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Courtesy of Mike Kovacs photo.net and the
Classic Cameras
(pre-1970) Forum
Ikonta 521/16 Lens/Shutter Overhaul
What I am presenting here is a lens and shutter overhaul on a Zeiss Ikon
Ikonta 521/16 with an uncoated Opton Tessar lens and a non-synched Compur Rapid
shutter. This camera had a jammed shutter and foggy optics. Many folders, their
lenses and shutters are alike in many ways, so I hope the presentation will also
be of use to people wishing to repair different cameras. This camera turned out
to be more difficult than the average repair case but I’m going to go slow and
show lots of pictures as encouragement to those that wish to begin in camera
repair.
Tools and Materials Used:
Click on Thumbs to enlarge:
| To start, we will remove all of the optics from the front and
rear of the shutter. The first step is to remove the infinity stop. On many
cameras, this is nothing more than a threaded post (circled) which can be
removed with a slotted screwdriver.
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| Once removed, you can rotate the lens past minimum focus and
continue to unthread it. When you do this, go slowly while pulling outward
slightly. Note the position of the focusing ring when it comes free. If it
was set right when you started and you put it back on the same way, then the
focus should be correct upon reassembly. We’ll deal with the focus in detail
later.
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| Sometimes when doing camera repair, you come across evidence of
a previous repairman’s handiwork. In this case, someone had bored a large
hole (circled), probably to free a stuck element. On this camera, the 2nd
lens element was tight and required a rubber pad to provide enough friction
to free it. Some cameras will also have slots or holes for a spanner wrench
on the 2nd element. Remove the 2nd element and set it
aside.
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| Next, we will remove the rear optical group, a cemented doublet on a
Tessar lens such as this. Flip the open camera over and remove the rear
element using a spanner wrench on the inner pair of slots (circled). Set the
group aside. |
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| Now that we have the optics out and set safely aside, we can begin to
tackle the shutter. On this Compur Rapid, there is a screw with two holes
for a spanner wrench. Turn the screw so the flat side faces the center of
the shutter. Other shutters open in different ways but most either copy the
Compur design, or use a threaded nut in the center that needs to be
loosened. |
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| Once the flat side faces inward, you can rotate the nameplate CCW to
line up the bayonet with the 3 scoops on the shutter housing. Lift the
nameplate off and set it aside. Under the nameplate is the speed ring.
Carefully rotate the speed ring without lifting it out and note how there is
a cammed surface on the lower right. This is changing the speeds, as is
another surface that puts the pallet on the slow speed escapement in and
out. There is also a space that the booster spring slides into for 1/500
speed. Once satisfied with this, wiggle the speed ring off and set it aside. |
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| Here is the view under the speed ring. Note the booster spring, the
release mechanism below it, the slow speed escapement and the cocking ring.
Do not attempt to wind and fire the shutter or the cocking ring is likely to
fly out. Have a good look at the cocking ring and note how it makes contact
on top with a slot that locks it when fully cocked, how it rides against the
pallet arm on the right side of the slow speed escapement, the release delay
on the left side of the slow speed escapement, and the shutter release
latch. It is not as bad as it sounds but it will not sit flat after
reinstallation until all these conditions are satisfied. |
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| If you are lucky, this is as far as you will need to go. Carefully place
a drop or two of lighter fluid on the slow speed escapement, replace the
speed ring and fire the shutter until the lighter fluid is dry. Try to hold
the camera at an angle that prevents excess lighter fluid from draining onto
the shutter and aperture blades. In many cases, this will bring a slow
shutter back to life. I would try it 3-5 times before giving up and moving
the next step. |
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| Life is not always that simple. On this shutter, the escapement will
have to come out. Remove the mainspring from its post on the left side of
the slow speed escapement and wiggle the cocking ring and the spring out.
The slow speed escapement is attached to the shutter housing with two
screws. Under these screws are oblong holes that allow the position of the
mechanism to be adjusted. Moving the pallet (right side) closer to the
inside makes the shutter run faster. Carefully mark the position of both
screws in relation to the escapement, remove them and lift the escapement
out of the shutter. I normally soak mine overnight in lighter fluid. The
escapement should run smoothly without lubrication in many cases. If it
still doesn’t run, I use a pin and dip it into Rem gun oil to obtain a tiny
drop. I apply a drop to the pallet shaft (the rocking arm) and the star
wheel shaft (the gear the pallet rocks against). That should be enough to
get most escapements running smoothly. Don’t over-lubricate them or you are
asking for trouble later when the excess oil attracts dirt. If the shutter
blades have oil on them, you can often remove that by gently dabbing them
with a tissue soaked with lighter fluid. Keep changing tissues and wiping
until they are clean.
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| However, this will not be enough for this shutter. When I hold open the
blade actuator, see that extra piece sticking out? You might also note in
the earlier photos that the shutter is not stopping down all the way light
tight. If you see something like this, or the blades are still fouling after
the tissue cleaning, then the rear of the shutter must be removed and the
blades individually cleaned. |
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| In the rear of the camera, there is another nut with 4 spanner slots.
This is the shutter nut. Remove it and the shutter will come free from the
lens standard. |
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| The aperture controls are removed with a single screw. Remove the screw
and set the aperture controls aside. |
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On the rear of the shutter are three screws. When they
are removed, you can separate the back (aperture) part of the shutter from
the front. You must be aware of a few things before proceeding. First, the
shutter release will drop out when you open the back as will the booster
spring. You can remove them before starting or deal with them as you open
the back. The release arm has a hairspring that goes into a slot on the
case. This is easily dealt with after the shutter halves are joined back
together. Second, you want to keep the front of the shutter facing down and
lift slowly. The 5 blades are loose and it's good to get a photo of their
arrangement before they drop out. Remove the three screws and carefully
separate the two halves.
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| Here you see how the blades work. Sometimes there will be a blade with a
tip that curves in or out. Sometimes (less often) there will be shims.
Document the arrangement carefully before proceeding. If you carefully push
the blade actuator, you can actually see how the blades pivot about a fixed
pin. Remove the blades and clean them individually with lighter fluid. To
reassemble, lay one on top of the other and keep at it until you get them
all back on. This is exacting work that requires a steady hand and patience.
Before reassembling, you can stop the aperture down and give that a good
cleaning with plenty of tissues and lighter fluid. Carefully lay the rear of
the case back on, make sure that it's properly lined-up and replace the
three screws. |
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Once you’ve gotten this far, it's pretty
much a matter of proceeding in reverse. If the shutter fires smoothly and
reliably, pat yourself on the back and put it back together. Remember I
mentioned the speed adjustment? If you have little in the way of equipment, a
PC with a microphone is more than good enough to check the 1 sec – 1/10
timings. I am also in the process of building a photodiode-based shutter tester
that interfaces through a sound card. You can move the pallet in and out to get
a good 1 second timing and the rest of the speeds should fall into line.
Mike inspired me to post my Tester
Sound Card Shutter Tester
I clean the optics with tissue or Q-tips and an optical cleaner. If you have
a blower, it’s a good idea to blow them first, then to clean. For really foggy
lenses, a freshly laundered T-shirt with a light touch will remove the fog.
Follow up with optical cleaner and air puffs. Early coated (mostly WWII vintage)
lenses have extremely delicate internal coatings so do take care in such a rare
case. I have not seen such a lens on a folding camera yet.
The last step that you need to complete is the focus setting. If it was good
to begin with and you install the focus ring starting at the exact spot that it
came off, then it should still be good. To get the focus back in the same place,
start by placing it on a little bit past your marked spot, go backward applying
light pressure and feel for the "pop" when it goes over the start point. It's
when you feel the "pop" that you should reverse directions and screw the ring
back on.
If you have a ground glass, take your camera outdoors and focus on an object
far in the distance, e.g. a radio tower. Make sure the coarse side of the screen
is facing the lens and that it sits in the inner film rails. If infinity lines
up on the dial with your focus on the ground glass, reinstall the infinity stop
and you are finished. If not, there are usually set screws on the focus dial. If
you back them off, you can reset the position of the dial without moving the
focus on its thread, then tighten the set screws and replace the infinity stop.
For a more elegant way to bring infinity indoors, see the links below. Or see
how Dave dose it on the cheap AGFA towards
the bottom of the page.
I normally also spend some intimate moments with my folder in the closet with
a flashlight. Check carefully for holes in the bellows and patch them if
necessary. The Zeiss folders I work on have not yet required any patching, even
after 50-70 years of service.
I hope this is of some use to would-be camera tinkers. Happy snaps!
Helpful Links:
Rick Oleson -
http://rick_oleson.tripod.com/index-27.html - bring infinity indoors, tech
notes
Daniel Mitchell -
http://daniel.mitchell.name/cameras/index.html - excellent notes on many
shutter types
Thanks to Mike Kovacs
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