Thursday, January 6, 2011

How to Get Sharply Focused Images

If the subjects in your pictures aren't sharply focused they won't look very good. They'll be missing one of the qualities that makes a photo an image and not just a snapshot.

Here are some things you can do to get tack sharp images. It's a combination of technique and equipment use, rather than just one thing.

It's the Photographer

You'll hear many people say it's not the equipment, it's the photographer. Well, yes and no. Photography is one of the few pursuits where equipment can make a pretty big difference and we'll look at equipment first.
There are some aspects of photography that if you want to get pro results, you have to use the same equipment the pros use. You can always rent instead of buying if your need is short term, or your photography equipment budget is tight.

A Tripod

The first thing you'll need is a good tripod.
That $15 el cheapo tripod on eBay or the $30 all plastic tripod deal at WallyWorld won't cut it; don't waste your money.

A tripod's only job is to keep the camera rock steady, and do it in a wide variety of positions. Some do that better than others. To shoot that tiny desert flower you may want the lens parallel to, but only 6 inches above the ground while it's on the tripod. Make sure your tripod is stable in all its possible positions.

You're going to need to make 2 purchases: tripod legs and a tripod head. There are two major types of tripod head: the ball head and the 3-way pan/tilt head. We'll cover the benefits each head type has in another installment of the blog.

There's really no way around it, a good tripod and head is going to cost at least a couple hundred dollars. The good news is, a good tripod and head will last a lot of years and become something of an old reliable friend. It's not unreasonable to expect a good tripod and head to last more than 15-20 years with reasonable care.

A last thought on tripods: Pros use a tripod most of the time. It doesn't matter if we are shooting inside or outside. It's one of the key things most amateurs skip, and it shows in their photographs.

A Special Note:  If your lens has an image stabilization system like VR, IS, or OS, most lens makers note it must be turned OFF when the camera and lens are mounted on a tripod. Otherwise the image stabilization system induces blur. Some newer pro lenses have a 'tripod mode' that still uses the image stabilization system but in a different mode. Be sure and read your lens users manual.
A Remote Shutter Release

The next tool to use for tack sharp images is a remote shutter release. Pushing the shutter release by hand makes the camera move a little bit. I know you're saying, "Get out of town, no way.", but it makes a noticeable difference if you use a remote release.

There are wired and wireless remote shutter releases. Check your camera's users manual for info on which will work on your camera.

Entry level cameras often lack the connector port required for a wired remote.

Using a wireless remote may mean it uses an infrared (IR) optical signal rather than radio signal and the optical IR sensor is usually on the front of the camera, so you need to have the remote in front of the camera so the camera's IR sensor can 'see' the signal from the remote. Note: Humans can't see IR, but it's still light and can be reflected so the IR sensor can see it. Improvise!

If you have a radio frequency (RF) remote that doesn't apply since radio can go through walls, around corners, etc.. Obviously, if you have a RF or a wired remote you can be behind the camera.

If there is just no way you can afford a remote shutter release, you forgot it, or don't yet have a remote shutter release yet most cameras have a built-in self timer. It's mainly there so you can set it and then run to be in the shot but I won't tell if you use the timer instead of pushing the shutter release yourself,  making the camera/lens/tripod vibrate slightly for a few seconds.

Mirror Lockup

Most entry-level digital SLRs don't let you use mirror lockup for making images, but they usually do have mirror lockup available so the image sensor can be cleaned. You'll need to check your camera's users manual for which applies to you.
Nikon calls it's mirror up anti-blur feature - Exposure Delay Mode (see the index of your camera users manual). When the shutter is released the mirror moves up out of the light path and the there is about a 1 second delay before the shutter opens and closes.
Nikon's newest top-of-the-entry-level-lineup  D7000 has the Exposure Delay Mode feature.
On Canon cameras the shutter release has to be pressed twice, once to raise the mirror, and again to take the shot so it isn't as useful for making sharp photos.

Mirror lockup doesn't make a big difference, but every little bit helps.

Know Your Lens' Focus Sweet Spot

You can find the aperture sweet spot for each of your lenses that delivers the sharpest focus by making just a few test shots.
Most lenses give the sharpest focus when they are not at the maximum or minimum of their aperture range.
At wide open the lens is using to much of the thinner lens edge to focus at it's sharpest, and at the smallest lens openings the phenomena of diffraction diminishes the sharpness of lens focus.
Most lenses deliver their sharpest focus in the middle apertures from about f/4 up to about f/16.
If you have Adobe® Photoshop®, when you have have a photo open you can use the File menu, choose File Info, then click on Camera Data and it will show a bunch of the camera EXIF info including the aperture used to take that shot.
Which aperture you use is chosen for several reasons, the sharpness of focus being just one of the reasons.

A High Quality Lens

Better optics produce photographs that have sharper focus.
Most camera and lens makers have 3 optical quality levels of lenses:
  1. Consumer
  2. Prosumer
  3. Professional
No doubt they also represent 3 cost levels:

but as long as you stay within the limits of a lens' strengths, you can't go to wrong.

Since You're Using a Tripod, Don't Increase the ISO

Raising the ISO increases the amount of image noise in your photo, and noise reduction decreases image detail (reduces sharpness).
Use the lowest ISO setting your camera has.
Of course you may need a higher shutter speed to stop motion in your photo, meaning that in dim light you may not have the luxury of not increasing your ISO. Still keep your ISO setting as low as you possibly can.

No Choice, I Gotta Do It Hand-Held

When push come to shove and a tripod 'aint happenin', there are still some things you can do.
  • Set the camera on something solid and stable.
  • Lean yourself or your arms against something solid and stable
  • Use burst mode. Often one or two out of a 12 shot or so burst will be nicely sharp.
  • Use your camera strap wrapped around your arm.

Post Processing

You can use image editing software like Photoshop® to sharpen your images.
Entire books have been written about how to sharpen photographs.
There are many ways it can be done and the content of an image has a lot to do with which techniques get used and how much sharpening gets done.
Sharpening can be done to an entire photo (globally sharpened), or to just parts of the photo (locally sharpened).
Photo sharpening is often just one side of a coin, the other side being noise reduction.
In the future we may wind up with a blog post that takes a closer look at how to sharpen photos.