Photography: Auto Exposure

“It doesn’t matter how long we may have been stuck in a sense of our limitations. If we go into a darkened room and turn on the light, it doesn’t matter if the room has been dark for a day, a week, or ten thousand years — we turn on the light and it is illuminated. Once we control our capacity for love and happiness, the light has been turned on.”  – Sharon Salzberg

Recommended blog site: Accepting the risk that no one will come back to read the remainder of this post, I highly recommend basilbloginc.wordpress.com. Basil is on safari and has dramatic photos and captivating narratives (zebras, giraffes, and migrating wildebeests).

My last post concerned two exposure adjustments (increasing illumination detail in the shadows and color detail in the highlights) which require processing in editing software. This post is for the many photographers who do not process their images with a computer.

Modern auto exposure (AE) systems are amazingly accurate throughout a wide range of lighting conditions. However, there are situations that are beyond their ability. Here, I will describe how to adjust for lighting conditions with which auto exposure systems have problems.

Correct exposure is crucially important because most digital sensors are capable of capturing only 5-6 stops of illumination in any one frame. The majority of cameras have only the 5 stop range which is a difference of 32 times as much light in the shadows as in the highlights. Therefore, if the highlights are more than 32 times brighter than the darkest shadows, then either the highlights will be blown out (completely white) or the shadows will be completely black. For comparison, with both midday sunlight and dark shadows within a scene, the highlights are thousands of times brighter than the darkest shadows.

Auto exposure limitations: Most photographs are made up of predominantly middle tones with some highlights and some shadows. To accommodate this, auto exposure (AE) systems attempt to get as much of the scene as possible to be mid-tone (specifically 18% gray).  Usually this works out fine. However, predominantly bright or predominantly dark scenes are not properly exposed. If your scene is mostly bright, auto exposure will exposure your scene to be middle gray. Thus a landscape of direct sun on fresh snow will have gray snow. If the scene is overall dark, auto exposure will produce an image lightened to middle gray. A black bear in a thick forest at dusk will be gray. (These examples assume that the camera’s auto exposure is set to assess all of its different auto exposure areas within the frame, called evaluative auto exposure).

Assisting the auto exposure system: To get correct exposure of these predominantly bright or dark scenes, you can tell your camera (before taking the shot) that you want the image of the snowy scene to be brighter than usual. This is done by adjusting the exposure compensation. (Most cameras have a button on the back or top that allows easy access to the exposure compensation function, usually marked “+/-“).

To get proper exposure of a bright scene, set exposure compensation to a positive (+) number. For a somewhat bright scene, such as direct sunlight on a light color dog in front of beige fence, start with exposure compensation +1/3 to +2/3 and adjust from there if needed.  For direct sunlight on sand, start with exposure compensation set at +1, and then adjusts if needed. For direct sun on fresh snow, set exposure compensation to +1  and 1/2 to +2.

Conversely, for dark scenes, indicate to your camera that you want a darker than average image, by setting exposure compensation to a negative (-) number. For a black dog in front of a dark green fence in shadow, start with exposure compensation of -1/3 to -2/3. For the deep red of the sky 15 minutes after sunset, try exposure compensation of -1.  For a black bear in shadow in a thick forest start with exposure compensation of -1 and 1/2.

Trouble shooting auto exposure – Basics. If you are following the above procedure and still get incorrect exposure, first check the basics.

  • Is auto exposure turned on?
  • Is it set to assess the area of the frame that you are interested in? (It may not have been reset after a recent adjustment)
  • Is exposure compensation telling your camera to vary from its usual exposure calculation? (Again, it may not have been reset after you last adjusted it.
  • Is auto exposure lock enabled, blocking the camera from assessing exposure independently for each frame?
  • Is some option turned on that overrides exposure compensation, flash compensation or manual exposure settings? For example, the Canon Rebel T2i has a feature that automatically corrects brightness and contrast for jpg images (Auto Lighting Optimizer). Its default setting is “On” (“Standard”). This option may partially override your exposure compensation and manual exposure settings when they are set to produce a darker image. This could produce a brighter image than you are expecting. (It affects only jpg, not raw, images.) This is a helpful feature for people who never adjust exposure downward themselves. However, I recommend disabling this feature if you do. However, for people who adjust exposure compensation themselves, I recommend disabling this feature for standard shooting. Enable it just when appropriate.  5) Do you have viewfinder light leak? This applies only to DSLR’s.  This type of camera has a mirror which, in its normal position, prevents light that comes into the camera through the viewfinder from reaching the sensor. However, just before the shutter opens, the mirror pops up and away from the sensor. With the mirror up, any light entering your viewfinder will provide the sensor with more light than was predicted based on “through the lens” illumination. . This can be a problem whenever bright light falls upon the viewfinder, but particularly when direct sunlight is on the viewfinder.  The greatest change/error is exposure occurs when initial exposure was determined while the eye was blocking much of the light from reaching the sensor, but when the photographer moves back just prior to the shot, allowing direct sunlight to fall upon the viewfinder. Before dismissing this as arcane and insignificant, consider that Canon DSLR’s come with a viewfinder cover attached to the shoulder strap (It’s easy to overlook this small black rectangular cover).

When only the main subject needs to be properly exposed: The examples discussed above assume that you have the auto exposure system set to assess all of its possible auto exposure areas within the frame (full evaluative metering).  However, there are occasions when the lighting varies so much that not all of the frame can be properly exposed. Thus we choose our main area/subject of interest to be well exposed and let the remainder of the frame go over/under exposed (such as when you take a photo of a groom in a blue tux that is standing in front of a bright white canopy).

When only a portion of the frame can be properly exposed, there are three common options offered by most cameras: partial, center-weighted and spot metering. Partial metering determines exposure based solely only the central area of the frame. Use this when you want correct exposure for  a fairly large subject (without caring whether the background turns out very bright or  dark (For example,  you may want your light brown dog to be properly exposed, regardless of whether the background is very bright or dark) . If your subject is not in the center of the frame, point the center of the frame at your subject and press the shutter button half way down. This establishes exposure appropriate for your subject. While still holding the button half way down, recompose the image, then shoot. Many cameras have, in addition, a button that will keep the auto exposure unchanged while you recompose. This (auto exposure {AE} lock button) is usually located on the camera back (may be marked with an asterisk).  When this is pressed, the current exposure settings are locked in until the shutter button is pressed. Thus, the shutter release button does not need to continuously held half way down to keep the exposure compensation from changing settings.  This is particularly useful for tripod work. In some cameras, AE lock applies only to this one frame. In other cameras, its effect carries over to subsequent frames until it is turned off (With this “carryover type”, don’t forget to turn it off when finished).

Center weighted auto exposure metering: A second way to limit the amount of the frame that auto exposure assesses, is called center weighted metering. In this case, exposure is calculated by giving the central area of the frame priority. However, instead of ignoring the remainder of the frame as with partial metering, the remainder of the frame is changed by a smaller amount than is the center. This would be useful when you are primarily interested in properly exposing a central subject, but do not want the background to be way too bright or dark. An example would be a flower photo with a main subject and additional flowers within a bright background. You do not want the background flowers to be blown out (grossly overexposed). Center weighted exposure is a good choice here.

Spot metering: This determines exposure based exclusively on a smaller central portion of the frame than is utilized by either partial or center weighted metering. This is great for a main subject that occupies only a small portion of the frame. For example, let’s say you are at the zoo, ready to photograph a leopard that is 20 feet away from you. If you spot meter with the very center of the frame on the leopard, it will be properly exposed regardless of whether the background is bright or dark.

I hope this will be helpful to someone. I welcome comments, criticism and suggestions for future blog topics.

I am available at NaturePhotoRehab.com to assist clients in transforming their nature photos into impressive works of art that they are proud to give as gifts or to hang on their own wall for inspiration.

©2012 J. Michael Harroun  NaturePhotoRehab.com

Digital Photography: Optimum Exposure

“I’ve missed more than 9,000 shots in my career. I’ve lost almost 300 games. 26 times I’ve been trusted to take the game winning shot and missed. I’ve failed over and over and over again in my life and that is why I succeed.”  – Michael Jordan

For many years, Michael Jordan was, by far, the world’s best basketball player. He was capable of phenomenal physical maneuvers and accuracy previously thought to be impossible. That is why I find this quote so impressive, both for its humility and for its wisdom.

My last post was about thoughts and feelings. This post focuses on technique. Specifically, it explains how to get the best detail in the low light and shadow areas, and another adjustment for maximizing color detail in the highlights of your photos.

Digital sensor limitation: In a digital camera, the actual picture is taken by a sensor which is made of millions of pixels. It is these pixels that actually “see” the light. When bright light is falling on a pixel, much more information about the light is recorded than when it is being exposed to low light. As a result, hundreds of times more gradations of light are recorded from the bright areas of a digital photo than from the low light areas. As a result, shadows show relatively little detail.

Correcting for limited detail in darker areas:  There are two stages to the correction. First, slightly overexpose your initial image. Second, use your editing software to decrease the exposure an equal amount (if it appears too bright). You end up with an image correctly exposed, but with more detail in the low light areas and shadows.

A drawback to this overexposure technique is that gradations of color will be lost in the highlights, resulting in a blotchy appearance of very bright areas of color. If your primary interest is fine detail in color, please skip down to “Optimum exposure for color”.

Correction Stage 1: Controlled overexposure is the key. But how much overexposure is appropriate? (If there is too much overexposure, detail in the highlights will be lost or “blown out”). The precise amount of overexposure is determined by using the histogram (The dreaded histogram… but wait, don’t go. This is not terribly difficult).

A histogram is simply a graphic representation of the light that the sensor is “seeing”.  The histogram looks like a mountain range. The right side of the mountain range represents the brightest areas of your photo. The higher the peaks, the greater the number of pixels sensing bright light. (“The right is the bright”). Conversely, the left side represents the dark areas and shadows in the photo. The higher the peaks on this left side, the greater the numbers of pixels exposed to low light. (Since this histogram is representing light intensity, it is called a luminance histogram.)

How to display the histogram: All DSLR’s (of which I am aware) provide a histogram. Many, but not all, other types of digital cameras offer this feature (Check your camera’s operation’s manual). Most cameras display the histogram only in the playback mode. To have the histogram display, first go to the playback menu. Find histogram. Set it to on (If you have a choice between luminance and color histogram, choose luminance).  Now, playback any image so that it shows on the screen. If the histogram does not show on your screen, use the display options button (located on the camera back, usually near the screen and labeled “disp”) to cycle through the display options until the histogram shows . (If you have an option for a histogram display in your pre-shot viewfinder or “live view” screen, it can usually be turned on in the recording menu. You can make your adjustments directly without using the playback mode).

Determining correct overexposure: (For most lighting conditions, exposure compensaton is going to be +1/3 to +2/3 stops). We will be moving the mountain peaks of your histogram toward the right, approaching the far right end of the baseline, without going so far that any of them abruptly disappear.

  • Turn on automatic playback so that your image shows on the screen immediately after your shot is taken.
  • With exposure compensation set to zero, take a photo in your usual manner.
  • In playback mode, check the histogram for your image.
  • If the peaks on the right end of your histogram do not extend almost completely to the far right side of the baseline, then set exposure compensation up by +1/3 to +1/2 stop.
  • Repeat the same shot. Again check the histogram.
  • The peaks will extend somewhat more to the right (If they extend almost to the far right end of the baseline, then you are done with this stage). If there is still a lot of black space between your peaks and the far right baseline, set exposure compensation up another +1/3 to +1/2 stop.
  • Repeat the shot and check histogram again.  (Probably you are done now, but repeat if needed).
  • For most lighting conditions, in my experience, an exposure compensation adjustment of +2/3 stop is correct.
  • Here are two tips for remembering  this technique.  First, “The bright is on the right”. Second, “Moving (the histogram) to the right” is abbreviated Mttr, pronounced “Meter” as in light meter)
  • The above technique gives you correct exposure for that specific subject and lighting condition. Whenever lighting conditions change, check your histogram and, again, adjust exposure compensation with this technique.
  • A word of warning: Do not set it and forget it. Re-evaluate exposure for every new lighting condition.

Correction Stage 2: This is done with your editing software. Any editing program will work for this. It does not need to be elaborate (The program that came with your camera will work fine). Open the image that you just overexposed (If you like the way it looks, you can skip this stage).  If you image appears too bright, slide the exposure slider to the left to decrease exposure by the same amount that you increased it when taking your photo. (While you have your editing program open, you may wish to adjust white balance, contrast or any other parameter that improves the appearance your image)

Results: Now you have an image with correct exposure, but with more detail in the darker areas and shadows than it would have had.

Optimum exposure for color: A drawback of the above (luminance) overexposure technique is that fine gradations of color will be lost in the highlights, resulting in a blotchy appearance of the color in these areas.  For best detail in color highlights, an image usually needs to be underexposed a small amount. To determine the appropriate amount underexposure, use the color histogram, not the luminance histogram.  (If your camera does not offer a color histogram, I recommend “guesstimating” with exposure compensation of -1/3 in subdued lighting and of -2/3 in brightly lit conditions). Color histogram display during playback is usually set in the same way that the luminance histogram was set above (Set it in the playback menu and also with the display options button on the back of the camera).

  • Take a shot with exposure compensation zero. Check the color histogram.
  • Probably at least one color will extend all the way to the far right end of the baseline and abruptly cut off (No black area between the tips or all the colors and the far right baseline).  If that is what you see, decrease exposure compensation by 1/3 to 1/2 stop. (If the color channels approach, but do not abruptly disappear off the far right side of the baseline, then your exposure (for color) is correct already.
  • Repeat your same shot and again check the histogram.
  • If any color channel still abruptly cuts off at the far right, decease exposure compensation another 1/3 to 1/2 stop.
  • Probably you have good results by now, but repeat this procedure once more if needed.
  • Generally the correct amount of underexposure will be -1/2 to -2/3 stop.
  • Your color highlights will now be the best that your camera can offer.
  • However, whenever lighting conditions change, re-evaluate the histogram and adjust exposure compensation if needed.
  • A word of warning: Do not set it and forget it. Re-evaluate exposure for every new lighting condition.

I welcome comments, corrections and suggestions for future blog topics.

I am available at NaturePhotoRehab.com to assist clients with transforming their images into impressive works of art that they will be proud to either hang on their own wall or to give as a gift.

J. Michael Harroun(c)2012  NaturePhotoRehab.com

Photography: Wonderful Confusion

“How wonderful that we have met with a paradox. Now we have some hope of making progress.”  – Niels Bohr

I love  learning new facts about Nature. Obviously it is far to complex to be fully known or understood. In spite of this, I tend to drift into an illusion that all the important scientific facts are already known. Then, something new is discovered.  Recently five  new animal species were  found in  the rainforest of New Guinea. What? All these years of scientists and explorers poking around and researching, and they have not yet found all of the animal species here on earth.? Wow! That’s cool!

Several years ago two new species of  microorganisms were found near the top of a volcano in South America. Their respiration utilizes sulfur. That is unique. The respiration of all other plants and animals involves oxygen, carbon dioxide and water. No one knew that sulfur could be a basic component of respiration. Men have walked on the moon. Lots of facts are known  about black holes and  quarks. Yet we had not known all the types of respiration of earth organisms.  That’s cool!.

My personal  “find” yesterday was something new to me (No, not a new species).  It was a beautiful flower of which  I had never heard (Celosia).  I looked at it admiringly. Is this whole thing a flower? Or is much of it tiny modified leaves? A bracken? Hairs? Modified spines?  Or is it some type of fern?  Oh, wait! Those are the flowers, tiny and few. I still don’t understand what these brilliant spires are. But at least I know where its flowers are. How cool!

Some may ask what this has to do with photography. For me, photography is about becoming more aware. It is a matter of developing an “in the moment” awareness of, not only the things that I know and expect; but, even more importantly, an openness to the unknown and unexpected. What is even better, I get to touch it with my hand or study it with my eyes and photograph it with my heart. This is great! What a wonderful confusion!

I used to believe that I should know all the answers. Now I am content just to be alert and aware; just to know some of the questions.

I welcome comments and suggestions.

I am available at NaturePhotoRehab.com assisting clients to transform their photos into works of art that they are either proud to give as gifts or to hang on their own wall for inspiration.

Photography – Becoming a Professional

Listen to the Exhortation of the Dawn! Look to this Day! For it is Life, the very Life of Life. In its brief course lie all the Verities and Realities of your Existence.  – Kalidasa

A frequent question in photography groups is “What does it take to become a professional photographer?” That is best answered with a question in return. “Do you realize that a professional shoots what is interesting to another person or company, when that person wants it done”? Gone are the days of shooting what interests you, and when you are in the mood.

However, a condensed list of requirements follows:

1) strong marketing skills (and lots of time and energy to utilize them).

2)  Professional equipment (expensive!) and willingness to forgo all of the other things that could have been purchased.

3) Excellent technique (and the time and money necessary to achieve it)

4) Five years, more or less.  However, I do know of an account executive in New York who abruptly quit his job and moved to Santa Fe, New Mexico to support himself as a photographer. He does not recommend this approach for most people, although he did succeed.

5) Shoot what you love. Learn to effectively convey your feelings to other people through your images. The owner of a stock photography agency told me that he thinks these are primary keys to success.

Becoming a professional photographer has always been a long and rigorous journey because of the amount of competition.  With the advent of quality, affordable digital camera and lenses, it has become 1,000 times more difficult than it was 20 years ago.

However the principle determinants of financial success remain the same.

1) Frequent attendance of workshops put on by successful professional photographers who are also effective teachers

3) Ongoing mentoring by a successful, established photographer

4) Practice honing one’s skills by shooting and processing . In one survey, the average number of photographs taken and edited per day by the better professionals was 40.

5) Study for development of new skills for both photography its self and for processing.

6) Find a niche. I know of one lady in Taos, New Mexico who has supported herself and her family for years by shooting only cooked food dishes for restaurants, magazines, etc. She has only one camera and only one lens. Her “studio” is her kitchen. A more complex, and probably more practical, niche could be some combination of tilt-shift lenses, focus stacking, high dynamic range (HDR), panoramas, mosaics and composites of photographs and illustrations.

Although 5 years of dedicated work is a rough rule of thumb, the time can be greatly shortened by attending a school such as Brooks Institute in Santa Barbara, California. At Brooks, a typical single week’s schedule is likely to include 3-5 projects. Each project includes, planning, arranging for props, models, lighting and specialty equipment, shooting, processing, printing and presentation.  It’s rigorous, but upon graduation, many are offered (low-level) jobs.

When starting out, a professional photographer’s jobs are likely to be mundane and income meager. One might be shooting for a seed catalog or for K-mart junk mail or an oil refinery. For many years Ansell Adams supported himself by shooting dams and bridges for a railroad company. Induced Chaos Photography (inducedchaos.com) points out, correctly, that professionals must consistently produce high quality results day in and day out, regardless of how they are feeling or whether they are interested in the subject of the shoot.

Having effective marketing skills is essential for developing an income stream. Many people take classes in marketing. Early in one’s career, it is common to spend more time on marketing than on the photography itself.

Peter Lik is a dramatic example of the importance of marketing. Peter is a self-taught landscape photographer.   He used a panoramic film camera and perfect technique with which he generated wonderful nature photographs. His work was distinctive because film panorama landscapes were rare. Peter was an adventurer and individualist with no interest in marketing. As a result, his income was so low that he lived out of his car for 35 years. Several years ago he teamed up with a high-powered marketing firm. Currently he has over 14 galleries, each selling (huge) framed enlargements for $ 8,000 to $15,000. (His most expensive photograph is a multi-paneled mural the size of a large wall. It sells for $ 50,000. Last year he began a successful reality TV series (The Weather Channel-TWC) entitled From the Edge with Peter Lik. Wow! That demonstrates the power of marketing when your product is high quality.

In conclusion, the best advice for the budding professional photographer is “Follow your heart, but don’t give up your day job”.

I hope this will be helpful to someone. I welcome comments, criticism and suggestions for future blog topics.

I am available at NaturePhotoRehab.com assisting clients in transforming their nature photos into works of art that they are proud to give as gifts or to hang on their own wall for inspiration.

©2012 J. Michael Harroun  NaturePhotoRehab.com

Photography – Realistic Goals

garys red/wht 1“No road is too long for him who advances slowly and does not hurry, and no attainment is beyond his reach who equips himself with patience to achieve it.”     – Jean de La Bruyere

When a professional photographer goes on a shoot for a client, there is always an expectation of quality results. That is, after all, what the client is paying for. However, personal shooting is, for me, a very different matter. For this, I have two minimal goals and two maximal goals. My minimal goals are: 1) Do not damage or lose the equipment; 2) Relax and slow down enough to notice and appreciate some of the intricacies of the nature around me.  This appreciation provides me with feelings of wholeness and connection to the incredibly complex world of delicate balances that we call nature.

You may have noticed that neither of these personal shooting goals mentions anything about photographs. There is good reason for that, which is illustrated by an experience that I had yesterday.

I went with a photography group to a large botanical garden.  There were thousands of plants and at least 40 different kinds of flowers. The level of photographic skill in the group varied from beginner to professional. At the outset, most of the beginners, and some intermediate level members, rushed off to get photos of as many beautiful plants and flowers as possible.

I began consciously slowing down, preparing to reach my goal of appreciating and connecting with the flowers. I noticed that the sun was bright and fairly high in the sky. The flowers were, for the most part, at least partially in direct sunlight (which causes photos with washed out colors and dark shadows). When I found a flower with good lighting, the background was in direct sunlight (which is highly distracting in a photograph, drawing the viewer’s attention away from the subject). Some flowers were in dark shade (which allows good photographs of shape and color, but gives a flat appearance with no “life” or texture). Changing perspective on many plants was limited by the garden rules (stay on the paths, but do not block them or hinder the movement of other people). Add to that a frequent breeze, and conditions were not conducive to high quality close-up flower photos.

I decided to just spend time with the flowers while watching for a change in conditions. I spent at least 10 min with each flower variety that appealed to me. There were great colors, textures and shapes. I enjoyed them and developed exhilaration that is my goal #2. I experimented with the reflector and diffusing screen that I had, but could not control the lighting. No problem, it was practice and I was feeling fine.

Considering that I was in a large botanic garden, there were thousands of excellent photographic opportunities surrounding me. There were plenty of opportunities to take photos of variegated leaves, bamboo stands, ferns, actually thousands of plants. But I was in the mood for the flowers and their brilliant colors, velvety textures, sheen of sunlight, complicated shapes and wonderful smells. I took some practice shots and shots just to keep me slowed down and attentive. None of these were of a quality to enlarge and frame. I reviewed them, as I review every shot that I take, to see if I can learn something from it. However, all of this mornings images were then deleted. No photos… and I felt fine.

When I think back to that experience, I have satisfying memories. I am glad that I was there. I had met both of my first two goals: 1) don’t damage or lose any equipment and 2) slow down and develop a fulfilling connection with nature. My feelings awe, awareness and “aliveness” made the day worthwhile.

On the other hand, I think back to other photographers in our group who were hurrying around to get macro shots of many flowers. Some of them will arrive home with a lot of images.  However, considering the conditions, many of their macro shots are likely to be of poor quality. Some will be disappointed with their photographic abilities. It is worth remembering that sometimes the conditions are just not conducive to quality images, especially macro work. Sometimes it is just better to just have a pleasant walk.

The two goals that I have referred to thus far are my “minimal goals”. I have two additional goals that are more challenging. These I call my “maximal goals”: 1) to create photos that generate within me feelings similar to the feelings I had when the images were captured and 2) to create images that cause other people to get similar feelings to those that I had when shooting. This happens less often than my recreating feeling within myself. But when it does occur, I am filled with pleasure for being able to share the feelings of wonder and connection to the universe. This is my ultimate photographic goal. I reach it gradually more often. That lets me know that I am traveling down the correct path in this journey toward bliss.

Successful photography is the result of a surprisingly long period of practice, learning, practice, mistakes and disappointments and (you guessed it) practice. Be patient with yourself. Remember to enjoy the moments along the way.

I hope this post has been helpful to someone. I welcome comments, criticism and suggestions for future blog posts.

Through my website, NaturePhotoRehab.com, I assist clients to transform their nature photos into impressive works of art that they are proud to give as gifts or to hang on their own wall for inspiration. Specifically I provide photo retouching, complex processing and enhancements, enlargements, prints up to 12 x 18 inches and framing.

©2012 J. Michael Harroun

Sharper Photographic Images – Part 2

orange hibiscus burst 400x400“We are here to awaken from the illusion of our separateness.”   – Thich Nhat Hanh

This morning I was sitting quietly in the back yard with my friend, the orange hibiscus. We were enjoying the warm sun, blue sky, slight breeze and singing birds. I felt like singing myself. What a wonderful experience to be able to participate in it all. My friend was sending out a welcoming energy. So I accepted its message and gathered its images. Not only have I had this fulfilling experience, but I have pictures that will remind me of this event every time that I look at them.  Simply miraculous (and no cost for film or processing).

This is my second blog on maximizing the sharpness of photographic images. In Part 1, I commented on reducing camera shake,  file size/resolution, file type, lens cleaning, tripod use, mirror lock-up and the shutter release cable (or remote control). Today I’ll cover the importance of: aperture, lens hood, polarizing filter, viewfinder cover and some issues that can arise with autofocus.

Aperture. In a nutshell, generally use: f/5.6 for flowers or other close-ups, f/8 for general purpose, and f/16 for landscapes. (If you are a trusting soul or pressed for time, skip down to “Lens hood”).

The aperture is the opening through which light passes to reach the sensor. With wide/large apertures the light passing through the periphery of the lens is distorted and cannot be focused. (Larger openings are referred to with smaller f/ stop numbers. For example, the size of the opening at  f/4 is much larger than at  f/16. Confusing at first, I know). This presents  your main subject in focus but with a blurred foreground and background.  As aperture size decreases (larger f/ number), this distortion goes away, but another type of distortion develops (diffraction). The aperture size for the least overall distortion and greatest sharpness for most lenses is f/8.  This generally provides the absolute best/critical  focus of which the lens is capable, although the foreground and background will necessarily be mildly out of focus. (Great for portraits or wedding photography). Smaller openings/apertures (f/16) cause everything to be slightly but equally out of focus. People perceive that everything is in focus. Thus a small aperture, f/16, is good for landscapes. (Too confusing? Then use your cameras preset programs/modes i.e. sports/action, portraiture, nighttime, etc. It will adjust the aperture.)

Use a lens hood if your lens has one available. Light that hits your lens at an angle, cannot be focused on the sensor. It shows up as a slight haze over your image. A lens hood blocks much of this angular light, increasing sharpness. Frequently the lens hoods need to be purchased separately from the lens. (Be sure to get it one made by the same company that manufactured your lens)

Use a polarizing filter when shooting in bright light. A polarizing filter decreases surface glare and reflections, increases color and prevents stray light from reaching your lens at an angle. Each of these increases the appearance of some of the details, and thus the perception of sharpness.  Many pro photographers use a polarizing filter 90% of the time (or more). The polarizing filter blocks light waves vibrating at right angles to the filter’s intrinsic alignment. So, before checking your exposure, rotate the polarizing filter 180 degrees to determine the position at which it is most effective in blocking the reflections.  On the downside, polarizing filters block enough light from entering the lens are that it acts like a 2 stop neutral density filter, requiring an increase of aperture size or slower shutter speed to compensate. (In auto exposure, your camera will make this adjustment). When shooting in bright light this is usually of no consequence. In addition, a polarizing filter may cause vignettes (darkening at the corners of your image) depending on the specific lens and polarizing filter that you are using.  On the helpful side, a lens hood is generally not needed with a polarizing filter. I am talking here about a good quality polarizing filter (like B&W ®). A cheap one may cause distortion and therefore create more blurriness than without it.

Cover the viewfinder of DSLR cameras unless you are hand holding your camera and actually looking through the viewfinder.  Viewfinders of cameras with moveable mirrors allow light to enter from the back and reach the sensor, giving a slight haze overall. This is particularly important when using a tripod or framing up only with the screen.  When one is looking through the viewfinder, most of the light is blocked by our head. Many DSLR cameras come with a slip-on viewfinder cover attached to the shoulder strap.

Continuous shooting burst of three frames: When shooting handheld or when using a tripod, but physically depressing the shutter button, there is usually some camera movement, even when a person is being careful to avoid such movement. However, when the shutter button is continually being depressed, all camera movement can be avoided. When a burst of three frames is made, the second frame is usually sharper than the first; and the third frame sharper than the second.

Auto-focus (AF) issues:

  • Operator error: Auto-focus was not set back to its all-points default after you modified it previously.
  • AF could not establish any focal point. When this occurs, generally a red box appears in the viewfinder or on the screen, indicating that no AF is established. (Some cameras will not even fire if AF cannot be established.) Because the central AF point is usually the most accurate, try setting AF to assess only its central point. (Auto-focus with central AF point over your subject and shutter button half way down, then recompose and shoot.)

Here are some reasons why AF may not work:

  • There is too little light. (You might try using flash.)
  • The subject  is too small for the auto-focus to sense.
  • The subject is moving.

Auto focus works, but chooses the wrong place to focus. To prevent this, either set the camera to assess only the AF point that lies over the subject or set it to utilize only its central AF point. With the shutter button held half way down, position this central AF point over your subject, then recompose and shoot.

Manual focus for people who wear glasses: If you take off your glasses before manual focusing, what seems to be correct focus will be wrong. There are two ways to avoid this problem. The easiest alternative is to have a diopter adjustment on the viewfinder.  (Diopters are the measurement of the strength of glasses.) Cameras come in three varieties: no available diopter adjustment, built-in adjustment and slip-on viewfinder adjustment lenses which are purchased separately . Many of the built-in variety have a range of -2 to +2 diopters. If your glasses are stronger than that, you will need to purchase a slip-on viewfinder adjustment lens  in addition to using the one that is built-in. The second alternative for wearers of glasses, is to purchase a Hoodman® eye cup. These are effective and convenient, but expensive.

I hope that this will be helpful to someone.  Comments, suggestions (and criticisms) are welcome.

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