A few weeks ago I borrowed a mate’s Yashica Mat 124G, a fine Japanese made twin lens reflex camera. It’s most notable feature is its lens, a rather devastating four element Tessar clone. With the intent of buying this would be my second 124G. The first is an almost mint copy. I love this camera. Apart from its amazing lens the other advantage it has is no reflex mirror, no slap, no vibration. Also it is quite able to obtain sharp pictures when hand held down to 1/30th.
After all the usual checks, cosmetics, light meter, aperture and shutter speeds the last test is the lens. For this you fully open the aperture, set the camera’s shutter speed on “B” and trip the shutter. You then wiggle the camera/lens in front of a light source and check for nasties such as balsam separation, scratches and fungus. Balsam, as if you didn’t know, is the glue used to cement lens elements together. It is made from the resinous sap of certain trees. Being a biological and very green substance it is also susceptible to biological degradation and attack from fungus. Today, most lens elements are cemented using synthetics and most modern lens elements are mainly constructed from various polycarbonates (not green). When buying cameras and lenses you’ll be amazed at the number of people who don’t check for fungus. I digress. When examining the lens of this well worn 124G it became immediately apparent that the lens had a moderate degree of fungus which had grown all over one of the internal elements. As I have already mentioned the lens that the 124G has is a wonderful four element Tessar design. The front two elements are cemented, then there is an air space in which lives the shutter and aperture mechanism, finally the rear two elements in the last group, two elements cemented. I knew from previous experience exactly which surface was likely to have the fungus – the inner rear element. All you have to do is, using a lens wrench, screw out the rear group, clean and then pop it back. It takes about half an hour. Sure enough, when I had removed that rear element the fungus was revealed in all its ignoble glory. The element was carefully cleaned and inspected. The fungus did was fungus usually does – etched the glass. It had practically taken off all the surface coating of that inner element. Inner elements are coated just as much as the external ones. This is mainly to prevent light bouncing off the inner elements and causing a ghost image to appear on the negative. Oh yeah! And to prevent loss of light transmission, contrast and colour fidelity. When the process was complete and the element replaced it was time to load film and shoot a test roll. Sometimes you have to put two or three rolls through a camera after a lens element replacement (unless you have all the right equipment) as sometimes the element has not been screwed fully into its correct position. It’s hit and miss, but generally more hit.
Now to the sample shots. All taken at f/4 due to light conditions. Illford HP5+ in Rodinal. The first three is the rightful owner of said camera checking prices on the bay of e during an all day coffee fest in, dare I say it, the Bell Hanger, Chepstow. The rest taken locally. Considering the aperture was f/4 I think the repair has done its job. How the lens will perform under strong or difficult lighting with regard to the damage to the lens will be issue in Part 2.