| 摘要 |
<p>Photographic enlargers provided with a pinpoint light source, an optical system generating an image from the lamp to the optical center of the lense, a negative holder and a negative. The enlarger comprises two optical systems with identical or different focal distances, of which the focus object of one and the focus image of the other merge into one another thus creating an equal or proportional relationship between the image-object displacement. It comprises a multi-shelf negative holder, each shelf corresponding to a predetermined size. The optical system associated to a simple mechanical system eliminates all adjustments when focusing while preserving the usefulness of the diaphragm. The negative holder eliminates the adjustments of the optics when changing the size of negatives. These two systems may be associated independently in colour or black and white enlargers. </p> |
