Section 12The Screw-Mount Leica L
eica cameras are favorites of collectors. The name "Leica" came by joining the factory name (Leitz) with "camera." Some Leica models are very valuable. But just about all models bring a good price when they are in operating condition. The first production Leica appeared in 1925 and was supplied in two modelsone with a focal-plane shutter and one with a Compur shutter. After that, the drum-type focalplane shutter became a Leica standard. Very few collectors can boast about having an original production model. Leica a and b models are also rareand highly valued. It's unlikely you'll see one for repair. But many collectors do have one or more of the screw-mount Leicas dating from the 1940's"screw-mount" means the camera has a screwmount lens rather than the bayonet-mount lens introduced in the M-series Leicas. The IIIc was introduced in 1940. If you find one of the original IIIc models, it's even more valuablethe original IIIc has a red curtain. The Ic and IIc came slightly later. But the Leica IIIf may be the screw-mount Leica you see most frequently. Introduced in 1950, the Ill has two variationsthe red-dial Leica and the black-dial Leica. The names come from the color of the calibrations on the flashsync dial under the speed knob. Moving the flash-sync dial changes the length of the sync delay. In the days of flashbulbs, the Leica photographer could set the sync delay according to the shutter speed and to the type of flashbulb. But these days, you only need the electronic-flash settings. These are: black-dial Leica1/30 second, flash-sync setting 2. red-dial Leica1/25 second at the flash-sync setting of 0 or 1/50 second at the flash-sync setting of 20. When you're checking the flash sync with a Leica Ill, set the combination of settings indicated above. You should then get a full aperture with electronic flash. There's also a difference in the shutter-speed range between the red-dial and black-dial models. With the red-dial Leica, the three slowest slit-width shutter speeds are 1/25 second, 1/50 second, and 1/75 second. The black-dial Leica has more conventional shutter speeds1/30 second, 1/40 second, and 1/60 second. Either model may or may not have a built-in self-timer. Models with the self-timer are slightly more valuable to collectors. And, depending on the condition, the red-dial IIIf is slightly more valuable than the black-dial IIIf.
There's also an army version of the IIIf that is all black. But it's unlikely you'll see one. If you do come across a black IIIf, handle it gentlyit's worth several times as much as the other versions. The If and IIf, simplified versions of the III, came a little later. The last of the screw-mount Leicas, the Ill, is very similar to the IIIf, The IIIg has a more sophisticated viewfinder that shows automatic frame lines for 50mm and 90mm lenses. Also, the IIIg has a simplified flash-sync system. There's also a Ig, but this limited-production camera is very rareand very valuable. For illustration purposes, we'll use the Leica IIIf. Many of the Leica IIIf features serve to illustrate the fundamentals of 35mm cameras. So, as we go through the Leica IIIf, we'll point out the features that are typical of 35mm design. If you want to learn more about 35mm design features, such as film transport systems, please refer to the Alii companion publication, Camera Technician's Guide.
FEATURES OF THE LEICA Illf
The shutter in the Leica IIIf is similar to the drum-type design discussed earlier. The wind knob at the top of the camera both cocks the shutter and advances the filmjust turn the wind knob in its arrowmarked direction. Notice that the speed knob rotates at the same time. The speed knob rotates with the curtain drum. After cocking the shutter, lift and turn the speed knob to set the shutter speed. The slowest slit-width shutter speed in the black-dial Leica is 1/30 second. But the shutter-speed calibration at. 1/30 second is 30-1. The calibration means that you also leave the speed knob at 30-1 for shutter speeds slower than 1/30 second. Set the slower shutter speeds with the slow-speed knob at
FIG. L1 Removing the body shell.
THE SCREW-MOUNT LEICA/125
the front of the camera. The setting on the slow-speed knob determines the amount of retard engagement. The slowspeed knob also controls the pallet in the slow-speed governor. Check the operation at the slowest shutter speed1 second. The 2nd curtain should move smoothly through the retard. The operation at 1 second will give you an idea as to the camera's condition. If the shutter hangs open at the 1second settingor if the 2nd curtain struggles to get through the retardthe slow-speed governor needs cleaning and lubrication. Unlike the later Leica M3 described earlier, the IIIf has separate viewing systems for the viewfinder and rangefinder images. There are two eyelenses at the back of the camera. Use the eyelens to the left to focus the lensturn the focus ring until the rangefinder images superimpose. Use the eyelens to the right to view and compose the picture. Load film in the camera by first removing the base plate (the plate at the bottom of the camera). Turn the lock lever at the bottom of the camera to the open position. Then lift the lock-lever end of the base plate from the camera body. Next pull out the take-up spoolthe take-up spool has a friction fit over the take-up sleeve. You can now engage the film leader with the take-up spool. Insert the film cartridge and take-up spool into the bottom of the camera. The "bottom-loading" design makes it difficult to check the shutter operation with the camera assembled. You must first remove the body shell, the black shell that has the leather covering.

INTERLOCKING STUDS DISENGAGED
1st-CURTAIN LATCH 1st-CURTAIN CAM
FIG. L6 Sequence of the 1st-curtain release action. In A, the shutter is in the released position. As you cock the shutter, the 1stcurtain cam turns clockwise; the 1st-curtain latch then latches the 1st-curtain cam (B). In C, the flat release spring has disengaged the lst-curtain latch.The 1st-curtain now rotates counterclockwise as the 1st curtain crosses the film aperture. observe the 2nd-curtain latch. But you've already seen the basic design in your earlier study of focal-plane shutters. There's one more operation you can see from the bottom of the camerathe curtain brake. The curtain brake goes into action after the 1st curtain has crossed the film aperture.
FIG. L7 BACK OF CAMERA, RELEASE BUTTON PUSHED DOWN 128/THE SCREW-MOUNT LEICA

BRAKE LEVER

FIG. L8 Bottom of camera, shutter released. You've seen that the spring-driven 1st curtain fires across the film aperture at a high rate of speed. If the 1st curtain came to a solid stop, it would bouncethe 1 st curtain would re-enter the film aperture. The curtain brake cushions the 1st curtain at the end of the travel. The 1st curtain then comes to a gradual stop to prevent curtain bounce. As the 1st curtain nears the end of its travel, the lst-curtain cam strikes the brake lever, Fig. L8 and Fig. L9. The brake lever now causes a brake shoe to engage the inside of the brake drum. You can't as yet see the brake partsthey are on the other side of the bottom plate in Fig. L8. Fig. L10 shows the brake shoe and drum that sit on the inside of the bottom plate. A flatted end of the brake-lever shaft fits in the open area of the brake shoe. When the lst-curtain cam drives the brake lever as shown in Fig. L9, the brake-lever shaft spreads the brake shoe. The brake shoe then comes against the inside of the brake drum. The brake drum rotates with the lst-curtain curtain drum. So, as the brake shoe slows the rotation of the brake drum, the brake drum slows the rotation of the lst-curtain drum. The 1st curtain comes to a gradualrather than an abrupt stop. How about the 2nd curtain? Some focal-plane shutters also provide a brake for the 2nd curtain. But many focal-plane shutters, like the Leica IIIf, have only a lst-curtain brake. The lst-curtain brake also tends to brake the 2nd curtain. After the 1st curtain has crossed the aperture, it doesn't move all the way to its stopthe lst-curtain brake prevents the 1st curtain from moving to a solid stop. Now the 2nd curtain fires across the film aperture. As the 2nd-curtain drum nears the released position, it comes against the lst-curtain drum (you saw this operation in your study of drum-type focal-plane shutters). And the 2nd-curtain drum drives the lst-curtain drum a little further in the release direction against the pressure of the brake. Now the brake cushions the 2nd curtain to prevent bounce. The end of the brake leverthe end that the lst-curtain

BRAKE LEVER SHUTTER COCKED

ECCENTRIC

SHUTTER RELEASED
FIG. L9 During the release cycle, the 1stcurtain cam drives the brake lever as shown by the curved arrow.
BRAKE-LEVER SHAFT FITS HERE

BRAKE DRUM

BRAKE SHOE
FIG. L10 Brake shoe and brake drum.
cam strikesis an eccentric, Fig. The eccentric provides your adjustment for the brake. Later in this section, we'll cover the brake adjustment. The procedure for adjusting curtain brakes applies to all focal-plane shutters.
THE SCREW-MOUNT LEICA/129

REMOVING THE TOP COVER

The speed knob is held to the 2nd-curtain release lever by three setscrews. You can reach the setscrews through clearance holes at the outer circumference of the speed knob. Lift the speed knob against its spring tension. Then, working through the clearance holes, loosen each of the three setscrews. Finally, lift the speed knob straight up and off the shaft of the 2nd-curtain release lever. On the bottom of the speed knob, you can see the halfmoon cutout that operates the sync contacts. The sync contacts, Fig. L14, remain in the center of the sync dial. As the speed knob rotates with the lst-curtain drum, its cutout determines when the sync contacts close. The movable sync contact is spring loadedthe spring moves the movable sync contact against the fixed sync contact. A solid portion of the cam under the speed knob holds the sync contacts openthe movable sync contact can't move against the fixed sync contact. As the speed knob rotates during the exposure cycle, the half-moon cutout reaches the movable sync contact, Fig. L15. Now the movable sync contact moves against the fixed sync contact to fire the flash. As you turn the sync dial, you're just setting the starting position of the movable sync contactthe point during the movement of the 1st curtain that the sync contacts close. It may seem that the sync contacts would also close during the cocking cycle. They do. But, thanks to a safety switch, Fig. L12, the flash doesn't fire. The use of a safety switch is common in focal-plane shutters. As you cock the shutter, the contacts that fire the flash close. But the safety switch is open, Fig. L12. The open safety switch disconnects the sync contacts from the flashcord terminal. The safety switch closes during the release cycle. Now the closed safety switch connects the sync contacts to the flashcord terminal. When the sync contacts close, Fig. L13, the flash fires. In the Leica IIIf, the safety switch is under the 2nd-curtain latchyou'll be able to see the safety switch with the top cover removed. Set the rewind lever (the lever just in front of the release button) to the advance position. Then remove the screw hold ing the rewind lever. Lift off the rewind lever and the bushing that fits over the rewind shaft (the shaft from which you removed the rewind lever). Moving the rewind lever to the rewind position disengages the sprocket. The sprocket can then turn in the reverse direction as you rewind the film.

BOTTOM

CUTOUT SIDE

FIG. L11 Speed knob.

SAFETY SWITCH

SYNC CONTACTS

FIG. L12 During cocking cycle.
SAFETY SWITCH SYNC CONTACTS
FIG. L13 During release cycle.
MOVABLE SYNC CONTACT FIXED SYNC CONTACT BOTTOM OF SPEED KNOB

FIG. L14 Shutter cocked.

SYNC CONTACTS CLOSED
FIG. L15 During release cycle.
130/THE SCREW-MOUNT LEICA
Unscrew the knurled shield that fits around the release button, Fig. L16. The wind knob screws onto the top of the take-up sleeve, Fig. L16. A setscrew locks the wind knob in place. You can reach the setscrew through the hole in the outer circumference of the wind knob, Fig. L17 (you may have to lift and rotate the film-reminder dial to locate the setscrew). Loosen the setscrew around two turns. Then unscrew the wind knob from the take-up sleeve.

KNURLED SHIELD

WIND KNOB

WIND-KNOB SETSCREW

FIG. LBack of camera.

COUNTER DIAL

TOP OF TAKE-UP SLEEVE
FIG. L17 Side of wind knob.
REWIND SHAFT SCREWS COUNTER GEAR COUNTER GEAR
FIG. L18 Top, wind knob removed. The take-up sleeve and the counter dial arc now loose. But you can hold the take-up sleeve in place to see how the counter dial operates. The top portion of the take-up sleeve is an eccentric that fits in the center of the counter gear, Fig. L18. A slot in the counter gear fits over a pin, Fig. L19. The pin allows the counter gear to slide back and forth. But the pin only allows the counter gear to rotate slightly. As the take-up sleeve rotates, its eccentric causes the counter gear to slide back and forththere's enough clearance between the teeth on the counter dial and the teeth on the counter gear to allow the back-and-forth movement. The counter-gear teeth then disengage on one side as the counter gear moves back. Then, as the eccentric shifts the counter
FIG. L19 Top, counter dial removed.
THE SCREW-MOUNT LEICA/131
gear, the counter-gear teeth pick up the next tooth on the counter dial. The counter dial advances one frame calibration. You can now lift out the counter dial, Fig. L18, the counter gear, Fig. L19, and the take-up sleeve. Earlier we described how the gear at the top of the take-up sleeve provides the one-way clutch for the film advance. With the take-up sleeve removed, you can see the pawl spring at its top end, Fig. L21. The end of the pawl spring fits into the notch in the one-way pawl, Fig. L20. When you turn the wind knob in the advance direction, the pawl spring holds the pawl disengaged as shown in Fig. 20. But when the curtains pull the take-up sleeve in the reverse direction, the pawl spring pulls the pawl into engagement with the take-up-sleeve gear, Fig. L5. The pawl then permits the take-up sleeve to turn in only one directionthe film-advance direction. When you replace the take-up sleeve, fit the end of the pawl spring, Fig. L21, into the pawl notch, Fig. L20. The large compression spring at the bottom of the take-up sleeve is the slip spring for the film take up. Earlier you removed the take-up spool; the take-up spool fits over the center cylinder of the take-up sleeve, held by the three spring tabs, Fig. L21. The center cylinder of the take-up sleeve is a separate piece. As the take-up sleeve turns, the compression spring carries the center cylinder. But you can hold the center cylinder and still turn the take-up sleevethe compression spring now "slips" as the take-up sleeve turns. Practically all 35mm cameras have such a slipping clutch on the take-up spool or take-up sleeve. As the film wraps around the take-up spool, the diameter of the take-up spool increases. And the larger the diameter, the less the take-up spool must turn to wrap on the same amount of film. But the wind knob always turns the same amount. The slipping clutch then allows the take-up spool to stop after the correct amount of film has been advancedyet you can continue turning the wind knob to complete the shuttercocking cycle. You can often trace film-advance problems to the slipping clutch on the take-up spool. For example, suspect the slipping clutch if the camera tears the perforation holes in the film. Torn perforation holes indicate that the clutch isn't slipping freely enough. After the film has advanced the proper amount, the sprocket stops. But the take-up spool keeps turning as you advance the wind knob. If the clutch doesn't slip freely enough, the film will be pulled past the locked sprocketand perforation holes will tear.

RETARD LEVER

1/1000-SECOND HOLE
BULB HOLE HIGH POST (1/1000 SECOND)
LOW POST (1/30 SECOND THROUGH 1/500 SECOND)

FIG. L27

2nd-CURTAIN CAM
FIG. L28 2nd-curtain cam with 2nd-curtain release lever and speed-control disc removed.
FIG. L29 On slow speeds, the 2nd-curtain cam must push aside the retard lever.
THE SCREW-MOUNT LEICA/135
deeper the engagement between the retard lever and the 2nd-curtain cam, the longer it takes for the 2nd-curtain cam to push aside the retard lever. As the 2nd-curtain cam is pushing aside the retard lever, the 2nd curtain is creeping toward the film aperture. Finally the 2nd-curtain cam gets past the retard lever. And the 2nd curtain fires across the film aperture to end the exposure. As you cock the shutter for the next exposure, the 2ndcurtain cam rotates counterclockwise. Now it appears that the retard lever is in the way of the 2nd-curtain cam. But,until you release the shutter, the retard lever sits below the plane of the 2nd-curtain cam. The 2nd-curtain cam then passes above the retard lever. Then, when the 1st curtain crosses the film aperture, the retard lever moves upinto position to catch the 2nd-curtain cam. The part that moves up the retard lever is the retard-rod spring at the bottom of the camera, Fig. L31. The lower end of the retard rod sits on the top of the retard-rod spring; the retard lever attaches to the upper end of the retard rod. A pin on the underside of the lst-curtain cam operates the retard-rod spring. With the shutter cocked, the end of the retard-rod spring moves downtoward the bottom of the camera. The retard-lever spring, Fig. L24, then pushes down the retard rod. Now the retard lever sits below the plane of the 2nd-curtain cam. But when the lst-curtain cam reaches the released position, Fig. L31, its downward-projecting pin pushes up the end of the retard-rod spring. The retard-rod spring pushes up the retard rod. And the retard lever moves into the plane of the 2nd-curtain cam. The slow-speed knob also has a time setting. At time, the retard lever moves its maximum distance toward the 2ndcurtain cam. Here the time plate, Fig. L30, blocks the movement of the retard lever. The 2nd-curtain cam can't push the retard lever aside. And the shutter stays open until you turn the slow-speed knob to another setting. The time plate has an adjustmentafter loosening the screw,

RETARD-ROD SPRING 1st-CURTAIN CAM

TIME PLATE

FIG. L30 Time action. you can slide the time plate closer to or further from the retard lever. Adjust the position of the time plate for proper time operation. If the time plate doesn't catch the retard lever at the time setting, slide the time plate closer to the retard lever. If the time plate catches the retard lever at the 1-second setting, slide the time plate away from the retard lever.
REMOVING THE SPEED-CONTROL PARTS
You may wish to disassembly the speed-control parts for cleaning and lubrication. It's especially critical that the 2ndcurtain latch is clean and properly lubricated. To remove the 2nd-curtain release lever, take out its center screw. Carefulthere's a loose compression spring under the screw. The compression spring holds the 2nd-curtain release lever against the speed-control disc. Remove the compression spring and lift off the 2nd-curtain release lever. Next remove the screw on the outer circumference of the speedcontrol discthe screw holds the speed-control disc to the shaft of the lst-curtain drum. Lift off the speed-control disc. You can now reach the 2nd-curtain cam, Fig. L28. If you cock
FIG. L31 Bottom of camera.

FLAT RELEASE SPRING

FIG. L32 2nd-curtain latch.
136/THE SCREW-MOUNT LEICA
and release the shutter, you'll get bulb operation. There's nothing to disengage the 2nd-curtain latch. The 2nd-curtain latch then continues to hold the 2nd-curtain cam until you let up the release button. Disconnect the spring from the post on the 2nd-curtain latch, Fig. L25. Then remove the shoulder screw that holds the spring. Lift the 2nd-curtain latch up and out of the camera body, Fig. L32.

SLOW-SPEED KNOB

RANGEFINDER FRONT-PLATE SCREWS
LUBRICATING THE SPEEDCONTROL PARTS
After you've cleaned the parts just removed, you can apply lubrication. Lightly grease the two cam lobes on the 2nd-curtain camthe cam lobe that comes against the retard lever, Fig. L29, and the surface that's engaged by the 2nd-curtain latch, Fig. L28. The 2nd-curtain latch must move freely up and downdown when you depress the release button and up when you let up the release button. Use shutter oil to lubricate the shaft of the 2nd-curtain latchthe areas that come against the bearings in the camera body, Fig. L32. Lubricate the latching surface of the 2nd-curtain latch with grease. Also use grease to lubricate the posts of the 2ndcurtain latchthe posts that the 2ndcurtain release lever strikes to release the 2nd curtain. With the 2nd-curtain latch removed, you can more clearly see the safety switch, Fig. L24. Remember, the safety switch completes the circuit to the sync contacts during (he release cycle. As the 2nd-curtain latch moves down, it closes the safety switch. You can now replace the 2nd-curtain latch and connect the spring, Fig. L25. Make sure the 2nd-curtain latch moves down freely when you push the release button. Then replace the speed-control disc with its screw. Install the 2nd-curtain release lever on top of the speed-control disc.

SCREW FOR BOTTOM PLATE ACCESS HOLE

FIG. L33

DRUM LIGHT SHIELD PALLET-CONTROL GEAR

LOWER LIGHT SHIELD

FIG. L34

SLOW-SPEED GOVERNOR

Seat the compression spring at the top of the 2nd-curtain release lever and replace the screw.

REMOVING THE FRONT PLATE

You can clean and lubricate the curtain rollers after removing the front plate, Fig. L33. Removing the front plate also allows you to reach the slow-speed governor. If the camera has a self-timer, remove the complete self-timer mechanism. Two screws at the front of the front plate hold the self-timer. Now remove the four screws around the lens opening and the screws around the edge of the front plate. Depending on the version of the camera, there may be a short front-plate screw at the bottom frontalso remove this screw if it's present. Do not remove the bottom-plate screw indicated in
THE SCREW-MOUNT LEICA/137
Fig. L33. Lift off the front plate together with the slow-speed knob. Two of the three light shields within the focal plane are now loosethese two light shields were held by the screws around the lens opening. Carefully note the position of the light shield around the curtain drum and the light shield above the slow-speed governor. Fig. L34 shows the drum light shield lifted outthe drum light shield passes to the inside of the upturned tab on the lower light shield (the light shield above the slow-speed governor). The light shield next to the tension rollers also passes to the inside of the upturned tab on the lower light shield. You can't as yet remove the light shield next to the tension rollers. But you can remove the lower light shield, Fig. L35.

RETARD ROD

RANGEFINDER LEVER

PALLET LEVER

FIG. L35
The upper end of the pallet-cam follower rides against the outer cam surface of the slow-speed cam, Fig. L36. The lower end of the pallet-cam follower couples to the upturned tab on the pallet lever in the slow-speed governor, Fig. L35. A spring on the slow-speed governor moves the pallet into engagement with the star wheel. To disengage the pallet, the slow-speed cam pushes the pallet-cam follower in a counterclockwise direction, Fig. L36. The lower end of the pallet-cam follower then pulls the pallet lever from right to left in Fig. L35. The pallet lever now moves the pallet out of engagement with the star wheel. As you replace the front plate, you'll have to couple the pallet-cam follower to the pallet lever. A hole in the front plate provides access to the lower end of the pallet-cam follower. Working through the access hole, Fig. L33 and Fig. 36, you can couple the pallet-cam follower to the right of the pallet-lever tab, Fig. L35.

FIRST-GEAR SEGMENT

FIG. L37 Slow-speed governor, shutter cocked.

PALLET

FIG. L38 Slow-speed governor, shutter released.
But with the Leica IIIfand, as a general rule with other focal-plane shutters as wellyou don't want to remove the curtains for cleaning. Removing the curtains is very timeconsumingand reassembly can be difficult. Fortunately, it's rarely necessary to remove the curtain rollers. You can even replace the curtains without further disassemblywe described the technique in Making and Replacing Shutter Curtains (Section 10). Flush cleaning is the technique for cleaning with mini-
FLUSH CLEANING THE SHUTTER
You can now clean the slow-speed governor as described in Section 3, Cleaning & Lubrication. Lubricate the gear pivots of the slow-speed governor with oil.
SCREWS HOLDING SLOW-SPEED GOVERNOR
FIG. L39 Bottom of camera.
THE SCREW-MOUNT LEICA/139
mum disassembly. To flush clean a mechanism, work in the cleaning solution to the bearing surfaces. Then blow out the cleaning solution. Compressed air works best. But you can also use your hand blower. With a focal-plane shutter, you can use a small brush such as an artist's brush. Use the brush to deposit the cleaning solution into a bearing. For example, say you're cleaning the tension rollers. Deposit the cleaning solution between the central shaft and the outer shell at the top of one tension roller. Use your thumb to rotate the tension roller back and forth. And slide the tension roller up and down, working in the cleaning solution. Then blow out the cleaning solution. The cleaning solution carries out the dirt and dry lubrication. Repeat the procedure a couple of times to make sure the bearing is clean. Then proceed to the next bearing surfaceMake sure you clean all four bearing surfaces for the tension roller (two tension rollers, top and bottom). Also clean both ends of the curtain drum. Reach under the 2nd-curtain cam to clean the upper bearing of the 2nd-curtain drum. And reach under the lst-curtain cam to clean the lower bearing of the lst-curtain drum. Remember to repeat the cleaning procedure for each bearing. The process may seem slow. But it's a lot faster than removing and replacing the curtain rollers. After cleaning the shutter, lubricate each bearing with a tiny drop of oil. You may prefer to remove the pallet-control gear, Fig. L34, for cleaning and lubrication. Since the pallet-control gear turns with the 2nd curtain, it must be very clean and properly lubricated. Lubricate the shoulder of the shoulder screw that holds the pallet-control gear with shutter (clock) oil.

lever. Or, if the shutter is released, you can push the pallet lever against its spring tension as you scat the slow-speed governormake sure the pallet lever sits alongside the pin on the pallet-control gear, Fig. L38. REMOVING THE RANGEFINDER For most repairs, it isn't necessary to remove the rangefinder assembly, Fig. L40. But you can remove the rangefinder after taking off the front plate. The roller on the rangefinder lever, Fig. L35, rides against a cam formed at the back of the lens. The rangefinder lever then moves a prism in the rangefinder. And the prism moves the movable rangefinder image. A screw holds the rangefinder lever to the rangefinder. Working from inside the shutter opening, Fig. L35, remove the screw and washer at the end of the rangefinder lever. Lift out the rangefinder lever. Three screws hold the complete rangefinder assembly two are under the rangefinder lever you just removed. The third is next to the flange for the rewind shaft. Remove the three screws and lift out the rangefinder assembly. Looking at the underside of the rangefinder assembly, you can see a screwhead extending from the eyelens tubethe screw provides the coupling for the eyelens-focus adjustment. Remember that you can adjust the focus of the rangefinder image for your own eyesight. Moving the screwhead slides a lens within the eyelens tube. The screwhead fits in the slot of a coupling lever at the top of the camera body. A fork at the end of the coupling lever straddles a projection on the rangefinder-focusing disc (the disc around the rewind flange that's engaged by the rangefinder-focus lever). When you replace the rangefinder assembly, fit the screwhead in the slot of the coupling lever. Fig. L40.

EYELENS TUBE

REPLACING THE PALLETCONTROL GEAR AND SLOWSPEED GOVERNOR
Remember that all parts that rotate with the curtains should be lubricated with shutter oil that includes the pallet-control gear. Lightly lubricate the inside of the pallet-control-gear center hole. When you replace the pallet-control gear, note the timingthe pin on the pallet-control gear must point to the slow-speed governor with the shutter released. Fig. L38 shows the timing. Replace the slow-speed governor with the shutter in the cocked position. The pin on the pallet-control gear, Fig. L37, then clears the pallet

RANGEFINDERFOCUSING DISC

COUPLING LEVER
SCREWS HOLDING UPPER CLEAT
FIG. L40 Top view, rewind end.
140/THE SCREW-MOUNT LEICA
REPLACING THE FRONT PLATE
Install the light shields, Fig. L35 and Fig. L34. Remember the positions of the drum light shield and the light shield by the tension rollersboth light shields pass to the insides of the upturned edges of the lower light shield, Fig. L41. As you seat the front plate, couple the pallet-cam follower to the retard leverwork through the access hole in the front plate to couple the pallet-cam follower, Fig. L42. FIG. L41 Now replace four of the front-plate retaining screwstwo at each side. If the camera has the fifth front-plate screw at the bottom front, Fig. L41, the screw is slightly shorter in length. And the screw threads into a cleat mounted to the inside of the camera. One of the screws around the lens mount also passes into a threaded cleat, Fig. L41. The cleats are separate parts held to the camera body by screws. You can see one of the threaded cleats in Fig. L35this is the cleat for the screw around the lens mount. It's possible that the threaded cleats may have shifted out of position. The screw hole in the cleat won't then align with the screw hole in the front plate. The cleat shown in Fig. L35 is held by two screws within the accessory-shoe cavity, Fig. L40. Loosen the two screws. You can then work through the screw hole by the lens opening, Fig. L42, to align the screw hole in the cleat. Replace the screw by the lens opening. Then tighten the two screws in the accessory-shoe cavity. If the camera has a screw at the front bottom of the front plate, Fig. L42, the cleat is held by the screw shown in Fig. L44one of the screws holding the retard-rod spring. Loosen the screw at the end of the retard-rod spring. Then align the cleat and replace the front-plate screw. Tighten the screw at the end of the retard-rod spring.

1/500 ECCENTRIC

1/1000 SECOND

1/1000 ECCENTRIC

ADJUSTING THE SHUTTER SPEEDS IN THE LEICA IIIf
Once the exposure appears uniform across the film aperture at 1/1000, you can check the accuracy of the shutter speeds. Again, precision requires test equipment. But you can use the florescent lamp to set 1/500 and 1/1000 as described in Checking and Adjusting Shutter Speeds with a Focal-Plane Shutter,
FIG. L43 2nd-curtain release lever at bulb (top) and at 1/1000 second (bottom), shutter cocked.
Start with 1/500 second. Adjust the 1/500 eccentric, Fig. L43. for an accurate exposure. For a faster exposure time, turn the eccentric in the direction that will disengage the 2nd-curtain latch sooner. Then set 1/1000 second. Adjust the 1/1000 eccentric for an accurate exposure.
SCREW HOLDING THREADED CLEAT
2nd-CURTAIN TENSION ADJUST
FIG. L44 Bottom of camera.
1St-CURTAIN TENSION ADJUST
142/THE SCREW-MOUNT LEICA
The slit-width shutter speeds1/1000 through 1/30should now be correct. Set the speed knob to 1/30 second. And set the slow-speed knob to 1 second. Check the 1-second exposure. Adjusting the slow speeds requires repositioning the slowspeed cam. The adjustment moves the retard lever either closer to or further from the 2nd-curtain cam. If you move the retard lever closer to the 2nd-curtain cam, you increase the depth of engagement. The resulta slower shutter speed. To reach the slow-speed adjustment, first loosen the setscrew on the outer circumference of the knurled slow-speed knob. Now unscrew the knurled knob. Removing the knurled knob from the slow-speed knob uncovers the adjusting collar, Fig. L45. The adjusting collar screws into the slow-speed knob. And the locking screw, Fig. L45, screws into the back of the slow-speed cam, Fig. L36. By changing the relationship between the adjusting collar and the locking screw, you move the slow-speed cam in or out. Moving in the slowspeed cam increases the depth of retard-lever engagement. To adjust at 1 second, unscrew the locking screw a partial turn. Then screw the adjusting collar in or out. When you retighten the locking screw, the slow-speed cam sits at a new position. Turn the adjusting collar clockwise for a slower shutter speed or counterclockwise for a faster shutter speed.

ADJUSTING COLLAR

LOCK SCREW
FIG. L45 Knurled knob removed from slowspeed knob.
CHECKING AND ADJUSTING CURTAIN BOUNCE
Earlier we mentioned the purpose of the brake lever, Fig. L44the brake, you'll recall, prevents the curtains from bouncing into the aperture after the exposure. Curtain bounce may not be a major concern in an antiqueunless you're going to use the camera photographically. You can check for curtain bounce by setting the full-aperture shutter speed (1/30 second in the black-dial IIIf, 1/25 second in the red-dial IIIf). Watch through the back of the film aperture and hold the camera to a light source. With some practice, you can detect the curtain bounce when you release the shutter. Curtain bounce shows at the closing side of the film aperture. If the 1st curtain bounces, the shutter briefly reopens at the closing side. You'll see a slit of lighta strip of white running down the closing side of the film aperture. If the 2nd curtain re-enters the film aperture, you'll see the opposite effecta dark-colored strip running down the closing side of the film aperture.
Either lst-curtain or 2nd-curtain bounce means that the brake action is insufficient. Increase the brake pressure. In the Leica IIIf, you can increase the brake pressure by turning the brake-lever eccentric toward the lst-curtain cam. What if there's too much brake action? Try holding open the shutter on bulb. If there's excessive braking action on the 1st curtain, the lst-curtain bar may still be visible from the back of the film aperture. But the same symptom will result from insufficient tension on the lst-curtain tension rolleror from a dirty shutter. Then let the shutter close at the bulb setting. Can you still see the 2nd-curtain bar in the film aperture? If so, the brake may again be too tight. The 1st curtain hasn't sufficiently overcome the brake, causing the 2nd-curtain bar to remain in the film aperture. You've seen that the lst-curtain brake also serves as a brake for the 2nd curtain. But the 2nd-curtain has additional braking actionas the pallet-control gear strikes the pallet lever, it helps brake the 2nd curtain, lst-curtain bounce is generally more common than 2nd-curtain bounce. Many focal-plane shutters do have separate brakes for each curtain. For examples of brakes in modern focal-plane shutters, please refer to the Camera Technician's Guide published by Alii Service Notes.

THE SCREW-MOUNT LEICA/143
Repair Tips for Unfamiliar Cameras
efore starting on an unfamiliar camera, gather all the repair information you can getespecially if the camera has value. The sheet Sources for Assistance includes suppliers of repair information on specific cameras. Unfortunately, it's not always possible to find information on the older cameras. If there's no information available and if you can't find a "junker" for practiceyou may have to prepare your own repair manual as you go. But again if the camera has value, don't attempt repairs until you've gained proficiency. You might make a photo record of your disassembly. The photos you take will provide invaluable reassembly reference. Or make sketches to show spring positions, wire connections and routing, timing points, etc. The better your sketches and photos, the more useful your repair information will be. Here are some tips you can apply when working on an unfamiliar camera:
shutter-speed or aperture controls. Rotating the ammeter housing puts the needle in a different position for the same amount of light. Or the linkage may move the pointer or doughnut above the exposure-meter needle. If the ammeter housing rotates, there's another danger the housing is probably spring-loaded. The linkage then moves the housing in one direction; the spring moves the housing in the other direction. You can determine what part is moving before disassembly. Change the shutter speed. Is the exposure-meter needle moving? Or is a doughnut moving? Also check the operation while you're changing the diaphragm setting and the film-speed setting. To prevent damageand to give you a chance to note timing pointsit's desirable to let off as much tension as possible from the ammeter spring. Usually, the shutter-speed and film-speed controls rotate the ammeter housing. And in most cases, you can let off the maximum amount of spring tension by the following settings: 1. Set the shutter speed to bulb. 2. Set the film speed to the highest ASA setting. There are exceptionsand that's why it helps to gather specific repair information. But the combination of bulb and the fastest film speed generally rotates the ammeter housing in the direction that lets off spring tension. Then determine what parts must be removed to take off the top cover. With a 35mm camera, you'll usually have to remove the wind lever and the rewind knob. You've seen that me rewind knob normally screws onto the rewind shaft by holding the rewind shaft, you can unscrew the rewind knob. But also check for a screw at the top of the rewind knob. If the screw holds a rapid-rewind crank, it should normally be left in place. However, the screw may be holding the rewind knob to the rewind shaft. Removing the wind lever may lose spring tensionthe tension on the spring mat returns the wind lever after the cocking stroke. Usually, though, the return spring is on the wind shaft. You may also lose, spring tension when you remove the counter dial. A spring may return the counter dial to the start position when you open the back cover. When the counter dial reaches the start position, it comes against a stop. Here, there's still some tension remaining on the counter-dial spring-that's the initial tension. You'll lose the initial tension when you remove the counter dial.