Taking apart the AF-S 105 1.4

[Ilkka Nissilä]

I read a lot of comments about the swirly bokeh, does it go away if the lens is stopped down to f/1.8 or  f/2 ? If so I don't see that as a problem.

Stopping down you don't get a circular highlight. I know it is subtle difference but ... I can try to do some tests to see when it becomes imperceptible.

I've used the 105/2 DC for a very long time and never seen anything giving the impression of swirliness in the out of focus areas in images made with that lens.

[pluton]

We actually have/are a few guys here that take our new lenses apart to see ans check underneath the skin,,, I remember clearly the discussions when the first AFS 1.4G lenses came out,,,

Yes, Eric, thank you for the correction.  I still can visualize the photo that [presumably] you made of the little DC motor that drives the focus mech.

[pluton]

The part with the Ring- Type SWM must have been 'lost in translation' or something like that at Nikon, at least I hope so,,, yes embarrassing indeed.

We'll check to see if they quietly remove that statement in later editions of the ads/brochures/promo material..

[Macro_Cosmos]

I really wonder if there's any limitations for Nikon to use a Ring-type SWM in their fast prime lenses.

The only f/1.4 lens I can recall that uses a Ring-type SWM is the 50mm f/1.4G. The other extremely expensive f1.4 and most of the economical (but great) f1.8 lenses all use a compact SWM.

Nikon's 200mm f/2 uses a ring SWM, their prime telephoto lenses and zoom telephoto lenses all use this type of motor. Even cheap lenses such as the 70-300mm VR uses a ring SWM.

Ring SWMs are more powerful and they are capable to drive larger elements, however I do think they are also less precise, but of course a lot faster.
Compact SWMs aren't that cheap to make, it's not the "Chinese toy motor" that some cough people likes to claim it is. I think it allows finer adjustments, it is more precise but a lot slower and less powerful.

But here, we have Canon, using ring-type SWMs in some of their newer fast f1.4 prime lenses: https://www.lensrentals.com/blog/2015/12/canon-35mm-f1-4-mk-ii-teardown/

All this is really confusing. Nikon did claim on their 105mm/1.4E page that, to paraphrase "the lens uses gearless swm", which obviously isn't true. I knew it after handling the 105mm. It's squeaky and not fast. Not that huge of a problem, but hey, this is bad PR. This combined with the heavily edited sample photos, and one portrait which the photographer failed to nail the focus on the eye.

I'm a big Nikon fanboy actually, but this riddle has been bothering me for some time now. There must be legitimate reasons for Nikon to not use a ring-type SWM in such lenses. The 105mm is expensive, justifiably so. Not a lot is saved by using a compact SWM.

[schwett]

We'll check to see if they quietly remove that statement in later editions of the ads/brochures/promo material..

they already removed it from the website...

[Erik Lund]

,,,
Ring SWMs are more powerful and they are capable to drive larger elements, however I do think they are also less precise, but of course a lot faster.,,,,,,,

The 1.4 lenses are slow by design to achieve a precise focus, so Nikon states. Similar when you use a TC-E20 on any lens the focus speed goes down a very clear design choise, you can tape over the last pin on the TC and it will focus at full speed, but the camera will often miss the target focus plane and focus right past it (Hunt for focus) very easy to test for yourself

Ring motors less precise? I don't know I have never seen any statements from Nikon on this and certainly not in my experience, they are very precise,,,

[Akira]

When I had my AF-S 24/1.8G at the Nikon service, they told me that the standard position of the SWM motor will be off over time.  When it is off, the focusing element in the lens will fail to stop at the position precisely following the "stop" command transmitted from the camera.  That's why the AF-S lenses need periodical calibration.