slow shutter speed

Color Fringing Fungus: An Example of Chromatic Aberration by Todd Henson

Side by side example of chromatic aberration

Today I wanted to tackle the topic of chromatic aberration, what it is, and how to attempt to correct it. Please click on all the photos in this post to see larger versions.

What is Chromatic Aberration?

This topic has the potential to get very technical as chromatic aberration, also called color fringing, is something caused by the optical physics of lenses. But I don’t want to get too technical, so a simple description is that chromatic aberration is unwanted bands of color, most often along the edges of objects in the photo and often when there is strong contrast between light and dark areas. It’s best to start with an example, so look at the closeup photo below of some fungus where I’ve circled the areas showing chromatic aberration.

A closeup showing chromatic aberration in regions where light and dark meet

See how the top section has a band of magenta color along the lower edge of the light band on the fungus, right where it transitions from light fungus to dark background? In the middle and lower sections the fringing is in the form of bands of green color. Neither the magenta nor the green are a natural part of this scene. They are distortions caused by imperfections and limitations in the lens.

Chromatic aberration is generally more likely to occur when using wider apertures, so you can reduce or eliminate it by stopping down to a smaller aperture. But sometimes this won’t create the photo you’re trying for and you need to use a wider aperture. In those cases you may end up with some color fringing. Thankfully, today’s software provides methods to correct this.

Auto Correcting Chromatic Aberration

I used Adobe Lightroom for these examples. This is from an older version so it’s possible the options may look different on the version you have but the concept is the same.

Shows I’ve checked Remove Chromatic Aberration and Enable Profile Corrections under the Profile section of Lens Corrections in Lightroom.

Lightroom provides a means of automatically correcting chromatic aberration, and in this case it was done by checking a checkbox labelled Remove Chromatic Aberration within the Profile section of Lens Corrections. I also check Enable Profile Corrections to correct other sorts of lens distortions. Sometimes Lightroom does a great job and this is all I need to do. But as we’ll see, sometimes it doesn’t correct as much of the color fringing as I’d like.

Below are examples showing the uncorrected closeup followed by an attempt at Lightroom’s autocorrection of chromatic aberration with specific sections circled in red to show the color fringing. Notice, even after the correction there still is a fair bit of color fringing.

Shows the uncorrected sections with chromatic aberration

Shows the autocorrected sections. Note, there is still noticeable color fringing.

Below is a slideshow of the above two images. Click on the photo to cycle between uncorrected and autocorrected.

Manually Correcting Chromatic Aberration

I wanted to remove more of the color fringing than Lightroom did when I checked the Remove Chromatic Aberration box. So I clicked on Manual and used the dropper tool to specifically select the areas of the photo that were showing the strongest color fringing. I did this multiple times, over both the magenta and the green fringing. This told Lightroom the specific color fringing it should attempt to correct.

Shows the default settings for the Manual section of Lens Corrections in Lightroom.

Shows the settings after manually using the dropper tool to select regions with strong color fringing.

Below are examples showing the uncorrected closeup followed by my attempt at manually correcting the chromatic aberrations. By using the manual dropper I was able to do a much better job at removing the specific color fringing present in this photo.

Shows the uncorrected sections with chromatic aberration

Shows the manually corrected sections. Most color fringing is now gone, or at least reduced.

Below is a slideshow of the above two images. Click on the photo to cycle between uncorrected and manually corrected.

Conclusion

Chromatic aberration won’t be a problem in all photos. In fact, I’d say it’s not a problem in most of my photos. And in many cases when it is present Lightroom does a great job automatically correcting the color fringing. But in special situations, often when I’m doing macro work with wide apertures and subjects with strong regions of contrast between light and dark, chromatic aberration will become a problem and I’ll put a little more effort into manually correcting for it.

Below is the final photo after manually correcting for chromatic aberration.

The final photo after manually correcting for chromatic aberration.

Bonus: Hidden Flying Insect

Did you happen to notice the tiny little insect hiding in the photo and closeups above? I’d not even seen it until I zoomed way in using Lightroom. Below is another of the closeup images where I’ve circled the little creature in red.

Check out the tiny flying insect on the fungus.


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Painterly Kingfisher in Flight by Todd Henson

Belted Kingfisher Flyby

Sometimes paintings that look very much like real life are called photorealistic because they appear almost like photographs. Similarly, photography can be used to create more painterly images, even using techniques mostly performed in camera. Today we’ll explore one method of doing this, that of panning with a subject using long exposures to create intentional motion blur, and it doesn’t require pro-level cameras or lenses.

The Setup

On July 3, 2009, my brother and I visited Luray, Virginia and their fabulous Greenway, a beautifully maintained park system with a stream and walkway that runs through the town. In one area we heard the call of a belted kingfisher and watched as it repeatedly flew quickly upstream, and then back downstream. I had with me the kit lens that came with my camera, an 18-200 mm f/3.5-5.6 lens. In this case the 200 mm helped me get a little closer to the kingfisher, but if you photograph larger subjects or are willing to have a smaller subject then you can easily use a shorter focal length just as well.

The kingfisher was moving quickly and the light was a little subdued under the leaves of the trees. I doubted I could get nice clear photos of the kingfisher in flight, though I did initially try that, so I eventually settled on creating slightly more abstract painterly photos. I wanted the kingfisher as large as it could be so I zoomed in as far as I could to 200 mm. There wasn’t a lot of light so I knew shutter speeds would be an interesting challenge. I opened up the aperture of the lens all the way, to f/5.6 at 200 mm. I then raised my ISO to 640 to let me set faster shutter speeds. This gave me shutter speeds between 1/15 to 1/60 of a second. I could have worked in manual exposure mode and set everything, and if you want a specific look this is what you should do, but given I was panning through different areas with different light levels, and I was just having fun experimenting, I chose to work in aperture priority mode, my typical setting, where I choose the aperture and let the shutter speed fall where it may.

The Kingfisher Soars

Technique: Panning

So what is panning? It’s moving the camera with the subject and letting the background blur. If you see the bird coming from the left then face straight ahead and twist your body towards the left. Find the bird in your viewfinder and begin focusing. Stick with it as it flies by, pressing the shutter button in continuous mode so you create many images as it flies by, with you continuing to track it as it does, twisting your body to the right. Keep with it as it flies by to the right until it’s flown beyond your view. Hopefully, somewhere in that group of photos you’ve created a winner.

It requires a lot of experimentation to find just the right shutter speed for your subject. Do you want the subject in perfect focus, or are you willing to let the subject remain a bit blurry as I chose to here? And how fast is the subject moving? The shutter speed you need will depend on those factors, so you’ll need to practice to find what works for you in that specific instance.

The Kingfisher Calls

Painterly Aspects

Notice how different each of the three photos here look. In the case of the first photo, Belted Kingfisher Flyby, the bird is moving very quickly so I’m panning very quickly which creates a complete blur to the background. The shutter speed is 1/15 second so there’s plenty of time for the background to blur. You can see how far the bird, and my camera, moved in that time by looking at the length of the lighter colored lines in the photo.

The second photo, The Kingfisher Soars, is similar but the bird was flying at an angle so I didn’t pan quite as fast, and I used a faster shutter speed of 1/50 second. You can see the lines of color from the background are shorter. They begin to look a little more like long paint strokes.

With the third photo, The Kingfisher’s Call, I’m now at a faster shutter speed with 1/60 second, and the bird isn’t moving nearly as fast, almost hovering as kingfishers sometimes do. Look closely at the lines of color and light in the background of the photo. See how much shorter they are? Now, perhaps, they most resemble strokes of a paintbrush. And the bird is almost in focus, or at least more so than with the other two photos.

One thing to note, you could find a fast enough shutter speed that works with both the subject movement and your ability to pan, such that you actually get the subject almost completely in focus and the background a blur. This can be a lot of fun, too. But in this case, trying for a more painterly effect, I was fine with the subject remaining a bit blurry from the motion. I thought it contributed to the look of the images.

Post-processing

So the majority of the technique is in-camera using the three basic camera settings of shutter speed, aperture and ISO. But I did do work in post after I’d downloaded the photos to my computer. I used Adobe Lightroom to adjust exposure, lessening some of the highlights, darkening some shadows, blurring the backgrounds a bit more by lowering clarity, and accentuating the kingfisher by keeping the whites of its body bright and the colors dark and bold.

Below are before and after examples of each photo showing how it looked before I began processing in Lightroom and when I’d finished so you can see what effect this had. Click on each image to cycle between before and after

Final Thoughts

So what do you think? Have you tried this before? If not, give it a go. And you don’t have to photograph a bird to do this. You can chose any moving subject, such as a car or bicycle. In fact, you don’t even have to chose a moving subject. I’ve show before how you can use this technique on landscapes to create slightly more painterly views of the world. Give it a try, and let me know how it goes.

For other examples, see A Day for Abstracts in the Forest and Turbulence in Motion.


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Tips For Blurring Moving Water by Todd Henson

I’ve been asked in the past how to blur moving water from rivers and waterfalls in a photograph. It all comes down to shutter speed. The slower the shutter speed the more blur in the water. Below are a number of tips to help you do this. You don’t have to follow all of these tips to blur water. Pick whichever ones you’re able to use. Just realize some of them may not get the shutter speed as slow as you’d like. That’s when you may need to try the other tips.

Stabilize Your Camera

If you want a sharp image of everything but the water you’ll first need to stabilize your camera. The best way to do this is to put it on a good tripod. If you don’t have a tripod you can try resting the camera on something stable such as a stone wall or a large rock or tree. Just be careful not to let the camera drop.

Use a Remote Shutter Release or Self-Timer

To reduce the chance of introducing shake into the camera during the exposure it’s best not to press the shutter button with your finger to start the exposure. Two options for avoiding this are a remote shutter release, or setting the camera’s self-timer such that your exposure begins some number of seconds after you press the shutter button.

Using the self-timer is the least expensive option if your camera supports it, though you will lose a little flexibility in choosing exactly when to start the exposure.

There are two options for remote shutter releases: cable releases that attach to a special connector on your camera and wireless releases. At present I use a simple cable release that just presses and optionally locks the shutter. Some higher-end cable (and wireless) releases include intervalometer features which let you take a photo every so many seconds for some period of time.

Shoot Early, Late, or on an Overcast Day

It’s best if it’s not a bright sunny day as the sunlight can blow out the white highlights in the water. Try to photograph very early or very late, before the sun is up or after it has gone down. Or pick an overcast day when clouds will hide the sun. This reduces the quantity of light in the scene, reducing the chances of blowing out highlights, and requiring a longer exposure in your camera, increasing your chances of blurring the water.

This was shot on an overcast morning. Less light meant a longer exposure. ISO 200, aperture f/36, shutter speed 15 seconds.

Adjust Your ISO

Set your ISO to the lowest setting your camera allows. The ISO controls how sensitive your camera’s sensor is to light. The lowest setting, for example, 100 or 200, will require more light to make an exposure. Your camera will need more time to collect more light which will help you achieve the slow shutter speed you’re after.

Stop Down Your Aperture

Stop down your aperture as far as you can. To do this use a larger f-stop number, such as f/16, f/32, etc. This closes down the aperture, making a smaller opening that light will need to travel through, requiring more time for the camera to gather enough light to make the exposure. This lets you shoot using slower shutter speeds. Be aware, though, that the very smallest apertures can cause diffraction, which may reduce the sharpness of your photo. If this happens you’ll need to open up the aperture just a bit.

A wider aperture results in a faster shutter speed allowing you to see more detail in the water. ISO 200, aperture f/4, shutter speed 1/50 second.

A smaller aperture results in a slower shutter speed allowing you to blur the water. ISO 200, aperture f/11, shutter speed 1/8 second.

A wide aperture results in a faster shutter speed, freezing action and showing more detail in the water. ISO 320, aperture f/6.3, shutter speed 1/1250 second.

A small aperture results in a slower shutter speed, helping convey action by blurring the water. ISO 320, aperture f/25, shutter speed 1/60 second.

Use a Polarizing Filter

If everything above still isn’t enough to slow the shutter speed down enough to create the blur you’re after then you may need to resort to filters that fit over your lens. The first to try is a polarizing filter if you already have one.

A polarizing filter is often used to reduce reflections and glare on surfaces such as water and leaves, to create richer colors, and to darken skies. A side effect of these filters is reducing the amount of light that reaches the sensor, usually by about 1 to 2 stops. This isn’t a lot but it might be enough to get the shutter speed slow enough to blur the water.

Using a polarizing filter and a small aperture helped slow down the shutter speed, blurring the water from the fountains. ISO 200, aperture f/25, shutter speed 1.6 seconds.

Use a Neutral Density (ND) Filter

If nothing else will get the shutter speed slow enough you’ll want to invest in a neutral density filter. Think of this as sunglasses for your camera lens. It’s a dark filter that reduces the amount of light entering the lens. Neutral density filters are available in a range of levels, some reducing 1 stop of light, some 3 stops, some 5, 10 or even 15 stops of light. You can even find variable neutral density filters that let you turn the filter like a polarizer to change the density of the filter. With neutral density filters you’ll be able to slow the shutter speed down as much as you’d like.

You can also stack filters, using multiple neutral density filters to slow things down even more. And you can stack a polarizing filter and neutral density filters. Just be aware that if you stack too many filters you may begin to see the filters at the corners of the image. If this happens you either need to remove some of the filters or crop the image when you’re finished.

A polarizing filter in the middle of the day allowed a slow exposure, but not slow enough to really blur (or still) the moving water. ISO 200, aperture f/22, shutter speed 1/8 second.

A polarizing filter and a 5-stop neutral density filter in the middle of the day allowed a slow enough exposure to blur (or mostly still) the moving water. ISO 200, aperture f/22, shutter speed 4 seconds.

It's reasonably early in the morning without a filter. ISO 200, aperture f/11, shutter speed 1/80 second.

Adding a Singh-Ray Gold-N-Blue Polarizer and a 10-stop neutral density filter shifted the colors and slowed the shutter speed way down, introducing a lot of blur into the water. ISO 200, aperture f/11, shutter speed 67 seconds.

In this triptych I used a Singh-Ray Vari-N-Duo filter, which combines a polarizing filter with a variable neutral density filter, to gradually slow the shutter speed down by increasing the amount of neutral density. All images are ISO 200 with an aperture of f/25. The left image has a shutter speed of 1/8 second. The center image has a shutter speed of 4/5 second. The right image has a shutter speed of 8 seconds.

I hope these tips for blurring moving water have been useful to you. It can be a lot of fun and it can really add a nice dynamic to a photograph. So head out there and try a few of them out, see what kinds of interesting photographs you can create.


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