Nikon Metering Coupler

[Kenneth Rich]

I recently completed removal of exposure metering "forks" on the Nikkor  lenses that still had them, and having done so I thought it might be wise to replace the screws to stop moisture, dust, foreign body entry into the lens.  The down side is that the screws could be too long to seat.  Will I cause mechanical damage/interference  if I over=tighten these little screws?

[Akira]

I've tried to use the original screws to cover the holes, but, as you say, the original screws were so long that hits the barrel, which prevents the aperture ring to rotate smoothly or the long screws lock the aperture ring.  I've experienced that with Ais 50/1.4.  In those cases, I'm pretty sure that some internal part is damaged or at leased scratched.

The Nikon service offered the removal of the prongs and replace the original screw with the shorter ones.

[Roland Vink]

I do the same with most of my AI and AIS lenses (the screws on my AI 50/1.8 are too tight to get out). In most cases you can replace the screws with no problem - the lenses look better with the chrome screws heads than with empty holes. In some lenses, such as the AI 400/5.6*ED and AIS 50/1.4, the screws are too long, they will bind against the inner barrel and effectively lock the aperture ring. If you decide to replace the screws, take care as you tighten them, if you feel any resistance or the aperture ring no longer turns freely, take the screws out.

To get around the problem, the previous owner of my AI 400/5.6 removed the prong and padded out the screws with a short strip of metal like the base of the original aperture prong. I have seen lenses for sale (ebay) with no prong where the chrome screws are replaced by shorter black-headed screws. These must be the screws used by Nikon Service that Akira mentioned, I'm not sure where you can get these screws from.

[Akira]

I have seen lenses for sale (ebay) with no prong where the chrome screws are replaced by shorter black-headed screws. These must be the screws used by Nikon Service that Akira mentioned, I'm not sure where you can get these screws from.

Yes, that's right, Roland.  The shorter screw Nikon Service replaced was black.

[Hugh_3170]

I prefer to just have empty holes - less to fall off or to go wrong.

However another solution is to find some very small diameter washers and use one or more of these to provide a pad under each of the existing screw heads.  The thickness of the washer(s) under each screw head should be about that of the prong which is removed in order to prevent binding when the screws are tightened.  The small washers are much easier and cheaper to find than are the shortened M1.4 flat head screws of the correct length.

[Akira]

Frankly speaking, I would doubt the need of removing the prong in these digital days.  My only reason for removing the prong on my Ais 50/1.4 was that the shadow of the prong was a bit disturbing when I wanted to see the aperture value displayed in the viewfinders of film Nikons.  Now that the digital Nikon don't have the optical window to reflect the engraved numbers engraved on the aperture ring into the viewfinder, you don't necessarily have to remove the prong?

[Roland Vink]

I remove the prong because it is not needed on my cameras, and because they could catch the inside of my camera bag or scratch the next lens.

[Akira]

I remove the prong because it is not needed on my cameras, and because they could catch the inside of my camera bag or scratch the next lens.

Roland, you carry too many lenses...   

[Kenneth Rich]

Thank you all for your replies. I doubt I will be paying Nikon Service to replace 24 screws unless i have a good Lotto win. M1.4 washers seem to be the solution for me-  or leaving the holes there!

[Roland Vink]

I'd just try putting the screws in before looking for washers, in most lenses the screws will go in with no problem. If they are too long it will become apparent very quickly, and if you take a little care no damage will be done - it's only then I would start to look for other solutions.

Akira - is it possible to have too many lenses?

[Hugh_3170]

To lessen damage to other lenses in ones bag is a very good reason in its own right.

Also, if one is converting a non-Ai lens to Ai by milling the the aperture ring to form the meter coupling ridges for Ai cameras, more often than not the Metering Coupling tab has to be fully or partially milled as well (along with the edges of the two attachment screws), so I prefer to simply remove the Metering Coupler tab in such cases.  My argument is partially to do with convenience and partially aesthetic.  Others disagree on this point, but that is just the way I see things in this instance. 

I remove the prong because it is not needed on my cameras, and because they could catch the inside of my camera bag or scratch the next lens.

[Kenneth Rich]

Aesthetics!  Exactly my sentiment.

[MFloyd]

I like the aesthetics of my "prong" lenses. And Erik Lund is able to revamp a pre-Ai lens while preserving the prong 

[Roland Vink]

Aesthetically, the older lenses do look better with the prong, they look strange without it. AI conversions which grind off the base of the prong and part of the attachment screws don't look so nice, although it does the job. AI, AIS and K lenses with proper AI kit look very good without the prong.

[bobfriedman]

i have had no problems removing the prong and replacing the screws.