Archived posting to the Leica Users Group, 1999/06/23
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]My 28 year old Pradovit Color with 2.5 / 90mm Colorplan lens has been brought out of retirement after sitting idle in its original packing box for about 15 years. I removed the top casing and blew away as much of the residual dust as possible followed by a short burst of canned air from about ten inches to remove any trapped dust but avoiding any direct contact with the mirror behind the projector lamp or the optical elements in front of the lamp. The projector lens had been removed before using the canned air. With the top casing removed and the lamp lit up I could see that the side of the optical element nearest the lamp looks as if it was covered with tiny tiny pin prick marks. With the top casing in place, the lamp lit up, and looking obliquely though the lens as the slide changer worked I could see a reflection of those very very small pin prick marks. The pin prick marks on the rear elements were seen to be present before I used the canned air to remove any trapped dust. The images I projected today seemed to be as crisp and as sharp as were images made and projected fifteen years ago. So, either the prick marks were present fifteen years ago and the projected images are as negatively impacted today as they were fifteen years ago, or the prick marks have arisen in the last fifteen years and are of no apparant consequence today. Is anyone able to surmise whether these prick marks are actually on the surface of the optical elements and if so what they are and whether they could spread, or whether they are being reflected off the interior casing of the projector itself? If in fact the pin prick marks are pit marks in the optical glass is there any advice as to the economics of having the glass reground, or replaced? Thanks in advance for any advice John Hudson Vancouver, BC