No matter what rangefinder you use, there’s a good chance that you’ll need to have the rangefinder calibrated one time or another. This is no big deal if you’re aware that the problem can happen (often as a result of bumping or dropping the camera)
Some cameras will need adjustment more than others, and the Voigtlander Bessa range seem to be more prone to rangefinder misalignment than others (this can be said for the Epson RD as well, which is basically a digital Bessa).
Many older cameras have a pretty simple adjustment process, and there’s quite a lot of info on the net documenting the process. However much of the Bessa range is still relatively new, and at first it seems as though the whole adjustment process is a guarded secret. Naturally, many Bessa owners weren’t too keen on paying a full service fee for a 10 minute RF alignment, so they begun to search for ways to do it themselves.

There’s quite a lot of info floating around the internet on this subject, but I noticed much of it either lacked pictures or description of “simple” steps. I’ve attempted to combine all of my research together in one place and provide some instructions based off my own personal experience. This process was completed on a Bessa R3A, however I’m told most of the Bessa range is very similar.

*Disclaimer. It’s recommended you ignore these instructions and get your Bessa calibrated by a registered Voigtlander technician if :

• You don’t have experience pulling apart and fixing cameras,
• You’re not confident with small tools,
• You’re clumsy,
• You don’t take responsibility for your own actions and will want to blame your broken camera on me.

1. First of all, to calibrate the rangefinder you won’t necessarily need to take the entire top plate off. It is possible to remove part of the hot shoe that will give you access to the adjustment screws. This can be a tricky process particularly if you don’t want to scratch the black paint on your hot shoe. You’ll need a small flat head screwdriver or even a toothpick to wedge and pop/lift up the cover plate illustrated in the photo below.

When you lift the edge up enough, the cover will pop up and you can slide it out in the direction of the arrow above. It’s important to have patience with this step, as it’s easy to get frustrated and be a little too forceful. You don’t want to break or scratch anything.

2. When you get the cover off, you’ll see the bracket is held on with 4 screws shown in the image below.

Taking these screws off should be pretty simple, they weren’t on too tight with my camera. You’ll need a size #00 Philips head screwdriver for this.

3. Now that you have the bracket off you’ll be able to access the adjustment screws. I could only get a photo of one with the sub standard light I was working in, but I’ve show where the others are using blue circles. The screws are numbered from 1 to 3 for reference purposes.

You’ll need a long flat head screwdriver to adjust these screws. Also, you may need to remove any “loctite” or similar residue around the screws that prevent you from turning them.

The adjustment process
Below is a description of what each screw does. Quite often you’ll only need to adjust one of these so don’t feel overwhelmed.

Screw 1: Rangefinder patch focus adjustment
Screw 2: Horizontal (left/right) adjustment for Infinity focus
Screw 3: Vertical (up/down) adjustment
*There is a 4th screw also, but to access it you need to remove the entire top plate. It calibrates the base length but you’ll hopefully not need to adjust it. 

Now we can start calibration. Once your camera is adjusted at infinity focus, everything should line up for close focus as well, but check just in case. My camera needed horizontal adjustment, yours might need vertical (or both). Find a place to set your camera up on a tripod where you have clear vision to something you can focus on for infinity (make sure it’s at least 5 blocks away, its better to be safe than sorry). Adjusting horizontal alignment wont affect vertical alignment, so don’t worry.

RF Patch Focus: If your rangefinder patch isn’t sharp then you’ll need to calibrate it also. Doing this first will make the other steps easier. Also, I’ve heard that adjusting this screw can sometimes move the horizontal alignment as well. I didn’t experience this but you may want to keep it in mind. Turn screw #1 to calibrate this. You may also want to do this with the Vertical alignment leaving the infinity and close focus adjustments to last. It’s not absolutely necessary though.
Horizontal: Set lens focus to infinity (use a lens you know is accurate), and then point the RF patch at an object in the distance. Adjust screw #2 which will move the patch left to right and stop when its properly aligned. Be very delicate and precise as it’s quite sensitive.
Vertical: With the lens still focused at infinity, adjust screw #3 which moves the patch up and down. It’s a larger screw and isn’t as deep as the others so it might be easier to access. Once again be very precise.
Close Focus: I’ve never done this adjustment before, so cant speak from experience. Every time I’ve adjusted at infinity the close focus has been fine. To calibrate close focus you’ll need to remove the top plate and access another screw which isn’t covered in this guide. However I’ve been told that very small adjustments can be made using screw #1. You should be adjusting your lens at 1m for close focus calibration.

After you’ve adjusted all the screws for calibration you can put something on them like “loctite” that will help prevent misalignment in the future. To reassemble everything you just reverse the dis-assembly process. I’ve only had to do this once, and to be honest id you’ve had to re-calibrate several times you may want to consider why this is happening.

Update: Thanks for all the positive feedback, I’m happy this guide has been helpful to so many people. Just remember to be slow and systematic and the whole process should be complete without any issues at all.
Have fun 🙂