Archived posting to the Leica Users Group, 2001/03/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Douglas Cooper wrote: The (Rollei) lens (especially the less expensive 3.5!) is unparalleled, and a unique -- and useful -- focal length: equivalent to approx. 41mm in 35. _______________________________________________________ Doug, wonderful though both the 75mm Xenotars and Planars are, they are actually equal to a 49mm lens on a 35mm camera *in side to side* coverage. The commonly used diagonal measurement of coverage is confusing because it can only be valid if the frames are the same shape. Otherwise, you're comparing apples and oranges. Manufacturers of medium format cameras normally measure lens coverage on the diagonal, as do makers of TV sets and computer monitors, but it is misleading, and in some cases, I think intentionally so. For instance, you will often hear that the 50mm lens for 6x4.5 or 6x6cm is equal to a 28 on a 35mm camera. But in side to side coverage, the 50 is only equal to 33mm -- much closer to a 35 than a 28. Lenses for 35mm cameras and 6x4.5 or 6x6cm cameras relate to each other at approximately a 3:2 ratio, or 2:3, depending on which way you're going. So the 150mm lens on your Hasselblad is about equal to the 100 on my Canon (RF, of course, just to stay on topic), and a 40 for your Hasselblad is equal to a 26 on my Canon, if there were such a beast. Likewise, the 90mm Elmerit I wish I had is about equal to the 135mm lens on the Contax 645 (137.5mm, to be exact). This is quite easy to check for yourself. Dave Jenkins