Autofocus without mechanical movements?

Focusing a lens requires moving the lens back and forth. That's the way it has been for over 100 years. This is even true with Nikon's SWM (silent wave motor) and Canon's USM (ultrasonic motor), where the mechanism for moving the lens back-and-forth is quiet.

Today I just stumbled on the following news that a company raised $30 million dollars to create cameras that can autofocus without mechanical movements! You apply voltage to a lens that changes the refractive index. WHOA!!!!!! I've heard lenses that can change opacity by applying voltage, but changing refractive index is a first for me. Imagine, if this is possible on a teeny-weeny scaled lens, who knows what the future of big lens technology will be like in another 100 years? In the 22nd century, we'll probably look back to 2010 and laugh at the $8000.00 super 600mm f/2.8L/G FX SWM/USM auto focus lens that weighs 999 tons.

• http://venturebeat.com/2010/02/04/lensvector-raises-30m-for-improved-autofocus-in-camera-phones/
• http://www.lensvector.com/product.php

Hyperfocal Distance > $5500 camera

What's the solution to taking consistently sharp pictures in extremely challenging conditions, such as a bunch of people dancing in extreme darkness? You know that a $100 point and shoot just won't do the job because the high ISO setting on cheap $100 camera is way too noisy, and the auto focus on a little camera is horrible. Even a $500 SLR camera won't do justice. Heck, a $1000 SLR used improperly won't do it either. On the other hand, a top of the line $5500 camera body with 1000000 computerized AI auto focus and expensive high quality $1000 prime lens and extreme high ISO would work reasonably well. This is a viable solution. It's also a very expensive one too.

You don't really need a $5000 body and a $1000 camera lens. You just need to understand the limitations of your camera equipments. First of all, you don't need a zillion computerized AI auto focus like the ones on Nikon D3s ($5500) or Canon 1Ds mark IV ($5800). You don't need auto focus, period! People in the really manual film days took perfectly good pictures without auto focus. Their secrets? 1) super wide angle lens and 2) knowing what "hyperfocal distance" is.

There are many complex definitions to hyperfocal distance. Here is my simplified, Cliffs Notes version: by turning focus distance to a pre-known constant "hyperfocal distance" and constant aperture, all objects between a known distance to infinity will be in focus. For example, I know that on my APS-C SLR fitted with a 10mm lens, setting the distance to 3 feet (its hyperfocal distance) at f/5.6 means that all objects between 2 feet and infinity will be in focus, period. Combine this with TTL flash, then I simply make sure there is at least 2 feet between the camera and things in front of it, and shoot away. I don't even have to think, I just shoot away. It's that easy. Basically, I'm relying on the fact that 1) wide angle lenses have much deeper depth of field and 2) knowing what my hyperfocal distance and minimum focus distance is.

You can find out what your hyperfocal distance is by experimentation, by looking at tick marks on your lens, or by manually calculating it. It's more accurate to calculate it, so here are some links about this topic:

http://www.dofmaster.com/hyperfocal.html (what is hyperfocal distance)

http://www.dofmaster.com/equations.html (calculating hyperfocal distance)

http://www.dofmaster.com/dofjs.html (calculator that gives you hyperfocal and min distance)

Knowing about hyperfocal distance, everyone can take consistently sharp night pictures of moving objects using low end SLRs, TTL flash, and high quality wide angle lenses for a fraction of the cost. Sorry Canon/Nikon, I'm not buying your $5000+ camera with the latest and greatest computer + electronics gadgetry. Technology is overrated. Knowledge is cheaper.