[bikehead90]

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I recently took my M 50 F1.7 into the shop to eradicate the fungus problem. Their estimate came back at 36 GBP (I don’t know how to do the pound sign). Would you guys say it’s worth it, or should I scour eBay to get a non-fungused copy? This lens originally came from a lot of two lenses the other being a spotless M 135mm F3.5, which was my main motivation for bidding on it. I’ve got a M 50 F2 already and was considering selling that off when I got the 1.7.

Bonus: I just picked up a Vivitar 2X teleconverter for 10GBP from a pawnshop and in my excitement to find any sort of Pentax, I didn’t check for... fungus! Yes, it’s quite cloudy. This one I have two options: Return it or get it de-fungused. Help?

[twilhelm]

On the Vivitar, I would return it. 2X teleconverters of that age are cheap. The M 50 1.7 is an excellent lens, but can be found quite inexpensive also. The problem with fungus, you don’t know until you clean it if it has caused damage to the optics. For an M series lens, I’d do it myself, but I’ve done it before.

[bikehead90]

I’ve never done this. I’m really good with fine-detail (I build model kits), but I don’t really trust myself working on something as precise as a camera lens. On a side note: for future reference, what do I need to clean them myself?

[paulh]

I would simply replace the M50/1.7 with another. I've seen copies here on the PF marketplace for $30 or so. You could also place a "wanted" ad here on the Marketplace. I think your chances of getting a good copy are better here among forum members, rather than taking a chance on ebay.

[bikehead90]

The next question would be: what do I do with a fungus’d lens?

[twilhelm]

The next question would be: what do I do with a fungus’d lens?

Take it apart just to see if you can clean it, or sell as is. The old lenses are relatively simple, but make certain you buy high quality JIS screwdrivers before you start. A stripped screw will ruin the project if you don’t have experience. Also, a clean workspace helps. And take pictures for reference as you go. If you have pictures, many of us can help if you get stumped.

[bikehead90]

I have a high-precision screwdriver set, but I was doing some preliminary reading on this, and the writer suggested a lens spaner. Is this something you use? If not, what can I use to remove and subsequently re-set the lenses?

[pschlute]

and the writer suggested a lens spaner. Is this something you use?

You will need a spanning wrench to remove the collars that hold the elements in place. https://www.ebay.co.uk/itm/Pro-DSLR-Lens-Repair-Spanner-Wrench-Tool-For-Came...QAAOSwiVJbMfVs

To re-iterate what twilhelm said, it is important you use JIS screwdrivers. If your "high precision" set are not JIS, you risk damaging the screw heads.

[clickclick]

If you're handy doing things, which it sounds like you are, go for it. I feel like there's this huge taboo about taking apart lenses. It really isn't rocket science for most vintage primes. As mentioned, you need to get a good JIS screwdriver set, but also have whatever jewelers set you can get your hands on, because you will find some drivers from one set will just fit whatever better. In addition to the spanners mentioned, you will also want to get tools to remove the front rings, which is often your entry point. I've had good luck with this set:

amazon.com : 18 Sizes Lens Tool / Filter Wrench Set Rubber 37mm 43mm 49mm 52mm 55mm 58mm 62mm 67mm 72mm 77mm 82mm 86mm etc : Camera Lens Accessories : Camera & Photo?tag=pentaxforums-20&

A 50/50 mixture of ammonia and hydrogen peroxide is often recommended for fungus removal. Here are some links. The first is short and sweet and is focused on the optics specifically. The second ones gets into the whole disassembly etc.:

Fungus: how to prevent growth and remove it from optical components

How to Remove Fungus from a Lens

If you do get into something like a zoom that slides and rotates, do make a drawing of the pieces. Yeah, guess you could photograph, but I like sketching it out on a piece of paper that sits there for disassembly and reassembly. I think you learn the pieces better that way, and no batteries required I did a vintage Vivitar Series One that was a twist and pull, and went as far as laying down some of the bushings on the paper within outlines I drew matching the cutouts on the barrel. The differences between some of the nylon bushes and associated screws were very subtle. Something with motion like that can get complex, so care is needed.

Also, you'll find strategic dabs of what's probably lacquer (as always, someone correct me if wrong) on retaining rings and sometimes screws. I've been able to dissolve these with Q-tips wet with rubbing alcohol held on them.

When unscrewing the last bit of a focus assembly, pay particular attention to the alignment of the pieces. This can save lots of time getting pieces lined back up right for infinity focus etc.

I got into the fungus removal business from an 8 element Takumar 50 I bought on a Goodwill auction. After that, I've had a variety of others come my way. While I would only buy one on purpose for the right price, I'm no longer horrified by the prospect. Fungus can etch the glass or coatings, so you have no idea until you go to clean it what will happen.

[twilhelm]

If you're handy doing things, which it sounds like you are, go for it. I feel like there's this huge taboo about taking apart lenses. It really isn't rocket science for most vintage primes. As mentioned, you need to get a good JIS screwdriver set, but also have whatever jewelers set you can get your hands on, because you will find some drivers from one set will just fit whatever better. In addition to the spanners mentioned, you will also want to get tools to remove the front rings, which is often your entry point. I've had good luck with this set:

amazon.com : 18 Sizes Lens Tool / Filter Wrench Set Rubber 37mm 43mm 49mm 52mm 55mm 58mm 62mm 67mm 72mm 77mm 82mm 86mm etc : Camera Lens Accessories : Camera & Photo?tag=pentaxforums-20&

A 50/50 mixture of ammonia and hydrogen peroxide is often recommended for fungus removal. Here are some links. The first is short and sweet and is focused on the optics specifically. The second ones gets into the whole disassembly etc.:

Fungus: how to prevent growth and remove it from optical components

How to Remove Fungus from a Lens

If you do get into something like a zoom that slides and rotates, do make a drawing of the pieces. Yeah, guess you could photograph, but I like sketching it out on a piece of paper that sits there for disassembly and reassembly. I think you learn the pieces better that way, and no batteries required I did a vintage Vivitar Series One that was a twist and pull, and went as far as laying down some of the bushings on the paper within outlines I drew matching the cutouts on the barrel. The differences between some of the nylon bushes and associated screws were very subtle. Something with motion like that can get complex, so care is needed.

Also, you'll find strategic dabs of what's probably lacquer (as always, someone correct me if wrong) on retaining rings and sometimes screws. I've been able to dissolve these with Q-tips wet with rubbing alcohol held on them.

When unscrewing the last bit of a focus assembly, pay particular attention to the alignment of the pieces. This can save lots of time getting pieces lined back up right for infinity focus etc.

I got into the fungus removal business from an 8 element Takumar 50 I bought on a Goodwill auction. After that, I've had a variety of others come my way. While I would only buy one on purpose for the right price, I'm no longer horrified by the prospect. Fungus can etch the glass or coatings, so you have no idea until you go to clean it what will happen.

This is good information.

My first lens to de-fungus was an old Hanimex 135. Once I got the courage up to start, I was surprised that it wasn't a more complex process.

I believe (though I'm not entirely sure) the bit of lacquer is actually shellac. I use denatured alcohol to dissolve it, and from my woodworking days, I remember denatured alcohol dissolving shellac, but not lacquer.

[clickclick]

I believe (though I'm not entirely sure) the bit of lacquer is actually shellac. I use denatured alcohol to dissolve it, and from my woodworking days, I remember denatured alcohol dissolving shellac, but not lacquer.

I was having an internal battle with shellac versus lacquer, so thank you!

[swanlefitte]

I have the m 50 2.0 if its just the front lens its easy. Unscrew the name plate unscrew the front element. I use a big gatorade bottle cap with a broccoli bunch ruberband slightly overlapping the edge this allows you to press against the name ring and use friction to unscrew it. Once off you Unscrew the front element. I use 2 screwdrivers in the slots to turn it. Its just unscrewing those 2 things. As hard as opening a jar. Some jar lids are tighter than others.

[aurele]

PentaxForum did an interview of the wonderful Eric (the Pentax repairman in the US).

He said the A50/1.7 is very very often plague with fungus.

For the price, go get another one ! Or even a A 50/1.4.

[h4yn0nnym0u5e]

If you don't fancy having a crack at it, I'll take it off your hands and have a go myself, assuming we can agree a reasonable price! I'm in the UK.

Cheers

Jonathan