Establishing and marking infinity stops?

[Brian Ellis]

First, you can purchase used hinged infinity stops for the Graphic from Clayton Camera (they advertise in "Shutterbug")in St. Lous. You can use a mark on the focusing rail and save the cost of the stops but I kind of like being able to raise the hinges on the stops and zip the lens out to the stops, rather than having to try to eyeball the front of the lens and get it perfectly aligned with a pencil mark on the focusing rail. Many people do, however, use a pencil or some other kind of mark and it works fine if it is properly located on the focusing rail. Which leads to the next point concerning the location of the infinity stop or pencil mark. If you want to get it really right (as opposed to being in the very general ball park) it isn't overly difficult but it's also not necessarily simple. With respect to measuring from the film plane to "the lens," the problem is determining where on "the lens" you measure to. Focal lengths are determined by measuring to the nodal point of the lens. The nodal point is usually somewhere in the general vicinity of the center of the lens (except on telephoto lenses) but I don't know how you would go about finding it and measuring from it even if you could find it, though maybe there's some way of doing this that I don't know about. Secondly, lenses are seldom in fact the exact focal length as they are quoted. Manufacturers typically round their numbers. Thus a 150 mm lens (for example) is most likely really 148 mms or 152 mms when properly measured, not really 150 mms. For these reasons I personally wouldn't try to determine the infinity setting by measuring a distance equal to the quoted focal length from the film plane to "the lens." A better (IMHO) way is by looking at the ground glass but I think you need to focus on something farther away than a couple blocks. Infinity is a good bit farther than that. The recommendation that I've seen several times is something a mile away. Unless you live in the wide open spaces, finding an unobstructed view of something large enough to focus on that is a mile away isn't easy (or at least it wasn't for me). If you were going to use the rangefinder, and so needed cams and infinity stops and wanted to everything absolutely right, I think the thing to do would be to find a camera repair facility that has the necessary equipment to do it right. Marflex, the Linhof repair facility here in the United States, will place cams and infinity stops on Linhof cameras and there presumably are other repair facilities that can do this for other cameras. However, if you're not going to use the rangefinder I think the ground glass method should be sufficiently accurate for your purposes, if you can find something that is far enough away and large enough to focus on.

[Bill Moore]

If your rangefinder is accurate using the lens you now own, all you need to do is establish distance scales for the new lenses. Focus thru the ground glass while moving the unlocked front standard back and forth. Establish a point for infinity, make matching pencil marks on the bed and the moving rail. Focus at 15 feet, by moving the unlocked front standard again. Put another mark on the bed matching the rail mark. Do this again at 6 feet. You will then have three marks on the bed and one mark on the rail. Matching the rail mark with any of the other three will set the focus at that distance. In practice, focus using the rangfinder, look at the distance scale, note the distance, if it is 15 feet, turn you focus knob out until the pencil mark on the rail lines up with the bed mark for 15 feet. You will be focussed at 15 feet. If you could find them, you could actually install a set of Graflex distance scales for each lens you own, yet never actually change the adjustment of the rangefinder. Each time you focus, you would note the distance on the scale, then transfer this setting to the other distance scales.

[Chris_732]

The only point to be aware of is that Graphic front standards tend to have a bit of slop when not locked down. That is, you can end up with a bit of swing if not careful. I mark one side of the rail with a pen or pencil, then use a nice plastic drafting square to locate the other side. You can line it up along the edge of the one rail to make sure it's square. This works better than relying on the standard to lock down square to establish the marks, since it probably won't be true. If you always stop way down it won't matter anyway.