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Meaning of AI vs. AIs?

Major Black , Nov 28, 2005; 07:17 p.m.

What is the difference betwen AI and AI's lenses?

Are AI the lenses with the prong coupler thingie that work on the old F camera?

I am going to sell some lenses with the prong coupler and want to know if they are considered AI or AIs. Thanks for any help. :-)


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Alan Olander , Nov 28, 2005; 07:31 p.m.

AI and AIS both have the "prong coupler thingie" or "ears". Non-AI lenses have them, too. Here's a link that shows the differences: http://www.nikonlinks.com/unklbil/nomenclature.htm

Eric Bogaerts , Nov 28, 2005; 07:33 p.m.

All manual focus Nikkors, with the exception of the series e manual focus lenses, have the metal "rabbit ears" prong. That has nothing to do with a lens' AI or AIS status. Roland Vink has a website set up whereas you can check the serial number of your lens to tell which version it is (non AI, AI, and AIS).

AIS lenses are very easy to tell from a visual standpoint. There is a slight "scoop" on the metal part of the lens' mount. AI lenses aren't quite as easy to differentiate from non AI lenses, particularly if they've had an AI factory ring installed on them.

Go here: http://www.photosynthesis.co.nz/nikon/serialno.html

Bernard Frank , Nov 28, 2005; 08:24 p.m.

What do you mean, Eric? I think AI lenses are easy to differentiate from non-AI since they have the second row of smaller aperture numbers, in addition to the diaphragm lever. Don't you think so?

Kelly Flanigan , Nov 28, 2005; 08:49 p.m.

Many of the real old Nikon F lenses had no auto diaphram,and thus no fork. AIS lenses have an orange minimum f stop; ie like F22 in orange. Only some cameras really need the AIS versus AI feature.

Kelly Flanigan , Nov 28, 2005; 09:03 p.m.

AIS makes the diaphram ring rotation linear; the Nikon FA uses this. AIS also in some lenses brought a less robust, downsized lighter mount, ie lower cost design with less screws. The upsize is than some folks crave AIS over AI lenses; and this creats valueable deals in the AI used market. Folks pay higher for a less robust lens, with the same optics and coatings!. Some lenses have an enhanced multicoating versus a regular multicoating, good for bragging, but really a wash in most cases. The FA FG and 2XXX series and a few others use the AIS linear feature.

Eric Bogaerts , Nov 29, 2005; 01:31 a.m.

Bernard: I have an AI 50mm f/2 in front of me, and it has the second smaller aperture scale on it. I had forgotten about the orange colored minimum aperture. In terms of the aperture lever, as far as I know all Nikkors with an auto aperture have an apeture lever. The AIS lens aperture lever movement is linear, versus the AI apeture movement which is non-linear.

When I look at Nikkors on the used market, I swing the lenses to look at the mount or I want to see a picture of the lens mount - easy and quick. Roland Vink's website is a quick resource if I get a serial number.

David H. Hartman , Nov 29, 2005; 03:56 a.m.

“AIS makes the diaphram ring rotation linear; the Nikon FA uses this.” --Kelly Flanigan

No, it is the aperture coupling lever and the stopping down of the aperture that is linear. This is necessary for Shutter Preferred and Programmed modes so the camera can accurately stop down the lens.

This feature was first used buy the FA and later by the F4. There is one other that used this feature in a manual focus, non-CPU lens, perhaps the N6000 or something. For those who are interested, information on this third camera can be found at Photography in Malaysia.

To those who wish to add a CPU to their manual focus Nikkors the AIS is more desirable if they use S and P modes. If not AIS v. AI makes no difference.

“The upsize is than some folks crave AIS over AI lenses; and this creats valueable deals in the AI used market. Folks pay higher for a less robust lens, with the same optics and coatings!” --Kelly Flanigan

“Crave?” Come now, there are important functional differences between AIS and AI Nikkors over and above the linear aperture issue.

AIS Nikkors are smoother and faster focusing. I prefer AIS Nikkors in lenses I’ll use for candid photography. This generally means 50mm and longer but I don’t mind the smoothness of my 28/2.0 AIS. The AI Nikkors have a longer throw on the focus ring so they provide longer, more useful distance scales and generally have more graduations on the DOF scale so I generally prefer AI Nikkors for 50mm lenses and shorter. For example the 24/2.8 AI. OK, so how can I prefer both AI and AIS for 50mm lenses? I guess I’d rather have (as I do) a 50/1.8 AI and I’d rather have (as I do) a 50/1.4 AIS because of the general use I have for each.

“Same optics and coating?” Very often the same optics but some AIS Nikkors have the newer Super Integrated Coatings. I own two: a 135/2.8 AIS and 28/2.0 AIS. I’ve compared the 28/2.0 AIS with SIC and without. This is not the best way to judge the worth of Super IC coatings as these lenses are very flare and ghost resistant. I have other less flare resident AF Nikkors with SIC so I can say that lenses with SIC have less colorful ghosts. I don't consider SIC worth replacing most of my manual focus lenses but it can't be worse then the older IC coatings. It's very safe to say that SIC is very useful in zoom lenses. I would likely prefer a 24/2.8 AIS with Super IC over my 24/2.8 AI but I have not had a chance to compare lenses. The 24/2.8 is quite prone to ghosts under adverse lighting.

“Good for bragging?” Can you prove that’s all it’s good for? Give me facts not sarcasm.

“…and a few others use the AIS linear feature.” --Kelly Flanigan

Whoa there! Actually all AF Nikkors are also AIS lenses and have that “linear feature.” All AF Nikon SLR(s) and DSLR(s) that offer Shutter Preferred and Program modes (that's all of them isn't it?) require the linear feature for those modes.

Anyway “Lust” would be a better word than crave because I have a general lust for Nikon glass, AIS, AI, AI(ed), Pre-AI, AF-D and even G Type with certain restrictions.


Dave Hartman.

NAS is not evil; NAS is good! (sm).

PS: Now don’t say I’m being mean. You need to check your facts.

Bernard Frank , Nov 29, 2005; 09:14 a.m.

That's just what I was saying, Eric. I was responding to your (quote):

" AI lenses aren't quite as easy to differentiate from non AI lenses, particularly if they've had an AI factory ring installed on them. "

Maybe you meant "AI lenses ARE EASY to differentiate..."

Anyway, I think this thread is very useful. Particularly David H.'s post (as usual). So many people don't know what the differences are and how to tell the versions apart. Here is a photo that might be of some help. "Rabbit ears" can be found on AI lenses (it's irrelevant), but they serve no purpose except on non-AI older bodies.

Kelly Flanigan , Nov 29, 2005; 10:14 a.m.

Dave; many of us who started with the Nikon F view the AIS as downsized lenses, with SOME ones that are cost reduced, ones that are less robust. Not many cameras really need the AIS features. Paying more for the same optics with a sometimes lighter duty mount is appalling. With the 105mm F2.5 the AIS adds a lens hood, thus the mechanics were changed. The grease was changed somewhere roughly in the AI to AIS change, I have seen radically more grease migration to the optics with AIS than AI lenses. IF a persons cameras dont need the AIS feature; why pay more for a lens? Many of the classical robust non AI lenses were redesigned with lighter mounts with less screws, plastic parts inside, cheaper greases, in the move to AI or AIS. With alot of lenses there is no change in the optics with non-AI to AI to AIS , like the 105mm F2.5 from 1971 on. The Olympus OM-1 fad of the 1970's caused alot of the major camera lines to go into a downsize, slimming down, cost reduced product line. Cars got slimmer too. BUT then too there was a radical increase in optical computing power; and some lenses were redesigned. The AIS being a linear diaphrame is from Nikons blurbs as what the AIS feature/change was for. It is meant for the lay puplic; who usually only buys a lens or two in their lifetime.

Marketing has to say that newer lenses are "better" to sell more lenses. Long ago some Nikkors had a steel stop down lever in the lens; then they when to aluminum for lower mass. With some of these steel versions; the arm would get little wear with a motor drive, but sometimes had resonance/bounce issues at faster frame rates. The lighter aluminum versions get a wear notch after alot of usage, but have less resonance/bounce issues of the diaphrame.

With samples of one tests, folks here skirt sample variation and talk alot about AIS verus AI in a lens such as the 105mm F2.5 that really has the same optics since late 1970, in the pre AI days. The result is folks pay more for a lens that has the same optics.

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