Michael
-----Original Message-----
From: Roger Eichhorn [mailto:eichhorn@xxxxxx]
Sent: Monday, January 5, 2009 11:43 PM
To: 'List for Photo/Imaging Educators - Professionals - Students'
Subject: Re: Olympus DSLR
Canon's "S" lenses were not suitable for the Canon 10D I recently replaced with a 50D that accommodates them just fine. Naive me, I thought it was because the S lenses projected too far into the camera body and interfered with the mirror mechanism. The sensors in the 10D and the 50D are the same physical size, so sensor coverage can't be the issue. So what is it if it's not mechanical interference? Roger On 5 Jan 2009, at 7:20 PM, editor@xxxxxxxxxxxxxx wrote: > I misspoke when I said "nothing digital about smaller lenses". As > others have pointed out, there are indeed unique considerations when > it comes to designing lenses (particularly short focal length > lenses) for digital bodies. > > In response to the previous post, I too cannot think of any DX- > specific 70-200mm lens, yet there is no reason there could not -- or > even should not -- be. > As an example of what you can do when you put your mind to it, both > Nikon and Canon (and others) offer DX-sized 18-200mm ultra zooms > that work only with the smaller sensor cameras and not their full- > frame cousins. > > As for the notion of shallower angle, this is only of particular > import when it comes to short focal length lenses. Long lenses by > and large do not need to compensate thusly. > Consequently, any older 70-200mm lens will work just fine on a new > small-format digital body (even though it is significantly bigger > and heavier than it needs to be to cover the sensor). > > One last thing that should be obviously apparent: there is no "free > ride" when it comes to optics. > In order to acheive such a "narrower angle" of light lens designers > have had to compromise the design of the lens to use (sometimes > extreme) retro-focus techniques to pull this magic trick off. > The upshot of this is that historically, wide angle digital lenses > have not been as sharp (or even generally available) as their same > focal length film cousins. However, today that is not necessarily > true anymore. > > For an extremely in-depth article that explains the historical > context of wide-angle lens design vis-a-vis digital sensors, please > consult http://www.luminous-landscape.com/essays/Leica-M8-Perspective.shtml > which focuses on the unique problems faced by Leica with their > rangefinder digital camera design decisions. > > Cheers > J Michael Sullivan > > > > -----Original Message----- > From: David Dyer-Bennet [mailto:dd-b@xxxxxxxx] > Sent: Monday, January 5, 2009 01:32 PM > To: 'List for Photo/Imaging Educators - Professionals - Students' > Subject: Re: Olympus DSLR > > On Mon, January 5, 2009 11:57, editor@xxxxxxxxxxxxxx wrote:> A full- > frame Canon or Nikon 70-200mm zoom film lens is identical in size> > to its digital counterpart.I'm not aware of any "DX" or "EF-S" > 70-200 zooms in the first place; theyall cover the full frame.> The > digital lens will undoubably cost more: it is newer and likely will> > have Auto focus and Image Stabilization.>> An APS-C-specific lens > *WILL* be smaller, with the emphasis on it being> designed for the > smaller sensor.> There is nothing "digital" about smaller lenses -- > the size of the sensor> will dictate the size of the glass.I listed > a couple of areas in my previous message where lens designers > aredoing this differently for digital sensors.-- David Dyer-Bennet, dd-b@xxxxxxxx > ; http://dd-b.net/Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/Photos > : http://dd-b.net/photography/gallery/Dragaera: http://dragaera.info
