SMC Pentax-M 1:3.5 135mm with fungus

is this worth paying to be cleaned or is it something I could do myslef
or is it cheaper to pick another one up of ebay.
I've no idea how much it would cost to have it cleaned professionally

I made a typo in the subject heading it should read 135mm not 13mm
how do I correct this ?

I'd have a go. These are common on ebay and not expensive.

I've successfully cleaned several Taks including a couple of 135mm F3.5 ones. The Taks are quite easy to take apart, but I'm not sure about the M's. I have taken apart a 28mm F3.5 M and it was more difficult than the Taks were, but I think it's worth a try - nothing to lose really.

Regards
David

They're a common lens, a replacement shouldn't cost more than £20 so you're nothing out having a play.

Just remember which bits fit where when you take it apart. If you have any bits left over afterwards...

I guess I could have a go at taking it apart if anyone has any pointers
as to how, that would be much appreciated. The fungus is mainly in the front lenses so I guess I should start there.

You will need some good quality (I stress good quality) jewellers or precision screwdrivers. The screws on these things are bloody tight and if you don't have a quality precision screwdriver you are likely to break the tip or bend it at least. You would also be best to get hold of a lens wrench or something similar as the internals are quite difficult to get apart without one of these. If you can get to the surfaces where the fungus is, it should be pretty easy to get it off with some isopropyl alcohol or similar.

Regards
David

Thank you all I'll let you know how I get on

Christopher.

I've not taken one of these apart but usually the front elements are easy to get to.

Most lenses use the name ring, the part with the lens type, serial number and Asahi Opt. Co on it, to hold the front element in. The name ring uses the same threads as the filter. I'm not sure, but there may be a retaining ring holding the front element in, under the name ring. If there is it usually uses three screws to hold it in.

To remove the name ring you need a rubber disk with an outside diameter less than the filter size but it does not want to rub the lens front element so it needs to clear the lens front element. I usually use a conical rubber part from a kitchen waste fitting but any suitable rubber part that can be used to grip the name ring will do. You can trim it to size easily. Using the rubber disk you simply unscrew the name ring by applying pressure to the ring and turning.

It is not just the quality of screwdrivers that is required. Japanese lenses use JIS headed screws and normal phillps pointed screwdrivers can damage the screws. That said, I seem to have no problem with a small precision screwdriver set I bought in Lidl!

Hydrogen Peroxide and Household Ammonia, 50-50 mix is recommended as an agent for cleaning fungus. Not sure where you get it from but I have used vinegar and it seems to work. Wash off with water after use and make sure it is completely dry before reassembly. Damp is what makes the fungus grow in the first place!

Reassembly is simply the reverse.

Must be worth having a go.

Title changed

If you are lucky, the fungus might be limited to only the front element.

These are normally easily removable.

First you unscrew the 'beauty' ring (the metal ring around the front element which has the lens model etc engraved on it).

Form there you may need a lens spanner to undo the slotted front element retaining ring. The front element might also be held on with screws but it should be reasonably self evident.

Once you have the front element off you'll be able to see if the fungus has spread further.

Clean off the fungus with a micro-fibre or lint free cloth with acetone or alcohol. If using acetone, be sure to keep it away from any painted or varnished surfaces.

Don't use commercially available nail polish remover unless it is transparent and states that it's 100% acetone.

This video might help.

"davidstorm" your not wrong in saying that the screws are bloody tight I've only manage to move 3 of them and stripd about 3 screwdrivers in doing so I need to find a good set of screwdrivers.

"gartmore" thanks for updating the title

and thanks everyone else for your help.

Christopher

All cleaned now everything done from the front as I had no luck moving the screws at the back two of them were solid but as it turned out I had no need to, now the lense lives for another day.

Looks great!

the Friendly Invasioned PENTAX_M 135mm.I need a advice how to clean front lenses .Back two lens cleaned now but how to unscrew front elements ?