I'll like to add to your good points by saying that faster aperture also helps Auto focus due to fact that AF sensors are probably calibrated for F2.8 & may loose their sensitivity for slower apertures (If that's correct theory), also there's good chance that routine aperture settings on faster lens will deliver more sharper image across the frame compared to kit lens (not a theory but could be fact).Amolmdhttp://www.flickr.com/photos/amolmd/sets/72157594348971243/..
Amolmd wrote:.
I'll like to add to your good points by saying that faster aperturealso helps Auto focus due to fact that AF sensors are probablycalibrated for F2.8 & may loose their sensitivity for slowerapertures (If that's correct theory).
Not quite, but close. AF sensors rely on light and contrast. Simply put, the bigger the hole in your lens, the more light will reach the AF sensor..
In fact, unless it is a bright day, most AF sensors cannot function at f/6.x and below. The camera will hunt and hunt for focus..
The more expensive lenses have a much superior quality of glass in them, and much larger elements as well, both of which help in the transmission of light through the lens. They are also built more strongly, to enable them to be used a lot more regularly, in often demanding conditions, and tested and adjusted in the factory to deliver consistent results. All of which is important to the professional user, which is the target market for these lenses. And all of this costs money, which is good value if you need to be able to take pictures at any time, not just when the sun is shining and everyone can hold still and watch the birdie..
If you get the chance, bung a pro grade lens on to your camera and shoot for as long as you are allowed to - then shoot the same scenes with a consumer lens. The difference will (generally) amaze you. There are some truly amazing consumer lenses out there, but most of them are shadowed by their more expensive pro brothers.Rob.
If you're bored...http://braveulysses.deviantart.com/gallery.
'Have the courage to be ignorant of a great number of things, in order to avoid the calamity of being ignorant of everything.' Sydney Smith (1771-1845)..
To the best of my knowledge, most AF systems are designed to work out to f/5.6 or so. Not a problem in daylight, but it can make a big difference once you move indoors or the sun goes down. f/2.8 can get you AF in much dimmer light than f/5.6 can..
Crime Scene PhotographyA small gallery of personal work: http://picasaweb.google.com/PID885..
Caoedhen wrote:.
To the best of my knowledge, most AF systems are designed to workout to f/5.6 or so..
The confusion may be because of Canon!.
Canon cameras sometimes have extra Af sensors that only kick in if you have a lens with a max aperture of f2.8 or faster. This improves AF performance when you are using those lenses..
I am guessing Nikon has no such foibles, from your comments...
The explanations in this thread are all good, but I will say one thing which you can take or leave..
Don't buy a more expensive lens unless you understand/see/desire the difference you get..
Some people will shoot with the kit lens and never need a faster aperture, or improved glass. Not because they are poor photograpghers, but because of their style, their usage, what they photograph, etc. So I would never recommend buying a more expensive lens to get 'something better' unless you are using something and your have reached it's limits of performance..
I've seen people trade in 1600 lenses because for them it performs the same as a 300 lens..
My advice - get the kit lens and enjoy it. You may never buy another lens, but if you decide you do, you will know exactly what you require from your own experience. It might be a faster aperture, better IQ, IS/VR, different focal lengths, better build, physical size, weight, aperture blades, AF speed, filter size... You get the idea..
A..
Good advice.Rob.
If you're bored...http://braveulysses.deviantart.com/gallery.
'Have the courage to be ignorant of a great number of things, in order to avoid the calamity of being ignorant of everything.' Sydney Smith (1771-1845)..