[rollei_list] Re: 6 x 9 search
----- Original Message ----- From: <qwhozeiss@xxxxxxx> 
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, August 30, 2007 4:25 PM
Subject: [rollei_list] Re: 6 x 9 search
Wrong----on a Speed of Crown Graphic with the Kalart rangefindger you can focus more than one len. You need not go to the ground glass to handel longer or shorter lenses. You find were the infinity is on said len is and lock it down with another set of Graphic infinity blocks. Then use the rangefindger as normal. The rangefindger is stupid, it doesn't know what lens is on the camera, all it knows is were 10-15-25-50 etc. feet are, it's an optical ruler. Sometime people want to make takeing harder then it is. 

T. Mike
That won't work. While the infinity stop will get the alternative lens set at infinity no other distance will be right. The extension of each lens from infinity will be different. The rangefinder will simply move the focus track to the position it would be in for the lens its calibrated for. If, for instance, the RF is calibrated for a 150mm lens and a 127mm lens is mounted and set at a second infinity stop the RF will want to move the front quite a bit too far to focus on closer distances. The only way to focus alternative lenses without using the ground glass is to mount auxilliary distance scales on the bed along with a set of infinity stops for each lens. The scale is set up for each lens. To focus use the rangefinder and read the distance from the scale for the "normal" lens and transfer it to the focus scale for the lens in use. That will get you very close. For Speed and Crown Graphics Graflex supplied a great many scales. These were for several nominal focal lengths and for a range of typical variation of production lenses for that focal length. Scales are getting hard to come by now so getting an exact match may be difficult unless you make your own. The matched scales are very close and usable for tape measure focusing. If you have only an approximate scale it is useful mostly for adjusting flash exposure. BTW, I have never seen anything in print about how Graphic focus scales are calibrated. The theoretically correct point is the entrance pupil of the lens but many cameras have focus scales calibrated from the focal plane. The latter is useless for determining bellows extension exposure correction for very close distances. However, the Graphic scales go down only to about 4 feet. 

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Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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