Correct resistance of Nikon focus ring?

[connloyalist]

How smooth / stiff did Nikon intend the focusing ring on it's manual focus lenses to be? Some of my lenses are a bit on the loose side (50mm 1.4 AI, 24mm 2.8 pre-AI), many are perfectly fine (105mm pre-AI, 35mm, 50mm and 100m series E lenses). But my 135mm 3.5 AI is quite stiff and the 200mm 4.0 AI really needs some effort, although still usable.

I am assuming that the "perfectly fine" category is correct and that on the others the grease has thickened over the years? Interesting by the way that the series E lenses are best in that respect.

I also assume that the only work around is to disassemble the lens and re-grease it?

Regards, C.

[caspert79]

[kiddo]

i have 24mm pre Ai , 55micro 2.8, 105mm 2.5 AI and 300mm ED IF, first one i guess never serviced and kind of soft dry but easy to use, second recently serviced but stiff for my taste (for ex. yashica ml 55mm macro 2.8 is very easy to focus and i suspect never been serviced), 105mm stiff focus and 300mm very easy to use .

[stevemark]

[connloyalist]

[stevemark]

[kiddo]

my rokkor 35mm 1.8 first version is so nice to use, just like a very high quality lens (i suspect never been serviced before), but Septon is about the same league and some years older i guess. Ni/Canon-Topcor i have are just a split of fifty fifty on focus smoothness so i guess it had to do a lot with the quality of grease used at that time, some would use a better one or maybe according to the threads as Steve was mentioning on Leica (maybe that might be an excuse so customers would pass by sooner for a CLA - just like so many software updates on modern cars?)

[mdarnton]

Lenses I've had serviced by one of the bigger Nikon service centers came back to me flying with just a fingertip, almost like they had no resistance at all. None of mine are really difficult. 24/28, 28/2, 35/2, 50/1.4, 50/1.8 Series E, two 50/3.5 Micros, 105/2.5, a 70-210 Series E zoom, even the 200/4 is great, but the shorter ones are best, longer ones maybe 25% stiffer but still loose. Not all have been serviced, but all are light to focus compared with any other brand I've owned. I always assumed that this was intentional and part of the Nikon thing. The AF lenses that I own have just about no resistance at all, but I think that's required for the AF.

Only my non-AI 135/2.8 turns hard, and I think that one is still running on the original 1960-vintage grease.

[BrianSVP]

Generally, the older lenses (pre-ai, early ai and ai-s lenses) are intended to be more damped, but none should be difficult to turn.

The formulation of grease used on the earlier Nikon lenses more typically entirely loses its oil fraction over time, leading to a more loosey-goosey feel than it would have had new, but sometimes it leads to a grittier feel with more resistance, more typically on models with all-aluminum helicals than bi-metal helicals. The cheaper the lens, the more likely to be all-aluminum.

Many of the Series E lenses have part-plastic helicals and typically had a somewhat looser feel than their predecessors when new but end up stiffer as the grease dries out. The AF lenses are entirely undamped and use only light oil if any lube so as not to stress the AF motors. They should have little to no resistance.

[BrianSVP]

[quote="stevemark"]

[stevemark]

[Doc Sharptail]

Most of my lenses are nikkors, and I've had few problems.

Some have touched on a few aspects of grease on the helicoids.
This grease does not simply dry out- it seperates as mentioned above, creating the oily aperture blade condition, and in extreme cases, oily lens elements.
Heat, and disuse seem to be the major culprits with grease degradation.
The trunk of a car in mid summer, or storage near heat sources are things to avoid.
I think the helicoid grease needs to be used a little to avoid degradation as well. If the grease is being worked along the helicoids in normal use, there seems to be lesser chance of it degrading.

I try to store my lenses properly, with the mounting bases downwards, and rotate the focusing rings at least a few times a year. There has been little in the way of problems.
I had a 200mm f4 here with sticking blades, and slightly tight focusing that was bought in that condition- but it still functioned properly despite the stiff focus.
Other than that, no real problems.
I've noticed on lenses with damage to the filter ring area, the focusing feel is a lot stiffer than normal.

I like a very slight resistance to the focus ring.

-D.S.

[RokkorDoctor]

[BrianSVP]

[RokkorDoctor]

As a note of interest;

Whilst many people's first reaction when they see a plastic component is: "cost cutting!", the reality is more complicated than that. There is a cost cutting element, but it is not the only consideration.

Many of the "plastic" components used in lens barrels where dimensional stability is crucial (e.g. helicoids etc.) are high-quality injection-moulded composite materials, usually something like a PC-GF30, which is a polycarbonate with 30% glass-fibre-fill. The injection moulds required for that are expensive to design (certainly in the 80's/90's), are expensive to machine, and have a short service life allowing for only small production runs before a new mould has to be machined. Thus the cost reduction of switching from machined metal parts to injection-moulded engineering composites, whilst a factor, is often overestimated.

Plastics are used for cost-cutting, yes, but also for weight reduction, the ability to form complex compound curved shapes, and a reduction in the number of machining operations required. Fewer machining steps are not necessarily cheaper since complex one-piece high-precision injection mouldings are expensive, but it does reduce the probability of cumulative machining errors/tolerances, a big advantage of complex one-piece injection mouldings.

Another advantage of injection moulded composite parts is that they often have screw holes for self-tapping screws, and don't need to have all screw holes pre-threaded; that is definitely a cost advantage during production.

[stevemark]

Thanks a lot @ Brian and Mark!

Concerning "plastics" / high quality composite materials I have two stories to add which come from my direct contacts with Sony engineers back in the 2008-2011 time frame:

1) While the outer shell of the Sony A900 24 MP DSLR is made out of AZ91D magnesium, the main chassis uses both aluminium and carbon fiber. The (expensive!) carbon fiber was used due to its low expansion coefficient which in turn was very important for precise AF metering.

2) The Sony AL 2.8/28-75mm generally was seen as a mere clone of the Tamron 2.8/28-75mm (at twice the price of the Tamron). However the head of Sony optical engineering for camera lenses told me that the Sony version did use an expensive carbon fiber material while the Tamron was made from cheaper materials. In addidtion, the electronic chip of the Sony was proprietary, guaranteeing faster and more accurate AF operation.

S

[Doc Sharptail]

[RokkorDoctor]

[KEO]