Teleconverters

July 23, 2019

The old adage that you don’t get something for nothing applies here. Teleconverters are short lens extensions that attach between the lens and the camera body. They multiply the focal length, usually by a factor of 1.4, 1.7, or 2.0, thereby magnifying the image. Since the aperture is a function of the focal length, it multiplies the aperture by the same factor. The result is that you lose light. You also lose image quality.

So why would you want to use something that seems so deleterious to your images? You can still get decent image quality if you understand the shortcomings of teleconverters and when you should and should not use them. It is also worth mentioning from the start that any teleconverter that can be had for under $150 is probably not worth using at all. A good teleconverter will cost you almost as much as a decent lens. The Canon ones are right at $430.

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Canon Series III Extenders

It is always best to put a high quality teleconverter behind the highest quality lens you can get. This usually means a fast, prime lens, i.e. one that’s f4 or f2.8 and has a fixed focal length. Putting an inexpensive, off-brand teleconverter behind a $400 zoom lens will probably yield images that would not be suitable for even web-based display, especially if you are used to enjoying sharp images.

Great egrets taken with and without 2X extender

A technical advantage of using a lens with a teleconverter rather than a longer lens is twofold. One, you get the added flexibility of being able to remove it should your subject move closer to you and two, with a teleconverter, you retain your close focusing distance. So whereas a 400mm lens may only focus as close as 15 feet, a 200mm lens that normally focuses down to 9 feet, will still have the same ability to focus down to 9 feet with a 2x teleconverter installed. In this way you can do macro photography with a long lens, something usually reserved for short lenses.

Green heron at 1000mm (500mm lens plus 2X extender)

I often couple my 500mm f4 lens with a 2x teleconverter for a resulting system of 1000mm at f8. This is a powerful combination but it is quite slow. I would never consider hand holding this. For one, it is quite heavy, but because of the extreme magnification (think narrow angle of view), very small movements will induce blur into the image. So since I’m always using a tripod and a gimbal mount and this lens has good image stabilization, I can easily shoot even in reduced light at this aperture.

Cormorants at 1000mm (500mm lens plus 2X extender)

One way to get around the aperture loss is to mount a long lens on a cropped sensor camera body. In this way you get the effect of a 1.6X teleconverter but you don’t get the aperture loss. You do however get a loss due to sensor noise, especially at higher ISO values. I purchased a cropped sensor camera body just for this setup. I use it for almost all of my long lens shots. In fact, the images seen on this page were shot with that body, where the effective focal length (as compared to a full frame sensor) is 1600mm!

Backlit Scenes

July 23, 2019

One of the rules of beginning photography is that you never shoot into the light. One of my suggestions is that you learn the rules but then you learn to break them creatively and this is one of those situations where you can get dramatic images by understanding what’s going on with backlit scenes.

1-backlit1 NASA gantry at sunrise

Film and digital cameras do not have the dynamic range to be able to capture the brightest brights and the darkest darks all at the same time in one exposure. They have a range of lightness values that they can capture while still resolving the many slight brightness variances across the entire range. This array of lightness values is called the dynamic range. There are techniques you can use to either reduce the dynamic range of the scene or grab multiple exposures that capture it all.

Let’s start with the easiest scenario. One in which you don’t really want to capture it all. Backlit scenes offer wonderful opportunities to capture very dramatic images. As in the example above, I exposed for the mid range and bright areas in order to let the lows go dark and make a nice silhouette. These are pretty easy to do. They almost take themselves since the bright background will almost certainly dominate and cause you to underexpose the foreground completely. And if it’s not dark enough, you can always make adjustments in post-processing.

By now, I hope everyone is already shooting in RAW rather than the default JPEG format. RAW allows you to work with the data that the camera captures, which is 16-bit rather than the reduced 8-bit format. What that means is that your brightest and your darkest values are divided into 65,535 different shades of each of the three colors, red, green, and blue versus the 256 levels that you get with 8-bit data. Even though your output to a screen or a printer is going to be limited to 8-bit, operating in the full 16-bit allows you to decide how that large amount of data gets squeezed into that narrow output. You can recover apparent saturations and clipped data where detail would otherwise be lost.

So, what can you do to change the dynamic range of the scene? The easiest is to use light modifiers (reflectors) or flash to add light to your subject if it’s not too far away.

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Gratiot Lake Road lit from behind

In this image, by Wendy Podmenik, the subjects were heavily backlit by the strong sunlight coming through the fiberglass panels behind them. I held a gold reflector off to the photographer’s left, to direct some of that light back on to their faces. Without the reflector, the subjects would have been very dark and although they could have been lightened up in software, noise would quickly start to increase, thereby lowering contrast and saturation.

The most common method of reducing the dynamic range of a scene is to use flash. I’m not a big flash user. Unless it’s done properly, it can look harsh and unnatural. There are people who specialize in flash photography and I’ve certainly done my time in a studio under controlled conditions, but I prefer to use available light which almost always looks more natural.

A more complex method of compressing the dynamic range of a scene is to take multiple exposures and then combine them in software to create a result that essentially lowers the highs and raises the lows from what is essentially a much wider dynamic range image than any one by itself. There is a lot of software out there to do this. I use PhotoMatix Pro with limited success. Sometimes it just brings out too much noise for my liking. But when it works, it works well.

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A scene captured with three different exposures and then combined in software

So, what do you do when you can’t modify the scene and you can’t take multiple exposures? You do your best to place the dynamic range of your sensor within the dynamic range of the parts of the scene that you want to capture. I have a lot of experience with doing exactly that from shooting live music. This is, by far, the hardest type of photography I have ever shot. Not only is the lighting often backlit, but it is almost always changing in color and intensity (faster than you can make decisions about it and react), it’s either way too bright, or no where enough, your subject is almost always moving, and there is often fog generated which reduces the scene contrast.

For my live music shooting, I use a Canon 6D body. It has the best high ISO performance of almost any other camera on the market and surely the best of any in its price range. I have found that for so much of the backlit scenes on a live stage, I like to shoot in aperture priority with my lens wide open at f2.8. I set my ISO to automatically adjust as needed in order to keep my shutter speed up as high as possible. High is a relative term because many of my shots are made with a shutter speed of less than 1/50 and that’s at ISO values of 6000 all the way up to 12800.

Since I’m wanting to keep as much of the source light from saturating as possible, I often underexpose by 1 to 2 eV levels using my exposure compensation dial. This does often underexpose my subject but the highlights are less likely to saturate because of it.

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Kenda "Obi Wan Kendabi" Legaspi of The Creepshow, lit primarily from behind

Here is such an example. There were bright lights behind and to the left, coming over her shoulder as the primary illumination, with almost no light from the front. Had I not added exposure compensation, my camera would have metered for the dark face and the lights behind would have been horribly overexposed. What’s deceiving is that I lowered the highlights, making the scene look evenly lit. By keeping the lights within or close to the dynamic range of the camera, I was able to bring up the darker areas, while taking advantage of its superior low noise performance.

Pretty silhouettes are actually quite easy to shoot. It’s when you want to preserve detail in both the highlights and the darks that you need to think ahead by either modifying the existing light or exposing in such a way that you can recover seemingly lost values during software processing.

Extension Tubes – The Poor Man’s Macro

July 23, 2019

While photography is often quite expensive, there is one thing you can do that will cost you little but will greatly enhance your photographic tool set. Macro photography involves capturing images that are near life-size or greater than life-size. There are all sorts of macro lenses and associated equipment for great macro work but it can get complicated and expensive very fast. So I always tell people to invest in a set of extension tubes. But contrary to my normal philosophy of sticking with the brand of the camera body that you shoot, I go way off track to suggest that you get the least expensive set you can find. Just make sure it has all the contacts that pass the lens information back to the camera. A decent set can be had for about $80 and it will make a world of difference in your capabilities.

1-extension-tubes-1024x397 Set of three inexpensive extension tubes

To give you a quick primer on camera optics with respect to close focusing, you can follow along with a little test of your own. Pick up a small lens, just something that is easy to handle. Mount it on your camera body and note the closest that you can focus. It could be two feet for example. Now, remove that lens but hold it in place, just in front of the mount, and look through the view finder to see how closely you can focus. But rather than move the focus ring, move the camera-lens unit closer to the subject until it comes into focus. It should be noticeably closer. Note that as you move the lens away from the camera body, you have to move closer to your subject in order to get sharp focus.

This is the principle behind the extension tubes. All they do is mount the lens farther from the focal plane of the camera. This is what’s going on inside your lens but it has a range based on its size, price, and design. Macro lenses are optimized to be able to move the internal components farther at the expense of weight, size, and price. Their optics are also optimized for close focusing.

In use, leave your focus ring along and instead, focus by using the zoom ring (unless it’s q prime lens of course) and by moving closer to and farther away from the subject. It takes a little practice to get the hang of it but by playing with the two, you can select a magnification that you want and achieve good focus.

The extension tubes offered by your camera body manufacturer will not work any better but will cost three or four times more. The knock offs, as long as they pass the electronic signals between the lens and the body, will work just fine.

Don’t make the mistake of thinking that macro is just for small subjects. I always carry a short extension tube with me, even when shooting with big lenses. Often times I’m set up with my big 500mm lens (which has a minimum focusing distance of just over 12 feet. Fine for the vast majority of what I shoot with that lens. But if a humming bird were to come within ten feet of me for example, I’d never be able to get the shot. With the extension tube, I can quickly reduce my minimum focusing distance and get the shot.

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Uncropped shot of baby doves taken with a 300mm lens and a short extension tube

In this example, I wanted a close up of some baby doves but I couldn’t get very close without disturbing them. A long lens allowed me to shoot from farther away but because of the minimum focusing distance of the lens and where I wanted to shoot from, I could not achieve proper focus. A extension tube solved the problem.

So, why don’t we just keep the extension tubes mounted all the time? The caveat is that they really shift the focusing range, not extend it. So although you can focus closer with one mounted, you lose on the other end. Your ability to focus far away disappears. This is akin to putting on reading glasses and then trying to walk around while wearing them.

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Uncropped image of dogwood blossom taken with 70-200mm lens and extension tube

Get yourself an inexpensive set of these little gems and open up a new chapter in your shooting.

Back Button Focus

July 23, 2019

With most cameras, the shutter button performs three functions. A half press starts the autofocus and analyzes the scene for the metering, and a full press releases the shutter. In many situations, having one button do all of these tasks is fine. But in situations where you want a little more creativity, especially where you have a moving subject, separating the focus from the image capture may be more useful.

Most DSLRs today allow you to redefine the functions of many of the camera’s controls. You can use this feature to move the focus activation to another convenient location, the most popular being one of the buttons on the rear of the camera, within easy reach of the thumb. This is referred to as back button focus. It’s a little tricky at first since it’s foreign to think of focusing separately but once you realize how liberating it is, it becomes natural.

Consider the following example where you have a small subject, the singer’s face, that is constantly moving. It makes sense to switch your camera’s focusing mode to constant. For Canon, it’s called AI Servo. In operation, you follow your subject around, placing the focus point on your subject while holding the back button that you redefined for focus activation. Once you have the scene you desire, you can either release the back button, thereby locking focus so you can recompose for your desired composition, or, if your subject is in constant motion, you hold the back button (that’s where the AI Servo mode comes in handy) and shoot away with the shutter button.

Cy Curnin of The Fixx.

In this case, I was using the center focus point and was following the face, waiting for a pose that I wanted to capture. With my thumb on the back button, the focus system was constantly adjusting focus (AI Servo) while I was waiting to snap the picture. When the time was right, I simply released the back button, holding the current focus, quickly recomposed the frame, and pressed the shutter button to get several shots.

You can certainly shoot by focusing with the shutter button but separating it does give you the freedom to choose to focus when you want and lock focus quickly by releasing the button. It is especially useful when you are shooting different compositions of a scene but your distance to the subject is not changing. Keeping the focusing separate from the shutter release keeps you from inadvertently focusing on the wrong part of the scene. It’s also handy when other objects are entering the scene and may interfere with your focusing.

It takes a little while to get used to separating the focusing from the shutter release but once you get used to it you will find that you have more control over your camera. All of my camera bodies are set up in this manner now. If you are happy with your current operation then separating focus and shutter release may not be for you. If you decide to give it a try, check YouTube for all sorts of tutorials on your specific camera model.

What is RAW?

July 23, 2019

I’ll cut right to the chase. If you’re not shooting in RAW yet, you should start doing it…yesterday. And once you get the hang of it you will wish you had started earlier.

To go over some numbers for illustration, your camera is capturing the lightness information from a scene in 16-bit. That means that the range of lightness values from the darkest black to the brightest white is 2 raised to the 16th power, or 65,536 (in each color band or in grayscale). But unless you’re shooting in RAW, your camera is only putting out a total of 2 raised to the 8th power (8-bit), or 256 different values per color band. The advantage of shooting in RAW is that if you do your processing in the 16-bit domain, you can recover so much more detail out of your images than the built-in processing can, much the way Ansel Adams and others took a wide dynamic range negative and massaged it to fit a narrow dynamic range piece of paper.

The camera manufacturers do a great job of developing processing algorithms for automatic image adjustments for JPG output but when doing your own processing you have so much more control over what your final image looks like. Although you can do some processing on 8-bit JPG images, you can never get close to what you can do with the RAW data from the camera.

This graphic demonstrates the difference between 8 and 16-bit information in just a grayscale image. Computer displays cannot truly replicate 16-bit data but this is a representation of how much information you lose by not shooting in RAW. The fine differences get reduced greatly.

To think you are being a purist by taking an image directly out of the camera via JPG is to let an algorithm make sharpness, lightness, and contrast decisions for you. The same holds true for taking a RAW image as is, with no processing. ALL images need some adjustments because of the degradation introduced by the lenses and electronics. They are being done on the JPG images, just by generic algorithms any not by you, the one who witnessed the original scene.

The tricky part with working with RAW images is that you can’t see the extra data directly because the current display standard can only deal with 8-bit data. In order to work within the RAW domain, you use the same sort of histogram in your processing software (i.e. LightRoom, Photoshop, Adobe Camera RAW, etc.) that you have in your camera to visualize what’s going on in the image and modify the histograms by way of sliders and numerical inputs, which in turn show up on your screen.

With no processing, images look dark and lifeless, the colors are muted, the white balance is off, and although you cannot see the noise, there will be plenty of it evident. All images also need a little bit of sharpening and contrast adjustment.

Consider this image of a great egret. Without any processing, the entire image is dark and devoid of any detail, all of which I remember seeing. The white areas should be as bright as they were in the direct sun.

3-RAW 3-RAW Unedited, RAW image

When you do your own adjustments, you get to decide what details show up in the highlights and the dark areas. It may seem as if you have created data when you have only optimized the data that the camera had captured. The details that you will see were there all along but they were effectively hidden by the narrow range of lightness values until you pulled them out and decided for yourself how they should fit within the narrower, 8-bit output file. You also get to decide how much sharpening and noise reduction to apply, both of which are necessary to some degree.

4-RAW 4-RAW The edited result

In the processed image you can see all of what you saw when you viewed the scene. The whites are white and bright and the darks are dark but no so much that the detail is lost.

In the live music example below, the scene was monochrome, being lit with only red lights. I decided to turn this into a grayscale image but I was able to do it the way I wanted to – the way I remembered seeing it. I saw all the detail that is seemingly lost in the red, unprocessed version. By working with the data that was already there I was able to produce something that was very close to the original scene, just without the color.

People have written books on the subject of processing so I won’t go into any more detail here. Just know that by shooting in your camera’s default JPG format, you are losing precious information that you could have used to make a much more vibrant and dynamic image.

If you don’t understand processing software then by all means shoot jpg and have fun. Just don’t lose sight of the full power of photography by doing your own processing. Sure, you can over do it and make things look fake, but at best you want to reproduce the scene as you saw it and not as the algorithms think you did.