I recently purchased the notorious Planar 50mm 1.7 at a bargain price, due to its faintly fogged rear element (see attached photos), which my trusted local photographer diagnosed to be an early spread fungus.
Now, I know this will lightly affect image quality - I bet even not at all. The things I worry about are fungus possibly spreading to the inner elements, since it now appears to be living only on the last one, as well as avoiding possible contamination with other lenses.
My question is: is that rear element easily accessible?
It appears to be so, provided one owns a lens spanner: just by looking at the lens it seems very easy. The two notches just around the glass (and the screws as well) suggest it's possible to unscrew just that element.
However, I couldn't any video and/or step-by-step article and/or documentation that explains how to begin from the rear side of the lens, which makes me wonder whether it's possible at all or not. Moreover, from the available videos (e.g. like this one) I noticed that in order to access the blades, for example, one needs to start from the front side, actually...
Even if it eventually turns out to be possible, I'm worried about possible recalibration issues: can dismantle this lens lead to this kind of problem, whether I'm starting from the rear or front side?
Thank you in advance.
P. S. How should I clean it in the meanwhile? I have brushes, blowers and a lenspen. Should I use them without any worry?