Getting it Right in the Digital Camera : digital cameras

Showing posts with label digital cameras. Show all posts

Thursday, April 18, 2019

Introduction to Digital Photography, An Overdue Course Syllabus

Upper Garwin Falls, Wilton NH

Green River Falls, Guilford Vt

I am in the middle of my Introduction to Digital Photography Class at Keene Community Education. I have been offering this 4-week course, twice a year, for several years and I continue to be amazed at what seems to be an endless supply of local people who are desperate to learn about how to use their digital cameras. The class has never failed to be fully booked immediately after the course is announced.

The program includes 8 hours of class time and two photo shoots to nearby locations. Eight hours is not enough, but during that time I try to cover a broad range of topics. In the first class, I start with a discussion of the features offered by various classes of cameras and how to approach learning the mind-boggling array of features. I show how and where to upload and archive images and the advantages of different image file types (emphasizing RAW of course). It is a lot to pack into the first two hours.

Rockport Ma

In subsequent classes I cover the control of exposure, approaches to composition and the opportunities and challenges of shooting in various kinds of light. Somewhere in there I try to squeeze in discussions of image sharpness, focus and control of color balance.

Old Home Day, Chesterfield, NH

It is a lot to explain and in preparing my classes I have drawn heavily on the discussions I have written in many of my blog articles. My students often ask whether I have a course syllabus and I generally direct the to my blogs. Most of the information and examples are there, but it is not always easy to find. Included here is a list of links selected from over 400 blog articles that cover the key areas of my course. They are organized to roughly match the order of the classes. Hopefully these chapters will also provide a helpful introduction to the amazing world of modern digital photography for those who will never be able to participate in any of my classes.

Central Square, Keene NH

Nuts and Bolts

My first class is generally the most challenging for the students and myself as it includes such a broad range of topics. The relative advantages of large sensors and small sensors, lossy vs lossless file types, and the long list of approaches to image archiving are just a few of the topics covered.

Intro to Digital Photo Class, Spring 2018

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Exposure

Exposure is not just about the brightness of the image. How we combine Aperture, Shutter Speed and ISO also effects important aspects of the imaging, including depth of field, portrayal of motion and image noise.

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Composition

Lower Purgatory Falls, Wilton NH

The “Rules of Composition” should never be allowed to restrict your own creative vision, but they can provide some helpful starting points. The rules are all based on what looked balanced and beautiful to the eye of others, and what works for your eyes has equal validity. Picasso said “We all know that Art is not truth. Art is a lie that makes us realize truth”. Your compositions should be a path to realizing your own personal truth.

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Using Light

In New England, the light is always changing. Whether it is the warm beauty of the “Golden Hour” or the harsh brilliance of the midday sun, it is important to recognize the conditions, and plan your shooting to respond to the challenges and the opportunities that they provide.

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Sharpness and Focus

The apparent sharpness of and image is not only related to proper focus, but also the steadiness of the camera. These are important topics, but I never know where I will be able to slip them into my presentations. It usually depends on how many questions I must answer and how many images I end up critiquing.

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Final Thoughts

Here are some of my random thoughts about art, photography and the state of digital photography’s place in the world of fine art and media. It is the kind of “artsy” talk I pledged to never use when I started my blog more than 10 years ago.

Jeffrey Newcomer
www.partridgebrookreflections.com

Sunday, June 14, 2015

Tips for Sharp Focus

Finding Focus

Over the years I have published a number of articles about achieving sharp focus in digital photography. I have spent much time discussing the use of focus stacking, blending several variably focused images to obtain otherwise impossibly wide depth of field. It is a perfect example of how digital photography has opened creative options that are not possible with film. In special situations, focus stacking is a powerful tool, but most of the time sharp focus has more to do with careful adherence to good technique, which applies to both the film and digital processes. This week I would like to discuss just a few tips that may improve your photographic focus. Let's start with the digital cameras and those giant LCD screens

LCD Focus

Zoomed Live View Focusing

It may be surprising, but some people actually still gaze through a viewfinder to compose and focus their images, but with the proliferation of larger sharp LCD screens many cameras have dispensed with the optical viewfinders all together. The LCD provides an excellent real-time view of the scene and, when zoomed in, can be helpful in the fine adjustment of focus, especially in low light, but the viewfinder is better for routine focusing when a quicker response is necessary.

Although helpful in some special situations, manual LCD focusing is general awkward. The screen works best to compose the image while relying on auto-focus to control; the focusing.

LCD Brightness
One major challenge LCD focusing is the difficulty seeing the image clearly in bright light. It is a simple thing, but adjusting the LCD brightness to its maximum level can make a difference. Just remember to have a spare battery on hand, since the bright screen will more quickly drain power from the camera.

Through the Viewfinder
If your camera is still blessed with a good viewfinder, it offers some definite advantages for manual focusing. It is less bothered by bright light, but I find that, on occasions, I still have to shield the eye cup from glare using my hand or hat visor. Here a few other points to consider on your search for perfect focus.

Diopter Adjustment

If, as you gaze through the viewfinder, you never seem to get the scene to appear sharply in focus, the first step should be to adjust the diopter. Most cameras have a knob on the side of the viewfinder which adjusts the optics to match your vision. Start by focusing the best you can and then turn the knob until the view becomes clear. The adjustment will vary from person to person and with or without glasses. My diopter knob tends to easily get knocked out of focus, so I need to readjust every so often.

Using Focus Points

My vision isn't as sharp as in my youth and the act of manual focusing is additionally complicated by my variable focus glasses. The result is that I have come to depend more on my

camera's auto-focus capabilities. The accuracy and adjustments of auto-focus are different on every camera, but in general, modern digital cameras do a remarkable job at nailing the focus. The key is to grab your manual and take the time to understand how your particular camera focuses and then practice until the adjustments become automatic. The key issues include: the locations of the focusing points, how to select the individual or groups of focus points and which points are most accurate. Not all focus points are of equal accuracy. On my Canon 5D Mark II the

center point is a "crossed" type, which means that it is sensitive to both horizontal and vertical lines. The other focus points are sensitive to either horizontal of vertical lines and are about one half as sensitive as the central focus point. When possible, I use the center point, but at times the peripheral sensors work better to nail the focus when the subject is away from the middle of the field. I have previously discussed the use of the full field of focus points to allow Hand-Held Focus Stacking . Auto-focus is steadily improving and new cameras may have more focus points and a greater number of more accurate sensors. Grab that manual and figure out how your auto-focus does its magic and then practice, practice.

Following Focus

Once you have mastered your camera's auto-focus peculiarities, the next step is to read on in the manual about the various focus modes. My camera has a "One Shot" mode used to hold focus on stationary subjects, as well as two action modes, "AI Focus" and "AI Servo" used to maintain focus on moving subjects. It is a profound mystery to me that, when in AI Servo mode, the camera is able to

adjust focus as a subject changes its distance from the camera. Even more remarkable, when in AI Focus, the camera can detect when a stationary subject starts moving and follow it from there. It doesn't always work perfectly, but the fact that it succeeds so often is a miracle. Many cameras have these capabilities and if yours is so blessed, do it the honor of learning how to use it. Just think of the tack sharp images you will get as that ravenous Lion hurtles toward you with ever shortening points of focus centered on his gleaming white teeth!

Finding infinity
Although the broad concept of infinity may be impossible for our feeble minds to fully grasp, when focusing a camera the location of infinity seems quite comprehensible and finite. By definition, infinity focus is the point of focus beyond which all more distant objects remain sharp regardless of how far away.

Mount Monadnock - Infinity Focus

It would seem that all you should need to do, to focus on infinity,

would be to rotate the lens barrel as far as it will go toward the little infinity squiggle. Older lens had a hard stop at the infinity point, but today, most lens can rotate beyond infinity. As Buzz Lightyear would say, "To infinity and Beyond!". In auto focus the lens is designed to stop at infinity, but when manually focusing it is possible to go too far so that proper focus needs to be pulled back and confirmed visually. Lens manufacturers give various reasons for the removal of the hard stop at infinity, including compensation for changes in the glass related to variable

temperature, reduction in wear on the auto-focus mechanism and, undoubtedly most important, reduction in the price of manufacture. They argue that the ease of manual focus is less important now that most people are using their very capable auto-focus systems. Regardless of the reasons, the simply rule is to be careful when manually focusing to infinity. Again read your manual and experiment with the settings. In good light it is easy to focus visually on a distant object and then check the lens to see precisely where infinity lies. Many lens', including my workhorse 24-105mm, have a little check mark at the infinity point.

Be aware, on many zoom lens (those described as "Varifocal"), the focus will vary as the focal length changes. Zooms that maintain focus while zooming are called "Parfocal". My 24-105 is of the Varifocal variety, and so I can't zoom in to focus and then expect to be able to hold sharpness as I pull back.

Hyperfocal Distance

The hyperfocal distance is the closest point of focus beyond which everything will appear sharp. This distance varies depending on the focal length and aperture. The hyperfocal point is key to capturing those dramatic landscapes, with both foreground detail and distance vistas in sharp focus. There are various precise and a few approximate approaches to determining this distance, but I well save this more involved discussion for another blog.

Focus Stacking

As I mentioned at the beginning, Focus stacking is a technique in which multiple, variably focused, images are blended to create a potentially limitless depth of field. I've discussed this approach in previous articles, but it should be noted that this is another area in which digital photography has expanded creative capabilities and broken bonds to the physical limitations of our expensive optics.

Focus Stacking I

Focus Stacking II

Hand-Held Focus Stacking

Hopefully these few tips will be of help in achieving consistently sharp focus. The key is to use careful technique to control both the sharpness of your focal point and also the size of the full depth of field.

And finally if you feel that you have done everything right and your images are still uniformly fuzzy, make sure that you are holding the camera steady. Perfect focus can't compensate for even a little camera jiggle. Get a tripod! and more than that, actually use the damn thing!!

Jeffrey Newcomer
Partridgebrookreflections.com

Sunday, May 10, 2015

Digital File Types

The Basics from Your Digital Camera

Digital photography has reached a remarkable level of beauty and sophistication. The output from today's digital cameras are capable of reproducing an amazing range of color, subtleties of tone and detail. This is even more remarkable given the fact that, at their essence these images are nothing more than collections of million of sterile little zeros and ones. This week I want to briefly discuss how those digits are stored in image files and how the choice of the file type can affect the results of the final image.

The Basic Choice, Lossless vs Lossy
There is a long list of image file types that are available, but only a few which are routinely used to record images within todays digital cameras. Most commonly these include JPEGs (.jpg), TIFFs (.tif) and various versions of RAW files. The choice of file type centers around two factors, image quality and file size and as is true for almost all of photography, the decision involves compromise. The highest quality image files (TIFF and RAW)

record the photographic data with what is referred to as "Lossless"
algorithms that retain all of the information from the sensor. The resulting images are of higher quality, with optimal tonal range and less noise and they are less subject degradation during editing or copying. The only disadvantages of lossless images are their requirement for editing to reach their full potential and their substantial size. TIFFs and RAW images fill memory cards quicker and take longer to save. The longer save times becomes a significant issue when capturing bursts of images such as when shooting wildlife or sporting events.

JPEG Have Trouble with High Contrast Situations

The opposite of "lossless" are those file types that achieve smaller files by compressing and discarding the data. These are somewhat

JPEGs struggle to Salvage Detail in Shaddows

comically referred to as "lossy". Within digital cameras, JPGs are the primary example of this compressed format. JPEG algorithms reduce file size by throwing out data and reducing the tonal depth. Depending on the level of compression, the results are files which are much smaller, allowing quicker recording of bursts of images and room for more pictured on the memory cards, but there is a significant price to pay for the compression. JPEGs and other Lossy file types have poorer tonal range with higher noise and artifact. They stand up much less well to aggressive editing or repeated copying. Depending on the image's intended usage, this loss of quality may not be important, but, as we will see, it is important to understand how the choice of original file type affects your ability to reach your photographic goal.

Those are the basics, now let's look at the individual file types.

Lossless Files

Doing It in the RAW

Capt. Zerubbabel's Rest

Many, but not all digital cameras have the capability of recording images in "RAW" format. RAW files record the "naked" data from the sensor without any loss of tonal depth or color information. They are totally unedited within the camera, although the image that you see on the LCD screen is actually a JPEG rendered within the camera to allow for quicker display and a better sense of how the final image might look. RAW images are like film negatives. They contain the maximum amount of information from the sensor, providing the greatest capability to undergo editing and adjustments of brightness and color balance. RAW files are substantially larger than compressed formats, but given the inexpensiveness of memory and the greater processing speed of modern cameras, this is not a major disadvantage.

Capt Zerubbabel Snow returned to Chesterfield after fighting in the Revolutionary War
He died in 1795 and lies next to his father, John Snow, in the West Burying Grounds.
"Winter is Coming !"

Perhaps the RAW file's greatest disadvantage comes as a consequence of its greatest advantage. The down side of the format's ability to be manipulated is that RAW files must be edited to reveal their true beauty. Unedited "raw" RAW files appear flat with low contrast and washed out colors. All the glorious potential is there but it must be brought forth in post-processing. For me this is he most exciting part of working with RAW files. It is akin to the darkroom magic of watching prints slowly appear from the developer bath, but if you want to snap the picture and be done, then RAW is not for you. All I can say is that if the quality of your images is important to you, then learning to work with RAW images is unarguably worth the effort.

Whose RAW is It Anyway?
There is no single RAW format. Each camera manufacturer has their own proprietary format and provides the software required to
edit it. Lightroom, Photoshop and many other photo editing programs can read

Spring Sentinel, Keene, NH

most of these formats, but every time Canon or Nikon comes up with a new camera or wrinkle in their format, the software companies have to scurry to catch up. The persistent question is, if a camera company disappears or looses interest, will support for their RAW files vanish as well. For this reason Adobe has created their own open source RAW format called Digital Negative ".dng". My standard workflow involves archiving the proprietary RAW files in a separate directory and then converting the files to DNGs that I use as my working images. It may sound complicated, but, happily, Lightroom can do it all automatically as I upload the files from my memory card.

TIFF
Tiff files might be more appropriately discussed among the various "output" file types, used to store and transmit images after processing, but some cameras have the option of recording images

Persistent Maple

in this format. TIFF (Tagged Image File Format) files are often used to store images since the image files are Lossless. Like RAW files, they retain all the information on brightness, contrast, color balance and saturation, but unlike proprietary RAW formats, TIFFs are universally accessible to essentially all editing software. TIFFs come in 8 and 16 bit versions with the same quality advantages in the 16 bit files. When used to save files edited in Photoshop, TIFF files have the ability to retain most of the layers created by that program, but this capability comes with a cost in file size. TIFFs can be gigantic, but this is less of an issue when the file is coming unedited directly from the camera. For me TIFFs are primarily useful when I want to send an easily readable, full resolution, edited image to a friend or client. When I want to record losslessly in the camera, I stick to RAW.

Lossy Files

JPG
JPG stands for Joint Photographic Expert Group and is the most

Central Square Gazebo, Keene, NH

common file type, found in essentially every digital camera. Again it uses a lossy algorithm to record image data into compressed files. JPEGs undergo processing within the camera including "Baking in" the color balance based on the camera settings. The resultant images can often look better than unprocessed RAW images, but this preprocessing limits the ability to make adjustments during editing in Lightroom or Photoshop. The level of compression of the JPG file can be adjusted, but in all cases the resulting images are reduced in tonal depth, usually from the RAW 12-16 bits to only 8. 8 bit images have only 256 tonal gradations for Red, Green and Blue as compared to more than 64,000 with 16 bit images. This difference may not be apparent in small images

RAW or JPEG, Makes Little Difference on the Web

designed for sharing on the internet, but it becomes strongly evident when they are manipulated in Photoshop or other programs, resulting in loss of detail, color banding and restriction of the ability to enlarge the image. Despite the loss of quality, JPEG is a popular format because the images come out of the camera requiring little if any processing to get an acceptable picture and because the image files are much smaller making them easier to store and to share.

The Quality Shows with Bigger Images

Size Matters
A full resolution, 21 megapixel RAW file coming from my Canon 5D Mark II is 25.8 megs in size compared to only 6.1 megs for a 21

megapixel maximal resolution JPEG. This means that more than four times as many JPEGs than RAW files can be stored on any memory card. It also means that, with the JPEG files, I can shoot a burst of 78 images before the camera will be forced to pause in order to buffer the data. In RAW I am limited to only 13 images in a burst. The choice of higher levels of JPEG compression has further impact on both the file size and image quality. At the highest degree of compression the file size drops to one megapixel, but, at a resolution of only one meg, image quality severely suffers.


Dancing Lady. When trying to anticipate the action, JPEGs allow longer bursts of images. For only the second time in years of shooting Stonewall Farm's "Dancing of the Ladies", I caught a lady in full kick.

The Choice
It really comes down to what you want to do with the image after it leaves the camera. Modern digital cameras are remarkably sophisticated and, in unchallenging situations, do an excellent job

Many cameras can record image in two formats

recording images in JPEG. If your only goal is to grab that picture of the ham sandwich you had for lunch, and transmit it as quickly as you can, to as many people on the internet as possible, then JPEG is the way to go. If your goal is to go beyond the mere FACT of the image, and explore the remarkable quality and capabilities of modern digital photography, then RAW is the ONLY choice. And, when the situation arises, during post-processing, you can always compress that delicious RAW ham sandwich into the tiny JPEG that it truly deserves.

Jeff Newcomer
partridgebrookreflections.com

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