Nikkor 45mm 2.8 GN

[madNbad]

I've posted this on another site but tossing it out because there is so much knowledge here:

I recently bought a very nice Nikkor 45 GN. The serial number places its date of manufacture sometime in late 1968 or early 1969. It has the nine blade aperture and the connector switch works well. The lens looks almost unused but my question is about focusing. When the focusing ring and aperture are linked there is no play in the focusing ring at all. When uncoupled the focusing ring has a fair amount of slack before it actually starts to focus. Is this normal with this lens or would a good cleaning tighten up the focusing ring? I've used many different Nikkors over the years but this lens was never one of them. I didn't pay a lot for this particular lens and tried it out today on the Df and the performance is better than expected making it a keeper. Any ideas would be appreciated.

 

[Hogarth Ferguson]

I have this lens, for almost the entire focus throw it seems like there is almost no movement, at the last bit of the turn it moves rapidly.So, from about infinity to 5 meters, it looks like the lens does not move at all. From 5 meters to about 1.4 it moves a bit, then at 1.4 to .8 it really jumps.

I barely used this lens, it was given to me. I didn't even realize you could lock the focus/aperture. I figured there was something special about it, just never looked into it.

 

[madNbad]

On the bottom of the lens there is a Guide Number scale, select the GN, lock the focus and the aperture with the switch and the aperture changes as you focus to provide better control for flash photography. It was a mechanical means of trying to improve flash results for event photographers. Several months after Nikon released this lens, Braun introduced the first thyristor flash and rendered it obsolete. Other than its' pancake size, it doesn't have a whole lot going for it. Close focus is just shy of a meter, it's only 2.8 and not the sharpest of lenses but it is incredibly small for an SLR lens. The copy I have the focusing ring has almost no resistance between infinity and 30 meters then it starts to focus. That's why I'm trying to find out if the slackness is inherent to the design.

 

[splitimageview]

The one I had had similar behavior

 

[Contarama]

Camera porn deluxe

From TCS. Yotsuya F2 Eye-level finder with the 45/2.8

http://tokyocamerastyle.com/image/348982626

 

[madNbad]

Found the answer to my question. The 45 GN uses a cam for focusing instead of the traditional helical. The cam was used to insure the aperture blades would move as the lens was focused when linked. When the focusing ring is unlinked from the aperture it needs to move to a point where the cam is engaged. Since there is not much change in the focal point between infinity and thirty meters, that accounts for the slackness. As a bonus for Leica and Canon users, the focusing throw is from right to left. The later 45 P (Pancake) uses a helical design. Not much of a close up lens but here's an example, Nikon Df, f22@1/500 ISO 320:

[/url]1MD_0656 2 by Michael DeLuca, on Flickr[/IMG]

A crop from the same image:

[/url]1MD_0656 by Michael DeLuca, on Flickr[/IMG]

 

[leicapixie]

Thank you all about "no feel focus" of lens!:bang:
I stopped using it, thinking (wrongly) not focusing!
I used it decades ago as a compact street lens, mostly for flash use.
Big strobe units, flashbulbs all not auto quench, it was great.
Very sharp (Tessar like) lens, contrasty and very little distortion.

 

[Robert Lai]

As a flash bulb user, I love this lens. It gives me guaranteed correct exposure, as long as I set the correct guide number for the bulb/ film in question. It is also very sharp, and petite. There is nothing not to love about this lens. Finally, it focuses in the Leica / Canon direction, so I don't have the moments of confusion when I switch over from my Leica cameras.

 

[Huss]

Yeah the focus feel is a bit funky, but the lens is great.

Nikon F, 45mm GN, Fuji C200, D850 scan:

 

[madNbad]

Here's a link to the article I found: https://richardhaw.com/2016/03/13/repair-gn-auto-nikkor-45mm-f2-8/

The lens is at the shop getting a CLA, mostly to replace the dried out lubricant. I also bought a couple of 12 packs of Sylvania 25B flashbulbs for fun.

 

[Robert Lai]

Thanks for the link to Richard Haw's article on the lens. His Youtube video well explains the use of the lens.

He recommends using a flash meter to determine your initial guide numbers. This is fine for electronic flash. However, for flash bulbs, it presents problems. The Gossen Luna Pro F, for example will only sample the light output for 1/100 of a second. Depending on which part of the flash bulb's output it starts registering at, there is a significant discrepancy at what the proper exposure should be.

I have a Quantum Instruments Calcu-Flash II, which allows flash exposure calculation from 1/15 to 1/500 seconds. It has a trigger to fire the flash and start the monitoring of the output. Using the 1/15 setting will give you a better idea of the flash output.

In my earlier days, I spent many rolls of slide film and burned through many flash bulbs doing test exposures. My conclusion after all this testing is to just use the guide numbers on the flash bulb box. They form a reasonably good starting point for guide numbers.

 

[madNbad]

Lens had a CLA and the focus is smooth for the full range. There is still very little movement between infinity and about 15 meters but the slackness until focusing starts is gone.