You can do certain things like move the rearmost elements closer to the image plane, but thats because of other factors.
In the case of smaller sensor DSLR cameras vs Full frame DSLR cameras, the physical space required by the swinging mirror is reduced, so you can place parts of the lens closer to the image plane (Simply because its not going to get bashed into by the mirror flapping about). There are design advantages to this, but they have no effect on the ultimate focal length.. The more extreme example is to look at a rangefinder or mirrorless camera. By getting rid of the entire SLR viewfinding mechanism that normally sits between the lens and the image plane the lenses can become smaller still.. Notice the massive difference in size between a 50mm f1.8 lens on a Leica vs one on a Nikon or Canon SLR, same focal length, same aperture, same film back, but the overall package is vastly smaller. Same again if you look at a Mamiya 7 vs an RZ. On 30/05/2012, at 1:46 PM, Deke Kincaid <[email protected]> wrote: I assume I'm missing something here, but as there are 2 lens types available for my camera, one designed for it and one that happens to use the same mount both 500mm isn't there 2 possible results from a '500mm ' lens? The only difference between DX and FX lenses is the size of the image circle, they don't need to make it as big on the dedicated DX lenses because they don't need to cover as large a sensor, so other parts of the lens can be made smaller. I'm not a nikon person but with the canon lenses equivalent (EF-S) they do more then just make the size of the lens board smaller. They actually move the lens element closer to the sensor then the equal 35mm lens. I'm not sure if Nikon does something similar. -deke _______________________________________________ Nuke-users mailing list [email protected], http://forums.thefoundry.co.uk/ http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
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