Timeline for Is focus shift inherent in the Zeiss Sonnar lens designs (more so than other lens designs)
Current License: CC BY-SA 4.0
8 events
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| Dec 8, 2021 at 8:34 | comment | added | Andréas Sundström | @BobMacaroniMcStevens I still doubt that focus shift would be one of the first thing to appear if a lens is off calibration (at least due to wear and tear). I'm not an expert in optical design, but my suspicion is that image quality (resolution, micro-contrast) is more severely affected by bad calibration than focus shift, since that seems to be the most sensitive aspects of an optical system. Focus shift is more due to spherical aberrations present in the lens elements, which I wouldn't think should vary that much over the years of wear (unless you're polishing you lens with a grinder). | |
| Dec 8, 2021 at 8:20 | comment | added | Andréas Sundström | @BobMacaroniMcStevens I'm all onboard with "what matter is if it destroys your image", and it hasn't so far for me. So all is well and good for that. It was perhaps poorly conveyed by me, but the question was more academic in nature than practical. A probably better formation of my intended question would be "Is focus shift inherent to the Zeiss Sonnar lens designs (more than in other designs)?" | |
| Dec 8, 2021 at 1:35 | comment | added | Bob Macaroni McStevens | Obviously that is why I mentioned specifications and set the context of my comment to the manufacturing process. It is also why the theme of my answer is test and see if it matters. That that’s not good enough for some people is just Billy goats over the bridge. | |
| Dec 8, 2021 at 0:21 | comment | added | Michael C | "All of it is good enough..." [*good enough as defined by the manufacturer.] That may or may not meet the definition of good enough for a specific user and use case. YMMV. | |
| Dec 6, 2021 at 18:27 | comment | added | Bob Macaroni McStevens | @AndréasSundström Lenses get dropped. Some more and/or harder than others. The variations among lenses increases over the years with use. In the same way some lenses have fungus and others don’t. Even in the factory, all the glass may meet the optical specifications but some exceeds the specifications and some of that exceeds further than other batches. All of it is good enough. Some is better. | |
| Dec 6, 2021 at 18:18 | comment | added | Bob Macaroni McStevens | @AndréasSundström The sources of the information that sparks your concerns probably did something where the optical trade offs could be seen on inspection. Test charts are designed to reveal everything. Even things that don’t matter except when shooting test charts. What matters is if it destroys your pictures. No one looks at a landscape and weeps because the corners are pin sharp. | |
| Dec 6, 2021 at 9:55 | comment | added | Andréas Sundström | Thanks! Although the reason why I asked was to see if anyone had any experience or knew about the issue so that I wouldn't have to burn a roll of film on test shots. Also, I'm not sure how focus shift could vary that much between individual lenses without also seeing (much larger?) effects on image quality. | |
| Dec 5, 2021 at 19:02 | history | answered | Bob Macaroni McStevens | CC BY-SA 4.0 |