Just What is Sharp?
It had been one of those amazing days for photography, where everything was put in front of us, to shoot to our hearts' content. We’d spent a great afternoon with Rocky Mountain Bighorn Sheep outside Big Sky, MT, and we were walking back down the road. Then, out of the corner of my eye I saw a dash of white. It could be only one thing, a Short-tailed Weasel. We stopped and watched, and a few moments later, the cutest critter in winter popped its head back up and stared at us. For nearly the next hour it entertained us, running to and fro, running between our legs and way down the hill, and then back again. It knew all the secret tunnels, and would go down one hole and back up another. In the dusk of day, on the backside of a mountain, swinging the 600mm around to keep up with it was a real challenge. And, oh, so much fun!
Editor's Note: This is a guest blog post from Moose Peterson.
While we still had a little bit of sun, I had made a whole bunch of clicks of the weasel that I really liked. But once the sun left—in that all-white world, with the all-white critter—that was when the great images really came to fore. But the shutter speed had really taken a dip with the temperature. Then came the one pose I really liked, and I went click. The next day it was on the blog, and the compliments came flooding in. The best compliment: a person wanting to buy a print of the image. That just killed me, because the image wasn’t sharp enough to make a print.
Just how sharp is sharp? This question has plagued photographers since the 1890s. How do you obtain a sharp image? How do you measure your results to determine that it is sharp? What complicates this process is that the one “secret” to a sharp image (which I’ll discuss shortly) doesn’t get out much, so perceptions and realities don’t match up. Well, just how important is sharpness, really?
In general, when we take a photograph and the subject is out of focus, what do we do? Speaking for myself, lack of sharpness is the main reason I delete an image from the day’s shoot. (Sure, you see photos where the subject is deliberately blurred to either communicate motion or to be artsy.) That’s how important sharpness is on the face of things—not sharp?...to the trash the image goes!
In the scheme of things, though, sharpness is very important to the mind’s eye. The mind’s eye goes to light/bright first in our photographs, and to sharpness second. These two simple truths can dramatically change your photography when applied to manipulate the viewer’s attention. In storytelling, which is what photography is, visually communicating means to successfully draw the viewer’s eye through your photograph, and continually bring it back to one place—the subject. That’s why we focus on the subject—the subject has to be sharp.
But that brings us right back to our problem. How do we obtain sharpness? How do we measure sharpness? In my piece, “What is the Best F/stop?” I talked about how we use sharpness. Now let’s talk about how we can obtain and measure sharpness.
Capturing it Sharp!
Just how important is that lens quality and camera body to the sharp image? I’ve seen lots of fuzzy images from sharp lenses, but I’ve never seen a sharp image from a fuzzy lens. And for a long, long time, I’ve not seen a fuzzy lens. So when it comes to placing blame for an out-of-focus image, it’s what I like to politely call “pilot error.” With that said, personally, I spend the extra bucks and buy Nikon lenses, and generally, the fastest in a focal length. There are two reasons for this: I like to shoot wide open to minimize DOF, and typically, the best glass is in the most expensive lenses. When you have a photograph enlarged so large that it is wrapped around a bus, that expensive glass pays off! But without a stable platform, the best lens will not perform its best, so that’s the first thing we need in the chase for sharpness.
Stability starts with the basics: handholding. Personally, the vast majority of my shooting is done handholding (I hate tripods), from 16mm to 600mm. And I’ll do this, without hesitation, at slow shutter speeds—down to 1/2 sec. This particular skill is not unique, but rather common amongst my peers, and comes from lots and lots of practice—in my case, over thirty years of it. Often I’m asked by photographers why their photographs are better on Sunday than on Saturday. This is because they are what I call Weekend Warriors, having that dang work thing messing up their photography, so they can only partake during the weekend. Saturday is spent getting familiar with their camera again, and on Sunday it’s like an old friend. So sharpness comes from practice!
Basic handholding is just that, a basic that must be learned by just doing it! It starts with the lens resting in the palm of your left hand. This uses gravity to force the lens down into your palm, which is the start of creating a stable platform. Grip the camera body with your right hand, and rest your finger on the shutter release. It’s important that you roll your finger to activate and fire the camera, not jab at it to fire it. Pull the camera against your forehead, and use a rubber eyecup, which acts like a shock absorber. Lastly, pull your elbows into your sides. This technique provides a stable platform for your camera while giving you the flexibility, if you need it, to twist at the trunk to pan with a subject. To me that’s essential, since I shoot lots of action!
When you’re shooting with a long lens, your technique needs to change up to capture a sharp image. The basics are placing your left hand on the lens barrel right above where the tripod head is located. That stops any vibration that starts at the camera from reaching the front of the lens and bouncing back. Grip the camera body with your right hand, and rest your finger on the shutter release. It’s still important that you roll your finger to activate and fire the camera, and not jab at it.
What if you wear glasses, or are shooting with a camera on a tripod with a short lens? And what about the mirror lockup feature? If you wear glasses, I regret that I’ve yet to find a great solution for pulling that camera body tight against your forehead. I’ve seen a number of solutions, but not one that I'd say is universal. When shooting with a camera on a tripod with a short lens, a cable release can be your best friend. Being an airhead (or lazy), I tend to forget mine, so I’ve gotten used to using the vertical firing button for firing the camera. That button doesn’t cause a movement like the normal shutter-release button. Some use the self-timer feature when they forget their cable release, and that is a viable solution—I’m just never that patient. And the mirror lockup feature, that works great, again, if you have the time. Any one of these, or combos, are viable tools you can use so that the camera doesn’t vibrate at the moment you go click. And that’s the goal.
Now, if you feel you need to stop your lens down to capture a sharper image, in my book you should chuck that lens! And if you even need to think about that while shooting, you’ve lost all the love of photography. I’ve seen the sharpness of way more images ruined in post processing, than from shooting with a lens at the wrong aperture. While technically all that hooey might be true, not once in all my years of shooting have I used that theorem, or had one photo buyer say my images weren’t sharp because I didn’t shoot using that theory. Life is too short, have fun!
And what about the sensor's role in this? Opening that can of worms is for smarter folks then me. I can only go by what I’ve seen in my own images. There are two images here, one is of a Grizzly Bear in a coastal meadow. The other is of a Greater Sandhill Crane. The griz was shot with a D1 & 400 f2.8AF, and the JPEG out of the camera created the 30x40 print that hangs behind my desk. The Sandhill Crane photo was the cover of one of my books, and was produced by the D1H, also a JPEG out of the camera. Yeah, sensors make a difference. The photographer makes a bigger difference!
(You’re wondering about tripods; that’s a topic for a later posting.)
Focus that Puppy!
While this seems obvious, with our autofocus cameras, the placement of the AF point to get a sharp image isn’t always obvious. Now there is no recipe I can provide that will work in every shooting situation. But what I can provide you with is a train of thought that might make finding focus and retaining focus faster much easier. Let’s start with remembering what has to be sharp.
What has to be sharp is our subject. The problem with this is that most don’t understand exactly what the subject is in their photograph, what it is that has to be sharp. A prime example is a portrait, be it a person or a critter. The one element of the subject in this scenario that has to be sharp is the eye; there are no ifs, ands or buts about this. Have you ever tried to place the AF point on the eye of a flying Bald Eagle, or on a model’s eye in a dimly lit forest? It’s pert near impossible! What can we do in this case?
You have two options, both totally viable, with one being a little faster. Focus works on a plane, a flat plane that is your camera’s sensor. That plane of focus extends out from that camera plane in geometric perfection. If you focus on any element in your photograph that is physically on the same plane as the eyes of your subject, those eyes will be tack sharp! The breast of a bird is on the exact same plane as their eyes. That’s true for every species, it’s basic biology, and that’s really cool. The breast is a big target compared to the eyeball, so by placing the AF sensor on the breast, the eye is sharp.
And if that doesn’t work, there is this old-fashioned thing known as manual focus. I have no hesitation in manually focusing when I need to. There was no AF when I started as a photographer, so that’s a well learned technique for me. While I rely on AF for the vast majority of my photography, no matter the subject, there are times when I will instantly shoot manually. Using AF-S Nikkor lenses in the M/A mode, you can instantly switch back and forth between the two focusing modes.
The one other variable in this is, of course, depth of field. This does extend the area of focus in front of and behind the point of focus. That’s a powerful tool in telling the story (refer to 'The Best F/stop'). But some like to use DOF to “correct” focus issues, because they are concerned that either the point they had chosen to focus upon, or the technique they were using, would otherwise produce a fuzzy image. There is nothing, nothing in camera or post that will fix a focus problem! You want the subject sharp, so it has to be sharp from your camera and focusing technique!
What’s the Sharp Secret?
The #3 question I get asked is a twofer—how do I get the great color and images that look so sharp? The answer is so simple, yet it’s not. The key ingredient that makes both color look more vibrant and your images sharper—is black. Yep, that one simple, yet vital color works all that magic, and so much more. Ever wanted to make your images more vibrant in post and turned to Levels, bringing that slider a little to the left, punching up the blacks? How about sharpening in post using Unsharp Mask, which adds a little black to the edge of a pixel? What’s working that magic in both of these post solutions? The addition of black! How can you work this magic at the camera?
Underexposure! Yep, that’s it, that’s the secret, that’s what I’ve been using for thirty years to punch up colors and trick the eye into thinking my images are sharper than they really are. It’s really hard to believe that this little thing can make such an impact, but it does. I can guarantee that all the photos you’re seeing here or on my website were underexposed a minimum of -1/3, and up to -3 stops. My “zero,” as it were, is -1/3. I underexposed my film as I do my digital, with it all having the exact same effect on the photographs and the viewer’s eye.
Okay, you understand and practice some or all of this. How do you measure if it’s all working and producing that tack sharp image?
Delivering that Sharpness
What’s the visual difference between tack sharp, sharp or kinda sharp? Must you even have tack sharp? If you put your images up on your computer monitor, do you have a tool that can measure such varying degrees of sharpness? Are your eyes trained to see these differences in sharpness? And more to the point, what degree of sharpness are you capturing and do you need in your photography? Sorry for the bad pun, but this is where things get a bit fuzzy. That’s because there is no way of measuring for sharpness of an image, and no visual scale for determining degrees of sharpness. If you’re not in the business, you might not even know how much sharpness you need. Let me give you some thoughts that might enable you to teach yourself what is sharp, and what is not sharp enough.
I started this piece with the story of a photo of a weasel, one simply not sharp enough to be more than a 25k web posting. It looks sharp at that small size, but any larger, and the image falls apart. How did I know that? It’s the lamest thing I can tell you, the most useless, but it’s the truth: experience. Experience comes from taking the image, enlarging it, and seeing what happens. For most, this means making the image larger in Photoshop. The one problem with this is the monitor—they are not all built the same. The monitors I depend on have resolutions of 1600x to 1900x, with the Wacom 21UX being a favorite. But I feel that you need a reference to know how that which you see on your monitor translates in the real world.
I want to encourage you to make prints for the sake of learning what’s sharp. You might have read that my own personal measure for image quality is the 24x30 print. When you take a file up to that size, any imperfection comes flying off the page at you! When you can take your file that large, you know you have a tack sharp image. (You might be saying camera resolution plays a part in this. Once you train your eye, you’ll see the difference.) If you can take your image to 17x22 and it looks great, but not to 24x30, you have a sharp image. If you can go 11x14 but not 17x22, then it’s kinda sharp. And here’s the real funny thing, you can easily publish a kinda sharp image in a magazine, and it will look sharp!
Many a photographer has talked to me about sharpness, concerned they just aren’t capturing it. In most cases, I find they just haven’t trained their eyes to recognize the varying degrees of sharpness. They are typically not underexposing, “tricking” the eye to see more sharpness than is technically captured. Sharp images are really easier to obtain than you might have experienced. The goal, though, is not to be satisfied with just a sharp image. You want to push your photography so the sharpness is one of the elements you are using in your photograph to tell a story. There is a technical sharpness you must obtain, but you want to move past that and use it to grab heart strings. When you’re doing that with your photography, then you will know just what is sharp!