Cleaning Mitutoyo Objectives

[svalley]

I have discovered that metal dust is being deposited on the rear element of my Mitutoyo objectives. This is very fine metal particles from screwing and unscrewing the objectives from the mounting plates. I cannot think of a good way to avoid the production of the dust and it sticks to the glass so tightly that compressed air does not easily dislodge it. I have used a lens-pen brush and a lightly wetted cotton swab and then pec-pad tissues. This all takes an incredibly light touch to avoid scratches. I also cleaned a fair amount of metal dust from the threads of the protective cases for each objective. Once They are clean I will give them a blast of compressed air after each use.

Does anyone else have problems with this? Any safer/easier solutions?

[enricosavazzi]

I have discovered that metal dust is being deposited on the rear element of my Mitutoyo objectives. This is very fine metal particles from screwing and unscrewing the objectives from the mounting plates. I cannot think of a good way to avoid the production of the dust and it sticks to the glass so tightly that compressed air does not easily dislodge it. I have used a lens-pen brush and a lightly wetted cotton swab and then pec-pad tissues. This all takes an incredibly light touch to avoid scratches. I also cleaned a fair amount of metal dust from the threads of the protective cases for each objective. Once They are clean I will give them a blast of compressed air after each use.

Does anyone else have problems with this? Any safer/easier solutions?

Are you screwing/unscrewing objectives very often? And into what type of adapter, aluminium or brass? Aluminium is softer, and wear of anodized aluminium (e.g. blackened) produces highly abrasive aluminium oxide dust (the same kind of material used to grind and polish lenses). Also, if the adapters have not been properly cleaned after machining, they may continue to spread fine metal dust.

Like all microscope objectives, the Mitutoyo M Plan Apos are meant primarily to be used on a rotating objective changer (usually made of brass), or semi-permanently mounted into an adapter. You just screw them in, and they stay there afterwards. That said, screwing and unscrewing them occasionally should not be a problem, and I never had the problem you observed.

If it is not possible in your use to leave the objectives screwed into whatever you use, you might consider permanently mounting each objective into its own adapter, and switching adapters instead of objectives. The farther the used thread from the rear element of the objective, the less likely it is that metal dust will fly to the glass.

It may also help to screw/unscrew the objectives with their axis horizontal instead of pointing straight down. This way, any metal dust should fall out instead of falling on the rear element.

[svalley]

Are you screwing/unscrewing objectives very often? And into what type of adapter, aluminium or brass? Aluminium is softer, and wear of anodized aluminium (e.g. blackened) produces highly abrasive aluminium oxide dust (the same kind of material used to grind and polish lenses). Also, if the adapters have not been properly cleaned after machining, they may continue to spread fine metal dust.

Thanks for the comments. I have been changing objectives fairly often and of course, I should have anticipated this problem. Live and learn.

I just ordered some extra mounting rings and will keep the objectives mounted once they arrive. My wife said she will sew me some little velvet bags to protect them.

Steve

[lothman]

for cleaning and removing particles I use bergeon cleaning putty.

https://www.youtube.com/watch?v=o3LJGa9z-h8

you can put a small ball on a tooth pick and pick up particles deep inside a camera/lens, what is better as blowing them deeper in ;-). It leaves no residue and is well proven under watchmakers!

[ChrisR]

There's a sensor cleaning stick which has a tacky plastic piece on the end. I expect that would do it. Sorry can't remember the name. It doesn't mind sensor cleaning fluid, which may be appropriate to put on the rear lens - not sure about that.