| 摘要 |
A fixed focus enlarger having a frame which encloses an image focussing area which comprises located on the frame a removable transparency holder having a transparency aperture and an enlarging lens located at a predetermined distance beneath the transparency aperture, the enlarger being characterized in that there is also provided an extension tube which is insertable between the top of the said frame and the said removable transparency holder and which when in position in the enlarger increases the distance between the image focussing area and the enlarging lens by a predetermined amount, there also being provided means either to decrease the focal length of the enlarging lens by a predetermined amount, or means to decrease the distance between the enlarging lens and the transparency frame by a predetermined amount, so that in either case when the extension tube is in position in the enlarger a predetermined area of part of a transparency can be focussed on the focussing area to form an image of that part of the transparency which is the same size as that formed of the whole transparency in the absence of the extension tube. In one embodiment a negative lens is used to increase the focal length of the enlarging lens. In another embodiment the enlarging lens is held in a panel the position of which in relation to the transparency aperture can be altered.
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