7 Tips For Tack Sharp Photos

We recently spent a lazy morning at La Purisima Mission. While there I took pictures of grandma with her grandsons. We had a lot of fun, and I got some great shots. There was one problem, however. Some of the well composed pictures were not tack sharp.

One of the cool features of Aperture (thank you Apple for killing off another great product) is that you can see where the focus point was placed in each shot. When photographing people it is always best to focus on the eye nearest you. Doing so creates an accurate depth of field that draws attention to your subject and it makes sense to how our brains are wired.

Notice how it's blurry right on the red focus point?

Notice how it's blurry right on the red focus point?

When we got home I uploaded the photos to my computer, and was disappointed with a number of them. I'm sure you can understand why. Many of the best shots were fuzzy making them unusable. 

Some of the photos were tack sharp about one inch behind or in front of the focus point. I've noticed this pattern for a while now. Is it me, the camera, the lenses, all of the above? Let's find out.

Focussing then Moving

I shoot with the Nikon D7100. When shooting portraits I always set the camera to the "single focus" setting. Single focus allows you to frame the composition of each shot by moving the focus point to a specific place within the frame allowing you to create an artistic look.

In single focus mode the focus point locks when you press the shutter button halfway. At that moment it is important that both you and your subject stay still. If you don't then the distance you move (either backwards or forwards) will alter where you are actually focussing.

One way to correct for this is to set your camera to the "Continuous Focus" setting. Continuous focus is meant for live action sports, or anything fast moving. When shooting portraits it will help you correct for movements - especially when your subjects are small children with their chasing parents.

Just know that the lens can be a half second slower than you are when moving around, so you can still get a fuzzy shot. And continues focus will drain the battery faster since it is continuously driving the focus motor.

One thing I found that works is to set the focus lock "chirp" loud enough so your subjects hear it. When they do they know to stay still. I also press the button halfway to lock the focus then release it. I do this a few times until I feel confident that everything is lined up and ready, and then take the shot. 

Increase The Depth of Field 

If changing your focus setting gives you sporadic results try increasing your depth of field. Shooting at f/2.8 makes for a nice buttery background that separates your subject from background distractions, but it also tightens up the focal plane. 

Increasing the f/number will increase the distance between the front of the focal plane to the back of it. Setting your aperture to f/5.6 will give you a few feet to work with whereas f/2.8 and lower will only give you a few inches. 

And if you are shooting portrait photography with a long lens you need not worry about bokeh. A 200mm focal length will give you plenty of blur at f/5.6 while still drawing attention to your subject.

Back Or Front Focussing Issues

You tried holding still after locking in your focus, you changed your focus setting from single to continuous, and you increased your depth of field by changing to a larger f/number, but you still have issues with sharpness. If so, you may need to adjust the point where the camera is focussing. 

Most modern cameras have adjustments that allow you to fine tune the front to back focussing of all your auto focus lenses. Nikon's auto focus adjustment is aptly named Autofocus Fine Tune whereas Canon calls it AF Microadjustment. This setting will allow you to make millimeter adjustments to each of your lens' focal plane.  

Until I get around to writing an article about how to adjust the fine tuning of your camera's focussing system you can learn more about it here.

Lighting

After all that, if you still have issues check your lighting. Auto focus systems require light for the CCD to make accurate predictions as to where the best focus point is. If you need a little more light you can turn on your camera's auto focus assist illuminator. It is a small light that illuminates your subject just enough to create contrast.

It is this contrast that the CCD uses to set the focus. The best way to obtain contrast is to place your focus point on a line where light and dark meet. So when focussing on the eye for example, use the line where the eyelid meets the eye.

For landscapes use a tree, rock, or hillside. Just be sure to focus on a spot where light and dark come together. In low light a definitive line may be just enough to get you the tack sharp focus you want.

Stop Shooting In Auto Mode

I can't stress getting out of Auto enough - Learn to shoot in manual mode. Or at least use Aperture Priority. The biggest issue you will face when you shoot in Auto is that the camera takes control of what it thinks the frame should look like. Often, the end result is not what you want. 

Auto mode's primary objective is to create an accurately exposed image. It is not meant to take an artistic photograph. When shooting in Auto the camera guesses at what it thinks you want, but instead captures an average boring snapshot. 

In order for Auto to achieve proper exposure your camera may lower your f/number just enough to create a shallow depth of field. It may slow your shutter speed so much so that it creates motion blur. Or it may raise the ISO to the point that the image grain is just too much to bear.

In every photograph you need to keep the ISO low enough to minimize the digital noise, and the shutter speed fast enough to meet the demands of your subject's movements. The rule of thumb is that your shutter speed should be set no lower than the focal length of the lens.

For example, if you are shooting at 200mm your shutter speed should be no slower than 1/200th of a second. But not all camera's shoot at that speed. If not, you would need to round up to 1/250th of a second. 

Now if you read my variable aperture lens article then you would know about crop sensor cameras and their crop factors. As if things couldn't get more complicated, you need to take the cropped multiplier into consideration and set your shutter speed to that number. 

Case in point. If you have a 200mm lens with a Nikon crop sensor then you are effectively shooting at 300mm (200mm x 1.5 crop factor = 300mm full frame equivalent).

In that case, to avoid motion blur you need to set your shutter speed to 1/300th of a second. If your camera doesn't have a 1/300th setting then round up to the next one. The further out your lens can reach the more exaggerated it makes small movements. So shooting fast with a long lens is the best way to freeze action.

When you take control of the exposure triangle you can make the photograph look exactly how you imagine the image. At that point it becomes a lighting issue that you may or may not be able to control. And variable aperture lenses lose light as you zoom, which creates other problems.

Focus Points

My D7100 has a lot of focus points that cover most of the frame - 51 to be exact. That means they cover the fringes of the lens where the glass curves. This may cause some lenses to be less sharp at the edges.

If you notice this happening then place your focus point more toward the center. Full frame lenses may not have this problem, especially when used on crop sensor cameras.

Whereas, shooting with lenses designed for cropped sensors on a full frame camera may increase the likelihood of blurry images - along with vignetting. Shoot lots and practice. Get to know your gear. It will take some time to become familiar with it.  

Recalibrate

If you tried all of these suggestions and you still get poor auto focussing then you may need to have your gear sent back to the manufacture for them to recalibrate it. Or find another hobby, but I'll leave that for you to decide.

Now get out there and do your part to stop flooding Facebook with blurry underexposed images.