This lens is made of two lens groups, with the aperture between them. the whole inner part moves together when focusing.
Is there possible any failure?
Of course You know, that this beautiful plastic toy can fall in pieces – but what can be the reason, when You collect the pieces, You mount the together correctly (with some glue) – and the photo is not sharp at all??? In normal case this lens has a sharp picture, even at F1,8… Ok, not perfect, but for 110 euros…
This is the lens group from the back side. At first look there was nothing to see – but when I looked to it from the near, I observed, that one of the lens from this group is dislocated a little bit (approx. 1 mm). The outer lens is only pressed in the plastic case, and the case is melted on 3 points to keep it on its place….
I cutted the melted parts with a sharp knife, and after this it was possible to pull it out with th knife.
Before pushing back to it’s place, it is advisable to clean the inner surfaces. For this operation I used 97% ethyl alcohol and ear cleaning cotton swabs. After the wet clening I cleaned it with dry ones – but cotton swabs will never clean it pefectly, so it comes th wonder-weapon – some microfiber cloth glued on a cotton swab. You have to push it with quite big force on the surface – but the result is a very clean, shining surface, without any trace of dirt.
After cleaning I blowed with pressurised air (NOT canned air, which is not air – I have now a small dry compressor), pushed together, glued with some 2 component resinbased glue – and that’s it.
The lens has the original optical quality now. I wonder, how many people have the same problem, with the 50 mm F1,8, gettng a worst image after some time….
(pictures made with a Nokia phone – sorry about their quality)