Art of Composition Part Five

In the last installment of this Art of Composition series, I discussed the differences between APS-C (crop) sensors and full-frame sensors in relation to depth of field (DOF from here on out).

In the last installment of this Art of Composition series I discussed the differences between APS-C (crop) sensors and full-frame sensors in relation to depth of field (DOF from here on out). And since DOF, and thus bokeh, are incredibly important to the “look and feel” of our photographs (read: composition), I am going into a lot of detail covering this topic.

In this article, we are going to continue the DOF discussion by looking at two common ways in which people attempt to “get closer” to their subjects: teleconverters and high-resolution sensors.

To be clear though, when I say high resolution sensors, what that really means is the assumption because you are shooting with something like a 45 or 50mp camera, you have PLENTY of megapixels to crop in on the subject once you get back to the computer.

Both of these solutions, teleconverters and cropping the image, have an impact on the DOF and bokeh of an image. So, I think it’s important to touch on these so you can get an idea of how such choices ultimately affect your photography.

Let’s start out with looking at the new obsession with high-resolution sensors (30 megapixels [MP] and up)...

On the surface, having lots of megapixels doesn’t impact our DOF at all. In fact, some even argue that it’s possible more pixel sites in a given area may help to decrease the perceived DOF for an image. Personally, though, I haven’t seen anything that convinces me that the effect is tangible enough to notice.

However, what very much does have an effect on our DOF is using these high-megapixel cameras for the purpose of being able to crop in on a subject.

By now, many of you have probably already made this connection. In previous articles, I talked at length about how both focal length and the distance from you to your subject have a huge effect on DOF. And in the last article I wrote in this series about crop sensors versus full-frame sensors, I discussed how APS-C cameras affect DOF by creating a greater working distance for a given focal length, and thus greater DOF.

So, it should be obvious by now that setting out into the field with the idea that you are absolutely going to crop in on your subject to make it larger in your composition means you will end up with significantly greater DOF than if you had simply gotten closer to your subject.

This reliance on megapixels is a bit of a pet peeve of mine, largely for this very reason.

Don’t get me wrong here — I too will crop in on a subject when necessary. But “necessary” is subjective. And so is what I consider to be an acceptable crop for myself.

Of course, some folks have mobility issues. Some cannot afford longer lenses. Some cannot carry longer lenses. I completely understand this. And hey, we all do this thing called wildlife photography for our own personal reasons. Maybe it’s a matter of getting out of the house, enjoying nature, the thrill of the hunt, or maybe it’s art, maybe it’s to make money, or maybe it’s to “win friends and influence people”. But when it comes to the visual art of all this, the look and feel, how we make our subjects stand out, and how we arrange the picture space, approaching the subject as though you can crop in later truly makes a big difference in the end photograph. For me, as a working artist, depending upon megapixels for the ability to make big crops later on is a recipe for disaster.

All too often, I see photographers choosing to do this simply because they can. I’m sure you have heard plenty of folks talk about this – especially in the field. “Oh, I can just crop in later. . .” But, just like working with an APS-C sensor, cropping in on your image doesn’t suddenly change the lens and all the physics involved with light and magnification.

This is a little bit of a rehash here, but let’s look at the DOF calculator again in regard to this...

If I’m photographing a bear with a 500mm lens set to f/4 at 30 meters away (about 100 feet), I am going to have a DOF of a little less than three feet/one meter.

At three feet, this means the bear’s nose to shoulders will all be in focus. You don’t need anything more than this, of course. It means that everything in front of the bear and behind the bear will progressively fall out of focus. And the farther away it is, the softer that stuff is. The more bokeh you will have. And the more isolated your subject will be from all the other stuff in its environment.

But let’s say you aren’t 100 feet away. Let’s say you’re photographing with a 50MP sensor camera with the same lens and aperture. Only this time you are 100 meters away (about 328 feet). Sound ridiculous? I see it every time I step foot in a place like Yellowstone National Park.

In this example, your DOF suddenly becomes 31 feet.

This means everything inside of a 30-foot bubble around your bear will all appear to be in focus. That’s every stick, every clump of sagebrush (if the bear is a grizzly in Yellowstone), every limb, every thing in that bubble will be in focus. And then, slowly, VERY slowly, as objects in the composition get progressively further from this bubble, they will begin to soften.

Now crop in on this, making all the “in-focus” stuff in the composition bigger, more prominent, more noticeable, more important, and more distracting.

With 30 feet of DOF, you are going to have a difficult time isolating your subject from its environment. At 30 feet of DOF, you’ll have to get very creative to piece together a decent composition.

This is why a discussion about DOF is so important when it comes to composition to begin with. This is why I am spending so much time talking about these things. Sometimes, we NEED to isolate our subject from its environment as much as possible, and the only way to do this is by working with a very shallow DOF. And sometimes, this isn’t possible given distance and equipment and situations. And it’s here where you need to understand the limitations of the equipment in your hands and then how to go about solving these problems otherwise.

Relying upon high-resolution sensors to be able to crop photos simply means you are relying on “getting away with” being further away from the subject. And this, in turn, means you will work with significantly more DOF in a composition than you would if you got closer or worked with a longer lens. And it means that understanding the art of composition is even more critical to success than it would be otherwise.

I admit, though, that you cannot always get closer. Some subjects are far too dangerous. Some situations are not conducive. Sometimes, there are laws in place dictating this. So, what’s an alternative to cropping?

Enter: the teleconverter.

You are probably already familiar with teleconverters, so I don’t need to go into a description of what these are and how they work. However, I will say that I never work with anything larger than a 1.4x teleconverter myself. Hard stop. NEVER.

Anytime we use a teleconverter (TC), we lose at least one full f/stop from our lens. So, if we are using a 1.4x TC on a 500mm f/4 lens, this means we MUST stop down to at least f/5.6. This isn’t a choice, of course. You don’t decide to do this or not. Your camera and lens will do this automatically for you. It simply won’t allow you to work at f/4.

At f/5.6, you have effectively cut the light in half from what it would be at f/4. This means one full stop of light. And this means INCREASED DOF.

So, on the surface, it all seems counterintuitive. If I want less DOF, how on earth is working with a smaller aperture going to help me?!?

It’s a logical question.

However, the other major thing that affects DOF, as I have already written about in this series, is focal length.

A 500mm f/4 lens with a 1.4x TC attached becomes a 700mm f/5.6 lens. And this increase in focal length more than cancels out the DOF loss from the stop down to f/5.6.

Calculators again…

Using the example again of a bear at 100 meters (328 feet), only this time with 700mm at f/5.6, we achieve a DOF of about 20 feet.

Sure, this is still a lot more than three feet if we are working from only 30 meters away, but it also increases the size of your subject in the composition (while retaining your resolution) and does shave about 10 feet off the DOF. And when it comes to controlling the picture space, 10 feet can make a huge difference.

Frankly, there is not true substitute for getting closer to a subject or working with a longer lens when it comes to depth of field and bokeh. But when I simply cannot get closer, when it’s absolutely out of the question, teleconverters are the best option for me. It does mean that I will still need to think long and hard about my composition otherwise and compose creatively, but it also means that I am working with the shallowest DOF possible for the situation.

Now, I primarily shoot Nikon equipment and in my humble opinion, until very recently Nikon couldn’t make a decent teleconverter to save their life. Canon and Sony? No problem. Rock solid. But Nikon? Using a teleconverter was quite often a big pill to swallow because of the degradation of image quality and sharpness. Of all the lens / TC combos I used in the days of DSLR cameras, it was the Nikon 200-400 VRII with the 1.4TC III that was the best. However, to get results I was truly happy with, I would have to typically stop down to f/8.

This is one of the very big limitations with using teleconverters in general, however, even with Canon and Sony.

We already know that an f/4 lens suddenly becomes an f/5.6 lens when we add a 1.4 TC to it. But often we need to stop down to f/6.3 or even f/8 to obtain the type of sharpness we are looking for. This is all lens and teleconverter dependent, of course. The more expensive the lens such as a 400mm f/2.8 is going to work a lot better in this respect than a 200-600 or 100-400. And with the 200-400 + 1.4 TC, I had to use f/8 to be truly happy with the results.

All of this changed with mirrorless technology, however. By removing the mirrors from the cameras themselves and instead focusing directly off the sensor, camera manufacturers across the board were able to make teleconverters that were much sharper and much more reliable. And as a result, you will always find the Z mount Nikon 400mm f/2.8 with built in 1.4 TC attached to a Z9 in my camera bag these days. Nikon finally got their @#$% together here. But make no mistake here: in soft light, in low light, I still find that I need to stop the lens down another 1/3rd of a stop – as I do with both Sony and Canon.

But that’s enough about that.

If your someone who likes to depend upon your high-resolution sensor to crop in afterword, I recommend looking into using a 1.4x TC with your lens instead. Better yet, just get closer with your feet if at all possible.

Although using teleconverters does equate to a smaller working aperture, the increase in focal length will have a noticeable effect on your DOF and compensate for the change in f/stop. This in turn makes composing a little less challenging — especially when you are dealing with a cluttered environment.

To be continued...