Archived posting to the Leica Users Group, 2007/07/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Jul 24, 2007, at 10:25 PM, Mike wrote: > Getting to this late. I'm not familiar with this model, but Arri cine > cameras are basically SLRs. On the classic models there is a rotating > mirror that reflects light into the viewfinder when the shutter is > closed. The lenses have a fairly long focal distance so I suspect > that > the angle of the light rays to the film or sensor is fairly straight. > > Mike D > > Lawrence Zeitlin wrote: >> While browsing through the web, I came across the Arri (motion >> picture >> camera) newsletter describing the D20 demonstration back allowing >> Arri >> cine cameras to be retrofitted for video capture. >> >> http://www.arri.de/news/newsletter/articles/09211103/d20.htm >> >> One of the features of the D20 is that the frame size is the same as >> that of normal 35 mm motion picture film, 18 x 24 mm. This allows >> normal >> cine lenses to be used with the same field of view and focal range as >> with film. This gives rise to several questions relevant to the >> Leica M8 >> and 4/3 lens concepts. >> >> Motion picture frame size is about the same sensor size as that being >> used in current digital DSLRs and the M8 and fractionally larger than >> that used in the 4/3 system. The 4:3 cine aspect ratio is exactly >> that >> of the 4/3 system. How does Arri use normal cine lenses with >> normal back >> focus on a sensor this size without suffering all the image >> deleterious >> effects so carefully described in the Leica literature. Thanks for the comment Mike. You are probably right. The lenses must have a long back focus to clear the rotating mirror shutter. Also on the 35 mm movie cameras I am familiar with, the standard lens is 50 mm, this is roughly equivalent to using a 70 mm lens on a 35 mm still camera. I suspect that there is adequate space between the lens and the shutter. What really surprises me is that no one has engineered a teleconverter type adapter to permit Leica lenses to be used on DSLRs. Mounting a Leica lens on a 4/3 camera would only require extending the back focus by 10 mm and a suitable adapter flange. This should be piece of cake for a good optical engineer. The adapter might be costly if it was designed to preserve Leica lens quality but you would only need one for all your lenses. Of course autofocus and auto stopdown wouldn't work but I'm used to that with OM lenses on my Oly E500. Perhaps there is insufficient demand. Or that Leica doesn't want to impact sales of the costly M8 in favor of cheaper 4/3 system cameras. Shades of the CL - - . Larry Z