All canon SLRs have an EF lens mount and accept all EF lenses. The EOS 20D and most later, non-professional models also accept EF-S lenses, specifically designed for digital cameras.
EF-S lenses only cover the APS-C size sensor, not the larger 35mm frame. EF-S lenses will not fit other EOS cameras. Both EF and EF-S lenses autofocus.
The EOS system also includes TS-E lenses. These have tilt and shift movements. Tilting the lens alters the plane of depth of field, which can create some interesting focusing effects. Shift, which refers to the lens moving sideways, helps to control perspective, especially when photographing tall buildings
MP-E is a designation used for a macro photography lens, the MP-E65mm.
TS-E and MP-E lenses fit all EOS cameras, but do not autofocus.
The EF lens mount has a red alignment spot at the top. The EF-S mount also has the red spot, but additionally features a white alignment square to the right. Both mounts accept all EF lenses. The EF-S mount also accepts EF-S lenses.
Nikon have continued to use the Nikon F lens mounting system, first introduced on the original Nikon "F" camera in 1959 right up to latest D-SLR available today. While every Nikon lens ever made share the same lens mount the compatibility of the lens varies depending on the camera body used.
Used on Nikon SLRs and NIKKOR lenses from the introduction of the Nikon F in 1959 to current models, the bayonet-type F-Mount is the communication link between Nikon SLRs and NIKKOR lenses.
Noted for its rugged construction and outstanding reliability, the F-Mount is distinctive also for its degree of compatibility with NIKKOR lenses and a design that can accommodate future system advances. Nikon has maintained the basic structure of the mount for the 50 years of its use, and currently some 400 different NIKKOR lenses are compatible with the system.
One of the biggest advantages of the Nikon F-Mount is that you're able to choose from a large selection of lenses including: AF NIKKOR and AF-S (Silent Wave Motor) and PC-E perspective-control NIKKOR lenses.
By adapting and extending the capability of the F-Mount and NIKKOR lenses, Nikon has incorporated technologies like autofocus, advanced metering, distance information technology, electronic aperture control in G-Type NIKKOR, VR (Vibration Reduction) image stabilization and Silent Wave Motor (AF-S) technology, thus maintaining a significant degree of compatibility and demonstrating an ongoing commitment to photographers.
Nikon digital SLRs have either an FX or a DX sensor. The FX sensor, measuring 24x36mm, is roughly equivalent to the size of the 35mm film frame. The DX sensor is smaller, measuring 15.8x23.6mm.
DX-NIKKOR lenses are engineered and optimized for use on Nikon DX-format D-SLRs and are designed to cover the smaller image area of the DX sensor. When a DXlens is mounted on an FX-format Nikon D-SLR, the camera’s DX-Crop Mode is automatically engaged, introducing a 1.5x magnification (cropping) factor.
Nikon digital SLR cameras that utilize the DX-format imaging sensor are designed as smaller camera bodies than those utilizing the larger FX-format sensor. Therefore, DX-format NIKKOR lenses can be made smaller as well. Because fewer materials are used, these lenses are less costly to produce.
The FX/35mm lenses are designed for use on Nikon digital SLR cameras that utilize the FX-format or 35mm full frame imaging sensor.