Servicing a lens??

Ray Vardy,
Disassemble the lenses is complicated.
Although manual lens has no electronic parts, yet is not for everyone.
Pay for cleaning may not be worth the price. But perhaps compensates if the lens is of high value.
For those with skill, perhaps to disassemble the parts easier, eg the first lens of the front or back. Dismantle the entire lens is at risk of fail to mount back.  
Here in my home town I paid the equivalent of us$ 60 to clean the lens.

I disassembled to clean a lens Helios (cheap) and I could assemble ... he he
I cleaned the glasses with hydrogen peroxide and ammonia in a mixture of half. It was good ...
Other lenses more complicated (and expensive) I did not dare to disassemble ... I chose to pay.

A Olympus Zuiko 50mm 1.8 OM mount is a good lens...
But you need to buy an adapter OM to Nex and still have clean the lens... verify that compensates...

Good luck.

 

The bottom line with DIY lens servicing is that, even with good mechanical skills and experience in fixing small mechanisms - without specific lens repair training, it's a 50/50 chance. You can improve the odds a lot if you can find some technical drawings or diagrams of the exact lens you're working on in the web (better yet if someone had posted a step by step thread or video). If you have a realistic expectation that the lens could get ruined, you can carefully dismantle it by trial and error and treat the exercise as a learning experience. It you happen to pull it off, then that's a bonus. If not, you've gained the knowledge of the inner workings and assembly for such a lens which could prove useful (for the next time?).

Prime lenses have relatively simple designs but they are all constructed differently and so have different dismantling procedures requiring different tools. Besides the basic set of jeweller's screwdrivers you can easily get for cheap at any hardware store, the other tools required can be expensive. If you can make your own special tools then good, but otherwise the cost of these specialist tools can be prohibitive for a one-of repair job. You'd be amazed how difficult it can be to remove a simple threaded collar (and how easy it is to strip the tool notches or dimples, and render it completely unserviceable) without a proper tool.

Spanner Wrenchs/Lens Tools
Lens Tools

Like Luiz mentioned, a 50-50 mix of household grade ammonia and hydrogen peroxide seems to be the preferred cleaning agent for mould. Lens tissue, a blower brush, and a meticulous eye is needed to remove dust during reassembly. I have no experience with the Zuiko 50mm but here's what a vintage CZJ 50mm looks like.

https://www.talkemount.com/f12/carl-zeiss-jena-tessar-50mm-1-2-8-nex-5n-927/#post5799

The dilemma we all face with legacy lens acquisitions is that, the cost of the lens servicing done by a professional can often exceed the price of the lens itself.

 

Most lenses are quite simple to take apart, clean and put back together. By far the biggest hassle is getting everything back together so that the focusing is correct. Mark the positions before taking things apart. Even doing that it can be a tedius repetition of trial and error to get it right. I've taken apart and cleaned a variety of lenses. I've destroyed none, and accidentally damaged a couple but I've saved 10's. The first time is the most daunting but after that most lenses have very similar construction. Get yourself a decent screwdriver set and a caliper to use as a slotted ring wrench, it's cheaper and works just as well as a dedicated slotted ring wrench. If you have another camera, it wouldn't hurt to video the whole thing in case you forget what goes where.

 

Good move...

 

See LensRentals.com - Front Element Scratches

Small particles tend to have only a very small effect on the picture. As spots get larger, or the aperture changes, they can sometimes become more visible.

Mold and haze do spread, so it is still best to have it taken care of before it does visibly affect the images.

 

Watch the G.A.S. meter!