Focusing at the right distance with lots of DOF keeps everything in focus

Will Back-Button Focusing Make Me a Better Photographer?

All right, DSLR owners. I’ve had so many people ask me this summer about back-button focus and how and why to use it that I thought it would make a good post. Since this is (as usual) a long post, let me just summarize by saying if you don’t understand “focus-and-recompose,” focusing modes, focus selection points, critical focus, the focal plane, depth of field, and how to control all of these things, you probably should worry about those before you worry about using the back button to find focus. Back-button focusing is a great tool to achieve better control over autofocusing, but if you don’t understand how to control focus and what settings and techniques allow you to do that with autofocus now, it’s really not going to make a big difference for you.

That said, here goes my explanation of what back-button focusing is, why I use it, and some pointers on how to enable it on your camera if you want to give it a whirl.

First, what the heck are people talking about?

Back button focus means using a button on the back of your camera body to autofocus instead of autofocusing when you half-press/press the shutter button.

Why would you want to do that?

By separating autofocus from the button that also releases the shutter, you gain complete control over when your camera is focusing and when it isn’t, you can stop switching between autofocus modes and leave your camera in continuous focusing mode, and you make it easier to avoid releasing the shutter when you don’t mean to.

Why wouldn’t you want to do that?

Well, personally, I think back-button focusing is the bomb and I’ve been using it for so many years that it’s the first setting I adjust when I buy a new camera body because I can’t handle focusing via the shutter button.

That said, I have one big caution for you when it comes to switching to back-button focusing: choose when to make the switch cautiously. Your brain is programed to believe that the shutter button autofocuses right now. If you switch to back button, you will need to practice daily for about 2 weeks (depending on the neuroplasticity of your particular brain) to retrain yourself to go for the back button to find focus before you press the shutter. You would not want to make the switch and then go on the once-in-a-lifetime trip and/or to a once-in-a-lifetime event without having taught yourself this new habit before you get there–you will forget to focus and make a bunch of blurry photos at first.

Also, because of this need to create an unconscious habit, you don’t want to switch back and forth between using the back button technique vs the shutter button–you will get yourself very confused.

I Don’t Get It–Why is Back-Button Better?

In spite of all the hype about back-button focusing, a lot of students don’t get it at first. They look at me puzzled and try to understand why they would care which button causes the camera to focus.

So, let me tell you a little story about why I was so enthused when I learned about back-button focusing.

Back when DSLR screens weren’t so big or bright, I was doing a lot of landscape photography on a tripod. I found manual focus to be extremely difficult because the viewfinder focusing screen was terrible and I hadn’t yet invested in a loupe for my LCD screen, so I couldn’t see if I was in focus in daylight. So, I would put my camera on the tripod, compose my image, and then decide where I should focus based on DOF and hyperfocal distance. Then, I would begin the struggle of turning the camera to point at the place where I wanted to focus, hold the shutter button halfway, and then try to recompose the image back to what I wanted without releasing the shutter. I invariably either took the shot while still adjusting or lifted my finger and my focus unlocked. When you lose focus lock and then press the shutter button again, the camera re-focuses on whatever it picks to focus on instead of where you want to focus.

I then discovered there is a little focus lock button on Canon’s that if you press it, focus will remained locked “for a few seconds” giving you an unspecified amount of time to reset and shoot before it turns off. This little button just stressed me out because I was racing against a clock and I didn’t know how much time I actually had before the focus would unlock.

Then, I learned about back button focus. And, ahhhh, breathed a sigh of relief. I could still autofocus, but once I found focus with the back button, I was free to move the camera with both hands for as long as I wanted until I was ready and could get the shot I wanted. And so my love of back-button focusing was born.

If you’re not using autofocus on a tripod a lot (Manual focus avoids this problem), you will not have the same appreciation for this struggle. That doesn’t mean back-button focusing doesn’t still have many advantages.

By the way, even though I now have the tools to manually focus on a tripod, my lenses allow full time manual focus, meaning I can manually focus even when the lens is set to AF. By using back-button focus, I can leave my lenses on AF at all times and I don’t have to worry about undoing my manual focus when I press the shutter button.

I’m Not Autofocusing on a Tripod–Why Would I Care?

A big reason it can be hard to grasp why back-button focusing is so powerful is if you haven’t spent much time working on gaining control over focus in general. If you’re going around autofocusing with all your selection points turned on in single focus/one-shot focus mode (or if this sounds like gibberish to you), you actually have no idea where you are focusing. If you have no idea where you are focusing, back-button focusing probably isn’t the first step you need to take to get control of focus.

Personally, I have 3 bodies that have 61 focus selection points. Those 61 focus selection points are handy when I’m trying to get a shot of, say, a Cliff Swallow in flight. It’s a tiny bird that swoops and dives erratically and I cannot pan with it well enough to keep it in focus using my normal technique. As such, those 61 focus points become very handy when the bird is against a sky or other background that doesn’t fool my camera into focusing on the background (and I’m in continuous focusing mode and I have tracking set properly for such a subject).

The rest of the time, I use either 1 or 9 focus selection points. If I’m shooting landscape, portraits, etc, I use 1 focus selection point. If I am shooting moving subjects like birds that aren’t as erratic or small as swallows but are likely to fly, I turn on focus point expansion that allows me to find focus using the center point, but will activate the surrounding 8 points if the subject moves to help keep the subject in focus.

Now, this is about when students ask, “But I want more than one thing in focus. How am I supposed to get multiple people in focus if I only find focus in one place?” Well, I have news for you: critical focus only occurs at one distance from the camera. If 4 focus points light up when you press the button, it’s because the camera thinks all four of those things are the same distance away. If you want multiple people in focus, you need to understand DOF. This is the diagram I use to explain the relationship between where you find focus and how DOF keeps more than that distance sharp to students:

DOF and Focal Plane Diagram.001

So, first understand how focus works and how DOF helps you get what you want sharp, then worry about whether you should be using the back button to find focus or not.

Once you are very clear on what the focal plane is (which is technically where your camera sensor is positioned in your camera body, but is also often used to mean the plane of critical focus in the scene/subject you are shooting) and how to control DOF, you will realize the advantage of using one focus selection point whenever possible: it let’s you decide what should be sharpest in your image instead of your camera.

All of the Images in this Gallery Used the Focus-and-Recompose Technique (All of my Images are Made Using Back-Button Focusing)

Once you make the switch to using only one focus selection point, you then will want to make a lot of use of “focus-and-recompose,” which is what I was doing in the tripod example. However, focus-and-recompose is a fundamental technique  whether you’re on a tripod or hand-holding. It allows you to get both the focus you want and the composition you want without being dependent on a focus selection point being in the right place (if you are in one shot/single focusing mode). It means that, for example, you can use the center focus selection point (which always has the greatest ability to focus the most precisely in all cameras) to autofocus on a subject’s eyes and then lock focus and recompose so that your subject is artistically framed in your image. It gives you the ability to control critical focus without losing control over composition. The key is to ensure that when you recompose, you don’t change your distance from the subject as this will cause focus to shift forward or backward based on your movement.

The other key is that if you recompose, you must hold the focus. And this is where back-button focus becomes a life saver. If you have to half-press the shutter and hold it while you shift, you may either accidentally press the shutter all the way or let go of the shutter all together. Then you have to start over. With the back button, you can simply press the back button to find focus, release, and then concentrate on recomposing. When you press the shutter, because you have turned off focusing on the shutter button, your focus does not change and, as long as you also haven’t changed the distance from you to the subject, their eyes will be the sharpest thing in the image even though the focus selection point is no where near their eyes when you eventually do press the shutter button.

There are also advantages to using back button focusing when you are continuously focusing (AF-C on Nikon, AI Servo on Canon). As you track a subject in motion, you hold the back button and it keeps focusing, giving you more control on when you focus vs fire (it can be challenging to pan while holding the shutter button half way without firing). If the subject stops, you can release the back button, locking focus as if you were in one-shot/single mode and fire away. Essentially, you gain total control over when the camera is autofocusing and when it is not. It’s a beautiful thing once it clicks in your head how much easier it is to control focus this way.

This also means you never have to switch between one-shot/single focusing mode and continuous focusing mode–if you’re not pressing the back button, your focus is locked regardless of which focusing mode you’re in. By comparison, when you use the half-press of the shutter to focus, if you’re in continuous focusing, it keeps refocusing until the shutter releases, meaning it’s not possible to focus-and-recompose.

To summarize, back-button focusing is an advantage in all situations. There are fewer settings you have to use to control focus when you back-button focus and you gain greater control with less coordination. I honestly cannot think of any reason not to switch to back-button focusing other than ensuring you have the time to develop the habit before you make the switch.

You Convinced Me–Now What?

Remember, if you make the switch, you will forget to focus at first. Do not, say, decide you are going to make the switch because you are shooting a wedding tomorrow and you want to give it a try. Make the switch and really pay attention to whether you are finding focus when and where you want until you find yourself automatically pushing the back button without thinking about it and getting the results you want. Then, you can go shoot a wedding with back-button focus. 🙂

Now, the remaining question is, how do you turn it on/disable the shutter button focus? This requires finding the setting in your manual (which is usually different for each camera) that will allow you to assign functions to your buttons. You will, unfortunately, not find anything called “back-button focusing” in your manual.

In Canons, these settings are in the custom function menus and are pretty obtuse. Once you find a setting for the shutter button in custom controls, set it for “Metering Start” (or another setting that doesn’t include anything with AF in it) which will disable focusing with the shutter button. Find the settings for the AF-On button (the button is in upper right corner of camera back and furthest to the left of those 3 buttons—very convenient to find with your thumb once you get used to it). Make sure the AF-On button is set to “Metering and AF Start.”

In Nikons, it’s even more obtuse, but I don’t look at Nikons every day, so maybe it makes more sense to a Nikon shooter. In any case, you also need to go to the custom setting menu, to controls, and then go to assign AE-L/AF-L button. Choose AF-On from that menu. If the shutter button is also in that menu, check to make sure it isn’t enabled for AF-On as well. I’ve been told that in many Nikons you also need to set the camera so that the camera will still fire if it hasn’t been focused in order to get it to fire when it doesn’t know that you don’t want to refocus. That setting is also in the Custom Setting Menus under Autofocus and you want to set AF-C and AF-S priority selection to “release.”

Now, go practice, practice, practice! 🙂

 

 

What is acceptably sharp forms a wedge that runs roughly parallel to the ground rather than a plane that spans the entire angle of view and runs parallel to the camera sensor.

Just When You Think You Understand Depth of Field

Depth of Field is one  of those concepts that most budding photographers come at in a series of stages.

First, there’s just getting your head around what Depth of Field means. To keep it simple, if you don’t know what depth of field is, we generally think about it as the distance in front of and behind where we focused that remains acceptably sharp. Close-up portraits with blurry backgrounds usually have very little Depth of Field. Wide landscape scenes are often acceptably sharp from the closest object in the frame all the way to infinity.

Second, most beginning photographers learn to gain some control over depth of field (DOF) by changing the aperture of their lens manually (in Manual or Aperture Priority mode on your DSLR). The wider you open your aperture, the less DOF you get.

Third, it eventually dawns on photographers who concentrate on controlling DOF that you don’t always get the same DOF with the same aperture and you begin to understand the other variables in play that give you more or less DOF (sensor size, focal length, distance to subject).

Fourth, you may get really technical and look up the mathematical formulas to calculate DOF and realize that it’s all kind of a guess because how much DOF you get ultimately depends on the size the image is displayed at, how far away you are viewing it from, and how good your eye sight is.

At this point, you may fall into the trap of believing you fully understand DOF and you have all the knowledge you need to get as much control as possible over DOF in your photography.

Then, perhaps one day you discover the mysterious Tilt-Shift lens, which throws everything you know about DOF completely, well, tilted.

Here’s an example. With a normal lens, we expect the focal plane to be perpendicular to the camera sensor. Therefore, everything that is the same distance from the camera should be equally sharp. Take a look at this image:

What is acceptably sharp forms a wedge that runs roughly parallel to the ground rather than a plane that spans the entire angle of view and runs parallel to the camera sensor.
What is acceptably sharp forms a wedge that runs roughly parallel to the ground rather than a plane that spans the entire field of view and runs parallel to the camera sensor.

This image is straight out of the camera with no editing (it was also in a bracketed set of multiple exposures for the purpose of doing a composite; I just happen to like the slightly darker exposure the best for an example).

Notice the plane of critical focus doesn’t seem to be a plane at all. It’s more like a wedge shape that runs parallel to the ground. And the area above and below the wedge that is acceptably sharp is thicker closer to the camera than further away—check out the closest tree trunk and how much of it is acceptably sharp. As you go back into the image, less and less vertical distance is sharp.

Notice that the people on the bench are sharp, but the tree at the same distance to the left of them is rapidly falling out of focus. I particularly like this composition with this effect—it creates a tunnel effect that leads the eye straight to the people on the bench.

Here’s another example, also straight out of the camera. In this case, the focus was on the face of the sculpture, but the body falls out of focus even though it is the same distance from the camera. In this case it has the effect of a vignette created by blurring the edges. But notice that the distant trees directly behind the sculpture still look acceptably sharp at the height of the sculpture’s head.

Shooting this sculpture relatively close on a tilt yields a sharp face and blurred legs.
Shooting this sculpture relatively close on a tilt yields a sharp face and blurred legs.

In the next example, the sharper focus on the flowers vs the fountain keeps the eye lower, noticing the garden more. This is actually a “normal” use for a tilt shift lens—creating lots of DOF at a given height off the ground. This works really nicely for fields full of flowers, for example.

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Another popular use for the tilt part of a Tilt-Shift lens is miniaturizing a scene. This is a test shot through a window, but you can see how the shifted DOF causes the brain to perceive the scene as being a miniature version of a real scene:

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Once again, notice how the bricks to the right of the window are in focus, but as you get closer to the bottom of the window, they fall out of focus.

Now, you might wonder why you would buy an expensive lens in order to create these effects in camera given that this effect can be created in Lightroom or Photoshop. Truth be told, I would not buy a lens for the Tilt effect. It’s the shift effect that makes the lens worth it to me. We’ll talk more about that in another post . . .

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Why does a 22.3 MP camera produce a 7 MB file size?

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This file, after being resized to a small JPEG for sharing on the web, is now only 117 KB. The RAW version recorded in my camera was a whooping 28.6 MB.

First, let’s understand that megapixels refers to how many photo sites are in your camera sensor recording data to create an image. The number of photo sites equals the number of pixels (“dots”) in your image. The more dots, the smaller the dots are at any given print size, and therefore the greater the detail and resolution in your image.

So, many folks assume that if they have a 22.3 MP camera, they will get 22.3 MB files. There are many reasons why this likely won’t be true.

First, a mega pixel does NOT necessarily equate to a megabyte of data. How much data is recorded by a pixel (or, more correctly, a photo site on your sensor) varies. Brighter areas in an image record more data than darker areas. Also, badly over exposed or under exposed images record less data—the white goes to pure white and the black goes to pure black with no details. The same number of megapixels will produce different numbers of megabytes in different circumstances. Ultimately, the file size in MB is the total amount of data recorded by all pixels plus any “overhead” data added by the proprietary format.

Second, your camera has choices on how you want to record your image files. Some cameras have options to save different sizes of RAW format files and/or different sizes of JPEG format files (some even have TIFF choices). Here is an example of the different settings and the resulting file sizes from the Canon 5D Mark III manual:

Screen Shot 2015-02-18 at 12.03.26 PM

The different settings affect how many megapixels are turned on to record data as well as what file format the data is saved in, creating different file sizes.

So, what the heck does all this mean? RAW is a proprietary format that is unique for each camera vendor. It’s essentially your photo negative. It cannot be directly altered—if you edit a RAW file in software, you actually create a new file to save the changes. To share a photo, you have to convert to a standard file format such as JPEG eventually.

So, why not save all your images to JPEG in the camera to begin with? Well, there are good reasons to save JPEGs. For example, let’s say your shooting in completely predictable conditions (like a studio), you have all your settings dialed in and you know nothing is going to change on you. Shooting in JPEG can save a lot of space and allow your camera to shoot faster without having to stop and catch up periodically.

However, if you don’t feel confident that you know how to “dial-in” all of your settings (including the post-processing settings in your camera that determine things like brightness, contrast, saturation as well as the white balance setting), you might not want to risk losing data for the sake of saving space.

JPEG files are compressed. However, some of the data is thrown away when the file is compressed. So, the file size you get is significantly smaller than the RAW file, but some of that is because the data has been squished together (but is still there) and some of it is because data has been thrown away, never to be seen again.

Notice that the largest JPEG file in this example is 7 MB for a 22 MP image. This does NOT mean that 15 MP were thrown away. All 22 MP were used to record data, but that data got compressed into 7 MB. By comparison, the full RAW format would produce a 27.1 MB file. This difference does not indicate how much data was actually lost.

While JPEG is “lossy,” it also reduces file sizes by compressing data in ways that don’t necessarily result in a loss of quality. For example, instead of recording 1000 pixels individually are a particular shade of red, the JPEG file might just record that these 1000 pixels are red collectively. In that sense, the data isn’t “lost,” it’s just consolidated. However, some data is lost and repeatedly editing a JPEG causes the losses to be more significant. Also, the quality settings you choose when saving a JPEG have a significant impact.

Two areas of data loss that frequently limit what you can do with a JPEG image are data that falls outside the dynamic range of the JPEG file (pure black and pure white areas with no details) and in color casts. If you have an over-exposed sky in a JPEG file and you try to reduce the exposure in software, the sky turns gray. If you have a RAW file, it might bring back the blue—it depends on how badly over exposed it is.

White balance doesn’t fix well in a JPEG file either. If you don’t have your white balance just right, it can come out quite odd looking if you’re editing a JPEG. It can also be impossible to get the white back to white. Color-casts can ruin otherwise good images and are commonly seen in the images produced by beginning photographers.

As a general rule, if you want to do post-processing on your computer and you’re not overly concerned with hard drive space or memory, save the largest RAW files to get the maximum amount of data and the highest resolution images.

If you are confident you know how to control all the settings in the your camera properly so that you can produce final images with only the settings your camera provides and that the situation isn’t going to change suddenly (e.g., the sun coming out from behind the clouds can totally change your white balance), then you can save time and space by saving JPEGs.

Or, a simpler way to decide: are you a control freak? Save to the largest RAW format. Are you an efficiency freak? Save to the largest JPEG format. Do you not care at all how your images look? Save to the smallest JPEG format.

Frankly, I don’t know what to do with all those other choices. If you have to hand photos in JPEG format to people immediately while at a shoot, saving both RAW and JPEG makes sense to me. I haven’t come up with a use case that works for me for using smaller file sizes, however. And I sure don’t want to turn off a portion of the pixels I paid so much to have!

That said, camera makers don’t make up features just for the sake of adding features, so I’m sure there are use cases that make perfect sense for those settings as well.

This is how the birds and sky really looked in the golden hour glow. This also happens to be what Auto White Balance captured.

Weird Colors and White Balance

During a workshop this past weekend, several folks commented about having trouble with their images looking yellow or having other weird color casts. This is generally solved by changing your White Balance Settings.

What is White Balance? Back before we had miniature super computers in our cameras, film photographers would use different film or filters to prevent photos from getting weird color casts based on the temperature of the light they were shooting in. Being able to adjust white balance in your camera is one of the great advantages of digital photography.

However, if you think about your camera as a computer, it has to be programmed to mathematically recognize white, which sometimes it does quite well. White balance basically tells the camera “this is white” and it then shifts all colors based on what it believes is white.

So, why is white not always white? Light has a temperature. That temperature causes us to see the light as more blue or more yellow and it can dramatically impact how all colors look.

For example,we once lived in a house where we’d painted every other wall  a nice, neutral gray. One of those walls was in the kitchen, which was open to the great room where two more of the gray walls were located. If we had florescent lighting turned on in the kitchen only, the gray wall in the kitchen looked robin-egg blue while, in golden morning light, the gray walls in the great room turned a soft lavender. The difference was so striking that we once had a guest ask us why we had painted the walls different colors.

The walls were painted the exact same color from the exact same paint can. The difference in color that we see is caused by the difference in the color of the light striking the walls.

This means that in the great room, I needed a different white balance setting from the kitchen to make white look white.

Auto White Balance usually works great in my camera. It has worked great for me most of the time in 5 different models of digital cameras now, even going back to the early 2000’s. As the algorithms in the camera’s computer have improved with each camera upgrade, the percent has probably gone from 75% of the time to 90% for casual shooting.

But then there are the times when it doesn’t work so well.

Auto White balance often fails when:

  • The temperature of the light is outside the range of temperatures your camera’s Auto White Balance is programed to deal with.
  • There are multiple sources of light with different temperatures lighting your subject (e.g., daylight coming through a window plus incandescent bulbs plus florescent bulbs all in the same room. Or, if you’re using flash indoors, most flash units are the temperature of daylight, so that will also create the same kind of mix as in the first example.)
  • Your subject contains a lot of one color or a limited range of colors, which can fool your auto white balance into thinking the light is cooler or warmer than it is, depending on the dominant color(s) in your subject.
  • You are shooting in the golden hour around sunrise or sunset. This is not so much a failure of auto white balance as an over application. Auto white balance will often eliminate the golden cast to the light, removing the warm glow that we usually find quite pleasing.
  • You need the white balance to be absolutely accurate so that colors are represented truly (e.g., a product photo).

So, let’s say you’re shooting away and all your images look really yellow. What to do?

Before we go through the white balance adjustment options, let’s start by saying if you have set your camera to save your images in the RAW format, one option is not to worry about white balance and to set it in post-processing on the computer later. The down side to this is that your white balance accuracy will be dependent on your eye, your memory, and your monitor. If you really need exact colors, this is not the best way to achieve white balance (e.g., product photography, art reproduction, etc). If you just need it to look good, this works very well and can save you some headaches.

That said, even if you are using the RAW format, you may prefer to have good white balance in camera as well. It can make it easier to judge your images when you are not distracted by strange color casts. So here are some options:

First, check to see what White Balance Setting you’re currently on. If you’re on Auto, try picking another pre-programmed setting that best matches your situation. Indoors this gets trickier all the time because we now have all kinds of bulbs that come in all kinds of temperatures. So if your light looks warm to you, try setting the white balance to tungsten (incandescent bulbs). If the light looks cool, try florescent.

Second, you can try setting the temperature of your white balance using the “K” option for Kelvin temperature. Daylight during mid-day is around 5000-5500K. If you change the K value to something higher, your image will look warmer (more yellow). If you change the K value to something lower, your image will look cooler (bluer). You can experiment with this to see if there is a value that works particularly well for your situation, but I find the next method to work better.

Third, if you don’t need the colors to be absolutely correct but you’d like to be able to get your white balance pretty darn close in-camera without having to depend on your eye/monitor later, use a white balance target and take a picture of it in the same lighting conditions you’re going to shoot in. You can purchase a very exact neutral target for this purpose, you can use a white sheet of paper, or you can simply look for something in the same light that is neutral (white works very well for me). The target will be more accurate, but under most circumstances, anything white is good enough. The target must occupy a good portion of the frame for this to work, so zoom in.

Follow your camera’s instructions to set the photo of your target as your custom (Canon) or preset (Nikon) white balance. This will tell your camera “this is white in these lighting conditions” and your camera will measure what white is from that image and then adjust the white balance accordingly. This is a 3 step process:

  1. take a shot of something white/neutral
  2. tell your camera “use this image to determine what’s white,”
  3. set your white balance setting to use the “custom” (Canon) or “PRE” (Nikon) white balance.

This is a really important thing to do if your other white balance settings aren’t working well and you’re saving your images as JPEGs. It’s more difficult and sometimes impossible to fix white balance in JPEG images later.

Fourth, if you are shooting in circumstances where the color must be absolutely correct (i.e., mathematically correct vs to your eye) such as product photography, use a tool like the X-Rite ColorChecker Passport to set your white balance in camera and to also calibrate individual colors during post processing. This is a combination of exactly calibrated targets and software used in post-processing to ensure your white balance and colors are correct. Most people do not need this tool. However, if you do any product photography or art reproduction work, as I do, it is a huge time/headache saver.

But what if you’re white balance is making white too white? This used to be a problem in older camera models. I would get up at the crack of dawn or time my shoot around sunset to get that beautiful golden glow in the light and then my white balance would take it away! My 5D Mark III seems to leave my images nice and warm in Auto White Balance. But, if your camera is off-setting the light more than you want it to, try setting your white balance to florescent. Or, set a Kelvin temperature for the white balance that gives you the nice warm glow you’re looking for.

Finally, a word about flash. When you are using flash indoors, you can help prevent white balance confusion by using gels on your flash to match the temperature of your flash to the indoor light. If we revisit my first example:

Even though I was able to get the skin tones back to natural looking, the rest of the scene still looks a bit warmer than it did in real life. If I had gelled my flash to make the light temperature of the flash match the light temperature in the room, all of the colors could have been white balanced to look right. As it is, because some areas are more lit by the lighting in the building while others are more lit by my flash, it’s harder to achieve good white balance consistently throughout the image. Of course, there are many other problems with this image, so imperfect color temperature is the least of my concerns! 🙂

If your only flash is your pop-up flash built into your camera, here is a do-it-yourself project to create gels for a pop-up flash, but you can also buy gels. Here is a set available for pop-up at Adorama.

For speedlites/speedlights and other strobes, there are lots of options out there for gels.

There are a lot of great resources out there on how to gel your flashes. Since this post is already too long, here’s an article by the Strobist, who has many, many great articles on using speedlites.

Star Trails

Long Exposures: Part V

I’ve done many posts on things you can do with long exposures (see Disappearing Act and Long Exposures, DSLRs: Photographing Fireworks, Lightening and Long Exposure, and Long Exposures), but here in another one: Star Trails.

First, what is “a long exposure”?

When we talk about the length of exposure, we’re talking about how long the shutter is open in your camera to allow light in. Now, you may already know that how “bright” the image ends up being (or the exposure value) is dependent on the combination of shutter, aperture, and ISO settings. These 3 settings in combination control how much light reaches the sensor as well as how much light is required to get a given exposure value.

So, why would we talk about the length of the exposure separately?

How long you open the shutter determines whether you freeze motion or show motion blur and how much. So, when we talk about a long exposure, we’re really talking about showing motion in our images. Getting good exposure still requires a combination of setting the shutter, aperture, and ISO appropriately.

So, now that we’ve reviewed the basics, let’s get into a couple of examples of what you can do with long exposures (slow shutter speeds).

Star Trails

When we look at the stars, if we look at them long enough, then appear to move in the sky. This is because the earth is rotating so the stars rise and set just like our closest star, the sun. They actually move fast enough that we can record their path as a “star trail” if we leave our shutter open long enough. You can also take a series of photos and use software to combine them.

For the purpose of this blog, I’ll just tell you what I did to get this image:

Star Trails

  1. Find a location where it’s very dark and you are far from the city so you can see lots of brilliant stars in the sky.
  2. Attach remote control to camera (a remote is an absolute requirement for star trails).
  3. Place the camera on a tripod and frame what you want in the image and determine how/where you will need to focus (see next step).
  4. If you have something in the foreground on earth (like the trees in my image above), you might want to check a depth of field calculator to determine whether you need to find focus on the trees of whether you can simply focus at infinity. If you are focusing on something fairly close, you may need to use a flashlight or focus assist on your flash to find focus in the dark if you cannot see well enough to focus manually and your camera can’t see well enough with the available light to focus automatically. Just shine the flashlight on the thing you want to focus on, point your camera at that thing and lock focus (hint: this is easiest if you’re using back-button focusing, but that’s a subject for another blog post). In most cases, you will be shooting wide enough and at objects far enough away that you can simply manually set the focus at infinity and everything will look sharp. In my case, I was using a full-frame camera with a zoom lens at 27mm and my aperture at f/11. Worst case, focusing at infinity would keep everything 8 feet and further sharp. Since the trees were more than 8 ft above my head, I just set my focus at infinity.
  5. Now that you’ve found focus and locked focus, you can get your camera set on your tripod and framed the way you want again.
  6. Make sure your camera is set to “Bulb.” For some cameras, this is a setting on the shooting mode dial (where you pick Auto or Manual). For other cameras, this is an option in the shutter speed selection.
  7. Make sure your remote is set to “Bulb” as well. Bulb allows you to manually open the shutter and then manually close it.
  8. I personally like to just take a shot based on feel and then adjust from there. I started by trying to get a shot that just looked realistic. I left the shutter open about 70 seconds and this is what I got:

How the Sky Looked

  1. Because there was so little light in the area I was shooting in, I wasn’t worried about over exposing the trees with a very long exposure. If you have more ambient light, you might want to stop down more or turn down the ISO. In my case, I did f/11 for aperture and 1600 ISO. I used a higher ISO than usual because I wanted to ensure the sky registered enough light to clearly show the silhouette of the trees. Had I not been so sleepy by the time this shot completed and keeping my husband awake getting in and out of the tent to tend to the camera, I probably would have tried another shot with a lower ISO and longer exposure time to see how long I could get the star trails and if I could reduce the noise.
  2. Make sure you have a comfortable and warm place to sit where you can keep an eye on your camera. I was more worried about curious bears than people at our campsite since there wasn’t anyone else around. Also, set an alarm on your phone so you don’t forget when it’s time to close the shutter. For my example, I opened the shutter (by pressing the button on the remote 1x) and then set the timer for 30 minutes. However, I must have bumped the shutter button early because my metadata says the total exposure time was actually 1275.9 sec (21.26 minutes). The longer you leave the shutter open, the longer your star trails will be. However, be aware that extremely long exposures create more noise in the image and can build enough heat in the camera that it will shut itself off (hopefully) to avoid damage. At one time I recall reading a warning that there is a maximum limit to how long you can safely leave your shutter open on a digital camera, but I have not seen anything like that in years so this may be something only relevant for older DSLRs (or perhaps it was just a rumor).
  3. When your timer goes off, click the button again to close the shutter and go see what you got!

Trivia question: why do the star trails appear in a semi-circular pattern?

 

 

 

AU0A3353

FAQ: How Do I Copyright and/or Watermark My Photos?

I have been asked how to copyright photos about a dozen times now, so I thought it might be a good topic for a blog post.

Note: I am in the United States. If you are not, info about copyright laws may not apply. Also, I am not an attorney and this information is not meant to substitute for the advice of an attorney. I am telling you what I have learned, which may or may not be accurate. If you are curious about the law, please see a reputable attorney in copyright law who can advise you far more reliably.

Let’s tease the question apart a bit.

What is a Copyright?

Copyright is, literally, the right to copy something–in this case a photo. As it true for all written work (including this post), all photos are automatically and immediately subject to copyright protection the moment they are published. This is true whether you take any action to copyright your work or not.

This means any time you grab someone else’s photo off a website and share it on Facebook or print it or use it for wallpaper on your iPhone, or whatever, you are guilty of copyright infringement and you could be taken to court and sued.

If you are a photographer who cares about getting paid for your work, this works in your favor.

That said, you are not likely to get enough money if someone infringes on your copyright to make it worth taking them to court unless you have registered your images with the U.S. Copyright office.

As such, if you care or think you might someday care whether people are using your images without your permission, you might want to take a little time to learn about registering your images with the US copyright office. Here is another link that will take you directly to a tutorial on how to submit your images for copyright registration online:  http://copyright.gov/eco/eco-tutorial.pdf

What is a Watermark?

Sometimes people confuse a written copyright statement superimposed over an image with the copyright itself. This is called a “watermark” and looks like this:

Screen Shot 2014-10-16 at 9.58.02 AM

An image is copyright protected whether it has a watermark or not. The watermark serves only as a reminder to others that this work belongs to someone and they should not use it without permission from the copyright owner.

The Professional Photographers Association recommends including the copyright symbol, year the photo was taken, name of the photographer, and how to contact the photographer in a watermark along with a message such as “all rights reserved.”

While the idea of including contact information sounds good, there are two issues with this.

First, watermarks rapidly start to detract from the image. Some people make them huge and centered on the image, which I find ruins the image to the point I don’t even want to waste my time looking at it. There is a delicate balance between protecting your work and having annoying images no one can see through your watermark.

Second, choosing a way to contact you that will neither make you subject to stalkers nor change in your lifetime (your copyright lasts your lifetime plus 70 years after your death) could be quite tricky. Including a website where your images can be ordered might be a way to keep the watermark smaller but still make it possible for people to obtain the right to use the image.

How to Add a Watermark

If you are going to process a bunch of photos at once, you will want to use software that allows you to add a watermark as part of your normal workflow. I use Aperture, but Lightroom will also allow you to do this.

The first thing you have to do is create an image file to apply as your watermark. The good news is that you only create the image file when you need to change the information it contains (e.g., ©2014 Dianne Blankenbaker would need to be updated each year).

Once you create your watermark image, you then apply the watermark at the time you export your images out of the Aperture library.

The following video demonstrates how to create the watermark in Photoshop CC 2014 and how to Apply it in Aperture 3.4:

Another alternative is to use an app that allows you to add watermarks to images. Some of these work such that you open the image file in the app and then create the watermark for just that one image. Each time you want to watermark an image, you have to repeat the process. This is quite tedious if you are processing large numbers of files and really only works if you watermark images only rarely.

Image Resolution

Additionally, posting low-resolution images can help limit what others do with you work. It’s hard to use a <100KB image, for example, for the wallpaper on a 27” screen–unless you find pixellation appealing. But, it might look OK on the much smaller screen of a smart phone.

As a general rule, the images I post on my website and Facebook are between 100-200 KB. These images full size are 24+ MB–that’s 120-240X bigger than what I’m posting. I sometimes break this rule when I really don’t want an image to start pixellating on a big screen–pixellation looks like this:Screen Shot 2014-10-16 at 9.57.51 AM

It’s as annoying as a giant watermark over the center of the image to me–even worse because a low-resolution image can also appear out of focus.

42 second shutter speed (different subject)

Disappearing Act and Long Exposures

A while back, I posted a couple of long exposures on Facebook (see the post here) and asked if people could tell which one had been exposed for 1/30 of a second vs 29 seconds. It was a little confusing because the shot with the higher exposure value (that is, it was brighter) was the one with the 1/30 of a second exposure.

I thought I would explain the purpose of the exercise and talk a bit about how I achieved super long exposure times (shutter speeds) in bright sunlight.

First, if you know nothing about how a given exposure value was achieved other than the shutter speed, you cannot draw a conclusion about whether a brighter image has a longer shutter speed than the darker image. As a reminder, there are 3 settings that determine exposure: aperture, ISO, and shutter speed. The same exposure can be achieved with vastly different shutter speeds by adjusting the ISO and aperture to offset the difference.

So, if all you know is the shutter speed, what differences can you see that will tell you which had the longer exposure time? From an artistic perspective, we choose shutter speed based on whether we want to show or freeze motion. “Showing motion” means motion blur becomes visible in an image. So, our first test is “how much motion blur do we see?”

However, with this particular subject, the clouds are not moving quickly. The clouds are our best clue as to how long the shutter was open. But the clouds moved slowly enough that the difference in motion blur between the 1/30 of a second exposure and the 29 second exposure is relatively subtle. When you compare the 1/60 of a second exposure to the 77 second exposure the difference becomes far more obvious.

Likewise, moving water is usually a great clue as to how long an exposure is. As the exposure gets longer, fewer ripples in the river show.

The third difference you might notice if you look very closely is that the highway that curves around the river has no cars on it in any of the images with a 29 second or longer exposure time (shutter speed).

This happens to be one of the cool reasons to do super-long exposures. It’s a way of removing traffic and crowds from a scene. “But WAIT!” you ask, “What happened to slow shutters showing motion blur?”

Disappearing objects are the extreme of motion blur. The moving objects don’t reflect enough light relative to the total light signal to register as part of an image. This is a big difference in how cameras “see” vs how we see. We do not have a time factor that increases or decreases the exposure of what we look at. A camera, however, continues to gather light, exposing the image for the length of time the shutter is open in a quantity determined by the aperture size. How much light is needed to get a given exposure is then determined by the ISO.

So, why does this make moving objects disappear? Well, let’s look at the trees in our long exposure examples. They’re very dark. They reflect back less light than the river next to them. But they are sitting still, standing in one place, reflecting back that little bit of light in the same location for the duration of the open shutter. It’s enough to register a dark image of a tree. By comparison, the cars on the freeway are driving through the frame. They reflect only a little more light than the trees, but only for a split second in each point along their trajectory–the accumulative effect of the open shutter is lost on them. They would have to be very bright to register in the image–which is how you create light trails when cars have their lights on.

So, the bottom line is that if you can get your shutter slow enough that moving objects can’t reflect enough light to show up in the image, you can make them disappear.

The next question is, of course, how do you get a super slow shutter in daylight? We can stop down the aperture as much as possible (to the point before diffraction causes our images to fall apart, but that’s another subject) and we can turn our ISO as low as it will go, but at 7:52PM in July (more than an hour before sunset), that only got me a 1/30 of a second shutter speed.

All of the example images have the same aperture and ISO settings. Having reached the limits of my camera’s ability to control exposure, my only other option to get a slower shutter was to block some of the light reaching my camera’s sensor. To do this, I used a Heliopan 10-stop neutral density filter.

So what is a Neutral Density (ND) filter? From a technical perspective, an ND filter is called “neutral” because it is designed to block all colors of light equally. In other words, the color of the light should not be affected by an ND filter, just less light should make it through the lens.

That said, 10-stop ND filters reduce the light that reaches your sensor by 1000x. Many result in a color shift. In the case of the Heliopan, it’s a red shift. The good news is that it is something easily corrected via white balance settings in the case of the Heliopan (not true of all ND filters). I personally like the color shift in these examples and didn’t bother to correct it–it was like sunset came early.

To get the identical exposure with a 10-stop ND filter, if you are changing only the shutter speed, you would need to multiple the shutter speed by 1000. So, 1/30 becomes  33.33 seconds. If you really want this shutter speed, you need to use the bulb setting on your camera with a remote and time how long the shutter has been open. I did successively longer exposures using the Bulb setting to see what I liked best.

Neutral Density filters give you more control over light. They let you use much slower shutter speeds or allow you to open up your aperture significantly in brightly lit conditions where this isn’t otherwise possible.

If you like playing with motion or shallow depth of field in bright light, neutral density filters are a great option to explore.