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nikon 50mm
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PostPosted: Fri Sep 29, 2023 10:57 am    Post subject: nikon 50mm Reply with quote
A check and comparison of nikon 50's in my current set.



L-R:

Nikkor H 50mm f2, Nikkor K 50mm f2 pre-A/I, Nikkor 50mm f2 with factory A/I ring, Nikkor 50mm f2 with factory A/I ring, Nikkor 50mm f1.4 A/I-s.
The only difference worth noting here is that the chrome grasping ring on the K is a shade narrower than the other two K based variants. IIRC, the optical scheme stayed the same.



Nameplate and coatings comparison.
The single coating on the H is easily apparent here.
Note "higher" serial number on the pre-A/I K.



View of the mount ends.
Note K and the first from left A/I version are identical around the rear element. Second from right A/I variant uses a different rear element retainer ring, and has a prong that the earlier lenses lack.



Another view of the rear element ring prong. 50mm f1.4 A/I-s has similar, smaller and shallower prong.

I have another of the A/I versions at my sister's place. It is identical to the second from right lens, except it has 3 c/h bayonet screws, instead of 5.

The best explanation I came across for that protruding prong is that it was part of Nikon's earlier attempts at automated TTL flash control. I have yet to encounter a verifiable purpose for it.

-D.S.


PostPosted: Fri Sep 29, 2023 11:32 am    Post subject: Re: nikon 50mm Reply with quote
Doc Sharptail wrote:

Note K and the first from left A/I version are identical around the rear element. Second from right A/I variant uses a different rear element retainer ring, and has a prong that the earlier lenses lack.
...
Another view of the rear element ring prong. 50mm f1.4 A/I-s has similar, smaller and shallower prong.
...
The best explanation I came across for that protruding prong is that it was part of Nikon's earlier attempts at automated TTL flash control.

Wrong.


Doc Sharptail wrote:

I have yet to encounter a verifiable purpose for it.


Get a Nikon FA. Or an FG. Or an F4. Heck, even a F301 will do it ... !! Don't stick to your F2 Wink!

S


PostPosted: Fri Sep 29, 2023 4:03 pm    Post subject: Re: nikon 50mm Reply with quote
stevemark wrote:
Doc Sharptail wrote:

Note K and the first from left A/I version are identical around the rear element. Second from right A/I variant uses a different rear element retainer ring, and has a prong that the earlier lenses lack.
...
Another view of the rear element ring prong. 50mm f1.4 A/I-s has similar, smaller and shallower prong.
...
The best explanation I came across for that protruding prong is that it was part of Nikon's earlier attempts at automated TTL flash control.





Doc Sharptail wrote:

I have yet to encounter a verifiable purpose for it.


Wrong.

Get a Nikon FA. Or an FG. Or an F4. Heck, even a F301 will do it ... !! Don't stick to your F2 Wink!

S


I've had two FG, and one FG-20 cameras pass through my hands . (That lens with the prong came on a factory new late run FE.)
The cameras you list all have little in the way of provision for communicating with pre-A/I lenses, which is what turned me off the FE-2, and later cameras. The F2 is still the one that I keep- it runs circles around the others when it comes to longetivity, and backwards compatibility. Even the FE and it's decade lasting shutter resistor offered at least stop down metering. There's a plastic bodied F-XXX body in the junk box that does not get used- for the reasons listed above. Call me a caveman if you will- there's still not a single A/F lens here, which is fine by me Wink

If you are going to tell someone they're wrong, at least back it up with something. Shocked Shocked

-D.S.


PostPosted: Fri Sep 29, 2023 4:12 pm    Post subject: Re: nikon 50mm Reply with quote
Doc Sharptail wrote:

If you are going to tell someone they're wrong, at least back it up with something. Shocked Shocked

-D.S.


Don't worry (and certainly no need to be double-shocked)!! I thought you'd understand that I was joking ... (the smiley Wink should have told you).

Anyway, you should know that I very much appreciate the various F, F-1, F2, F3, and New F-1 bodies from CaNikon.
Nevertheless I was NOT joking when I told you to look at a FA / FG / F4 / F301 to solve your mystery!

S


PostPosted: Fri Sep 29, 2023 4:42 pm    Post subject: Reply with quote
Hi Doc,

That prong, or post, it tells the camera the max. aperture opening. At least the inner, higher part does so, judging from the comparison of a f3.5 and a f1.4 lens. What the lower, outer part of the articulated post does, I have not found out yet. However, this outer, lower part of the post is always 8.5mm protruding from the bayonet flange. The measurement is a bit shaky, but it´s the same on all my Nikkors. The inner, higher part differs. That might just be because there is sufficient room in the camera to accomodate it, and Nikon probably shortened it down on later lenses.

On the left the 20mm f3.5, right side the 50mm f1.4.



Both lenses again from a different angle. Both are AiS and therefore the smallest aperture is in orange.




Left side 50mm f2 Ai, right side 50mm f1.4 AiS. Notice the difference in color markings on the aperture ring.



Btw, Wikipedia, from where I have stolen that wisdom with the aperture post, has also something about an update on the bayonet that came with AiS for shutter/program mode enabled cameras. It´s the Focal Length Indexing Ridge — required for the shutter priority and other auto-aperture exposure modes of the Nikon FA, F-301/N2000, and F-501/N2020 cameras (although the FA will operate correctly in shutter priority and program modes with any AI lens). Later cameras did not require these features, and interoperate with AI and AI-S lenses identically. AI-S lenses with a focal length of 135mm or longer are indicated by a ridge on the lens mount, used by FA and F-501 to engage high-speed-biased Program Autoexposure. However, digital bodies ignore both the aperture indexing post and the focal length ridge.

I wonder if I identified that correctly. Left is the 135mm f2 AiS, right the 50mm f2 Ai.



The groove that all AiS-lenses have: Standardized aperture control. AI-S lens apertures move in a standardized fashion in relation to their stop-down levers. The levers of AI and pre-AI lenses were intended only to close the aperture to its manual setting. The advance of aperture control by the camera body itself, by partial actuation of the stop-down lever, meant more precision was required for consistent exposure. This feature is indicated by a Lens Type Signal notch in the lens mount. Note that despite popular misconception, the F4 is NOT capable of engaging P and S auto-exposure modes with non-CPU lenses.

Btw. that color coding on the aperture ring. It differs even between AiS lenses. The 135mm f2 has f8 marked in yellow, whereas it´s f11 on the 20mm and f5.6 on the 50mm f1.4. I´m sure that means something, probably the optimum aperture. Would be interesting to find out, since it´s useful also on modern bodies.


PostPosted: Fri Sep 29, 2023 7:15 pm    Post subject: Reply with quote
ZuikosHexanonsandVivitars wrote:
Note that despite popular misconception, the F4 is NOT capable of engaging P and S auto-exposure modes with non-CPU lenses.[/i]


I didn't know that as well, since I never was working with an F4 (though I have one). That's pretty amazing - especially since Minolta could do S and P modes with XD-7 and X-700, respectively, of course without CPU-lenses. Why not Nikon, ten years later??

The width of the prong clearly is related to the maximal aperture of the lens. In addition it enables the multi-metering on cameras such as the FA or the F4 (it's a kind of "on/off" switch; you can explore that by moving the corresponding lever inside the bayonet e. g. of an F4 and watch the viewfinder jumping from "integral metering" to "multimode metering").

The other feature of the prong - its length or better the length of its "second step" - is a mystery to me, too. No Nikon SLR I own has an additional pickup to scan the length (height) of this second step - neither FA nor FG, nor F4 or any of the F301/F501 models.

A possible hint comes from my experience with working with Sony engineers on a frimware upgrade for the Sony A900. The original firmware did accept lenses without CPU, but only in manual (M) mode. We were pushing the A900 guys to give us an aperture priority automatic exposure (A) mode, but for quite some time they refused to implement it since multi-metering would need additional information about the location (and the diameter?) of the exit pupil of the lens (but not about the maximum aperture!). In other words: The A900 multi metering wouldn't give a reliable exposure when used with non-CPU lenses. That' very true indeed - using non-CPU lenses on the A900 may result in under- or overexposure of up to 2 EV!

Another - much more prosaic - explanation might be that the elongated part of the prong simply protects the rear lens from damage: A prolongated prong usually is found on those lenses that have a protruding rear lens.

S


PostPosted: Sun Oct 01, 2023 5:22 am    Post subject: Reply with quote
ZuikosHexanonsandVivitars wrote:
Note that despite popular misconception, the F4 is NOT capable of engaging P and S auto-exposure modes with non-CPU lenses.[/i]


Neither do the later DSLR's on the pro-sumer side. I'm not sure about the single digit flagship series~ I can't remember if the D-6 has the folding A/I lever. The last camera I'm aware of having it was the DF. I doubt if the DF would do P-program or S-shutter priority automation with non-CPU lenses.

Incidentally, that A/I lever on the camera side is what detects the primary maximum aperture on the earlier, (and some later) cameras.

-D.S.


PostPosted: Mon Oct 02, 2023 7:38 am    Post subject: Reply with quote
Hi Doc,

Look up page 318 of the Df manual; it can neither P nor S with Ai and older, but the compatibility is impressive nevertheless.

https://download.nikonimglib.com/archive3/ofnoB00QeUNQ03zrQlV93Vwwa867/Df_(En)04.pdf


PostPosted: Mon Oct 02, 2023 11:06 am    Post subject: Reply with quote
ZuikosHexanonsandVivitars wrote:
Hi Doc,

Look up page 318 of the Df manual; it can neither P nor S with Ai and older, but the compatibility is impressive nevertheless.

https://download.nikonimglib.com/archive3/ofnoB00QeUNQ03zrQlV93Vwwa867/Df_(En)04.pdf


I can't get this link to work. I'll back track from the title later on.

That A/I lever has been one of the few sore points I've had with the Nikon DSLR line. Without the folding back lever, no stop down metering in manual. That point is also what soured me on the FE-2. It was nice to see it added back to the DF.

The flip side is that the D-810 will give full area multi-pattern metering as long as there is an A/I tab on the lens, and the focal length and maximum aperture are entered into EXIF data. I don't use that metering mode vey much- I don't care for the modern color rendition it provides, but that is a matter of personal taste.

-D.S.


PostPosted: Mon Oct 02, 2023 2:33 pm    Post subject: Reply with quote
Doc Sharptail wrote:
ZuikosHexanonsandVivitars wrote:
Hi Doc,

Look up page 318 of the Df manual; it can neither P nor S with Ai and older, but the compatibility is impressive nevertheless.

https://download.nikonimglib.com/archive3/ofnoB00QeUNQ03zrQlV93Vwwa867/Df_(En)04.pdf


I can't get this link to work. I'll back track from the title later on.

That A/I lever has been one of the few sore points I've had with the Nikon DSLR line. Without the folding back lever, no stop down metering in manual. That point is also what soured me on the FE-2. It was nice to see it added back to the DF.

The flip side is that the D-810 will give full area multi-pattern metering as long as there is an A/I tab on the lens, and the focal length and maximum aperture are entered into EXIF data. I don't use that metering mode vey much- I don't care for the modern color rendition it provides, but that is a matter of personal taste.

-D.S.


Add _(En)04.pdf to the end of that link
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