Just a noob question.
Money, IQ and zoom length aside, why do people prefer to use lens with aperture of f3.5, f4, f4.5, f5.6?
For me, i find that the f2.8 on the Tamron 17-50mm is perfect for every occasion, esp when it becomes dimly lit. I can get a sharper picture obviously when i stop down to f4.
Since money aside, wouldn't everyone prefer a F2.8 lens ? its fast enough and can stop down as well?
Hypothetically speaking, people prefer lens such as 18-200mm f3.5-5.6 for the ability to stop down?
In that case, if there is a 18-200mm F2.8 manufactured, would be optimum?
Just a curious thought, hope the seniors can enlighten.