grebeman
Mu-43 All-Pro
Why is there so much fuss made about this aspect of m4/3 and this constant comparison to 35mm. Go back to basics. Take the diagonal of the negative, or sensor in this digital age and divide it by the focal length of the lens. The resulting number gives you a quotient (just a fancy way of saying a number) that gives you a measure of the angle of view of the lens. This is independent of the format of the camera.
So a m4/3 sensor has a diagonal of just under 22mm, a 35mm negative has a diagonal of 43mm, a 21/4" square negative has a diagonal of 79mm, a 6x9 negative has a diagonal of 105mm, a 4x5" negative has a diagonal of 155mm. The standard lenses for these formats were always regarded as 50mm for 35mm, 80mm for 21/4" square, 105mm for 6x9 and 150mm for 4x5".
When you divide the diagonal of the negative by the standard focal length for each format the result is approximately 1 for each of these. If you use a lens of shorter focal length the number obtained is greater than 1, if a longer focal length lens is used, the number is less than 1.
Therefore on m4/3 the standard lens should be about 22mm focal length, lets call it 20mm and for simplicity and easy calculation lets call the sensor diagonal 20mm
Fit a 50mm focal length lens and do the simple mathmatics and the result is 20/50 = 0.4, therefore on m4/3 a 50mm lens is a long focal length lens, on 35mm the result is 43/50 = 0.86, on 21/4" the result is 79/50 = 1.58. Exactly the same focal length lens, different results on each format, different perspective obtained.
diagonal/focal length vs angle of view
0.35 = 20 deg
0.54 = 30 deg
0.73 = 40 deg
0.93 = 50 deg
1.15 = 60deg
1.40 = 70 deg
1.68 = 80 deg
2.00 = 90 deg
2.38 = 100 deg
2.86 = 110 deg
Barrie
So a m4/3 sensor has a diagonal of just under 22mm, a 35mm negative has a diagonal of 43mm, a 21/4" square negative has a diagonal of 79mm, a 6x9 negative has a diagonal of 105mm, a 4x5" negative has a diagonal of 155mm. The standard lenses for these formats were always regarded as 50mm for 35mm, 80mm for 21/4" square, 105mm for 6x9 and 150mm for 4x5".
When you divide the diagonal of the negative by the standard focal length for each format the result is approximately 1 for each of these. If you use a lens of shorter focal length the number obtained is greater than 1, if a longer focal length lens is used, the number is less than 1.
Therefore on m4/3 the standard lens should be about 22mm focal length, lets call it 20mm and for simplicity and easy calculation lets call the sensor diagonal 20mm
Fit a 50mm focal length lens and do the simple mathmatics and the result is 20/50 = 0.4, therefore on m4/3 a 50mm lens is a long focal length lens, on 35mm the result is 43/50 = 0.86, on 21/4" the result is 79/50 = 1.58. Exactly the same focal length lens, different results on each format, different perspective obtained.
diagonal/focal length vs angle of view
0.35 = 20 deg
0.54 = 30 deg
0.73 = 40 deg
0.93 = 50 deg
1.15 = 60deg
1.40 = 70 deg
1.68 = 80 deg
2.00 = 90 deg
2.38 = 100 deg
2.86 = 110 deg
Barrie