09-21-2010, 08:14 PM
[quote name='wim' timestamp='1285026199' post='3023']
Well, from what I see, retrofocus lenses, especially UWA, seem to suffer less from vignetting than non-retrofocus lenses, but that may have to do with the barrel sizes as well. And some of the retrofocus UWs are so incredibly good, I wonder how they will be able to improve them without making them even bigger, and that is also true for a short register distance, when the sensor still is quite large. Don't forget that at extreme WAs, the light rays tend to create shadows over the wells, and create all kinds of other (refraction) effects, like is happening with the Leica sensor, even with its special pixel arrangement. Retrofocus helps here, because essentially a second imaging system can be created that keeps the final light rays relatively parallel, thus getting around some of the innate problems of sensors and light incidence at steep angles.
Unfortunately, these designs do make for big and expensive lenses <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />. The Nikkor 14-24 F/2.8 and the Canon TS-E 17L come to mind...
Kind regards, Wim
[/quote]
Wim,
I wasn't really thinking about Leica rangefinder lenses. For digital life is easier with a long exit pupil, which prevents rays hitting the sensor at steep angle. Still you can put glas behind that exit pupil. If you remember the Zeiss lens for the R1, the image is still available on imaging-resource: http://www.imaging-resource.com/PRODS/R1/ZR1BACKFOCUS1.GIF , you see what I mean. This is not a super-Angulon RF lens. J.
Well, from what I see, retrofocus lenses, especially UWA, seem to suffer less from vignetting than non-retrofocus lenses, but that may have to do with the barrel sizes as well. And some of the retrofocus UWs are so incredibly good, I wonder how they will be able to improve them without making them even bigger, and that is also true for a short register distance, when the sensor still is quite large. Don't forget that at extreme WAs, the light rays tend to create shadows over the wells, and create all kinds of other (refraction) effects, like is happening with the Leica sensor, even with its special pixel arrangement. Retrofocus helps here, because essentially a second imaging system can be created that keeps the final light rays relatively parallel, thus getting around some of the innate problems of sensors and light incidence at steep angles.
Unfortunately, these designs do make for big and expensive lenses <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />. The Nikkor 14-24 F/2.8 and the Canon TS-E 17L come to mind...Kind regards, Wim
[/quote]
Wim,
I wasn't really thinking about Leica rangefinder lenses. For digital life is easier with a long exit pupil, which prevents rays hitting the sensor at steep angle. Still you can put glas behind that exit pupil. If you remember the Zeiss lens for the R1, the image is still available on imaging-resource: http://www.imaging-resource.com/PRODS/R1/ZR1BACKFOCUS1.GIF , you see what I mean. This is not a super-Angulon RF lens. J.
enjoy