Lenses on rangefinder cameras can be tested for focus accuracy and sharpness.
Although some rangefinder cameras are digital (the Leica M9 and Epson RD-1, for instance), rangefinders are largely relics of photographic history. Because of their simple but precise mechanics, rangefinder cameras are quite popular on the vintage used market. If you recently picked one up, it might be up to 40 or 50 years old, depending on the model. Before using it for serious shooting, it is a good idea to thoroughly test the lens and rangefinder focusing mechanism.
Instructions
Performing the Tests
1. Insert a 35mm film cartridge into the rangerfinder camera. On most models, open the back by pulling up on the film-rewind knob on the top left of the camera body. Place the cartridge in the compartment, protruding end down, and push down on the rewind knob. Stretch the film across the back of the camera and insert the end of it into the takeup spool. Fire the shutter and advance the film until the sprocket teeth engage the perforations on the film's edges. Close the camera back.
2. Set your camera's shutter speed to 1 setting past the ISO of your film speed (if you're using ISO 400 film, set a shutter speed of 1/500 of a second). Set the aperture, or lens opening, to f/16 by adjusting the aperture ring on the lens barrel. This combination provides you with a large range of effective focus, or deep depth of field.
3. Point your camera toward an object that is certainly more than 30 feet away, such as the top of a skyscraper or an object on the horizon line. Look through the viewfinder and move the focusing ring (near the rear of the lens barrel) until the two split-images are superimposed. This indicates proper focus. Shoot several frames. This tests the camera's ability to accurately focus on infinity.
4. Locate a closer, brightly lit subject, such as a vehicle or a tree. Look for subjects that exhibit a wide range of colors. Bring the subject into focus and take several pictures. This tests the sharpness and color rendition of the lens.
5. Move to a dim inside room inside, ideally one with soft lighting. Have an assistant sit about 3 feet from a window. Set the shutter speed to 1/60 second and the aperture to f/2, or else the widest aperture the lens offers. Focus the lens and take several portrait shots of your assistant. This tests the sharpness and vignetting of the lens wide open. It will shows how the lens performs with a shallow depth of field.
6. Finish shooting the roll. Try selecting a number of different aperture/shutter speed combinations while shooting a range of subjects in various lighting conditions. Take or send off the cartridge to a photo lab for processing.
Assessing the Results
7. Look at the first several frames of the roll. Check to see that the infinity focus point is clear and sharp. This indicates that the camera's rangefinder mechanism is accurately calibrated for use with the lens.
8. Check the frames that you shot in Step 4 of Section 1. Look closely at any hard edges or lines within the picture to determine how sharp the lens is. Also note the accuracy of the colors in the photo. If necessary, revisit the subjects for a comparison.
9. Look closely at the details in the portrait shots, to judge the sharpness of the lens while wide open. Subjects and details, especially those near the edges of the frame, will tend to be a bit soft--this is normal for any lens. Also look at the corners of the frame and note any vignetting (hazy black edging) that occurs. Slight vignetting is also typical for wide-open lenses.
10. Browse the rest of the frames you shot, judging each one for sharpness and color accuracy. If all appears normal, the lens on the rangefinder is ready for normal use. If you noticed faults in any of the test results, you might wish to have the camera or lens serviced.
Tags: shutter speed, rangefinder cameras, This tests, aperture lens, depth field, lens Also