Saturday, July 26, 2014

Demystifying the Histogram

The histogram is the topic for the week in the Boost Your Photography: 52 Weeks Challenge. (Join the Google+ Community to share your weekly photographs and receive feedback.) This article seeks to demystify some of the questions and confusion that generally arise when discussing histograms.

Demystifying the Histogram | Boost Your Photography

Histogram Terminology

Let's start with some basic definitions, as there are several different terms commonly used when discussing histograms.

Histogram: a histogram is a bar graph of the frequency distribution of tones in a photograph, ranging from pure black (0) to pure white (255). The higher the bar graph for a certain segment, the more that particular tone is represented in the photograph. There are two types of histograms: one that combines three different bar graphs for each of the three different color channels (blue, red, and green) and one that provides one bar graph for the entire photograph. We will stick to talking about the single, overall histogram for now, but you can see both versions below.

Demystifying the Histogram: colors vs. combined #histogram | Boost Your Photography

Clipping: clipping is a term used to refer to elements of the photograph that are recorded as either pure black or pure white. Once a section of a photograph has been "clipped," it becomes difficult to recover any detail from that particular part of the image, even with post-processing. (Think: a black silhouette or an all white window in an indoor photograph.) An ideal histogram includes nearly the entire range of tones from 0 to 255 with a minimum amount of clipping. In the example above, you can see that the histogram values nearly approach pure black (0) but not quite. This means that there is no clipping of black values, and you can see still subtle variations in the shadows of the framing leaves.

Visualization of clipping and blinkies: colors on the left show areas that are now pure black | Boost Your Photography

The Blinkies: the blinkies (or, the dreaded blinkies) are a warning that you can enable on many cameras to alert you to clipping in your photographs. After taking a photograph, you can review it on your camera screen, and you will see blinking sections of your photograph that indicate that those sections have been clipped. (In my Canon instructional manual, the technical term is "highlight alert," and it blinks only for overexposed areas, not underexposed ones.) In the example above, I used Levels to artificially clip many of the near-black values and change them to pure black (upper histogram shows levels). Now you can see that there is a greater frequency of values on the histogram that are at or near pure black (lower histogram). Detail has been lost in these areas.

Example Histograms

The simple answer is that there is not a "perfect" histogram. Every photograph is different, and there may be times when you deliberately want a mostly-bright tones photograph or a mostly-dark tones photograph.

"Normal" Bell Curve Histogram | Boost Your Photography

A general histogram of a well-exposed and well-balanced image will have a familiar, bell-curve shaped look. The edges of the curve should reach just towards the two edges but not touch (no clipping), as in the photograph above. This is an idealized version of what an appropriate exposure should look like for a photograph. Keep in mind, however, that every photographic situation is different, and a bell curve will not always represent what you are looking to convey.

High-Key or Overexposed Histogram | Boost Your Photography

A high-key histogram is one where much of the histogram is squished up to the right-hand side of the graph. Large sections of the photograph will be clipped and overexposed (rendered as pure white). The photograph above shows an extreme example of a high-key photograph and matching histogram.

Low-Key or Underexposed Histogram | Boost Your Photography

A low-key histogram is one where much of the histogram is squished up the left-hand side of the graph. Large sections of the photograph will be clipped and underexposed (rendered as pure black). The photograph above shows an extreme example of a low-key photograph and matching histogram.

Low Contrast Histogram: demystifying the histogram | Boost Your Photography

A low contrast histogram is one where the histogram is confined to the middle values on the graph and does not approach either the high or low ends of the histogram. Low contrast shots are common in situations with little or minimal contrast, such as a foggy or snowy day like in the example shot and histogram above. You can see the lack of pure white both in the greys of the photograph and in the absence of white values on the right-hand side of the histogram. There is also only minimal pure black values on the left-hand side of the histogram.

How to Use Your Histogram

Now that you have seen some extreme examples of histograms, you should have a general idea of what to expect from a given histogram and its accompanying photograph. If you are looking for a balanced photograph with a range of tones, you will want a histogram that fits the "general" example above. If your histogram is off-center, you can use exposure compensation to make your next photograph correspondingly lighter or darker as needed.

Adjust Exposure to Change the Histogram | Boost Your Photography

The graphic above compares two different photographs of the Grand Tetons, shot using exposure compensation. The top image was at 0, while the bottom was at -1 exposure. With the top image, it is clear that the clouds in the sky and the reflection are clipped (blown out), and the histogram shows that with the values on the right-hand side. The bottom image shows a more even distribution of tones across the full range. In this situation, using a negative value for exposure compensation allowed me to shift the histogram over towards the left. (Read more about exposure compensation in Explaining Exposure and Exposure Compensation.)

Other examples of when to use your histogram: if you are looking to capture dark silhouettes against a bright background, you can check your histogram to see if you have achieved pure black (a clustering of bars against the left-hand side). If you are looking to capture a subject against a bright white background, you can check your histogram to see if you have achieved pure white (a clustering of bars against the right-hand side).

How will you use your histogram? Share your thoughts or an example in the comments below.

(Looking to grow more in your photography? Consider joining the BYP 52 Weeks Google+ Community to share your weekly photograph and see what others are capturing.)

Wednesday, July 23, 2014

A Year Ago on Boost Your Photography

Consider joining in the Boost Your Photography: 52 Weeks Challenge! Our focus for July was on photography basics. In August we will be looking at different types, styles, and timings for photography. Join the Google+ Community to share your weekly photographs and receive feedback.

  • Long Exposure Photography at the Fair(e). A fair or carnival is an incredible opportunity to practice your long exposure photography. Bring along a tripod, and entire world of light and photographs awaits you! Read the full article for detailed suggestions and "how to" instructions.
  • Keeping Your Camera and Sensor Clean. The post lays out everything you need to do (and have) to keep your camera and especially your camera sensor clean, from basic day-to-day maintenance and prevention to what happens when you end up with a whole mess of dust and grime on your sensor (like in the photo above). Read on for the full details.
  • Spring Roundup. The very first round up, this one covered all of the posts from the first quarter of Boost Your Photography, all in one place!

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Monday, July 21, 2014

Puddle Photography Part Deux

Making the best use of puddles in the Tetons

Last year's post on Puddle Reflection Photography was a big hit, and I hope it inspired you to think differently about puddles. Still need ideas? Check out my newest post over at Digital Photography School on How to Create Amazing Reflection Photographs Using Puddles. The text and photographs are all updated and, as a bonus, you can get a behind-the-scenes look at some stunning reflection photographs from my recent trip to Grand Tetons National Park. 

Saturday, July 19, 2014

Black and White Photography: Do You Shoot or Do You Post-Process?

Black and white photography has changed tremendously since the days of black and white film. Now, digital shooters face a wide variety of options for shooting and creating black and white or monochrome photographs. But which method is best for you?

Monochrome photography is the topic for next week in the Boost Your Photography: 52 Weeks Challenge. (Join the Google+ Community to share your weekly photographs and receive feedback.)

Black and White Photography: in camera

The more traditional way to shoot black and white photographs is to do so in camera. Nearly all cameras, from point-and-shoots to DSLRs to phone cameras have an option for shooting and recording in black and white. This hearkens back to the days of film, where if you put black and white film in your camera, then you were shooting black and white images. (If you shoot JPEG, all color information will be lost, and you will retain only the black and white image. If you shoot RAW+JPEG, the color information will be retained in the RAW file, and you will retain a black and white JPEG version of the image.)

One of the biggest benefits to shooting black and white in camera is the immediate feedback. You can see the photograph on your LCD screen, which may guide you to try different angles, compositions, or exposures in your next shots. Because we do not naturally "see" the world in black and white, this feedback can help you train your eye to understand what works well in black and white.

There are many different ways to control and refine your black and white photographs in camera. Within the monochrome setting on my DSLR, there is the ability to adjust the sharpness, the contrast, or add a filter or toning effect. (Sepia is a common choice for monochrome toning.)

In-Camera Monochrome Settings (no post-processing for black and white) | Boost Your Photography

The series of six photographs above were all shot by manipulating the settings in camera with no post-processing involved (other than making the collage). The top row shots were left: monochrome default settings and right: monochrome with maximum contrast. The middle row shots were left: monochrome with minimum contrast and right: monochrome with default contrast, maximum sharpness, and red filter. The bottom row shots were left: monochrome with default contrast, maximum sharpness, and blue tone and right: color with standard settings. This is just a quick look at some of the many different monochrome effects you can create within your camera.

The biggest downside to shooting black and white in camera is that your black and white settings and conversion become baked into the final photograph when you are shooting JPEG. You cannot get back the color information and any post-processing changes will potentially degrade the quality of your image.

Black and White Photography: post-processing

The second option for shooting black and white is to shoot in color (or RAW) and to convert your photograph to black and white through a post-processing program, app, or web site. The benefit to this method is that you have significantly more flexibility in the final look of your photograph, but the downside is that you lose the instant feedback of "seeing" in black and white through your camera's display.

Comparison of the three different color channels for black and white conversion

One way to post-process a color photograph into black and white is to look at the three different color channels that make up the color image. (A color photograph is recorded by your camera's sensor by three different colors of sensors: blue, red, and green.) The comparison of all three channels and the color image, above, highlights some of the variation that can be found in black and white conversions of the same image. (If you are having trouble seeing some of the differences, look at the colors in the sky and the red sign across the three different channels.)

Another way to post-process a color photograph is to use a default conversion. Most photography software programs and apps offer different default methods for converting a color photograph into black and white. After you have chosen your default conversion you can also adjust other post-processing options such as contrast, exposure, vignettes, or dodging and burning to get exactly the look you wanted.

If you do not want to pay for a software program or app, you can also achieve great black and white looks with the free photography program PicMonkey available at article pinned above walks you through the steps to Make Your Black and White Photographs POP for Free with PicMonkey. This post includes a lot of screen shots to help you visualize  the whole process and follow along with your own photograph(s).

So, How Do You Black and White?

What about you? Do you have a favorite way for achieving black and white shots or a great conversion tip? Share your thoughts in the comments below!

(Looking to grow more in your photography? Consider joining the BYP 52 Weeks Google+ Community to share your weekly photograph and see what others are capturing.)

Boost Your Photography: Learn Your DSLR is now available from Amazon. Get the most out of your camera with practical advice about the technical and creative aspects of DSLR photography that will have you taking beautiful pictures right away.

Wednesday, July 16, 2014

An Introduction to Filters in Photography

An Introduction to Filters in Photography | Boost Your Photography
Filters are an important photographic tool, and there are many different types and brands available. This post will provide a quick overview of the four most common types of filters used with DSLR cameras, including what they are, how they are used, and example photographs taken with them. (All filters shown are the actual filters that I personally use when shooting.)

Filters are pieces of glass that attach to the front of your lens and serve a variety of purposes. Filters can be for protection or for achieving a certain effect or look in your photograph without post-processing.

There are two main systems for filters. Most manufacturers make screw-on filters that attach directly to the front of your lens. When purchasing this style of filter, you need to know the diameter of your lens (indicated with the Ø symbol). While you can attach more than one filter to your lens, you may run into the problem of the edges of your filter showing up in the corners of your image, which is less than desirable. Also, if you have multiple lenses with different diameters, you have to buy separate filters for each one.

The second system for filters is the Cokin series of filters and holders, where you attach a filter holder to the front of your lens and the filters themselves are larger than your lens and generally rectangular. With the Cokin system, you simply buy a different adjustable piece to attach the holder to lenses of different diameters, but you can use the same filters on all your lenses. The Cokin filters generally cost more up-front but are worth it if you need to use them with different lenses or want to use many filters simultaneously.

Personally, I currently use screw-in filters, and well-regarded brands include Hoya and B+W. If you are already further invested in photography, equipment, and lenses, you may want to consider the Cokin series of filters and holders. I am seriously considering making the switch myself when I can next justify the expense. If you are just starting out and only have a few lenses, then you can stick to screw-on filters, but if you know that you want the flexibility of the Cokin system, then it makes sense to invest in their filters from the start.

UV Filters

UV or ultraviolet filters are among the most common photography filters. Many new camera or new lenses come packaged with UV filters. A UV filter is a basic measure of protection for your camera and your lens. A quality UV filter has no negative impacts on your images or image quality, but the UV filter protects the surface of your lens from direct contact with dust, dirt, sand, fingerprints, and all other matter of debris. A UV filter can also protect your lens from breakage due to human error, especially if you drop or bump the front of your lens up against something. Recommended brands for UV filters include B+W and Hoya. Read more about the importance of UV filters in this post on Lens Accessories.

B+W UV Filter

Circular Polarizers

A circular polarizer is a two-piece filter. The near piece screws into the front of your lens, and the far piece is free to rotate. Just like polarizing sunglasses or car windows, a circular polarizer changes which wavelengths of light are visible through the filter. This effect can serve to emphasize the blue in blue skies and cut down or eliminate reflections in water.

Hoya Circular Polarizer

(Polarizer tip: if you have a pair of polarizing sunglasses, spend some time tilting and rotating your head while looking up at the blue sky or down at a polarized wind shield. You will get an immediate sense of the impact of a polarizing filter.) Polarizers also eliminate reflections and glare in water and are commonly used in waterfall photography. (Read more in Yes, Go Chasing Waterfalls.) You can read more about how to use a circular polarizer in the article Improve Your Fall Photography: use a polarizer.

Impact of a Circular Polarizer | Boost Your Photography

Neutral Density Filters

A neutral density filter blocks some amount of light from your lens and sensor. These filters are called "neutral" because they should not have any impact on the color or color cast of your final image. (Inexpensive neutral density filters often leave a blue or purple color cast in your photograph.) Being able to cut down on the amount of light reaching your sensor is useful in many situations when you want a longer shutter speed.

Fotga Variable Neutral Density Fader
(This is one I don't recommend unless you just want a cheap filter to see what the effects look like.)

There are many different varieties of neutral density filters. The one pictured above is a variable neutral density filter. Like a circular polarizer, it has two connected elements that can be rotated. The version of the left shows the minimum amount of light being blocked, while the version of the right shows the maximum amount of light being blocked. This allows you to control how much light is being blocked simply by turning the filter. Tiffin makes a well-regarded variable neutral density filter, but there are many different styles and brands of variable neutral density filters or neutral density faders available.

Impact of a Neutral Density Filter to Smooth Water | Boost Your Photography
20-second exposure obtained using a Variable Neutral Density Fader in mid-afternoon 

Most neutral density filters are sold in an individual "strength" and are not adjustable. These tend to be of much higher quality than the variable filters. You can stack filters by screwing more than one on to each other and adjusting the effect that way. This is where the Cokin system really shines, as it is very easy to slot different filters and different strengths in-and-out of the holder, and you can use several ND filters together without risking edges appearing in your image.

Zykkor Split ND Filter
(Again, this is a very cheap version to try out the effects. You can already see the purple color cast to this filter.)

Another type of neutral density filter to consider is the Split Neutral Density. A split ND filter only blocks light from half of the photograph, and you can find both hard split ND filters (a sharp dividing line in the middle) and gradual split ND filters (a more gradual transition, like the one shown above). Split ND filters are used when you have a scene that is much brighter in one half of the image than the other. With circular split ND filters, you spin and adjust the outer ring to level the split, while with the Cokin system of split ND filters, you adjust the filter holder itself.

Impact of a Split Neutral Density Filter | Boost Your Photography
Sunrise shot with the Zykkor Split ND Filter, which allowed significantly more color and light in the reflection to balance the brightness of the sky.

Split ND filters are commonly used by landscape and travel photographers to shoot sunrise and sunset images, especially with large foregrounds or reflections. In the example above, you can imagine how the sky was much brighter in reality than its reflection in the water. Using the split ND filter allowed me to better balance the two exposures - making the sky darker so that both the sky and the water reflection could shine.

Impact of a Split Neutral Density Filter | Boost Your Photography
Another example shot with the Zykkor Split ND Filter
For this photograph of the sunflowers, I used the split ND filter again to block out some of the light from the sky. Otherwise, the sky would have appeared much lighter, and the storm clouds would have lost some of their dark and brooding look.

Summary: Filters

There are many different styles, brands, and systems of filters available, and this article has laid out the four most commonly used by photographers. Think about what your current needs are and which filters suit you best. If you do not already have UV filters for your lens, start there. Then, think about what you shoot most. Are you outside where a polarizer would make a big difference? Do you aspire to shoot long, smooth waterfalls or impossibly smooth water shots? Then look into neutral density filters. Do a lot of sunsets or sky photos where a split neutral density filter would make the difference? Worried about the price tag? Consider buying a cheap knock-off ND filter just to try it out. If you are addicted to the look, upgrade. Whatever you choose, spend the time to really get to know your filter and what it can do for you.

Saturday, July 12, 2014

Strategic White Balance

White balance is one of the least understood aspects of photography. It is also the topic for the week in the Boost Your Photography: 52 Weeks Challenge. (Join the Google+ Community to share your weekly photographs and receive feedback.)

 Many of us simply rely on Auto White Balance or shot RAW images and fix the white balance in post-processing. For an introduction to white balance first read What the ... White Balance? , one of the most popular and most pinned posts on Boost Your Photography. White balance can be a powerful photographic tool when used strategically.

Strategic White Balance | Boost Your Photography

White Balance and Color

White light is made up of the entire spectrum of light (visible and invisible). Our eyes can readily adjust to changing lighting situations so that our brain generally always "sees" a white piece of paper as white, whether we are looking at it outside in full sun, under a tree in the shade, or indoors under a fluorescent light panel. A camera, however, is not so talented, which is why your photographs can have different color casts depending on the lighting and the white balance used.

This chart from Life in Edit by Esmer Olvera provides a great visualization of the different colors and temperatures of common light sources. The article also does a really nice job of laying out the step-by-step process of creating a custom white balance for a given scene. (This is particularly useful if you are going to be shooting a large number of shots under the same lighting conditions, like in portraiture or product photography work.)

As you can see from the chart, shade has blue-ish tones, which is why white snow can look blue when photographed in the shade. Indoor lighting has yellow-ish tones, which is why white walls often look old and yellowed when photographed using only artificial indoor lighting. The deep blues of Twilight give the Blue Hour its name, while the deep yellows and oranges give the Golden Hour around sunrise and sunset its name.

Using White Balance Strategically

Now that you have a general idea of what colors and tones different lighting situations can impart, you can start thinking about how to use white balance strategically.

The first way, of course, is to use white balance to "correct" the colors in your photograph. If you want your indoor white walls to appear white, consider using the fluorescent white balance setting. If you are shooting in full shade and do not want blue snow, consider using the shade white balance setting. The chart below from Digital Camera World provides a fuller description of each white balance preset in your camera and some situations where each comes in handy.

Now, the second way to use white balance strategically is to use it for creative effect. Are you shooting in the middle of the day but wish you could capture that warm glow of a Golden Hour setting sun? Try shooting in Cloudy or Shade. (In one of the first landscape photography books I read, the authors shared that they shoot all of their landscape and nature shots on Cloudy white balance for a warmer look.) You can see an example of such a difference below.

Strategic White Balance: auto vs. cloudy | Boost Your Photography

Shooting just after sunset but the sky has not yet gotten the deep blue tones of the Blue Hour? Try shooting in Tungsten white balance, which will emphasize the blue tones you are looking for. The two versions below are from the exact same shot - using the RAW file to show the difference between Auto and Tungsten white balance for twilight shots.

Strategic White Balance: auto vs. tungsten | Boost Your Photography

Strategic White Balance

Take the next step in using white balance. Spend some time evaluating your scene and deciding which white balance makes the most sense - whether to remove color casts or to add them creatively. Worried about making a mistake? Shoot in RAW, and you can adjust your white balance all you want in post-processing without losing any image quality.

(Looking to grow more in your photography? Consider joining the BYP 52 Weeks Google+ Community to share your weekly photograph and see what others are capturing.)

Wednesday, July 9, 2014

A Year Ago on Boost Your Photography

  • Stacking Photographs: Star Trails and Beyond. An overview of the technique of "stacking" multiple photographs to create extremely long exposures. This technique is commonly used with star trails, as pictured above, but has other applications. All you need is your camera, a tripod, a remote, and a free piece of software to create amazing results!
  • How Long Does Your Camera's Battery Last? Do you know the answer to this simple but important question? Read on for an easy technique for tracking your camera's battery life. Never get stuck with a surprise dead battery again!

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