From f/2.8 to f/5 is insignificant ?
The loss is insignificant for most lenses that are only capable of hitting maybe 1:3 at best. For a macro lens it is quite significant thus the reason I find it very reassuring that the Nikon macro lenses communicate this with the body.
Agree. Many folks have such a hard time with the concept of bellows effect that I wonder if Nikon should just let the actual apeture stay in effect and just correct exposure without showing what is really happening. Lol!
It is basic physics. The lens projects light over a larger area as it is focused on closer objects, resulting in a lower illuminance at the image plane. Aperture is the parameter that determines light flux per unit area. Shutter speed determines the length of time that light is allowed to accumulate at the image. Exposure depends on both shutter speed and aperture. Shutter speed is controlled by the camera, not by the lens. You, or the built in meter, will adjust shutter speed to compensate for the light loss as aperture is changed at close focus, not the other way around.
No. Neither of them lie. The effective light goes through the lens at 1:1 macro is less than the light would go through a true f2.8 (f5.0 in the case of 60mm Macro). But the real aperture IS STILL f2.8 (you get the depth of field of f2.8, but not f5.0). Sigma, Minolta also use the same way Canon does.
OK, I guess you are thinking that the camera closes the lens down to f5 instead of adjusting the shutter. This is not the case. If you set the lens at f2.8, it will be a true f2.8 when focused at infinity. As you focus closer, the "bellows effect" that eveyone's been telling you about kicks in. Because the lens extends to focus closer not as much light reaches the sensor or the film.
Huh? Where did you get that idea? Depth of field at distances much less than hyperfocal distance varies directly with effective aperture and inversely with magnification squared. Yes, you get the DOF of an f/5 lens with the 60 mm Micro when wide open at 1:1.
Canon's approach is standard for most older cameras; they assume the photographer knows what he or she is doing, and is able to correct for bellows factor when necessary with external metering or manual flash. TTL metering handles this for you, but on a Canon does not tell you the correct effective aperture. There is no magic in Canon cameras that enables them to give a "clearer idea of depth of field." In fact, by not reporting the effective aperture, they misrepresent DOF.
