AI superior to AI-S?

[John Koerner]

Some AI lenses do have CRC, yes, that has been known for a very long time. For example, 24/2, 24/2.8, 28/2, 35/1.4. However, one has to realise CRC is not just something one can add to an existing lens, the optical design has to be designed with CRC from the onset and in those early days with little or no computer assistance, this entailed long and gruelling efforts. The models I listed fall in this category. They had CRC in the initial design.

No reliable source documents the 28/2.8 AI had CRC at any time during its production run, comprising 150 - 200 thousand units. Adding CRC would entail computing the lens all over again, and retooling for its production. Which is what Nikon did when the 28/2.8 AIS with a new optical design, much improved near limit, and CRC, was launched.

I think MIR is a great source of info, but I agree it's a far cry from the Nikon engineers.

Could very well just have been a simple mistake on the MIR site ... and mistakes happen to us all.

Thanks for all the input, it is interesting reading, all of it.

[David H. Hartman]

Roland,

If you would like to add CRC information as to the type of implementation I suggest adding a lens schematic illustration in the photos link along with the photos of lens. I'm think many of these schematic images are available though some of the oldest probably are not.

Best,

Dave

[Roland Vink]

Ideally I would like my list to click through to a page about each lens, instead of just one picture. The page would have pictures of the lens, schematics, specifications, serial numbers, accessories, some notes on optical performance - sharpness, distortion, flare etc, some general commentary, and most important - pictures taken with the lens (that's what it's all about right?)

Given my limited time and resources, this won't happen any time soon. Nobody pays me for this (I get a few $100 donations per year if I'm lucky), and I certainly don't get any support from Nikon Inc. It might be a project for when I retire, but that's years away. In the mean time I make use of the pages from Richard de Stoutz for pre-AI lenses, and for cameras I link to dpreview. I suppose I could link through to MIR - there is a lot of good information but also mistakes and I find the commentary rambles on a bit. KR actually has some good reviews on AI and AIS lenses (such as AI 28/2.8 ), but not always accurate either - I suspect he lifts his figures on production numbers from my site, but sometimes they are really out - I contacted him about it once but never got a reply.

[Roland Vink]

I can, unfortunately, confirm, that the 105/2.8 Micro AIS has a CRC design that makes it quite susceptible to wear and tear.

This is a curious lens in some ways. It comes after the AI and AIS 105/4 micro which has a remarkably simple optical design with just 5 elements in 3 groups and no floating elements (or AF, VR ...), It focuses purely by extension giving a very long working distance for this class of lens. Optical performance is pretty even at all distances, perhaps a little weaker at infinity, and contrast is excellent due to the simple optics. It also has a useful built-in hood (especially the AIS).

The AIS 105/2.8 by contrast has much more sophisticated optical design. It has 10 elements in 9 groups - twice the number of elements and three times the air-glass surfaces. It has three "groups" of elements - a fixed teleconverter group at the rear, and two at the front in a double-gauss configuration with CRC. All this achieves a one stop advantage in speed. Sharpness is excellent, better than the old lens at distance, and about the same up close. But the working distance is shorter due to focal length shortening at close range. Operation with extension tubes is somewhat compromised due to the CRC mechanism. Contrast is lower due to the higher number of elements (my sample has newer SIC coating, looking into the front it does not look very transparent, even compared to other lenses with similar number of elements, not sure why). And for all the optical wizardry it still only gets to 1:2. There is no longer a built in hood either.

The AF 105/2.8 micro has a similar but refined optical design with 9 elements in 8 groups. It can go directly to 1:1 without extension tubes and contrast seems to be a little better - the front lenses do look more transparent. However it is relatively bulky and has more extreme focal length shortening at close range, and the focus throw is short - focusing near infinity requires a very fine touch.

Between the AIS 105/4 and AF 105/2.8 micro (and 105/2.5) I bypassed the AIS 105/2.8 micro for many years. Last year I decided to buy one and have not been disappointed. Of the 105 micros it is the most compact and the f/2.8 makes it useful as a general purpose tele which focuses closer than my 105/2.5. Sharpness is excellent and the bokeh is smooth - better than the AF which is a little harsh. The lower contrast hasn't been a problem either. Maybe it is not as robust as some other lenses, but I'm not hard on my gear so it should last for years.

[richardHaw]

f/2.8 is also much more useful for focusing

especially when fully extended

[David H. Hartman]

A full set of extension tubes from the PK-11a, PK-12, PK-13 and PN-11 can allow keeping the 105/2.8 AIS Micro with the focus ring close to the near focus limit. One will use the shortest tube necessary. This should keep the CRC in a better position for flat field subjects.

I'm nots having the CRC in wrong possition that important if the corners are well out of focus with large aperture like f/2.8?

Dave Hartman

[Erik Lund]

Did anyone notice this :

When I read:

However, Nikon's CRC system was not incorporated into the design yet and that was not until the late Ai or the Ai-S version in 1981, such feature was incorporated

I see the statement stated as an uncertainty : or like if he is not sure,,,

Otherwise it would have benn stated like this: and

However, Nikon's CRC system was not incorporated into the design yet and that was not until the late Ai and the Ai-S version in 1981, such feature was incorporated

BTW: Easy to see from the repair manual for the specific lens - They are not serial # specific,,,

[pluton]

The mir.com site is plagued with inaccuracies.  Just yesterday, I was reading there about Nikon teleconverters, and the site stated that the TC-14B (which a a protruding front element) is useable with the 135/2 Ai/AiS (which has a protruding rear element). 

[Roland Vink]

The TC-14B will fit the AI/AIS 135/2.8, maybe the 135/3.5 as well...

[Akira]

According to Nikon catalog from 1982 (before TC-14 splits into -A and -B), the only 135mm lens that is compatible with TC-14 is the f3.5 version.  The protrusion of the front elements of both the TC-14 and TC-14B looks the same.

[Erik Lund]

No the TC14A doesn't have a protution in the front!

[Roland Vink]

TC-14 and TC-14B are the same, the first is AI, the second is AIS. These are designed for telephotos and have a protruding front lens.

The TC-14A is designed for shorter lenses, no protruding element, so will fit any lens.

[John Koerner]

The mir.com site is plagued with inaccuracies.

The MIR site is plagued with more historic Nikon photos, and information, than any site I know of.

There are some inaccuracies, including typos, but it is a colossal effort that I am grateful someone took all that time to do.

It is easier to "point out the cracks" in a tremendous skyscraper ... than it is to build a better skyscraper

[Asle F]

The TC-14B will fit the AI/AIS 135/2.8, maybe the 135/3.5 as well...

No. TC-14B does not fit AI 135mm/2.8.

[Roland Vink]

Thank you for the correction. The TC-14B does fit the AIS version of the 135/2.8. Although it is optically the same as the AI, the collar around the rear lens is just a little wider so that TC-14B will fit.