- Cropped Sensor Formats (APS-C)
- These are smaller sensors
- They have higher manufacturing "yield" than larger sensors
- As such, they are generally much cheaper
- Photosites are generally smaller and more densely packed
- This generally results in lower signal-to-noise ratio, more noisy pictures
- This also means the maximum dynamic range (contrast ratio) of cropped senors is lower (less light gathering power per photosite)
- They have a narrower field of view compared to larger sensors
- Their narrower FOV has the effect of multiplying the focal length of any lens
- This may be beneficial if you need super telephoto lengths (i.e. 400mm on FF ~= 640mm on APS-C, effectively)
- This may be detrimental if you need ultra wide angle lengths (i.e. 16mm on FF ~= 26mm on APS-C, effectively)
- The additional "effective magnification" offered by a cropped sensor is only illusory, and is not actual magnification
- Given a large enough sensor with enough megapixels, and the same exact "crop" provided by a cropped senor can be achieved with a full-frame or medium format (however, the larger sensor would need some SERIOUS megapixels to achieve this.)
- The 1.6x crop sensor of a Canon 450D would require a full-Frame sensor with 31mp to achieve the same crop
- The 1.6x crop sensor of a Canon 550D would require a full-frame sensor with 46mp to achieve the same crop
- Given a large enough sensor with enough megapixels, and the same exact "crop" provided by a cropped senor can be achieved with a full-frame or medium format (however, the larger sensor would need some SERIOUS megapixels to achieve this.)
- These are smaller sensors
- Full-Frame Sensor Formats
- These sensors provide the same "usable" pixel area as 35mm film
- These sensors are larger, and have lower manufacturing yield
- This generally means they are more expensive
- The photosites are larger and often less densely packed
- This results in better signal-to-noise ratio, less noisy pictures
- Dynamic range is generally higher with larger photosites.
- (The new Canon 1Ds IV with a 30mp+ sensor is touted as having full 16bit RAW capability, which offers much greater dynamic range than the general 12bit RAW of cropped sensors)
- Their field of view is "normal" from the perspective of the bulk of the photography community and equipment
- A lenses focal length is as stated when used on a full frame
- Medium Format Sensors
- These sensors are often much larger than full-frame (up to 57mm or larger)
- They have extremely low yield, and thus their cost is extremely high
- They have high density, but large photosites
- This results in some of the best dynamic range possible in a digital sensor
- Leica and Hasselblad's latest medium-format sensors tout 24bit RAW
- They may have a much wider field of view than normal 35mm for a given focal length
- A lens of a normal 35mm focal length would be shorter on medium format, providing even greater field of view
- As with cropped sensors, the effect is illusory, and only useful when describing things at a technical level
- These sensors are often much larger than full-frame (up to 57mm or larger)
(Note that the effect of sensor size on focal length or the apparent magnification assumes a common lens system. Medium format cameras tend to be rather specialized, so a direct comparison here is likely impossible. For the sake of discussion, the effect given similar lens system and focal lengths would thread throughout the range of sensor sizes.)