Jim Roof
27-Feb-2002, 17:40
I recently picked up a cheap Sinar F2 in great shape that had three lenses throw n in - a 210 Caltar S-II (near mint), 135 Sironar f/5.6 (separation in both doub lets) and, the lens of most interest right now... Schneider 90 f/8 Super Angulon (an older lens, balsam used for cement, I think. A different lens formula from the more current one I have - totally different formula). Here's the question -
All of the black paint had chipped off of the cemented pairs front and rear. I emailed Steve Grimes and he kindly responded with a quote to fix both lenses but , considering the fact that they are duplicates of what I have already I opted t o play with them myself. I stripped the paint from the rear pair and almost imm ediately saw edge separation begin. I figured this lens would have been cemente d with a more modern material but from the speed of separation my guess it was b alsam. Once it became apparent that this would be an additional repair I went a head and dunked the doublet into liquid paint thinner and the next morning the t ask of separating the elements and cleaning them up was finished - now ingenuity is needed - and advice/suggestions.
I plan to recement the elements myself but have yet to finalize a plan on how to either mechanically or optically center them. So far it seems the best mechain cal approach would be to use a square Sinar filter to extend the plane of the el ements by placing the filter on the flat surfaces and carefully measuring the di stance off of my workbench until all four corners are the same height. I would do this for the larger piece (resting in a hard rubber 'O' ring to keep it in pl ace once leveled) and again once the smaller element is dropped into the new pud dle of cement. The filter would rest on the very back of the small element and again, I could measure the corner's distance from the table and make adjustments until they all match. I might even rig a stand that has adjustable height scre ws that could serve to pre-arrange the alignment prior to cementing and serve as support as curing takes place (at room temperature for the precure).
Sound feasible? Or am I crazy for taking this on? Anyone here tried this befor e? Should I try something with a laser pointer?
Thanks for any and all ideas.
All of the black paint had chipped off of the cemented pairs front and rear. I emailed Steve Grimes and he kindly responded with a quote to fix both lenses but , considering the fact that they are duplicates of what I have already I opted t o play with them myself. I stripped the paint from the rear pair and almost imm ediately saw edge separation begin. I figured this lens would have been cemente d with a more modern material but from the speed of separation my guess it was b alsam. Once it became apparent that this would be an additional repair I went a head and dunked the doublet into liquid paint thinner and the next morning the t ask of separating the elements and cleaning them up was finished - now ingenuity is needed - and advice/suggestions.
I plan to recement the elements myself but have yet to finalize a plan on how to either mechanically or optically center them. So far it seems the best mechain cal approach would be to use a square Sinar filter to extend the plane of the el ements by placing the filter on the flat surfaces and carefully measuring the di stance off of my workbench until all four corners are the same height. I would do this for the larger piece (resting in a hard rubber 'O' ring to keep it in pl ace once leveled) and again once the smaller element is dropped into the new pud dle of cement. The filter would rest on the very back of the small element and again, I could measure the corner's distance from the table and make adjustments until they all match. I might even rig a stand that has adjustable height scre ws that could serve to pre-arrange the alignment prior to cementing and serve as support as curing takes place (at room temperature for the precure).
Sound feasible? Or am I crazy for taking this on? Anyone here tried this befor e? Should I try something with a laser pointer?
Thanks for any and all ideas.