AI superior to AI-S?

[Bjørn Rørslett]

"(front group for CRC)... possibly the AIS 18/3.5"

The 18/3.5 AIS uses the rear lens cell for CRC.

[David H. Hartman]

Integrated coatings v. Super Integrated Coatings: what I notice is ghosts when they appear are more pastels or less saturated and not as intense with SIC coatings. Contrast is surely higher in difficult light.

Dave

[Roland Vink]

Thanks Bjørn, I struck out my comment in my previous post.

[pluton]

Did the Mk1 24/2.8(9/7) lens have front group CRC?

[Roland Vink]

No, none of the 24mm Nikkors have front CRC.

[richardHaw]

The 24/2.8  (Nikkor-N)

[Erik Lund]

No, none of the 24mm Nikkors have front CRC.

Suggestion:

Roland, maybe you have time to go through your database with regard to CRC, since we in this thread now have more or less all of the variants covered,,,

I know it's a lot of work but I would suggest that you enrich you data with an indication whether the CRC is CRC-F or CRC-R

[richardHaw]

so far what I have encountered personally (touched myself, forgot the others):

CRC-F:
55/2.8 Ai-S
105mm f/2.8 Ai-S
28/2.8 Ai-S (IIRC)

CRC-R:
24/2.8N

 

[FGAng]

Can I ask for descriptions of the workings of CRC-F and CRC-R?

I have a 24mm f/2.8 K that I am itching to take apart to clean the helicoid and regrease it.  Whatever materials would be appreciated.

Rick - thanks for the youtube link you sent earlier.

FG

[John Koerner]

There is no information concerning CRC and the 28/2.8 AI. So no reason to assume that lens version had the feature.

On the contrary, there is such information: the MIR site references this possibility in the opening paragraph on the Non-AI version, speaking of the late AI (not all AIs) as well as Ai-S version. It says:

• "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."

Therefore, based on my interpretation of the above paragraph by MIR, I assumed some of the later AI Nikkor 28mm f/2.8s implemented CRC.

On the other hand, Ken Rockwell affirms what you said on his page devoted to the AI version.

• "Optics
  7 elements in 7 groups. Nikon Integrated multicoating (NIC). Conventional design, no CRC."

However, Rockwell also says this:

• Nikon does not mark lenses that have CRC. You have to read the sales literature or look for yourself.

Two lenses in the 28 mm range do have CRC, viz. the 28/2 AI+AIS and 28/2.8 AIS. (plus the elusive 28/1.4 AF, but it is not relevant in the current context as there is no AI counterpart). Interestingly though these lenses did CRC by the front rather than the usual implementation with rear element(s).

Thank you.

Based on what I read, I think the probability exists that some of the late AI 28mm f/2.8s may have implemented CRC before the Ai-S versions became the norm, likely in 1981 (the Ai-S came out in August, while the AI continued to be made until September).

I am no expert, but most definitely interpreted the MIR site to suggest this.

[John Koerner]

Suggestion:

Roland, maybe you have time to go through your database with regard to CRC, since we in this thread now have more or less all of the variants covered,,,

I know it's a lot of work but I would suggest that you enrich you data with an indication whether the CRC is CRC-F or CRC-R

This is a very helpful suggestion.

[John Koerner]

If the AI also focused to 0.2m and the focus pitch was kept the same, it would require near 180° to cover the distance between 0.3 ~ 0.2m...

I assume you are referring to the 28/2? If so, yes, it does have CRC, but the AIS the extends the focus range further, not sure if they made any other refinements to the optical design.

If you were referring to the 28/2.8, the AI and pre-AI versions don't have it, only the AIS.

See above quotes from MIR, referencing late AI 28/2.8s having CRC ...

As for how CRC is implemented, as Bjørn said, the AIS 28/2.8 and 28/2 versions have the floating group at the front - when focusing you will see that the front element rotates inside the mount, and the gap between the front element and filter ring increases slightly. Other lenses with CRC implemented at the front include the AIS and AF 20/2.8, AF 16/2.8 fisheye, and possibly the AIS 18/3.5.

Interesting distinction, thank you. Any research on which implementation is superior?

Jack

[John Koerner]

For me this is mixed: the AIS Nikkors are generally smoother focusing with a shorter throw on the focus ring. This is good for PJ, PR, candid and street photography. I used to have a strong preference for AIS. AI Nikkors even new out of the box never seemed as smooth as AIS Nikkors. The long throw of AI Nikkors is a benefit to accurate focus and focus with live view.

That is exactly my impression and interpretation of the difference, thank you.

This is why I prefer the AI-S 28mm f/2.8 to the AI version ... but would prefer more precision-focusing on something like the Noct., especially since it has a razor-thin DOF at f/1.2.

Diffraction stars: an odd number of straight blades give a star with twice the spokes as the number of blades. I like 9 blade straight apertures more prevalent on AIS Nikkors for their 18 spoke stars. 7 blade straight aperatures give 14 spoke stars which is fine. 6 blade straight blade apertures give 12 spokes but they are superimposed on each other and you see only six spoke stars.

Interesting, thank you.

I also prefer odd sided polygon bright out of focus highlights and more sides are generally better.

So AIS v. AI is mixed for me.

Dave Hartman

Appreciate the insight

[Bjørn Rørslett]

The AI 28/2.8 Nikkor is  a 7/7 design, has no CRC, and focuses to 0.3 m.

The AIS 28/2.8 Nikkor is an 8/8 design, implements front group CRC, and focuses to 0.2 m.

It is always best to look inside the lens instead of building a case on non-verified information.

Thus, in order to verify the existence of the mythical AI 28/2.8 with CRC, a lens that focuses to 0.2 m and has the non-linear aperture mechanism of AI, needs to be evidenced.

[John Koerner]

The AI 28/2.8 Nikkor is  a 7/7 design, has no CRC, and focuses to 0.3 m.

The AIS 28/2.8 Nikkor is an 8/8 design, implements front group CRC, and focuses to 0.2 m.

Okay.

It is always best to look inside the lens instead of building a case on non-verified information.

That is pretty much what Rockwell said.

I wasn't "building a case," I mentioned a reference to this earlier ... and you emphatically said there was no reference ... and I showed you that, in fact, there was.

I realize there is a possibility MIR made a mistake, but there is also a possibility that "most" AI lenses don't have CRC, but that some may (if the reference from MIR is true).

Looking inside "a" lens (or even a few lenses) is not looking inside all lenses ever made of that type.

The 28/2.8 AI lens was made for 4 years. If the first 3 years' worth did not implement CRC, but the last 6 months did, right before the AIS change, which also did, it is possible to have the situation MIR referred to.

Again, I don't know, but there is a suggestion to this end.

Thus, in order to verify the existence of the mythical AI 28/2.8 with CRC, a lens that focuses to 0.2 m and has the non-linear aperture mechanism of AI, needs to be evidenced.

It may be worthwhile to look for an AI version of this lens on E-Bay, and deliberately select one with the latest-possible serial number, and have a look. Might have to be an asterisk* on the "no CRC" status of the AI 28/2.8

If the mythical creature exists, might be considered a collector's item