Too much dust inside the inner lens of an Oly 12-40 f2.8 Pro ?

Started 2 months ago | Discussions thread
cba_melbourne Senior Member • Posts: 3,143
Re: Too much dust inside the inner lens of an Oly 12-40 f2.8 Pro ?

martin_sc42 wrote:

petergerritsen wrote:

When zooming to 40mm the tube has a little play/wobble/rattle. maybe thats the reason dust can come in?

Sheers Peter

I am from Germany so "wobble" is a bit hard for me to exactly classify. Even at 40mm the tube part has less play as e.g. a non-sealed lens with my copy. Such play would also cause a little de-centering. Where are also no larger dust particles inside my lens.

While zooming from 12<->40 it is true that the tube movement is not fully smooth the rubber is basically a bit "jamming" so something might jump under this seal.

My problem is that at least according to my impression the dust is not in the "front chamber", also rather not in the back-chamber it is on the aperture control lens. What is the smallest lens in diameter and also bundles the light.

The air flow-in entry is under the Zoom ring what makes sense so the moving tube cannot push water in.

A really detailed design image of the lens is not published so i cannot 100% judge. It also might sound a bit arrogant. The most expanding and largest element is the front chamber, also the most easy one open and to clean ... if i had to design the perfect traveler lens i would try to design it a way that all flows through the front chamber fist.
As the shell of the lens is quite thick and layered this maybe even the case.
I will try to dig into this a bit more
Lens design image, not detailed enough.

Hi Martin,

I found a few cuts through this 12-40 lens that might help understand how it is built. I believe the camera attached is the EM1.1. It is really difficult to make such a cut, you cannot just slice through with a saw, lots of work to make it look as nice...

this is from an old thread in mu-43 from 2013:

This I found on a Japanese page

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