What's the value of auto focus in DSLRs?

Is the AF a very important thing? Is it difficult to focus manually? I'm going to buy a DSLR and i was choosing between Nikon d5100 and Canon 550d and someone suggested me not to buy Nikon because it doesn't have AF motor in body and nikon's AF lenses are expensive! So what's your opinion! Is AF really matters?

Auto focus has not been around for that long. And when you do portrait, sometimes the camera focuses on the nose, instead of the eyes - with shallow depth of field, the eyes will be out of focus.

The camera comes with a kit lens that has autofocus. So it's not your choice of not getting one for the first lens. Do take a photography course and you will have fun taking photos.

That's correct about Nikon's dSLR (lower end models) that has no autofocus motor inside the bodies.

AF is a very useful tool, but if you are serious you'll have to learn to manual focus too. Provided you have the dioptre on the viewfinder set correctly manual focus is not hard. I have to say that thanks to modern viewfinders having a plain view it's harder than on some older SLRs which had micro-prism and split centre focusing aids.

As for the cost of the motors in AF lenses, they come in various types depending on the "class" of the lens. Your lens with a basic in-built AF motor is not much more expensive than if it had a mechanical coupling. And the comparison with Canon is hardly fair as all their modern lenses have the motor built into the lens thanks to the lack of in camera motors in all their current cameras.

Autofocus is extremely important. The viewfinders that come in most DSLRs today make manual focus extremely tiresome and inaccurate, especially with large aperture lenses.

Your friend is an idiot.

Nikon AF-S lenses will autofocus with the 5100. That includes all of Nikon's inexpensive and excellent DX lenses, including the 18-55, 55-200 VR, 55-300 VR, 35 1.8 etc etc

AF is convenient and helpful, but not necessary. You do know that lots of us got along fine for many, many years without ever having it, don't you?

I still use a number of manual-focus lenses on my AF-capable Canon bodies. With adapters I can use my wonderful, outstanding old lenses (mostly Pentax K and screw-mount lenses) -- the 135mm f/2.8 I bought new in 1976 is sharp and contrasty even wide open, has beautiful bokeh, and is smaller and lighter than modern versions. No AF is even possible, manually focusing isn't hard at all.

That said, Nikon's AF lenses aren't any more expensive than anyone else's. You can also get Sigma, Tamron, etc.AF lenses for it. Pick the one of the two you feel most comfortable with.

Peace.

http://www.makingitasapro.blogspot.com/2011/05/good-fast-cheap-you-can-have-all-three.html

You can survive without AF in a dSLR. Your pictures may not be that razor sharp though. All digital lenses should autofocus with the right body. All Nikon bodies will autofocus with the right lens. All brand new lenses are expensive, whatever brand. What's my opinion? Get the most expensive model you can afford and deal with whatever limitations it carries yourself.