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The art of Manual Focusing
21 March 2008
You know what I’m amazed at? I’ve talked to several photographers who do photos for a living. Not even weekend warriors, I mean genuine photogs. One of them was even nominated for a Pulitzer for photojournalism in the 70’s. Now, it may depend on the individual type of work, but most of them praised manual focus. Not a single amateur or weekend warrior that I’ve talked to considers it more than an afterthought.
So, I want to talk about this.
With the difference between professional and consumer dSLRs ever narrowing (Canon 40D/5D anyone?), one would think that amateurs would learn to do more like the pros. Oddly, this is one instance where the opposite is happening - as cameras develop insane levels of cross-type auto-focus, pros are relying on AF a lot more.
Why the change? Well, as I mentioned, AF is getting a hell of a lot better for starters. Nikon’s D300, the blurring of the consumer/pro on that side of the fence, is up to 51 (I think) autofocus points. Most of them are cross-type, meaning that the sense lines horizontally and vertically.
For those who, like me, needed educated on this, let me explain. On most lower-cost bodies (Canon 300-450D, Nikon D40-D80), the AF points are arranged in some form of grid. The horizontal lines on the grid seek vertical lines in your composition, and vice versa. Cross-type points can be sensitive to either. If you’re trying to line things up on a Canon Rebel XT and wonder why it can’t really see the focal point of your horizon halfway through the frame when it’s sitting on no less than three AF points, that’s why. The line across the middle is searching for vertical lines in your picture.
Fifty-one cross-types means you can practically select an eyelash as your focal point. On a whole head. It sure is neat - except that actual AF distance is controlled by the lens, many of which aren’t quite so optimal in lower light circumstances. Maybe you’ll get it…or not, or maybe you got Uncle Fred instead of the dinner table because his face was closer to the light. In these situations, AF isn’t always optimal at all.
The problem is, modern dSLRs are caving to the consumer end. There’s a part in your camera called the “focus screen,” and it’s part of what makes the viewfinder and the light metering work. Cheaper, lower quality focusing screens and pentamirror viewfinder technologies make for dim and fairly indistinguishable viewfinders. Therefore, you almost have to use the viewfinder as more of a view-pointer, just aiming and letting AF take over. Light up whichever dot is closest to what you want to bring out, pull the shutter, and pray.
Pull the shutter and pray is exactly what the SLR was invented to avoid.
As hobbyists looking to take our photography to the next level, I’ve done a bit of research for how we can fix this:
- Pentaprism viewfinders: Pentaprisms are solid glass, and heavier than Pentamirror-based viewfinders which are hollow. However, the weight is for a reason - pentaprisms let in WAY more light, leading to a brighter, better viewfinder. You will only find these on Canon models that are 20D,30D,40D and above. For Nikon, the D80 is the first model - at a price point way cheaper than the equivalent Canon 40D ($899 instead of $1299).
- Focusing Screens: The focusing screen is the other big difference. Cheaper ones don’t let in the same amount of light, but worst of all they aren’t really designed to illustrate proper focus. Changing this out (more on this below) can make a big difference, particularly when you go to a Split-Prism model like the Kat’s Eye Custom filters. These are what existed for the older SLRs, and a lot of photographers really miss them. Most of those that do never knew you can get them still in your camera without a tremendous cost.
The viewfinder is not interchangeable, so you’ll get what you pay for here. However, the focusing screen is. You can purchase separate focusing screens like those from Kat’s Eye Optics for between $100-200. I’d highly recommend spending the full $200, as I probably will upon purchase of a 40D. On the 20D,30D,40D family, there is almost NO reason to not do this. Any camera repair shop that would normally work on your kit can do the switch for you, or you can do it at home if you’re feeling brave…
For those of us with lower-priced models, we’re still in luck - sort of. Same price, same product - but note that your AF points won’t work anymore. Most people don’t like having only full-time manual focus and not having the use of your AF points in the viewfinder puts you halfway there. Add that to the fact that the viewfinder is small and based on mirrors anyway, and you end up with not as much to gain. Then, figure the cost of the right focusing screen will be about half the cost of your camera. Maybe those hunting AF points aren’t so bad after all…
Whether you change viewfinders, cameras or focusing screens, one thing is for sure - shutting off your Autofocus and doing some practice on manual will improve your abilities for composition and give you a little understanding of how things should look through YOUR camera. I think (and the pros seem to agree, as that’s where I picked this tidbit up from) that though AF can be a life-saver, it shouldn’t be relied on entirely and there’s nothing like understanding your equipment and your skill.
So don’t be afraid to shut off that AF and go practice a bit! It’ll still be there when you need it…but you’ll know better how to catch and quickly correct it when it inevitably misses in lower light.
Oh, and a side note on the split-prism focusing screens - unless you go with the “Kat’s Eye Optics Plus”, the center circle will go dark while the aperture is higher than 5.6 (it’s meant for low light). It may also play a little havoc with your light metering, though there are very mixed opinions on that.
The more expensive Optics Plus version won’t start going wonky til somewhere between F11-F16, which is higher than one would usually shoot anything but landscapes at, which you should use a tripod for anyhow and will have plenty of time to line up your shots. And since modern lenses don’t actually move the aperture until the shutter is pressed, you won’t even notice it unless you press your little Depth-of-Field preview anyways.
Most of the models on the Kat’s Eye Optics page are already only “Plus,” so this problem is fairly self-correcting. But it’s a natural limit of split-prisms, and it’s worth getting used to it - photographers of the old SLR days worked with it for years, and there’s a reason for it. And they didn’t have half the lens quality we do now!
Topics: Equipment, Technique |