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Approximately, three months ago I install a lens on a camera (in a road). Now, I find that the screws of lens are loosen. I guess that it caused by temperature variation and vibration (because of a noisy fan). I want to fix two screws on a Fujinon CF50HA-1 lens as shown below:

enter image description here

These screws are used for locking focus and iris. As I read in web pages there are two solutions:

  • using locktite adhesive
  • using finger nail polish

My problems with using loctite are:

  • I heard some problem about gas out in this link when using locktite.
  • Should I use activator with my loctite? (I have a Laxeal 11 ones)
  • Does using activator damage lens?
  • If I want to change my settings of locking screws, is it possible to residue of loctite fall into lens?
  • I have loctite 222 and 243. Which one is good? It seems that 222 is weakest and is good for aforementioned purpose

My problem with finger nail polish

  • It is unknown in terms of temperature variation and resistance against vibrations. Can It resist on them?
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  • 2
    Asking which existing tool is better is not a Lifehack. Screwlok is the accepted tool and nail polish is a common hack alternative tool.
    – Chenmunka ♦
    Dec 29, 2019 at 15:13
  • Hi Babak, Welcome to Lifehacks. My original greeting to you and your response was removed by the moderator for some reason. Some moderators are a little overzealous. I'm sure it was not meant to be mean.
    – Stan
    Dec 30, 2019 at 14:19
  • 5
    This might be a better question in the Photography Lifehacks site.
    – Stan
    Dec 30, 2019 at 14:26

3 Answers 3

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The screws help to hold the lens adjustments from being changed. You would want them loose to change your adjustment and then to tighten the screws to hold the changes that you made for different lighting or subject positions.

Instead of glue to hold the screw positions, why not use a wide elastic band (shown in pink) around the lens (in black) covering the head of the screw so it won't turn—to hold the screw position securely yet temporarily?

Here's a side view diagram of the lens with the bands in place… Lens lock screw cover/bumper To change the setting, remove the band or slide it to one side, loosen the screw, make the adjustment, re-tighten the screw, and replace the band over the top of the screw cap to hold it from turning.

All you want to do is hold the screw cap from turning after it has been tightened.

Additionally, the thick rubber bands (one for each of the screws) will give some shock protection if the lens is hit or knocked by accident.

Wide rubber bands are usually used to hold some fruits and vegetables in bunches or to hold closed the claws of some large crabs and lobsters.

Good luck.

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  • Thank you @Stan. I can't imagine your solution, however it inspires me another solution.
    – Babak.Abad
    Dec 30, 2019 at 14:34
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Using fingernail polish has the benefit that it can be removed with acetone (fingernail polish remover) and reapplied if it wears away or loosens.

LockTite (cyanacrylate) is more stable (difficult to remove) and will lock the screw and threads rather than tighten them. It's an adhesive. Activators will make a bond between surfaces more stable strengthening the adhesive bond. Use this when you do not want to change adjustment or remove the screw.

LocTite also makes Lock-It "Liquid Lockwasher" Made with methacrylic ester. It claims to stop nuts, bolt and screws from loosening including vibrations.

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  • Please tell me about the effects of activator if have any experience or information
    – Babak.Abad
    Dec 29, 2019 at 14:43
  • The article you link to suggests this kind of a repair is done to the internal parts of the lens. I STRONGLY recommend you do not try this kind of a repair unless you have experience with optics. Outgassing is not an issue, here, as the parts are external. However, this kind of a repair can bond the lens threads making the lens unadjustable and possibly unusable. it is important to get the instructions in your native language so as not to misunderstand the materials and processes effects on the piece.
    – Stan
    Dec 30, 2019 at 14:25
  • Did you think the OP was referring to CA adhesive? The products mentioned are thread locker, which is quite a bit different.
    – piojo
    Dec 31, 2019 at 6:59
  • @piojo A site I visited referred to Loctite as a CA adhesive. No numbers were given. See the link provided by OP. I'll edit my answer to clarify.
    – Stan
    Dec 31, 2019 at 14:02
  • @Stan Oh, I don't blame you. Today, Loctite is a brand that's most well known for their CA adhesive. When the company started and for the first 8 years, it sold only thread locker (which I think they also called "loctite" rather than "thread locker"). Nowadays we should distinguish between company and product to keep things clear.
    – piojo
    Dec 31, 2019 at 14:54
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I note that your screws have splines on the side. I would find a strip of soft material like a plastic (hot melt glue stick or some similar soft plastic) or wood (a softwood) and drill two holes in it exactly the distance apart that the screws are, then push the stick onto the screws. The holes should be slightly smaller than the outer diameter of the splines so that the splines push into the material and become gripped, preventing the screws from turning. You may still need to employ something like Stan's elastic band idea to keep the screw locker from working loose if the lens is in a really hot/vibrating environment

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