Help! mount screw replacement

[Bern]

I bought a 135mm 3.5 K and 43-86mm 3.5 K both with a stripped screw on the mount. I was able to remove them both as I wanted to convert them to AI mounts.

What are the sizes of the screws for the mount or can anybody recomend where I can source replacement screws. I am from the Philippines and am willing to pay for shipping costs.

Thanks!

[richardHaw]

https://richardhaw.com/2015/12/29/best-practices-part-1/
 

[Roland Vink]

Contact this store to see if they have AI conversion kits for your lenses:  https://kamerastore.com/products/search-Conversion%20kit/
The end result is much nicer than modifying the original aperture ring by grinding off the lower edge.

[Bern]

https://richardhaw.com/2015/12/29/best-practices-part-1/
 

Thanks Richard, checked out your blog and you mentioned “Usually, M1.4 screws will be 0.3, M1.7 screws will be 0.35 and M2 screws will be M4. ” are the measurements is mm or inches? Pardon the question if its too silly... I just want to be sure so as not to strip the thread. Also, what is M4?

Bern

[Bern]

Contact this store to see if they have AI conversion kits for your lenses:  https://kamerastore.com/products/search-Conversion%20kit/
The end result is much nicer than modifying the original aperture ring by grinding off the lower edge.

Thank you Roland, but I already made the convesion by grinding the aperture ring for the 135mm. I will have to stay the surgery for the 43-86mm for the meantime. Their kits are reasonably priced, though.

[Hugh_3170]

There are three kits fo rthe 43-86 lens - Rolands Web Site shows which kit applies to which serial number range.  Some  of the differences are cosmetic in respect of their markings and their match of colours to the lens as a whole, but two of the rings are slightly diffrent in respect of their width.  As far as I recall all will fit and work on the various 43-86mm lenses, but with varying degrees of appearance and gaps.

[Bern]

I have the 43-86 K version. Would you know which would best fit among the three ai kits mentioned?

[Hugh_3170]

According to Rolands site, the K version of the 43-86mm f/3.5 lens was in production from Nov 1975 until 1977 and can accept Ai kits 65, 66, and 67.

As for which one looks best on your lens, you may need to check images of other converted lenses.  In Rolands' notes he hints that some late pre-Ai lenses had aperture rings the same as the early Ai lenses.  What is your serial number?

[Roland Vink]

Zoom lenses have greater manufacturing variability than primes. To ensure the infinity focus was consistent for each zoom Nikon used shims of varying thickness. The different thickness meant the height was different over the lower part of the lens including the aperture ring. To account for this variability, Nikon made three AI conversion kits for each zoom with different height. In theory a zoom with a thick shim should receive the highest kit and so on. I think the higher numbered kits are the higher ones but I'm not certain on that.

In practice it doesn't really make much difference. There might be extreme cases where a long lens with a short AI kit might not engage the camera's AI follower, or a short lens with a long AI kit might jam, but it's very rare. To be safe I'd pick the middle number, but failing that you should be ok with any of the options.

[Macro_Cosmos]

Thanks Richard, checked out your blog and you mentioned “Usually, M1.4 screws will be 0.3, M1.7 screws will be 0.35 and M2 screws will be M4. ” are the measurements is mm or inches? Pardon the question if its too silly... I just want to be sure so as not to strip the thread. Also, what is M4?

Bern

I share your pain, these tiny unconventional screws are a sore in the bottom, it's like they are designed to strip! Looking at the size, I'm gonna say they almost are.

M refers to the diameter in millimetres. M4 would be a diameter of 4mm. 0.3 refers to the thread pitch, now that's an annoyingly small and fine pitch!

Conventional M4 screws have a pitch of 0.7, M6 which I pretty much eat for my job has a pitch of 1. The imperial (non)equivalent is 1/4 inch - 20 (pitch), this is the standard tripod head mounting screw, along with 3/8-16, the latter can be converted to the former via a 20c adapter.

Imperial and metric threading is strictly non-exchangeable. One inch is 25.4mm, not the standard spacing which is 25mm. While also it's possible to mount imperial screws into their "equivalent" metric threads, one can't go further after about 50deg of rotation.
More here: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=9015

Wish the world just agrees on a standard, this imperial metric fuss has caused me many problems in both work and hobbyist imaging. Oh and the hex keys are also stupidly not exchangeable…

[Bern]

As for which one looks best on your lens, you may need to check images of other converted lenses.  In Rolands' notes he hints that some late pre-Ai lenses had aperture rings the same as the early Ai lenses.  What is your serial number?

The serial number is 800909, this makes the production date to be almost nearing its end. Does that mean I should get the Ai kit 66 or 67?

[richardHaw]

always mm 

imperial units is the invention of the devil 

[Erik Lund]

The serial number is 800909, this makes the production date to be almost nearing its end. Does that mean I should get the Ai kit 66 or 67?

Here you find exact information on Kit # and many many other details    Roland keep these pages updated 

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

[Roland Vink]

The serial number is 800909, this makes the production date to be almost nearing its end. Does that mean I should get the Ai kit 66 or 67?

As I mentioned earlier, any of Ai kits ( 65,66,67 ) should do. The Ai kit numbers apply equally to early or late serial numbers within the specified series. The different kits have different heights to account for differences in the length of the lens, they don't apply to early or late serial numbers within a series.