07-29-2010, 08:16 PM
First of all, I do think the test here on Photozone are great, in the first place because they are unbiased, and often have enough sample pictures to judge lens quality in real life.
As tor an optical bench for testing: it tells you nothing. Any fast (large aperture) quality prime lens will be limited in resolution by diffraction by F/4. Any slightly cheaper or lesser quality lens, or zoom lens for that matter, will reach that point at F/5.6 or F/8, some a little later, and some of the really lesser lenses will only reach that point where diffraction limits the sensor resolution, e.g. F/13 on APS-C and F/18 on FF, or mayeb even not at all.
In the past, in analog days, lenses were often tested with a specific film, which makes life a lot easier, because provided you always use excatly the same techniques and settings for shooting and developing, the only unknown factor is lens resolution and lens aberrations at a specific aperture. However, films used always were high contrast films with very little tonal gradation and developed to get the highest acuity and largest contrast difference possible, hence not a scenario used for normal photography at all.
Each new generation and different size sensor and signal processing assembly behaves differently, due to the AA-filter assembly applied, due to pixel spacing, lenslet placement, distance between well sites, signal processing algorithms, etc. So from that POV it does make sense to use an optical bench. However, because of the different sensors, it is of little use, because in the end we want to know how a lens performs in combination with its recording medium, film in the old days, and sensors in the modern days, as that is the only way to obtain an end result.
In short, if you'd want to do a theoretical analysis of the performance of a lens, an optical bench is fine, provided BTW that there is nothing that intervenes with the actual analysis, i.e., automated analysis by the software analyzing the air image rendered, not an image projected on some wall, or a human counting lines). This will allow to compare lenses of different brands against each other (an i am sure th eoptical companies do just that).
However, for real life photography it makes no sense at all, because this is all theoretical stuff, and there is much more to rendering an image that, e.g., just resolution or optical aberrations. It really is a package deal, which one person will like, and the other won't.
You'll find that there actually are some photographers who specifically use a certain lens to get a certain type of rendering, for a specific occasion, and for another shoot, they'll use another brand lens with the same FL and aperture because they need a different type of rendering. Certainly with large format film this was very common. Nowadays it is less so, but there are still photographers who do, and who have a selection of lenses to choose from just for a single FL, for specific rendering purposes.
Just my 2c.
Kind regards, Wim
As tor an optical bench for testing: it tells you nothing. Any fast (large aperture) quality prime lens will be limited in resolution by diffraction by F/4. Any slightly cheaper or lesser quality lens, or zoom lens for that matter, will reach that point at F/5.6 or F/8, some a little later, and some of the really lesser lenses will only reach that point where diffraction limits the sensor resolution, e.g. F/13 on APS-C and F/18 on FF, or mayeb even not at all.
In the past, in analog days, lenses were often tested with a specific film, which makes life a lot easier, because provided you always use excatly the same techniques and settings for shooting and developing, the only unknown factor is lens resolution and lens aberrations at a specific aperture. However, films used always were high contrast films with very little tonal gradation and developed to get the highest acuity and largest contrast difference possible, hence not a scenario used for normal photography at all.
Each new generation and different size sensor and signal processing assembly behaves differently, due to the AA-filter assembly applied, due to pixel spacing, lenslet placement, distance between well sites, signal processing algorithms, etc. So from that POV it does make sense to use an optical bench. However, because of the different sensors, it is of little use, because in the end we want to know how a lens performs in combination with its recording medium, film in the old days, and sensors in the modern days, as that is the only way to obtain an end result.
In short, if you'd want to do a theoretical analysis of the performance of a lens, an optical bench is fine, provided BTW that there is nothing that intervenes with the actual analysis, i.e., automated analysis by the software analyzing the air image rendered, not an image projected on some wall, or a human counting lines). This will allow to compare lenses of different brands against each other (an i am sure th eoptical companies do just that).
However, for real life photography it makes no sense at all, because this is all theoretical stuff, and there is much more to rendering an image that, e.g., just resolution or optical aberrations. It really is a package deal, which one person will like, and the other won't.
You'll find that there actually are some photographers who specifically use a certain lens to get a certain type of rendering, for a specific occasion, and for another shoot, they'll use another brand lens with the same FL and aperture because they need a different type of rendering. Certainly with large format film this was very common. Nowadays it is less so, but there are still photographers who do, and who have a selection of lenses to choose from just for a single FL, for specific rendering purposes.
Just my 2c.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....