Auto-Focus Can Kill A Good Picture!

Understanding How Your Camera’s Autofocus Works Is Critical! Auto-focus systems can cause more problems that you might be aware of. More often than they should be, photo counters are often charged with complaints that have nothing whatsoever to do with the actual photofinishing process.

These often include things like out-of-focus pictures. This is a fairly common complaint from a number of automatic focus camera owners.automatic focus camera

In a lot of cases it’s an operator problem. A lot of users fail to read the user manual closely enough to understand the operation of the auto-focus features of their cameras. Periodically it could be weak batteries or it could be a legitimate camera problem requiring professional attention. Essentially auto-focus systems work much like the human eye. Whatever object the eye looks at is in focus.

See some creative photographic work

The electronic auto-focus sensor or “eye” can only “see” one object at a time

The electronic auto-focus sensor or “eye” can only “see” one object at a time. You must determine what it is that your camera is looking at with the settings you use most commonly use. Read the manual! Occasionally the camera operator can accidentally set the camera for manual focus which will cause obvious problems. Quite a large number of folks will expect their cameras to do things they were never designed to do.

Many cameras will not take in-focus pictures at closer than four to five feet, especially the one-time-use cameras. Operators must read the labels and user manuals to determine the operating limits of the units they intend to use. Properly taken close-ups are always taken with cameras which feature a “macro” capability or special macro tube-and-lens assembly. Depending on quality, these can often be focused down to less than three inches.

With autofocus cameras……

With autofocus cameras, it is absolutely essential that the camera has a sufficient amount of ‘recovery’ time between exposures. The operator must give the unit enough time to set up the next shot before actually pushing the exposure button. This is especially true with cameras with batteries that are coming close to the end of their useful lives. Most often, the camera manufacturer has provided a ‘ready’ light to let the operator know that the camera’s ready to let you take another great picture.

CAMERA MOTION

Don’t confuse a focus problem with camera motion.

This is an available light shot taken while I was telling a story at a recent wedding. Note the “halation” or “ghost image” of the collar on my blue jacket close to my neck.

This is caused by a too-slow shutter speed. The subject has time to move a little while the shutter is open and actually recording the image.

Higher shutter speeds cure this along with either full or fill flash.

SUBJECT MOTION

Another problem with slow shutter speeds is when your subjects move while the shutter is open. Once again, a faster shutter speed and or flash will freeze any subject motion.

One of the most famous photographs in history was one taken of the interior of Grand Central Station in New York City somewhere in the 1920’s I believe.

It was a black and white photo taken at the busiest time of day but the best part was, not one single person showed up in the picture! The station appeared empty even though the photo was taken when the massive interior was actually chock-full of people.

No, it wasn’t massive retouching. It was a very clever photographer.

He had apparently been commissioned to do an interior shot of the new terminal but I understand the building was in use before it was completely finished. It wasn’t even remotely possible to stop people from using it so a way had to be found to accomplish the seemingly impossible, take a photo of the empty building.

He did it using a very slow film. He stopped the lens right down as far as it would permit and then did a very long exposure, about 60 minutes or so as I recall.

The upshot is that the film was so slow it didn’t have time to record any of the people who were all in motion. It did have time however to record the architectural features of the structure which were NOT in motion. Very cutting-edge photography for the times.

DIGITAL ZOOM

I’m often asked what the difference is between optical zoom and digital zoom.

There’s quite a bit actually – the term “optical zoom” simply means you are using the glass lenses to do the magnification. “Digital zoom” on the other hand simply increases the size of the pixels to make the image larger. For reasons of sharpness, the optical zoom is a far better way to go.

Here’s an analogy – take a tablespoon full of water and drop it in the bottom of a small glass. It covers the bottom of the glass quite well. It has some depth. Take another tablespoon of water and drop it on to a dinner plate and spread it around as far as it will go. It get’s pretty thin doesn’t it?

That’s what you’re asking of your camera…taking a small pixel and spreading it over a large area. It gets pretty thin.

Here’s what I mean. The following two shots were taken on the same day at the same time. The top one was taken with full optical zoom and the bottom was taken with full digital zoom.

The results speak for themselves.

Auto-Focus Can Kill A Good Picture!

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