First things first, let me take this out of the way: I am not a professional camera technician. However, I have had to adjust the rangefinder horizontal alignment on several Leica cameras, and I have found a method that works well for me. Proceed with caution and at your own risk. Poking tools inside your camera carries significant risk. If you are uncomfortable with precision adjustments, please send your camera to a qualified technician.
The Diagnosis
Before even thinking about adjusting the rangefinder, you need to confirm that it is indeed misaligned. The most straightforward way I have found to do this is to:
- Pick a target with high contrast details, such as a newspaper or a brick wall at a focus distance you feel comfortable working with (e.g., 1-3 meters).
- Focus the lens and check the patch. The image should be sharp and the two images should align perfectly.
- Take a test shot and review it. If the image is not sharp, it may indicate a misalignment.
Am I back/front focusing?
Before adjusting the rangefinder, it's crucial to determine whether your camera is back-focusing or front-focusing.
This can be done by taking a series of test shots, wiggle the focus ring slightly back and forth around the point where you believe the focus is sharpest. If the sharpest focus occurs when the focus ring is slightly turned towards infinity, your camera is back-focusing. Conversely, if the sharpest focus occurs when the focus ring is turned slightly towards the minimum focus distance, your camera is front-focusing.
The Adjustment
What you will need:
- 2mm Hex Key (Allen Wrench): High quality is essential. A cheap one may strip the screw.
- A high contrast target for focusing.
- Patience and a steady hand.
- A lens that you are comfortable working with.
- Good lighting conditions.
Pictured: Leica M (typ 240).
Steps:
- Start by putting yourself at 2 meters from the target, straight on, and focus the lens carefully on that target, using the rangefinder patch.
- Take a test shot and review it.
- Remove the lens from the camera body.
- Locate the rangefinder adjustment screw. The screw on the roller is for horizontal alignment.
- Using the 2mm hex key, make small adjustments to the screw.
- After each adjustment, reattach the lens, focus on the target again, and take a test shot.
- Review the test shot to see if the focus has improved.
- Repeat the adjustment process until the focus is sharp.
Always apply gentle, steady torque.
Note: Rangefinders are designed to be calibrated at infinity focus. However, many users find it more practical to calibrate at a closer distance, such as 2 meters. This is because most of their photography occurs at closer distances, and calibrating at 2 meters can provide better accuracy for their typical shooting scenarios.