Improving Rangefinder Patch Contrast

How to Fix – Improving Rangefinder Patch Contrast to make it easier to Focus

By Allan Burgess

How to improve rangefinder patch contrast on old 35mm film cameras. Most rangefinder cameras made in the 1960s and 70s have a coupled rangefinder connected to the lens. You see two separate images when you look through the viewfinder. The lens is focused on the subject by turning the focus ring until the two images come together and fuse into one. With older non-coupled rangefinder cameras this was a two-step process. You found the distance with the rangefinder through a separate window and then compose the photograph through another window. Improving rangefinder patch contrast.

Either way, the rangefinders work on the same principle. It is simple, accurate, robust, and requires no batteries to operate. Over time, the glass and mirror elements inside the rangefinder mechanism can become hazy making it difficult to see separate images. The little mirror in the mechanism can also lose some of its silvering. Although these faults can be professionally repaired the cost of doing so is prohibitive. 

I have read in numerous places on the Internet that the rangefinder mechanism can readily go out of alignment causing it to not triangulate the focusing range correctly. Should this occur it is easy enough to fix. Many of these old 35mm film rangefinders having a small hole into which a fine screwdriver is inserted to make the necessary adjustments. I’ve never had this problem with any of my old film cameras. I guess it is more likely to occur if the camera receives a hard knock bumping the components and the mechanism out of alignment. You can see a video of a rangefinder camera mechanism here.

Improving Rangefinder Patch Contrast 

When the camera is functioning correctly there is a small diamond-shaped or rectangular yellow/gold area in the centre of the viewfinder where the two images come together as you turn the focus ring. When the mirror degrades and the rangefinder elements inside the camera become dirty this diamond-shaped area becomes very pale. 

Some of these old rangefinder cameras had very bright viewfinders and rangefinders. The Ricoh 500G for example is excellent in this regard. The Canon Canonets are also very good. While the Yashica Electro 35 is notorious for having its rangefinder patch fade out to the point where it is very difficult to see. 

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Cellophane Over the View-finder

The methods shown here work by increasing the contrast between the rangefinder patch and the unobstructed view seen through the view-finder. By darkening the viewfinder window with Cellophane visibility of the patch will be improved. The downside is that the whole viewfinder will be darker and, in this case, tinted orange. The patch will be lighter. However, doing this will make the camera’s rangefinder useable again. 

If you are only going to put the odd film through an old rangefinder camera these rough and ready fixes may suit you. Some of my best rangefinder cameras have been picked up from junk shops and recycling centres for just a couple of dollars which is all part of the fun. Unless you have a particularly valuable old camera it doesn’t make sense to spend a lot of money sending it away to be overhauled. On this particular camera, I was able to fix the Yashica Electro 35 “pad-of-death” problem, which I was quite pleased about.

You can see methods for improving rangefinder patch contrast in the photographs below.

The rangefinder patch on this Yashica Electro 35 has faded to such an extent that it can’t be seen at all, except for a slightly lighter area, or by moving your eye position relative to the view-finder.
I have achieved a quick, rough fix by colouring-in part of the centre section of the view-finder window glass on the front of the Yashica Electro 35 with a black Sharpie pen. I have deliberately made the black spot (actually diamond-shaped) too large to show you what happens when you do. The reason the blacked-out area is different in this picture and the one below is the slightly different angle at which the photograph was taken through the view-finder.
This simple fix has made this otherwise excellent camera useable again. The focusing accuracy of the rangefinder itself is still spot-on.
The yellow arrow shows where you need to place your Sharpie spot. An even better but slower way of doing it is to cut a diamond-shaped spot from black insulation tape. The advantage of this is that it can be removed and replaced until you get it in just the right place.
The methods shown here work by increasing the contrast between the rangefinder patch and the view seen through the view-finder. By darkening the viewfinder window with Cellophane visibility of the patch will be improved. The downside is that the whole viewfinder will be darker and in this case tinted orange. However, it will make the camera’s rangefinder useable. In good light, it will work fine. Not being able to see a correct representation of the subject’s colours would drive me nuts.
Allan Burgess

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Allan Burgess

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