last couple of attempts at fitting the now CPU'ed 500/8, I then checked the dandelion with my macro lens and noted that the pins were falling out of their holes. At first, not completely just goofy alignment, which I pushed back into line, but then one literally popped out.
On closer inspection, the cause was the distorted body of the dandelion, making the non ideal square hole-round protruding pin even less ideal! .. to the point of disastrous failure.



Basically the square opening got so badly distorted, that it was no longer square(and thus only JUST) retaining the spring loaded pin.
The square openings were so badly distorted that the pins literally pushed out of their receptacles just enough so that they would bind against the camera body when being mounted/dismounted, which then distorted the dandelion body even more so, which added to the amount that the pin protruded .. and within a very short time the cpu was basically dead weight and the lens couldn't be mounted at all(well without a lot of force, which I'm not willing to attempt!)

I still have the chip tho. I have cut away the broken body section to reveal the insides as a memorial to be more doubtful on some of the things I want to achieve!

I have to say tho, I'm still interested in chipping many/all of my manual lenses, especially the 105/1.8, as the benefits are many and varied.
The one aspect of the dandelion CPU that I really liked, and appreciated with the 500/8 was the focus trap feature.
It allows you the option to hold the AF button during focusing whilst in AF-S mode, and as soon as the target is 'in focus' according to the AF range finder(green dot indicator) the shutter is triggered automatically.
With the 500/8 this can be vital to get a sharp shot or not, simply because it's such a dark lens to view through the vf .. less of a problem with the other faster manual lenses I have.

And a question for Erik on the topic of a dandelion for the 50/1.2. Is there really enough room between the mount and the rear lens for the dandelion?
Even tho my experience with the dandelion wasn't a positive one, I'm always willing to have another go at them if I perceive a shift upwards in quality in the product.
My main concern is always that sub optimal square opening for the round pins of course!
ps. my dandelion experience is from 2012-2013(exif in the images attached).

[Bjørn Rørslett]

"Is there really enough room between the mount and the rear lens for the dandelion?" [50/1.2]

Yes, it is for the 50/1.2 AIS. Not the AI.

[Bjørn Rørslett]

As to the Dandelions, I have seen a fair number of them become broken over the years. Usually when people contact me for help to get the problem fixed .... The standard remedy is to dump the Dandelion and replace with more sturdy stuff. Nikon's contact blocks have metal backing and are held in place by metal screws.

[Erik Lund]

"Is there really enough room between the mount and the rear lens for the dandelion?" [50/1.2]

Yes, it is for the 50/1.2 AIS. Not the AI.

Well when I finished removing the whole front of the Dandelion and sanded down the rear towards the glass there was room, I might have trimmed the rear housing a bit, can't recall, Bjørn has the lens now, maybe he can shoot a couple of closeup pictures of it

[richardHaw]

that's interesting. specially the focus trap thing. 

maybe one day somebody will produce a tougher version? maybe somebody should start a crowd funding program for this 

for such a high wear and stress item, i do expect that they use better materials for the dandelion chips. the coil spring could be replaced by a simple cantilever spring instead.

this feels like squeezing too many things in a tiny package and this might be the reason that they break over time.

[richardHaw]

Rick, I'm impressed by this very thorough write up.  I wouldn't do this kind of restoration work myself, but it is still well worth reading through.  Thanks for sharing it here!

I'm just curious: how is the aperture lever of the 55/2.8 you restored?  I've heard that there are three different versions of Ais 55/2.8 according to the period of production.  If the lever consists of two separate parts, the 55/2.8 is a second version.  The first and the third have one-piece levers.

Thank you, Akira! it is not difficult at all. to be honest, this lens is the first one that i restored.  some a-hole from yahoo! auction sold me bad sample and i had to open it up...

I am not sure about the aperture lever/horns. but i can tell you that the 55mm f/3.5 (metal to rubber focusing ring) has A LOT of variation inside throughout the years. this includes changes made to the helicoid key design and mounting,etc.

the Nikkor-S 50mm f/1.4 also has a lot of internal changes sometimes in between batches.

the changes were minir but will prevent you from swapping parts without modification 

[Erik Lund]

that's interesting. specially the focus trap thing. 

maybe one day somebody will produce a tougher version? maybe somebody should start a crowd funding program for this 

for such a high wear and stress item, i do expect that they use better materials for the dandelion chips. the coil spring could be replaced by a simple cantilever spring instead.

this feels like squeezing too many things in a tiny package and this might be the reason that they break over time.

The Nikon contact blocks are mad out of completely other materials, much more sturdy almost unbreakable,,,

The coil spring design is what makes it so compact, not room for the Nikon cantilever pins in the Dandelion at all... The parts and electronics inside are tiny!

[Akira]

Thank you, Akira! it is not difficult at all. to be honest, this lens is the first one that i restored.  some a-hole from yahoo! auction sold me bad sample and i had to open it up...

I am not sure about the aperture lever/horns. but i can tell you that the 55mm f/3.5 (metal to rubber focusing ring) has A LOT of variation inside throughout the years. this includes changes made to the helicoid key design and mounting,etc.

the Nikkor-S 50mm f/1.4 also has a lot of internal changes sometimes in between batches.

the changes were minir but will prevent you from swapping parts without modification 

Rick, sorry about your unfortunate experience with yahoo! auction, but the sense of emergency seems to have helped...

As for the aperture lever of 55/2.8, I heard that the two-piece aperture lever was replaced with the one-piece one because the two-piece version couldn't synchronize with the 10 fps continuous shooting mode of F2H.

[Bjørn Rørslett]

The proof that you can fit a Dandelion to the 50/1.2 AIS. Erik at his best

This method of attaching the Dandelion alleviates most if not all problems and weakness of the usual positioning, in which the chip will be exposed to excessive wear and tear. Still, the pins are on the long side so their tips will wear rapidly.

[Erik Lund]

thanks for the image Bjørn, the sleeves that house the coil springs for the pins are clearly visible.

Yes the pins are very far ouy as to not remove too much of the Dandelions very thin contact block and to not grind the element,,,

Can you check if I have removed a slight bit of the housing as well?

[Bjørn Rørslett]

"Can you check if I have removed a slight bit of the housing as well?"

Apparently you did.

[Erik Lund]

I thought so Thanks for confirming! It's tight the F-Mount