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I have a lens assembly from a projector (150mm Kodak Retinar) which is fully enclosed in plastic. Apparently the lens fell down at one point and someone put it back together. However, that person forgot a part and I found it this way in our electronics trash. I am not striving for optical perfection on the long run, i just want it to be functional again.

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Is there a proven way to get the single glass elements out? I thought of a suction cup, but I actually doubt that the household ones are strong enough?

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  • \$\begingroup\$ Sometimes there's some kind of retaining/lock ring with two small grooves cut into it, so you can remove it with a spanner wrench. I'm not seeing that, though. What does the back of the lens look like? \$\endgroup\$
    – inkista
    Commented Apr 1, 2016 at 16:31
  • \$\begingroup\$ Pretty much the same as the front. Both acessible lens elements seem like they have been pressed into place :-/ \$\endgroup\$
    – kamuro
    Commented Apr 2, 2016 at 10:08

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I would just glue some sort of "handle" to the elements. The "handle" could be a household suction cup like you mentioned, or something else non-metallic — perhaps a plastic spoon, for instance.

The type of glue you need to use depends on how much force you need to apply to remove the lens elements, and on what the lens elements are made of. Start with a milder, easier to remove adhesive, such as "glue dots" (the same stuff that they use to glue your new credit card to the paper letter when they mail it to you). Glue dots are better for use on plastic than rubber cement (which contains acetone).

Assuming the lens elements are glass and that they don't have special coatings, you could use cyanoacrylate (Superglue) to attach the "handle" to remove the glass. You can use acetone to remove the superglued "handle" from the glass. This would also work when reinstalling / repositioning the elements into the lens body, but word of caution: be careful when using acetone near plastic. Acetone can damage several types of plastic. Apply the acetone sparingly with cotton balls, swabs, and only to the glass. (Of course, when using any kind of volatile chemicals, use plenty of ventilation).

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  • \$\begingroup\$ I was finally able to open the lens, by pressing one of the lens elements on one side to tilt it in the housing (I was too afraid of glue sticking forever to the elements). It obviously only worked because there was no other element obstructing. I'd like to check your answer as the accepted solution, instead of answering myself, - you already put all the effort in this answer. Could you add this method directly to your answer? \$\endgroup\$
    – kamuro
    Commented Apr 14, 2016 at 15:21
  • \$\begingroup\$ @kamuro I appreciate that, but it's actually ok to answer and accept your own answer. \$\endgroup\$
    – scottbb ♦
    Commented Apr 14, 2016 at 16:30
  • \$\begingroup\$ But also if someone with a similar question comes around, he might profit from your information more than mine, because I think yours is more universal. \$\endgroup\$
    – kamuro
    Commented Apr 14, 2016 at 18:48

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