Designed for film cameras with the larger viewfinder needed for eye-control focus – EOS 3, 30, 33, 5, 50, 50E. Available in ten strengths: –4, –3, –2, –0.5, 0, +0.5, +1, +1.5, +2 +3 dioptres. Each lens comes complete with rubber frame and is ready to attach to the viewfinder eyepiece.
We covered dioptric lenses in the 'Eyes Right' article in the January-March 2011 issue:
Dioptric correction lenses date back to the days of film cameras. Apart from the EOS 1, 1N and 1V, these cameras do not have built-in correction. Instead, Canon produces a range of adjustment lenses which slip over the viewfinder eyepiece. The lenses are available in different strengths, from -4 dioptres (for short-sightedness) to +3 (for long-sightedness).
All EOS viewfinders, for digital and film cameras, have a built-in correction of -1 dioptre. This is because many people either suffer from slight short-sightedness, or will do in the future. If you have good eyesight the -1 dioptre lens should not cause any problems. Your eyes will automatically adjust to take account of the built-in lens, and you should not even notice.
There are three ranges of Canon dioptric adjustment lenses: Adjustment Lens E, Adjustment Lens Eg and Adjustment Lens Ed.
You will notice that there is no -1 dioptre lens in any of the ranges. This is because the designation is not the power of the dioptric lens itself, but the power when it is attached to the viewfinder.