Yashica TLR lens change

scyg · Dec 10, 2020

I swapped out the Yashikor on my D with a Yashinon from a parts 124g I had laying around.
Two takeaways - looking at the lenses side by side, I couldn't tell the difference between them, except for a slightly different color of coating. Same number of reflections, same magnification in each element. Wonder if the story about all Yashikors being triplets is baloney. Maybe on earlier models, but mine looked suspiciously like a Tessar clone. So I was wondering whether there's really a 1-to-1 relationship between the lens name and its optical design.
Second - I like the D's build quality a lot better than the 124g. All metal and solid as hell (no, not like a Rollie, but what do you want for the $80 I paid for it?)

So far everything is aligned and looks good on the ground glass (I also adjusted the viewing lens focus while I was in the guts of the thing). On with the film tests.

DWThomas · Dec 10, 2020

Hmmm -- the 124g Yashinons are described as 4 elements in 3 groups. As such, two of the elements are cemented together, eliminating two air/glass transitions. That likely eliminates two of the 8 possible reflections for four elements. There would be a change in refractive index which might generate one less obvious quasi-reflection, but not likely two. In a quick Googling it appears over the history of Yashica there are some blurs of the --or/--on naming convention.

I also don't doubt a well made triplet compares capably with a Tessar design at less than wide open aperture. I only have a 124g and I certainly have no complaints about optical performance in my typical use. Anyway, interestinginfo.

Alan Johnson · Dec 10, 2020

http://yashicatlr.com/LensesShutters.html
See "Real life experiences", seems it can be hard to see the difference between Yashikor and Yashinon unless prints are large from wider apertures.

Donald Qualls · Dec 11, 2020

On Tessar type lenses in which I've counted reflections, there is a faint reflection from the interface between the component of the cemented doublet. That should give six reflections and a weak seventh, vs. six all the same strength in a triplet.

ic-racer · Dec 11, 2020

The only TLRs I have encountered with fuzzy lenses are the plastic ones.
I have so many TLRs I have actually experimented the other way. That is, putting viewing lenses in the taking position to decrease the resolution.

scyg · Dec 11, 2020

The Yashikor wasn't a bad lens by any stretch of the imagination, but it did get noticeably soft at the edges wide open. That said I'm comparing it to my 500CM's Planar, which would be challenging for any lens. And it had ugly cleaning marks that probably didn't help resolution or especially contrast. I had the 124g lens plate with a clean taking lens just laying around, so decided to experiment. I might swap out the viewing Yashikor for the 124's brighter lens later, but that's more intense surgery than I had the nerve for right now. Anyway, I'm about to develop my test rolls, so should know whether there is any appreciable difference soon.

scyg · Dec 12, 2020

Developed my test shots. Don't see much difference between this and the Yashikor - similar softness in corners wide open - except the Yashikor had a tiny bit of pincushion distortion, and the Yashinon seems to go a bit the way of the barrel.
Checked the reflections in the lenses again, and they still seem to have exactly the same number - seven, six bright ones and one faint one, in the same order in both. I'd be willing to bet the D's Yashikor is the same optical formula as the later Yashinons.
Here are raw scans, no sharpening or other dark magic, at 2400dpi:
https://www.flickr.com/photos/44459362@N00/albums/72157717266939167

Ian Grant · Dec 12, 2020

scyg said:
The Yashikor wasn't a bad lens by any stretch of the imagination, but it did get noticeably soft at the edges wide open. That said I'm comparing it to my 500CM's Planar, which would be challenging for any lens. And it had ugly cleaning marks that probably didn't help resolution or especially contrast. I had the 124g lens plate with a clean taking lens just laying around, so decided to experiment. I might swap out the viewing Yashikor for the 124's brighter lens later, but that's more intense surgery than I had the nerve for right now. Anyway, I'm about to develop my test rolls, so should know whether there is any appreciable difference soon.

The difference is as expected comparing a Cooke triplet design to a Tessar, both have the same number of air/glass surfaces. The triplet lenses are nice for portraits at wider apertures, I had a Rolleicord with a Triotar in the mid 1970's and made some nice images with it.

Ian

scyg · Dec 12, 2020

Ian Grant said:
The difference is as expected comparing a Cooke triplet design to a Tessar, both have the same number of air/glass surfaces. The triplet lenses are nice for portraits at wider apertures, I had a Rolleicord with a Triotar in the mid 1970's and made some nice images with it.
Ian

There is a faint third reflection in the rear element of both lenses that falls in line with Donald Quals' comment above, and would indicate they're both cemented, and therefore more of a Tessar design. The film tests I made (https://www.flickr.com/photos/44459362@N00/albums/72157717266939167) showed very similar performance from both lenses, with the same softness in the corners wide open. The "new" lens has fewer scratches on the front element and seems to have less flare, so I'm happy I did it, but it's not as big a leap as you'd expect from going from a three to a four-element design.

Deleted member 88956 · Dec 12, 2020

I'm not sure if swapping beat up Corolla with a beat up Camry would reveal true differences between the two.

scyg · Dec 12, 2020

The Yashinon isn't beat up. That was the point of the whole exercise. I wasn't expecting to get Rollei/Planar quality out of it, but I did think I was changing a triplet to a Tessar clone, which it turns out wasn't the case. I was changing to a cleaner version of the same lens design.

Yashica TLR lens change

Deleted member 88956

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