Archived posting to the Leica Users Group, 1999/08/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]One word: Trigonometry Paul Franz - -----Original Message----- From: owner-leica-users@mejac.palo-alto.ca.us [mailto:owner-leica-users@mejac.palo-alto.ca.us] On Behalf Of Christer Almqvist Sent: Friday, August 20, 1999 12:22 PM To: leica-users@mejac.palo-alto.ca.us Subject: [Leica] Re: Lens coverage Can somebody please explain to me in simple language why the horizontal coverge is not 50% greater than the vertical coverage when the horizontal side is 50% larger than the vertical side (36mm vs 24 mm). When I wrote the above I was just looking at the figures for 21 mm (where horizontal coverage is 136.5% of vertical coverage), and now I see that the longer the focal length, the closer the ratio gets to 150%. So now the second question: why does the ratio of horizontal coverage to vertical coverage increase as focal length increases? > Tom Bryant wrote: On Lens coverage: > > Here is a table of some popular focal lengths with their horizontal x >vertical coverage, along with their diagonal coverage for the 35mm format: >The units are decimal degrees. > >14mm: 104.250 x 81.203, 114.182d 55 mm: 36.244 x 24.616, 42.943d >15mm: 100.389 x 77.320, 110.527d 75 mm: 26.991 x 18.181, 32.180d >17mm: 93.273 x 70.435, 103.678d 90 mm: 22.620 x 15.189, 27.032d >20mm: 83.974 x 61.928, 94.493d 135 mm: 15.189 x 10.159, 18.208d >21mm: 81.203 x 59.490, 91.702d 180 mm: 11.421 x 7.628 , 13.706d >24mm: 73.740 x 53.130, 84.062d 200 mm: 10.286 x 6.867 , 12.347d >28mm: 65.470 x 46.397, 75.381d 300 mm: 6.867 x 4.581 , 8.249 d >35mm: 54.432 x 37.849, 63.440d 400 mm: 5.153 x 3.437 , 6.191 d >50mm: 39.598 x 26.991, 46.793d 1000mm: 2.062 x 1.375 , 2.479 d > - -- christer almqvist eichenstrasse 57, d-20255 hamburg, fon +49-40-407111 fax +49-40-4908440 14 rue de la hauteur, f-50590 regnéville-sur-mer, fon+fax +33-233 45 35 58