07-11-2010, 01:39 PM
[quote name='you2' date='11 July 2010 - 01:46 PM' timestamp='1278848795' post='956']
Thanks wim. The reason I asked was not with regards to purchasing; but rather I read an article that made comments to the older lens having much better rendering. It was in context to how lenses developed for digital sensors lacked smooth colour transition.
[/quote]
Well, as far as I can/could see, they were very similar in that regard, and actually the F/4 IS maybe slightly better, except occasionally in background bokeh.
Do note that zooms are typically worse in these aspects than primes, and they always have been. It is inherent to the more complicated do-it-all design principles that have to be used, and the myriad of optical elements having to work together in this do-it-all concept.
As to smooth colour transitions in digital: I doubt this very much. I think people are confusing rendering in digital with rendering on film. Film has an innate thickness due to the emulsion being approximately 0.2 mm thick, which essentially means that the OOF to in-focus transition plays itself out over a much longer distance than is the case with digital, as sensors essentially have a thickness of zero. You need to add this 0.2 mm thickness to either end of the CoC, which means that you get an additional 60 % or so of area with a transitional effect compared to digital. Furthermore, the sharpness curve of digital is much steeper, giving further rise to this effect.
It is one of the reasons why I am an advocate of higher MP cameras. Essentially what this does is cause the transition to be much smoother, as there are more pixels to capture the gradations in a relatively sharply defined edge, hence making the transition much smoother. Furthermore, there is a better interaction with high MP sensors between sensor resolution, AA-filter, and lens resolution, making transitions much more smoothly than with lower MP sensors, where high and low MP must be regarded in relation to sensor size.. From my personal observations you start definitely noticing this effect at about 12 - 15 MP on APS-C, and 17 - 20 MP on FF.
If I look at lenses like the 50L, 24L and TS-E 17 and TS-E 24, I clearly see lenses designed for the digital age with very, very smooth colour transitions, so I don't see how this could actually be a fact unless somebody can underpin such observations with more or less scientifically obtained measurements.
One interesting development, however, seems to be the development of multi-aspherical element designs, possibly caused by the demand for incredibly sharp lenses over the whole image area at almost any aperture. These designs seem to show an interesting phenomenon, namely sharpness distributed in a wavefront almost, with more or less distinct areas of more sharpness at different distances from the optical axis. This seems especially the case with some of the newest zoom designs, and the effect thus created also seems to cause an interesting distribution pattern of smooth and less smooth colour transitions.
Other than that, older lenses often suffered more, or more severely, from optical faults, which cause essentially softness in colour transitions as well, obviously. From that POV it really is due to better design techniques than were possible, e.g., 30 years ago, for affordable lenses that is. Several new lenses that were designed not all that long ago, get close to apo-designs, for example, even if not listed as such. This means less spherical aberrations for example, which is one of the main optical defects to cause softness/blurriness, and if you like, good colour transitions (and good bokeh). However, this is both true for analog and digital. And this is also one of the reasons why several companies now design spherical aberrations into their optics, both for good bokeh in front of the DoF plane as behind it. What people generally perceive as good, smooth bokeh, also creates beautiful colour transitions... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />
Other than that, it is very, very easy to look at 100% or beyond with digital, which wasn't so easy with film, and the sharpness of sensors reveal really all, making it possible to really zoom in on any fault, whether percieved or real.
However, look at a print, from a proper viewing distance, and you may get a different picture (pun intended). Anything from a 6 MP APS-C camera for personal use, and anything from 12 MP, APS-C or FF, for professional use actually easily looks as good, if not better, than something shot on and printed from a 135 film-based colour negative. That is my personal experience, BTW, so YMMV.
HTH, kind regards, WIm
Thanks wim. The reason I asked was not with regards to purchasing; but rather I read an article that made comments to the older lens having much better rendering. It was in context to how lenses developed for digital sensors lacked smooth colour transition.
[/quote]
Well, as far as I can/could see, they were very similar in that regard, and actually the F/4 IS maybe slightly better, except occasionally in background bokeh.
Do note that zooms are typically worse in these aspects than primes, and they always have been. It is inherent to the more complicated do-it-all design principles that have to be used, and the myriad of optical elements having to work together in this do-it-all concept.
As to smooth colour transitions in digital: I doubt this very much. I think people are confusing rendering in digital with rendering on film. Film has an innate thickness due to the emulsion being approximately 0.2 mm thick, which essentially means that the OOF to in-focus transition plays itself out over a much longer distance than is the case with digital, as sensors essentially have a thickness of zero. You need to add this 0.2 mm thickness to either end of the CoC, which means that you get an additional 60 % or so of area with a transitional effect compared to digital. Furthermore, the sharpness curve of digital is much steeper, giving further rise to this effect.
It is one of the reasons why I am an advocate of higher MP cameras. Essentially what this does is cause the transition to be much smoother, as there are more pixels to capture the gradations in a relatively sharply defined edge, hence making the transition much smoother. Furthermore, there is a better interaction with high MP sensors between sensor resolution, AA-filter, and lens resolution, making transitions much more smoothly than with lower MP sensors, where high and low MP must be regarded in relation to sensor size.. From my personal observations you start definitely noticing this effect at about 12 - 15 MP on APS-C, and 17 - 20 MP on FF.
If I look at lenses like the 50L, 24L and TS-E 17 and TS-E 24, I clearly see lenses designed for the digital age with very, very smooth colour transitions, so I don't see how this could actually be a fact unless somebody can underpin such observations with more or less scientifically obtained measurements.
One interesting development, however, seems to be the development of multi-aspherical element designs, possibly caused by the demand for incredibly sharp lenses over the whole image area at almost any aperture. These designs seem to show an interesting phenomenon, namely sharpness distributed in a wavefront almost, with more or less distinct areas of more sharpness at different distances from the optical axis. This seems especially the case with some of the newest zoom designs, and the effect thus created also seems to cause an interesting distribution pattern of smooth and less smooth colour transitions.
Other than that, older lenses often suffered more, or more severely, from optical faults, which cause essentially softness in colour transitions as well, obviously. From that POV it really is due to better design techniques than were possible, e.g., 30 years ago, for affordable lenses that is. Several new lenses that were designed not all that long ago, get close to apo-designs, for example, even if not listed as such. This means less spherical aberrations for example, which is one of the main optical defects to cause softness/blurriness, and if you like, good colour transitions (and good bokeh). However, this is both true for analog and digital. And this is also one of the reasons why several companies now design spherical aberrations into their optics, both for good bokeh in front of the DoF plane as behind it. What people generally perceive as good, smooth bokeh, also creates beautiful colour transitions... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />Other than that, it is very, very easy to look at 100% or beyond with digital, which wasn't so easy with film, and the sharpness of sensors reveal really all, making it possible to really zoom in on any fault, whether percieved or real.
However, look at a print, from a proper viewing distance, and you may get a different picture (pun intended). Anything from a 6 MP APS-C camera for personal use, and anything from 12 MP, APS-C or FF, for professional use actually easily looks as good, if not better, than something shot on and printed from a 135 film-based colour negative. That is my personal experience, BTW, so YMMV.
HTH, 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 ....