SLR Camera Reflex Mirror 'Shock Absorber/Damper (Air Damper / Pneumatic Buffer)' Air Leak and Rebound Vibration

1. The fatal disease of mechanical SLRs: the physical shock wave from the reflector

In order to provide a bright field of view in the viewfinder, the mirror of an SLR camera must bounce upward at a very high acceleration at the moment of exposure, and rebound quickly after the exposure:

• The huge recoil inertia of metal striking (Mirror Slap):
• The reflector is composed of a thick glass reflector and a metal bracket, with a mass of up to 10g~20g;
• The powerful spring pulls it up violently within a thousandth of a second, hitting the metal limit frame at the bottom of the fuselage's pentaprism upwards;
• Fatal machine shock blur critical speed (1/4s ~ 1/30s):
• This violent mechanical impact excites strong resonant mechanical waves inside the fuselage;
• At handheld slow speeds such as 1/15 second, the shutter curtain has just opened, and the body frame is still vibrating violently at high frequencies due to the impact of the reflector, causing the sharpness of the entire film to collapse like a cliff;
• Brutal solution to traditional machinery: Heavy-duty SLRs such as Nikon F/F2 rely on the weight of the heavy body to resist impulse by adding a thick brass casting body weighing nearly 1 kilogram, but the price is that the camera is as heavy as a brick.

2. Miku Yoneya’s watch-level miniature carving masterpiece: Mini Air Cylinder (Pneumatic Damper)

Olympus creatively inserted a high-precision pneumatic damping system into the small body of the OM-1:

• Mini air piston and precision brass cylinder:
• Located deep in the lower right corner of the reflector box, a high-precision miniature brass cylinder with a length of only about 1.5 cm is designed;
• The piston connecting rod is directly hinged on the main drive rocker arm of the reflector;
• Aerodynamic Air Spring (Air Spring Action):
• When the reflector reaches the last third of its high-speed upward stroke, the rocker arm strongly pushes the piston into the cylinder;
• The air inside the cylinder is instantly highly adiabatically compressed, producing huge reverse air pressure buffering resistance;
• There is a tiny bleed damping hole (Bleed Orifice) that has been precision ground at the micron level on the top of the cylinder;
• The compressed air is discharged from the small hole at a gentle speed with controlled micro-damping, gently converting the violent kinetic energy of the reflector into a silent air flow to consume all the heat energy!
• Aural Miracle: The OM-1's shutter sound changes from the harsh 'frame' of a traditional DSLR! ’ The loud sound transformed into an extremely soft and gentle ‘click...’ sigh like the gears of a high-end pocket watch!

3. Pathological diagnosis of airbag damper leakage failure (Damper Failure)

After 50 years of air dust and aging, the cylinder system often suffers physical air tightness breakdown:

1. Piston miniature soft sealing cup ages and hardens:

• The piston head was originally made of specially made highly elastic, wear-resistant and oil-resistant synthetic rubber or precision ground graphite piston rings;
• The rubber hardens, shrinks and dries, creating a mechanical gap between the rubber and the inner wall of the cylinder;

2. Instant loss of air tightness:

• When the shutter is pressed, high-pressure air leaks directly from the piston gap, and sufficient compression back pressure damping cannot be established inside the cylinder;
• Typical failure symptoms:
• The shutter release sound becomes unusually sharp and harsh, accompanied by a crisp and harsh metal impact echo (the sound of iron striking);
• When shooting handheld at slow shutter speeds, the high-frequency micro-vibration blur rate at the edge of the film increases sharply by more than 50%;
• The strong beating, bumping and shaking of the picture can be clearly felt inside the viewfinder.

4. Specifications for disassembly, cleaning and damping grease coating repair of micro cylinders

The rigorous surgical standards used by professional old film camera repairmen to repair the OM-1 cylinder damping:

• Fine disassembly and positioning:
• Remove the front bayonet panel of the camera to expose the tiny brass damping cylinder mechanism on the outside of the mirror box;
• Use a precision watch screwdriver to remove the micro-connecting rod fixing pin and pull out the piston core smoothly.
• Remove aged grease and dirt:
• It is absolutely forbidden to have dust and dry sludge inside the cylinder!
• Use a cotton swab dipped in anhydrous ether or pure lighter fluid to thoroughly clean the inner wall of the piston and cylinder until the inner surface of the brass returns to mirror reflection.
• Iron law for damping grease selection (life and death viscosity):
• It is strictly prohibited to use low-viscosity sewing machine oil or machine oil (thin oil cannot seal the air gap at all, and will splash and contaminate the reflector!);
• It is strictly prohibited to use heavy-duty butter with too high viscosity (it will cause the piston to get stuck and the reflector to rise extremely delayed and get stuck in the air!);
• The only gold standard: Use high vacuum silicone grease (such as Dow Corning High Vacuum Grease) or a very small amount of Japanese precision damping grease (consistency code #3000);
• Dip a needle tip into a very small amount of invisible grease and apply it evenly on the side of the piston ring;
• Reassembly and damping debugging:
• Push in the piston and quickly push and pull the connecting rod manually: you should feel a full feel that is extremely smooth and gentle when pushed in, but with a clear sense of air rebound damping**;
• Reassemble the fuselage, and the shutter once again restores the silky soft sigh that has been sung for half a century!

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