Ok, it's myth busting time and the Manual mode is our subject for today. Everyone knows that the real pros and those who really know photography use Manual mode because it will give the best exposures. Oh, really?
So we look at our scene and decide we want f/8 for maximum sharpness from our lens. We set the aperture to f/8 and look at the little meter in the viewfinder, adjusting the shutter speed dial until the pointer aligns with the flashing mark. Alright, perfect exposure (it happens to be 1/125 second). We smugly smile as the newbies and semi-newbies around us take their photos in Auto and Program modes, with a few of the more enlightened ones using Av or Tv. But even then they are not going to get as good an exposure as us! Or are they?
The Av people set their aperture to f/8 and lo and behold, their cameras set the shutter for 1/125, same as our brilliantly done manual exposure! The Tv people set their shutter speed to 1/125 and their cameras set the aperture to f/8! How can this be? Worse yet, the Program and Auto people set *nothing* yet their cameras also choose f/8 at 1/125! The fact is the camera uses the same meter for *all* exposure modes and by using Manual and matching the little pointers all we have done is waste time and effort to get the same exposure as everyone else, the exposure the camera will set on it's own. Our smug smile quickly fades as the newbies take five (perfectly exposed) photos in the time it takes us to set up for one.
The point is, if we just want to follow what the meter indicates we are much better off using one of the auto or semi-auto modes. Oh, but we can set the pointers to something other than matching, like a stop more. Yeah, and so can exposure compensation yet it can still track the light *much* faster than we can manually. With rare exception, there is no valid exposure that Manual can set that can't be done in one of the Auto modes!!!
And what about those "rare exceptions"? Fireworks, where the dark sky will throw off the metering, and in this case we don't use the meter for Manual either, we set exposure according to experience and taste. There are more exceptions, but not many.
To be fair and honest, Auto and Program do not always set the exposure as we wish. Those modes use a lookup table for exposure values (see your manual) and set exposure accordingly, often biased towards shutter speed (to keep newbies from using too slow a shutter speed and getting blurred photos). However, if we do not like the settings the camera has chosen we can shift the settings to select any aperture or shutter speed, all while still keeping the same basic exposure value! Pretty slick, and very fast!
Even after all this some will still insist Manual is better. Yeah, so are carburetors, vinyl records, and film