A Simplified Method for Precision Calibration of Effective f Stops

F. G. Back

Many methods have been proposed to replace the geometrical f ratio by an effective calibration which takes the transmittance of the lens into consideration, but no method proposed so far has been accepted. The author outlines a new method of photoelectric lens calibration using the null method which compares the lens to be calibrated to a standard lens. This standard can be easily reproduced with a very high uniformity of performance. The method has been tested very thoroughly and is now in practical use for lens calibration. The accuracy obtained with this method is far superior to any procedure used so far. Its simplicity enables even an unskilled operator to obtain accurate results combined with a high working speed.

Print ISSN
Published
1947-08
Content type
Original Research
DOI
10.5594/J17823