dtcls100
Well-known
Recent testing indicates to me that the inherent optical differences in resolution between the newest lenses and older vintage lenses (1970's and 1980's) is surprising very low under near ideal testing circumstances. What has a much larger effect on image sharpness in the real world is how a manual lens is balanced and how well it snaps into focus, given that even tiny focusing errors and camera shake can tremendously degrade image sharpness.
At the outset, I am not a particularly big believer in most lens tests I have seen of lenses' optical sharpness, given sample variation, manufacturing tolerances, focusing errors, poor testing methodology, testing equipment problems, etc.
That said, I recently splurged on my first mirrorless camera, a Sony A7R3, which I have been using with adapted OM and Nikkor lenses. In setting it up and figuring out how it works, I noticed that it would be a very good tool for testing lenses, given the wide range of mount adapters available, as well as its precise leveling function, focus magnification, electronic shutter, etc.
I have conducted some quick tests, using a sturdy tripod, electronic timer, electronic shutter (essentially eliminating shutter shock), focus magnification (over 100X), and carefully leveling the camera using the leveling function. I also used top notch, new Novaflex OM and Nikkor adapters, which mount like butter and have zero play, to eliminate/minimize the slop, misalignment, poor manufacturing tolerances present in many cheaper adapters.
I tested a 1979 Vivitar Series 1 70-210 f3.5 zoom (version 1) wide open at its weakest focal length of 210mm, in taking pics of a sheet of music. I have never previously found images from this lens to be particularly sharp on film cameras. Based on my quick testing, it appears that any lack of sharpness is essentially due to focusing errors and camera shake. Using the magnification function, I saw that virtually imperceptible differences in the focusing had MAJOR effects on the image sharpness, as well as chromatic aberration, and that the image bounced around quite a bit while focusing, even when the camera was mounted on a tripod (the lens lacks a tripod mount). After carefully getting essentially perfect focus, I noticed that the purple fringing disappeared. Using a 10 second electronic timer, I took some images.
The images were shockingly sharp for such an old lens and were very close in sharpness to images of the same subject taken with a new Sony 24-105G lens (even with this new lens being shot at 105 vs 210mm). The main difference was that the newer lens had a little more contrast (not surprising given that the 1979 lens has a decent amount of internal dust).
Some quick shots of the same subject taken with a couple of my other older manual focus OM lenses (35-70, 35-80 Zuikos) led to similar results. The images were all outstandingly sharp.
This confirms my longheld suspicion that the inherent optical sharpness of many older lenses easily meets very high standards, even with the latest 42 megapixel sensors. The reason why images on these older lenses may be lacking in sharpness is pretty much attributable to user error -- focusing errors and camera shake. Even tiny focusing errors lead to substantially more color fringing and camera shake destroys sharpness.
Of course, some lenses are much easier to focus and handle than others, even if they have similar focal lengths and apertures. For example, the Series 1 zoom I tested is quite long and heavy. More importantly, it is front heavy and doesn't snap into focus as well as some other zoom lenses I have. I always had trouble holding it steady (even more so with the additional length of the adapter and even using the IBIS in the A7R3).
Carefully focusing the Series 1 zoom on a tripod (without the magnification function) showed how much one can miss focus. What looked like perfect focus at ordinary magnification was clearly well off when magnified 100x (with markedly lower resolution and much more purple fringing), although correcting the error typically involved only a tiny, almost imperceptible, turn of the focusing ring. This shows the limitation of lens testing using an optical finder, even ignoring mirror alignment in SLRs and dSLRs.
The central point of what I learned here is that the importance of differences in lens resolution between different lenses is vastly overrated by lens test reviews, given the inevitable, although tiny, focusing errors from using optical finders. Even many older lenses are surprising sharp under more ideal testing situations using a magnification function. What lens reviews really need to focus more on (pun intended) is on the balance of lenses, how easy they snap into focus, and their handling characteristics, as this appears to have much more of a real life effect on image sharpness than any real optical differences.
At the outset, I am not a particularly big believer in most lens tests I have seen of lenses' optical sharpness, given sample variation, manufacturing tolerances, focusing errors, poor testing methodology, testing equipment problems, etc.
That said, I recently splurged on my first mirrorless camera, a Sony A7R3, which I have been using with adapted OM and Nikkor lenses. In setting it up and figuring out how it works, I noticed that it would be a very good tool for testing lenses, given the wide range of mount adapters available, as well as its precise leveling function, focus magnification, electronic shutter, etc.
I have conducted some quick tests, using a sturdy tripod, electronic timer, electronic shutter (essentially eliminating shutter shock), focus magnification (over 100X), and carefully leveling the camera using the leveling function. I also used top notch, new Novaflex OM and Nikkor adapters, which mount like butter and have zero play, to eliminate/minimize the slop, misalignment, poor manufacturing tolerances present in many cheaper adapters.
I tested a 1979 Vivitar Series 1 70-210 f3.5 zoom (version 1) wide open at its weakest focal length of 210mm, in taking pics of a sheet of music. I have never previously found images from this lens to be particularly sharp on film cameras. Based on my quick testing, it appears that any lack of sharpness is essentially due to focusing errors and camera shake. Using the magnification function, I saw that virtually imperceptible differences in the focusing had MAJOR effects on the image sharpness, as well as chromatic aberration, and that the image bounced around quite a bit while focusing, even when the camera was mounted on a tripod (the lens lacks a tripod mount). After carefully getting essentially perfect focus, I noticed that the purple fringing disappeared. Using a 10 second electronic timer, I took some images.
The images were shockingly sharp for such an old lens and were very close in sharpness to images of the same subject taken with a new Sony 24-105G lens (even with this new lens being shot at 105 vs 210mm). The main difference was that the newer lens had a little more contrast (not surprising given that the 1979 lens has a decent amount of internal dust).
Some quick shots of the same subject taken with a couple of my other older manual focus OM lenses (35-70, 35-80 Zuikos) led to similar results. The images were all outstandingly sharp.
This confirms my longheld suspicion that the inherent optical sharpness of many older lenses easily meets very high standards, even with the latest 42 megapixel sensors. The reason why images on these older lenses may be lacking in sharpness is pretty much attributable to user error -- focusing errors and camera shake. Even tiny focusing errors lead to substantially more color fringing and camera shake destroys sharpness.
Of course, some lenses are much easier to focus and handle than others, even if they have similar focal lengths and apertures. For example, the Series 1 zoom I tested is quite long and heavy. More importantly, it is front heavy and doesn't snap into focus as well as some other zoom lenses I have. I always had trouble holding it steady (even more so with the additional length of the adapter and even using the IBIS in the A7R3).
Carefully focusing the Series 1 zoom on a tripod (without the magnification function) showed how much one can miss focus. What looked like perfect focus at ordinary magnification was clearly well off when magnified 100x (with markedly lower resolution and much more purple fringing), although correcting the error typically involved only a tiny, almost imperceptible, turn of the focusing ring. This shows the limitation of lens testing using an optical finder, even ignoring mirror alignment in SLRs and dSLRs.
The central point of what I learned here is that the importance of differences in lens resolution between different lenses is vastly overrated by lens test reviews, given the inevitable, although tiny, focusing errors from using optical finders. Even many older lenses are surprising sharp under more ideal testing situations using a magnification function. What lens reviews really need to focus more on (pun intended) is on the balance of lenses, how easy they snap into focus, and their handling characteristics, as this appears to have much more of a real life effect on image sharpness than any real optical differences.
