From the photos someone else posted of the screws they are at least M1.6 in size. Tensile strength is about 200 lbs for a decent M1.6 coarse thread screw. These aren’t going to break unless you do something phenomenally stupid to the lens which would result in other things breaking.
Sounds like poor QC to let loose screws without threadlock out of the factory. Nothing wrong with the design though.
As long as they're not working their way out it's all about tensile strength. I think a little blue loctite sounds like a good idea, as does e.g. an RRS or Kirk foot, as that will butt up against the screws and prevent them coming out. Though loctite should be plenty. BTW, I have an Arca-Swiss ballhead that once completely disassembled itself from vibration during transport... It arrived in bits in the tripod bag! It was an interesting experience to reassemble it, it wasn't nearly as easy as it might sound.
the solitaire wrote:
even considering Nikon would use the cheapest quality screws available (4.6), the amount of thread provided by the length of the thread that reaches into the lens, through the plate, the amount of force that could be applied to each single M2 screw, before the screw breaks, is 120 kg/265 lbs (for ease of calculation).
Either incorrect assembly or improper use would lead to failure of this mount. I don't see an engineering error here.
Be aware the screws don't "reaches into the lens". If they did you wouldn't be able to rotate the collar.
As for the screws "snapping" that's highly doubtful as many have noted. Anyway, I could see the screws coming loose if there was say an assembly issue where there wasn't some type of Loctite applied. I can also see this as a quality control issue. I don't see it as a "design" issue.
Regardless of all the vitriol and headline grabbing titles here, we (I) should at the very least thank the OP for bringing the issue up. I for one have checked, and will continue to periodically check my 70-200 F2.8E FL lens to insure there is noting loose from this point on. At this point in time I found no issues with my lens.
For the record, I'd already replaced the stock Nikon foot with a low profile Hejnar foot as seen in this post. Being the foot is screw-in, you cant see the four mount screws or even check them unless you remove the foot.
@Photon-catcher, though I don't agree with your overall assessment of the situation, I do thank you for pointing out the issue.
One lens has a few screws loose and that is supposed to cause a recall?
I don't know the EU definitions of a recall, but stateside it would be for something that represents a hazzard. I supose the lens could fall off the mount, land on your foot, and cause injury, but that is a stretch. Most likely the Nikon remedy is to send the lens in for repair service.
FWIW the Canon 100-400 II also has 4 small screws that tend to loosen over time. JIS drivers and a little loctite go a long way towards resolving the issue.
kwalsh wrote:
[...] Tensile strength is about 200 lbs for a decent M1.6 coarse thread screw.
[...]
Mechanical Engineering and materials science knowledge beats angry "the screws are too small". Great stuff.
To be fair, most people don't have an understanding of how strong a normal (not a cheap grade-five from a big-box hardware store) bolt is, don't know that three threads of engagement are enough for maximum theoretical strength, etc.. But they can easily find out if motivated, before ranting.
From a retired aircraft industry engineer, here's my 2 cents. Tightening issue aside your putting load on the screws in a manner that the design didn't take into account, loads coming from multiple directions instead of a load along the axis of the screws as when mounted on a tripod. If you use this to hang your camera on with these small tightly spaced screws I would check the tightness prior to every use. BTW the minimum thread engagement into steel is 1x Dia. and into aluminum 2 x Dia.
If these 4 screws loosens again, I should send the lens to them.
that is your best option.
please, do yourself a favor, when you are going to bring up a possible issue. state the issue plainly and simply. se if others have had the same issue. do not pull the fire alarm right of the bat. i know i have done it just not quite to this level of excitement.
I had the same problem with my VRii model, but not the S version.
I noticed the lens showed a little movement when on a tripod - even though it was locked down firmly. Sure enough - it was all four screws and they were loose. A half drop of blue Loctite on the threads of each screw did the job.
These lenses are designed so that the foot is capable of holding the lens and camera. It's a solid attachment. But if it ever feels loose, there could be a problem.
Andrew2 wrote:
Be aware the screws don't "reaches into the lens". If they did you wouldn't be able to rotate the collar.
As for the screws "snapping" that's highly doubtful as many have noted. Anyway, I could see the screws coming loose if there was say an assembly issue where there wasn't some type of Loctite applied. I can also see this as a quality control issue. I don't see it as a "design" issue.
Regardless of all the vitriol and headline grabbing titles here, we (I) should at the very least thank the OP for bringing the issue up. I for one have checked, and will continue to periodically check my 70-200 F2.8E FL lens to insure there is noting loose from this point on. At this point in time I found no issues with my lens.
For the record, I'd already replaced the stock Nikon foot with a low profile Hejnar foot as seen in this post. Being the foot is screw-in, you cant see the four mount screws or even check them unless you remove the foot.
@Photon-catcher@, though I don't agree with your overall assessment of the situation, I do thank you for pointing out the issue.
turbodude wrote:
does that Hejnar foot fit the S z mount?
It "might" being the mounts look the same, but that's simply a guess since I don't have the S-lens to compare it. Suggest you contact Hejnar if you're interested.
Just looked at the site and see they do list one for the Nikon Z 70-200/f2.8 S VR, but it's not the low profile one. You could ask about it.
