28mm Salvation

My poor 28mm lens.  Yes, I’m still on about losing that lens to the Gulf of Mexico.  I really really really liked this lens. The lens wasn’t even expensive.  It’s an old Minolta from the 80’s that has long since had its glory days.  It’s not the sharpest lens I’ve ever owned but it has this quality and character about it that I’ve grown attached.  I’m not sentimental when it comes to material things but there was something about it that kept it on my camera body more than any of my other lenses.  Normally, I would have just taken the incident as an opportunity to buy something bigger, better, and more expensive.  I even did a bunch of reading online trying research a good replacement for this lens but I just couldn’t seem to find anything consistent enough to sway me to a purchase.  I knew this little lens I had was great for what I shoot.  There it sat on my desk: soggy, salty, sticky and smelling of old brine.  I’ve never taken apart lens but what did I have to lose in trying to bring it back to life.  I couldn’t ruin it anymore than it already was.  I spent near 10 years in the Navy conducting 40X microscopic repairs to electronics; I figured some of that experience had to crossover into this. After much hemming and hawing, I decided to take a stab at refurbishing it.   A Wal-Mart, a few miles walk from the hotel, offered a place where I could buy the things I believed I would need to get the lens torn apart and properly cleaned.  A jeweler’s screwdriver set, 91% Isopropyl Alcohol, lens wipes, general purpose automotive grease, and a 1″ rubber replacement foot for a cane (I’ll get to that one later).  Once I got back to the hotel, I got the desk cleared off and laid everything out.  In addition to the stuff I bought, I had in my room a lighted vanity mirror to use as a parts drier, and a metal parts tray – I mean soap dish.  A quick prayer (God made the Universe and everything in it.  I’m sure He can help me fix a simple lens) and I was ready to try to breath new life into this old Minolta.

All the photos of the teardown were shot with an iPhone 6+

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I started out by removing the mounting ring at the back of the lens.  With that removed you could unscrew the rear element group, exposing the back of the aperture.  An element is optics-talk for a lens as part of a group of lenses.  What a mess it was in there.  I had to evict a few sharks and oysters in order to get along any further with my inspection.  The steel pins hinging the aperture blades had rusted, leaving junk all over the blades.  When I attempted to manually actuate the aperture I found it to be very stiff, and course.  The aperture should be smooth in operation with virtually no resistance to movement.  This had me concerned.  In order to fix it, I needed access to the front of it by removing the elements at the forward section of the lens.

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Minolta 28mm f/2.8 – Rear of lens with mounting plate removed and rear element group unscrewed.

In order to remove the front element, you have to first release a cover ring.  This is where that replacement foot for a cane comes in.  It offers a nice grippy tool that you can press onto the cover ring and rotate it without causing damage to the lens.  I spent probably 20 minutes trying to break loose that stubborn ring.  I think the salt water had gotten behind it and into the threads and dried up, leaving a gritty residue behind.  Here’s what it looks like after the water’s drained out.

Minolta 28mm f/2.8 - Front of the lens with cover ring removed.
Minolta 28mm f/2.8 – Front of the lens with cover ring removed.

Just as stiff as the cover ring, the front element group took some real effort to get it unscrewed.  There is so little room to get fingers in there and I didn’t have the proper spanner wrench.  I’m meaner and more tenacious than the lens and eventually won the battle.

Minolta 28mm /f2.8 - The lens disassembled front and rear.  Aperture assembly remains in the lens barrel.
Minolta 28mm /f2.8 – The lens disassembled front and rear. Aperture assembly remains in the lens barrel.

Because all I had available for buying tools was a Wal-Mart, they were terrible.  I knew those jeweler’s screwdrivers were going to be garbage so I bought two sets.  I’m so glad I did since I broke several of them just trying to get the screws out.  In the image above, you can see inside the lens barrel that it still has the aperture assembly inside it.  I could NOT get the screws loose that would have released it from the barrel.  When it comes to precision tools, if you have choices, buy expensive; it really does matter.  I had to do all the cleaning and repair to the aperture as it sits.  I washed all the lens parts under running water for a few minutes to remove any deposits of salt and sharks and oysters.  After the water bath I got them realllly drunk in alcohol.  Using Q-tips, I scrubbed everything down really well.  I then went after that rust all over the aperture.  The blades of an aperture are very delicate so I had to be careful when cleaning them.  I used the finger on one hand to support them from behind while I used the a swab in the other hand to go after that rust.  I got everything off of the blades but it did leave some minor oxidation staining behind.  It was smooth to touch so I figured it shouldn’t affect mechanical operation.  Now I needed to dry all the parts out before reassembling.  The tabletop vanity mirror I had in my room (no I don’t travel with one) has regular tungsten filament lights in it which can get quite hot.  Turning the mirror horizontal, I had this nice little hot plate I could set the parts on to dry off.  They got plenty hot in no time.  I would use my blower bottle to poof around all the little bits to force out any stubborn water or alcohol and then put it back on my “hot plate” for another round of baking.  Worked like a champ!

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After drying all the parts, I checked mechanical movements.  The aperture felt like brand new again!.  Inside the mounting plate, a spring mechanism which keeps the aperture under tension against the actuating rod needed a little bit more work to get it operating perfectly.  After exorcising those demons, I moved on to the focusing helicoid.  I put a thin coating of grease on the threads and turned the ring back and forth to distribute it.  What a difference that made!  The focus ring now feels thick and buttery smooth when I turn it.  I find it easier to manually focus a lens when the ring has a little bit of grip to it – not stiff but not sloppy either.  Next, I cleaned all the glass elements with lens wipes and polished them up with a microfiber cloth.  Time to reassemble everything.  As I put the lens together, I would take a moment to hit the internals, especially the glass, with my blower bulb to make sure no dust was in there.  Unless it’s a dust bunny, specks of dust don’t really have an impact on image quality when it’s on the inner elements but it still annoys me to see it in there.

All finished.  It looks spotless clean on the inside, the focus ring is smooth, and the aperture operates beautifully.  From the back of a lens, you can flick the aperture actuating rod.  You should see all the blades move together and they should be very quick in returning to the default position.  I listen for the “ssshnick” sound when I let it go.  This lens now ssshnicks like new.

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This morning, I was itching to get out to try the lens.  The weather was quite foul; windy, foggy, sprinkling rain, and dark skies.  Who cares, right?

The lens shoots like new again!  I couldn’t detect any residual weirdness as a result of my fumbling around with its guts.

Sony A7R w/ Minolta 28mm f/2.8 | f? @ 1/125th | ISO 100
Sony A7R w/ Minolta 28mm f/2.8 | f? @ 1/125th | ISO 100
Sony A7R w/ Minolta 28mm f/2.8 | f? @ 1/80th | ISO 200
Sony A7R w/ Minolta 28mm f/2.8 | f? @ 1/80th | ISO 200

After shooting those two, it started raining a little more.

Sony A7R w/ Minolta 28mm f/2.8 | f? @ 1/60th | ISO 1600
Sony A7R w/ Minolta 28mm f/2.8 | f? @ 1/60th | ISO 1600

That was all the shooting I could do.  It started to dump rain and I was near a mile away from the hotel.  I tucked my camera in my hoodie and started walking.  By the time I made it to the hotel, I was as wet as a 28mm lens that fell in the ocean. 😉

 

 

 

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6 thoughts on “28mm Salvation

  1. Tom-
    So proud of you for doing this. #1, as a micro tech, you have experience at digging into small things. #2, you saved a lens you really loved- and now I’m sure you’ll be even more fond of it, as you two now have even more of a ‘history’ together- and you saved its life.
    The lens in this era were well made mechanically, and meant to be able to disassemble and reassemble. I doubt you’d have as much luck with a modern plastic stabilized lens! Very happy for you that you were successful. Perhaps you’ll have to get you some more quality tools for jobs like this!

    Wes

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  2. Hi Wes! You’re right about the history thing now with this lens. Working on this lens reminded me of working on the old VW Beetles. Designed to be worked and all metal. Unlike the modern car which is stricken with complexity, custom tool requirements and everything is made of plastic. It would be very easy at this point to buy ugly lenses for parts to be used in mine, should the need arise. Having now seen how well this Minolta is built, I have even more confidence that it can take a beating and keep on ticking.

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  3. I”m not a ‘tech’ person so was not sure I’d enjoy reading the ‘stats’ of the process. . . . but I must say, you made it quite enjoyable, son! 🙂 THANK YOU! And best of all, so glad this lens has a new lease on life! I’ve enjoyed how you’ve used it over the last few months! Looking forward to more!

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  4. I’m always amazed at your ability and desire to “overcome” challenges and obstacles! I saw some of that when you were a little guy (“I’m gonna get my big gun and shoot your dog”! – when the pastor of our church invited you over to see his German Shepherd…not realizing you were afraid of dogs…). It’s so very cool that you took another “lemon in life” and used it as an opportunity to learn and grow…AND rescue a lens that most people would have written off and tossed it in the garbage! Kinda reminds of how God works…he sees all of us that “ruined” and sets about to heal us and rebuild us into something better than we were before! Proud of you, Tommy!!!

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