On Fri, Aug 28, 2009 at 10:54 PM, J.C. O'Connell<[email protected]> wrote: > FF Systems can achieve higher image quality despite using > inferior "average" lenses. Lens cost can be less with FF systems > because the lens doesn't have to be as good with > a FF system as it does for a APS-C system for same or even better > system image quality. Similar to the reason even a mediorce > lens on the 8x10 format destroyed the very best lenses on > the 35mm format. The larger the format, the lenses become > less critical, not more critical to overall system performance.
Unfortunately while that's a nice theory it is not born out in practice. As a practical matter it's easier to make a lens with the necessary Zone A(Centre) and Zone B(APS-C edge) performance for APS-C than to make one which has the necessary Zone C(35mm edge) performance for even low-MP FF. High edge performance on a 35mm image circle is simply harder than high edge performance on APS-C and there's not enough difference in format size to get the same effect as LF. High-MP FF, which is becoming the norm, is absolutely brutal on lenses. You have to move up to MF Digital to get pixel densities low enough for lens quality to start dropping out of the equation. Pixel density is the deteminant for how much lens performance matters. And FF these days has pixel densities in the same range as APS-C (The Sony 24.5MP bodies have an 11MP APS-C crop mode for example), but further out in the image circle of the lens. The A850 shares the A900's sensor as well as it's tendency to show the warts of lenses that performed well on APS-C cameras and on film cameras. These cameras, along with the 21MP Canons, obsolete all but the absolute highest-performing lenses if you want acceptable IQ from them. > > I don't know why some are confused about FF cameras, > its all about image quality. The higher the better. > This is why when 35mm cameras dominated there were > MF, 4x5, 8x10 and even larger cameras in use. Image > quality matters. APS digital is not the ultimage with > anything better being overkill. Just from a cropping > flexibility standpoint, higher image quality is better > > -- > J.C. O'Connell (mailto:[email protected]) APS-C is the same idea as 35mm was back in the day. The best combination of IQ, size and cost for most of the market. Cheap FF is a boon for those who need the absolute most IQ and are on a limited budget since they can spend more on the lenses they need, but for those who need better balanced performance APS-C remains the current sweet-spot. -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
