Post by casualcollector on Sept 6, 2008 20:46:00 GMT -5
I sat down this afternoon with eight different 50 and 55mm lenses. All eight were M-42 mount, Japanese lenses, of four brands from five camera manufacturers. I had thought that after a bit of examination I'd find some significant variations and have some definite conclusions as to who manufactured which. At first I thought I was going to divide them up between two manufacturers. Mamiya/Sekor’s subsidiary Setagaya Koki (origin of the Sekor half of the name) and Yashica’s Tomioka. I thought there would be noticable differences between the two makers. Now, I’m not so sure!
The lenses. Two Mamiya /Sekor 55mm f-1.8. One black and silver from the TL era, the other all black from the DTL era. 55mm f-1.8 Sears (Rikenon). 55mm f-1.4 Sears (Chinon) from a Sears ES-2000. 50mm f-1.8 Vivitar (Cosina). 50mm f-1.7 Yashinon DX. 50mm f-1.4 Yashinon DX. 50mm f-1.4 Sears (Rikenon).
I had assumed that the Mamiya and Rikenon lenses would all be from Setagaya Koki, The Yashinons, Chinon and Cosina from Tomioka.
Right away, the Mamiya and Rikenon 55/1.8s appeared to be the same lens with differences in the knurling of the focus and aperture rings. All three lenses had an A-M switch at the lower right. The mounting flanges and rear optic groups showed minor differences. Probably just running changes as production evolved over time. The all black Mamiya-Sekor had a more elaborate depth of field scale. The glass looked identical among the three. I was expecting the 50/1.7 Yashinon to be different, and it was. Aperture and focus scales were viewed through openings in a shroud between the focus and aperture rings. On the Mamiya and Rikenon lenses the scales are in full view. Beyond these cosmetic differences I found some similarities among the Mamiya and Yashica units. The lenses are nearly the same in size. Only about a millimeter of difference in any dimension. Relative location of aperture and focus rings is identical. The focus rings look the same except that foot/meter scales are reversed. The A-M switch is in the same, lower right, location. I couldn’t find any significant difference in the mounting flanges. Though the Mamiya and Rikenon lenses are labeled 55mm and the Yashinon as 50mm The glass and coating look much alike. The only difference I can see is that the rear element of the Yashinon extends further back from the mounting face than on the Mamiya and Rikenon lenses. One small oddity, the Mamiya 55s have half stop clicked aperture rings, the Rikenon 55 and Yashinon 50 are clicked at full stops! For as much as I was thinking these lenses came from two different makers, they sure look like they came out of the same factory.
The Vivitar (Cosina) 50mm f-1.8 is a slightly smaller lens. About three millimeters shorter and with a 49mm filter ring vs the 52mm of the others. The focus ring is a bit narrower with a rubber grip, the aperture ring a bit wider than the others. On this lens you view the depth of field scale through a cutout area of the aperture ring. The location of focus and aperture rings, location of A-M switch, mounting flange details, distance scales are all very nearly the same as the other group of lenses. The glass looks the same as the Yashinon optics, though the front element appears smaller in diameter. Oh, half stop clicks on the aperture ring. Overall, this lens looks like a member of the same family as the above four.
I really started this little examination not fully believing that Tomioka, who seems to get all the credit for these lenses, really produced them all. It seems odd that one manufacturer would supply lenses of 50 and 55mm focal length with f-1.7 and f-1.8 maximum apertures. I think it makes more economic sense to make them all to one specification. The differences among these lenses could be accounted for as changes in manufacturing techniques over approximately seven to ten years from oldest to newest. Or maybe they were made in different plants from the same plans. The f-1.4 lenses get a bit more interesting but this post is more than long enough for now.
What do you think?
Bill
The lenses. Two Mamiya /Sekor 55mm f-1.8. One black and silver from the TL era, the other all black from the DTL era. 55mm f-1.8 Sears (Rikenon). 55mm f-1.4 Sears (Chinon) from a Sears ES-2000. 50mm f-1.8 Vivitar (Cosina). 50mm f-1.7 Yashinon DX. 50mm f-1.4 Yashinon DX. 50mm f-1.4 Sears (Rikenon).
I had assumed that the Mamiya and Rikenon lenses would all be from Setagaya Koki, The Yashinons, Chinon and Cosina from Tomioka.
Right away, the Mamiya and Rikenon 55/1.8s appeared to be the same lens with differences in the knurling of the focus and aperture rings. All three lenses had an A-M switch at the lower right. The mounting flanges and rear optic groups showed minor differences. Probably just running changes as production evolved over time. The all black Mamiya-Sekor had a more elaborate depth of field scale. The glass looked identical among the three. I was expecting the 50/1.7 Yashinon to be different, and it was. Aperture and focus scales were viewed through openings in a shroud between the focus and aperture rings. On the Mamiya and Rikenon lenses the scales are in full view. Beyond these cosmetic differences I found some similarities among the Mamiya and Yashica units. The lenses are nearly the same in size. Only about a millimeter of difference in any dimension. Relative location of aperture and focus rings is identical. The focus rings look the same except that foot/meter scales are reversed. The A-M switch is in the same, lower right, location. I couldn’t find any significant difference in the mounting flanges. Though the Mamiya and Rikenon lenses are labeled 55mm and the Yashinon as 50mm The glass and coating look much alike. The only difference I can see is that the rear element of the Yashinon extends further back from the mounting face than on the Mamiya and Rikenon lenses. One small oddity, the Mamiya 55s have half stop clicked aperture rings, the Rikenon 55 and Yashinon 50 are clicked at full stops! For as much as I was thinking these lenses came from two different makers, they sure look like they came out of the same factory.
The Vivitar (Cosina) 50mm f-1.8 is a slightly smaller lens. About three millimeters shorter and with a 49mm filter ring vs the 52mm of the others. The focus ring is a bit narrower with a rubber grip, the aperture ring a bit wider than the others. On this lens you view the depth of field scale through a cutout area of the aperture ring. The location of focus and aperture rings, location of A-M switch, mounting flange details, distance scales are all very nearly the same as the other group of lenses. The glass looks the same as the Yashinon optics, though the front element appears smaller in diameter. Oh, half stop clicks on the aperture ring. Overall, this lens looks like a member of the same family as the above four.
I really started this little examination not fully believing that Tomioka, who seems to get all the credit for these lenses, really produced them all. It seems odd that one manufacturer would supply lenses of 50 and 55mm focal length with f-1.7 and f-1.8 maximum apertures. I think it makes more economic sense to make them all to one specification. The differences among these lenses could be accounted for as changes in manufacturing techniques over approximately seven to ten years from oldest to newest. Or maybe they were made in different plants from the same plans. The f-1.4 lenses get a bit more interesting but this post is more than long enough for now.
What do you think?
Bill
