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Mamiya RB 6×7 90mm Lens Slow Shutter Repair: A Step-by-Step Guide

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Mamiya RB 6x7 90mm Lens Slow Shutter Repair: A Step-by-Step Guide

The Mamiya RB 6x7 is a legendary medium format camera known for its exceptional image quality and robust build. However, like any mechanical device, it can experience issues over time. One common problem is a sluggish slow shutter speed, making it difficult to capture long exposures. This guide provides a step-by-step tutorial on how to diagnose and repair this issue in your Mamiya RB 6x7 90mm lens.

Understanding the Slow Shutter Mechanism

The slow shutter speed mechanism in the Mamiya RB 90mm lens relies on a delicate escapement system. This system uses a series of gears, springs, and levers to control the speed at which the shutter blades open and close. Over time, dust, dirt, and lubrication degradation can cause this mechanism to become sticky or sluggish, leading to slow shutter speeds that are not accurate.

Tools and Materials

Before you begin, gather the following tools and materials:

  • A small Phillips screwdriver
  • A small flathead screwdriver
  • A magnifying glass
  • Lens cleaning solution (e.g., PEC-PAD)
  • A soft brush (e.g., camel hair)
  • A lint-free cloth
  • A small container with distilled water
  • A small container with isopropyl alcohol (90% or higher)
  • Lubricating oil for camera mechanisms (e.g., Moebius 111)

Step-by-Step Repair Process

1. Disassembly

  1. Remove the lens from the camera body.
  2. Carefully remove the front lens element by unscrewing the retaining ring.
  3. Remove the aperture ring by unscrewing the screws securing it.
  4. Use a small Phillips screwdriver to remove the screws holding the shutter assembly in place.
  5. Gently lift the shutter assembly out of the lens barrel.

2. Cleaning

  1. Use a soft brush to remove any dust or debris from the shutter assembly.
  2. Dampen a lint-free cloth with lens cleaning solution and carefully wipe down the shutter blades and other exposed surfaces.
  3. Use a small amount of isopropyl alcohol on a Q-tip to clean any stubborn dirt or grease.
  4. Thoroughly dry all components with a clean lint-free cloth.

3. Lubrication

  1. Apply a small drop of lubricating oil to the slow speed escapement mechanism. Be sure to use a high-quality oil specifically designed for camera mechanisms.
  2. Avoid over-lubricating, as this can cause the mechanism to become sticky.

4. Reassembly

  1. Carefully reassemble the shutter assembly in reverse order, ensuring that all screws are tightened securely.
  2. Reinstall the aperture ring and front lens element.
  3. Mount the lens back onto the camera body.

5. Testing

After reassembly, test the slow shutter speeds to ensure they are functioning correctly. You can use a shutter speed tester or a long exposure test to verify the accuracy of the slow speeds. If the shutter speeds are still sluggish, you may need to repeat the cleaning and lubrication process.

Safety Precautions

When working with camera mechanisms, it's essential to exercise caution and follow these safety precautions:

  • Work on a clean and well-lit surface.
  • Avoid touching the shutter blades or other delicate components with your fingers.
  • Use a magnifying glass to help you see small parts clearly.
  • Be patient and take your time when working on the lens.
  • If you are unsure about any step, consult a qualified camera repair technician.

Conclusion

Repairing a sluggish slow shutter speed in a Mamiya RB 6x7 90mm lens can be a rewarding experience. By following these steps and exercising caution, you can restore your lens to its former glory and continue capturing stunning medium format images.

Remember that this guide is for informational purposes only. Always consult a qualified camera repair technician for any complex repairs or if you are unsure about any step. Happy shooting!

Slow Shutter Speed