THE LENS

The lens is the eye of the camera and probably the second thing most people visualize or think about in a camera. As this is a paper on restoration of cameras, it is not appropriate to discuss the qualities of this or that lens design. These are things that we have no control over therefore I will contain this discussion to the problems of older lenses.

Generally, a good cleaning of a lens will immediately improve the look of a camera. Since many older lenses were quite simple in their design and mechanical construction they are easily remove and the cells removed and cleaned. Leica developed a formula years ago which I still use in the shop for general cleaning, (93% distilled water, 6% white household ammonia, and 3% hydrogen peroxide). I realize that this is over 100% and that is why it runs out the top of the bottle, however lately I have been using a larger bottle! The purpose of the peroxide is to kill any fungus. This is a good general cleaner but there are several wonderful over the counter cleaners that have recently come out. Most of them contain ethyl alcohol aiding evaporation leaving almost no residue.

Start cleaning by first blowing as much of the dirt off as is possible. Use a Q-tip or a wet Kim-wipe held between tweezers. A mopping method is first used to float as much of the dirt off the surface as possible. Start in the center and use concentric circles to the outside to bring the dirt off to the edge. Blowing on the lens as you clean will help in evaporation of the cleaned leaving a clean surface. Frequently a good cleaning will take as many as 20 or more wipes or Q-tips. Most older lenses can be disassembled by un-threading the retainer ring. (A good spanner wrench or modified long nose pliers can be used for this job.) It is important to remember the order of the cells and which direction they face. A simple method is to use a washable Magic Marker putting a dot on the element as it is removed. This will clean off upon reassembly. Some fungus that grows on lenses gives off formulaic acid as a byproduct. This etches the glass. Forget it. Never attempt to disassemble cemented groups.

If the diaphragm is between the lenses, it may need to be cleaned. Remove the cells and with a small amount of naptha or white gas wash the blades in the barrel. While removing the blades is not difficult, it is a matter of practice. (After the first 500 lenses, it is easy.) Wipe the blades to remove as much old oil from them and then blow the blades dry. Test the ease of movement. This may take five or six tries to get them to the point where they will operate smoothly. Naptha is also an excellent cleaner for the operating ring and other mechanisms, however always follow safety procedures and maintain a flow of fresh air.

I do not recommend removing the blades unless you want to spend a lot of time reassembling them. Again, after 500 or so jobs it is easy.

The helicoid is the name for the threaded parts of the lens that moves when you turn the focus ring. Mostly the problem with this area is older grease that has either migrated out of the thread or has turned to concrete. The first problem is easier to remedy than the second. Marking is the easiest method to disassemble a helicoid group. Remove the stop screw and continue to unscrew the thread one group at a time. As you reach the end of the line carefully watch the exact point where the threads separate. Mark this point by scribing both parts in an inconspicuous place. Clean the threads with a toothbrush and Naptha. (Be sure to put your wife’s toothbrush back before she finds out.) If this is a multi ring group remove the rings one at a time.

Once the threads are clean, repack them with helicoid grease. Again, this is available from Fargo enterprises through Micro Tools. After the first group is re-assembled, test the ease of movement. It should be softer or easier than needed since there is a compounding as more rings are assembled. The goal is a free and smooth movement of the entire lens barrel for focusing.

If the grease has calcified to the point where nothing moves than prayer helps. Try Naptha, ammonia, alcohol, penetrating oil or dog piss. Age does strange things to some of the lubricants and there is no universal answer. The goal is to get it to move and come apart. Once that happens then it can be chipped out and re-lub’d.


Oh, did I tell you one of my favorite tools are chopsticks. The kind you get free at any Chinese restaurant. These are made of good bamboo that can be sharpened to any shape and do not damage things. They are great for cleaning the threads in a heilcoid, cleaning the slot out of screw heads, rubbing metal to remove corrosion or dirt, and as body bending tools. Eat more Chinese.


SHUTTERS

The shutter in its most basic form is a blade that covers the lens, moves away and returns once again to cover the lens after a given time. There are as many designs for these mechanisms as there are camera manufacturers. Some are simple and others very complex but they have several common features:

1. They have a blade to cover the lens.

2. There is a timing mechanism which retards the return of the blade

3. Some mechanism provides the power to drive the first two.

There are two main types of shutters in cameras. The first is a leaf shutter that has a series of shutter blades usually between the lenses of the camera. The second is a focal plane shutter that usually has a very thin curtain of material operating very close to the actual film plane area. Some of the other variations of the shutter include guillotine shutters which fit on the front of lenses; roller blind shutters which fit on the front of the lens; rotating pie wedge shutters; fan shutter blades which open and close like a fan; and many more designs that some creative mechanic came up with.

For the most part the problems you will encounter will be the result of age on lubricants or the migration of lubricants to areas that should not have them. Cleaning the blade and timing mechanism with Naptha will go a long way to alleviating many of the maladies. Do not lubricate the shutters. It is better to run a shutter dry than to over lubricate it. Shutters can be disassembled far enough to observe the operation of the mechanism without getting into trouble. A little intelligent thought will let you understand how they work and perhaps guide you to the trouble. If the shutter will charge, (cock), but when the release is pressed the shutter operating ring only travels a short distance you might check to see if the blades are stuck together due to migration of lubricants. If the shutter-operating ring does not move at all or if it is very easily charged you might suspect a broken main spring. If the mechanism operates and the blades open but it will not time out than suspect the problem is a dirty governor or gear train. Since there are so many designs, it is better to have a good foundation in the understanding of how a shutter works rather than the specifics of each design. I do suggest that if you have a quantity of cameras with one shutter type, for instance a rim set Compur, disassemble one from a junk camera and learn all you can about that shutter. The problems will be the same for each of the others.

Since the information on the subject of camera repair is rather broad, I do not want to breech it in this treatise. The information on the subject of camera repair is appalling small. A few non-repair people have attempted to fill the gap but almost no working repairman have made the jump. There are several books that cover the specifics of each camera and if it is your desire to learn that aspect please investigate these. If you can find them on the internet or Ebay the old “National Camera repair course” mostly written by Larry Lyles is by far the finest information you will find. Tommy Thominlson has written several books on repair that provide good basic information. “The Dark Side of the Lens” is a wonderful book and should be in your library as well as Joe Lippincott’s book “Care and Repair of Classic Cameras” The “C&C Guides” by Chuck Bertone and Phil Zimmerman are excellent but geared to the working technician and mostly for electronic repair. The manufacturer’s repair manuals are mostly useless, especially those of the 1960’s. Unfortunately, that is the majority of the list. Almost none of the other books are worth the paper they are written on.

Frank Marshman
copyright 2004

 

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