Imaging the Natural World

Image Resolution and Image Size

The question I get asked more often than any other in my digital imaging and Photoshop classes is “How big can I make a print from a file from my digital camera?” I will answer the question specifically, but first consider the factors that influence the answer to the question.

Native Resolution: This is the actual capture resolution whether by scanner or camera sensor. It is sometimes represented by file size, but specifying in terms of mega-pixels or pixel dimensions is more intuitive. In general, the greater the native resolution, the larger the size of the final printed image can be. However, it is important to note that camera sensors of the same pixel dimensions (resolution) do not necessarily yield images of the same quality. For example, sensors of smaller physical size will be more susceptible to noise than larger sensors with the same mega-pixel resolution.

Image quality: For a given “native resolution” the better the quality of the image, the more tolerant it will be to “up-sizing”. In many respects this is no different than the film world when the quality of the negative had much to do with how much enlargement the image could tolerate. Image quality depends on the quality of the equipment used to capture it, proper exposure, camera steadiness and the photographer’s technique.

Viewing distance:The distance at which a given image is viewed influences what the acceptable print resolution can be. In general, photographic prints in the traditional sizes of 8×10 to say 16×20 are viewed at roughly arm’s length or about three feet. Much larger images (panoramas often may fall into this category) are usually viewed from greater distances and may be rendered at a lower image resolution than the smaller ones.

Care in post-capture processing of the image: Even a high quality native image can be rendered unsuitable for large size prints by poor techniques durng post-capture processing. Techniques include such standards as tonal range adjustment, resizing and sharpening.

Viewer discernment: The judgment of photographic quality is truly in the eye of the beholder. For this reason alone, there is no universally accepted definition of an image resolution that equates to photographic quality. I have demonstrated this in my classes. I have shown prints of image resolutions from 180 ppi to 340 ppi. Seen individually, most students stated that they found the images of “photo” quality. However, when they see the prints together, they can easily distinguish between the one printed from the highest image resolution and the one printed from the lowest. In some cases, they can even put them in the correct order of increasing image resolution.

Image subject: This also is subjective, but the subject matter portrayed in the image can determine how large it can be printed. For example, still life photographs portrayed in an “arty” way, can sustain a greater degree of enlargement than images where the expectation of fine detail will require greater image resolution.

Media: The media used for printing can have a strong influence on the size a given digital image can be printed to. For instance, I have seen images printed on highly textured canvas that look wonderful, but fail when printed on a glossy photo paper or fine art media.

So there you have it; a lengthy list of considerations that impact the answer to the question of how large a print can be made from a given “native capture”. Now let’s talk some specifics.

Camera resolution required to make common print sizes as a function of image resolution

The data in the table presents a pretty discouraging picture. It is often claimed that image resolution must be 300 dpi to achieve “photo quality”. Does that really mean that we can only print to an 8″ x 12″ with an 8.3 Mega pixel camera such as the Canon30d as the above table suggests? In my experience, certainly it does not. I routinely print images from a Canon 30d to 16×24 and, on occasion, even larger. This is where all of the factors I listed above come in to play. For instance, I have settled on 240 dpi as my standard for most of my digital images from the Canon 30D, this allows me to print up to 9.7×14.6 without interpolation (ie using the native capture).

In addition, I have found that if the original image is of high quality and I take care in post-processing, that I can up-size or interpolate using Adobe Photoshop so that the final image size is 2 to 2.5 times the native size or in the case of my Canon30d, up to 24×36. In fact I prefer these images to those from my chromes scanned at 3600dpi and printed to the same final print size. So, the numbers in the table don’t present such a discouraging picture after all!

To determine your own “comfortable” image resolution, I suggest you select one of your best digital images. Judge it by critically inspecting it at 100% in Photoshop. Print that image using several different image resolutions withoutinterpolation. Compare the images and select the resolution that satisfies your expectation of image quality. Once you have selected your personal image resolution, print the same image up-sized. Try up sizing in the range of 1.5x to 2.5x using Adobe for the interpolation. Compare the up-sized images to establish your personal limits for image up-sizing.

Determining your personal working image resolution and up-sizing limits is exercising one of the exciting aspects of digital imaging: ultimately you are in complete control of the resulting image and have no one to satisfy but yourself.

Tides and Landscapes

Successful photography along shorelines that are impacted by tides is dependent on planning your outing with accurate information on two vital pieces of information about the shooting location:

1. Curent tide height and direction
2. Current lighting conditions

Of course, the weather is also a factor!

In the past I have relied on tide prediction software on my desktop before heading for a photo destination. Not having that capability in the field prevented spontaneous changes in my game plans.  Later I found an application for my pocket PC which allowed spontaneous in-the- field updating. The latest in the evolution is the “Tide Graph” software available as an iPhone application from the iTunes application store.

Hopewell Rocks, New Brunswick

This  photograph of the Hopewell Rocks in New Brunswick is an extreme example of the need for tidal information. The rocks are located in the Bay of Fundy which boasts  the greatest tides in the world. The seabed is open at low tide and provides opportunities to photograph the rock formations. At high tide, they become small islands in the ocean. In this shot, the tide was perfect for strolling the ocean floor but the harsh sunlight left much to be desired photographically. A future post will discuss another iPhone application I

Main Display Page

have found to predict sun and moon positions.

The main display page of Tide Graph is shown in the adjacent image. It contains all the information you need to time your photographic outing with respect to the tides. The information can be updated for a given day by dragging the target circle on the tide graph. Other locations and dates can be selected by tapping the current tide station displayed on the main display. Tapping the small map icon will bring up a Google earth display of the active location.

This is truly convenient application for me as I never travel without my cell phone and the price is right at $.99. Try it, you’ll like it!

Pulling the Trigger

Confrontation Over Fishing Rights

I have had the great fortune of two separate visits to McNeil River Game Sanctuary in Alaska to photograph the brown bears. Both of those visits were in the era before digital photography had come of age. Besides the cost of the trip, there were severe weight restrictions for each passenger on the DeHaviland Otter that flew us to the camp site. All camping equipment and food as well as photographic equipment had to be brought in for the week-long visit and the state recommended carrying an additional week’s supply of food in case the plane could not return on schedule to pick us up.

While film weight was not a big factor, the cost of film and the fact that any resupply was at best 100 air miles away from camp certainly was a concern.  I don’t recall how many rolls of chrome film I brought with me on each of the trips, but I do remember anguishing over how many of each emulsion type and ISO rating to include.

When I actually got to shooting, I was always faced with decisons on which film to load and then the more daunting prospect of having to cut back on my shooting when I realized that half way through the vistit I had chewed up more than two thirds of my film. This made pulling the trigger a difficult decision and I had to begin passing up great shots in the hopes that something better was yet to come.

I See You Says One Cub at McNeil River

I would welcome an opportuntiy to visit McNeil River again with my digital equipment.  Just think of some of the great advantages the digital era has brought. Instead of carrying multiple film types, I can now dial in an appropriate ISO for the situation at hand .  As my flash card fills with images, I can delete the “losers” and make more room for “keepers”.  As the cards  further fill up, I can transfer the images to a portable storage device and reuse  the cards.

The digital world has indeed freed me from the anquish associated with tough decisions when faced with limited supplies of film and once-in-a-lifetime photographic opportunities like those at McNeil River. That being said, for photographers like me that have only recently weaned away from film, pulling the trigger still presents challenges, but that is yet another tale.

Don’t Sweat It! The Camera That Is.

Several years ago I was hiking a trail along the north rim of the Grand Canyon. An unexpected severe thunder storm prompted me and several others caught in the open to seek shelter under a rock outcropping. It was crowded and we quickly became “close” friends. To protect my cameras from the elements I covered them with my rain jacket. I don’t know if it was the humid conditions caused by the weather or my body that caused both cameras to malfunction, but malfunction they did. When the storm ebbed and I uncovered them, both electronic displays were flashing and neither camera would function.

View from north rim of the Grand Canyon

How I wished  I had an “old fashioned” mechanical camera at that point. The photographic opportunities created in the canyon by the ebbing storm were fantastic!

It’s that time of the year in the north east when capturing a winter scene of new fallen snow prompts us to venture out in the cold with our camera gear. Going out into the generally dry winter air is not a problem for our equipment but bringing it back  into a warm and  humid indoor environment invites condensation on both the outside and inside. This is particularly a problem if you want to use the camera gear immediately when your lens and viewfinder will promptly fog up or , like my Grand Canyon experience, not work at all.

There is an easy solution. Place your camera inside a large plastic bag before bringing the cold camera indoors. Let the condensation form on the outside of the bag insterad of on your camera equipment while it warms to room temperature.

Adobe Photoshop CS3 for Intermediate Users – Going Beyond the Basics

THREE RIVERS COMMUNITY COLLEGE

This course assumes the students have taken the beginners course or have already mastered the basics of Photoshop CS3. We will create custom work spaces for Adobe Bridge and Photoshop that will allow improved performance. We will use the features of Photoshop to create
slide shows, PDF presentations and the merging of images into a single one. The course will cover the use and editing of metadata associated with images. We will work with adjustment layers to fine tune images and use layer masks to limit the extent of image adjustments.
The Adobe RAW processor will be used to process RAW format image files to get the very most out of the data included will be the double processing of RAW image files. Sharpening strategies and preparing an image for printing will be covered. Automating Photoshop routines
using actions and droplets will be explored. Strategies for file structures and workflow will be reviewed and the subject of color management will be introduced.

Adobe Photoshop CS3 for Beginners – The Help You Need to Get Your Start

THREE RIVERS COMMUNITY COLLEGE:

Prerequisite: Moderate Windows experience.
Books purchased through bookstore.
This course assumes students have no prior knowledge of Adobe Photoshop. Photoshop will be used to provide a thorough understanding of the basic construction of digital images. Setting
of Photoshop, Adobe Bridge and Adobe RAW processor preferences will be included and the default workspaces of each of the program elements will be used. Adobe Bridge will be used to upload images to the computer and to review, rate and label images. Bridge will also be used to catalog images for quick fast retrieval. The student will learn how to make contact sheets of images and create “picture packages” for printing. Basic digital image adjustments including cropping, tonal range adjustments, color correction and sharpening will be included.

Backyard Safari

Downy Woodpecker Canon 1D Mark III, f/8.0@ 1/60th ISO1250 600mm with 2x Extender

Northern Cardinal Canon !DMark III f/5.6 @1/200th ISO640 Canon 6000m with 1.4 Extender

Sparrow Canon1D Mark III f/5.6 @1/250th ISO 640 Canon 600mm with 1.4 Extender with fill flash

Today in southeastern Connecticut began with an ice storm that coated the trees, cars and ground. Shortly after my first cup of coffee the power went out and remained out for the next seven hours. The ongoing storm made my backyard feeders very active with cardinals, jays and woodpeckers among others.

With the heat off in the house  and all necessary chores on hold because of the lack of power, I decided to occupy my time with a little backyard bird photography. It was sleeting pretty hard and I remained inside aiming my lens through the kitchen window.

Eastern Cardinal Canon 1D MarkIII f/5.6 @ 1/200th Canon 600mm with 1.4 Extender using fill flash

While the weather was hardly safari -like I thought the icing on the branches provided an interesting additon to some rather ordinary birds.

Blue Jay Canon 1D MarkIII f/8.0 @ 1/160th Canon 600mm lens with 2X extender using fill flash

Mystic 4 Annual Event of Learning & Networking

MYSTIC HILTON, MYSTIC CT

“What every dealer DOESN’T want you to know.”

Do you perform any “in house printing?” How much ink and media do you waste. Pro Digital Gear, a leading nationwide Epson Prographics Dealer, will enlighten you to a simple, easy to use, color management work flow, that will save you money and time! This seminar will explain why you must calibrate your monitor and how to perform this calibration, assign monitor and printer profiles, how to “soft proof”, and the mechanics of an Epson Printer Driver. You will learn what a “RIP” really is and whether or not you need one. All attendees will receive a Pro Digital Gear/Epson Gift Certificate that has a $50.00-$100.00 value towards specific Epson Pro Products. This will be an educational seminar you won’t want to miss!

The Wimberly Tripod Head

Last night I was enjoying an old  (May 1988) copy of my favorite photographic magazine “Outdoor Photographer” . I always marvel at the change in equipment that time has wrought. This issue didn’t even mention the word digital let alone have any digital camera ads!  

An article that I found particularly interesting was written by Frank Oberle on his techniques and equipment for capturing eagles in flight. What I focused on was not the camera or lens that he used at the time, but instead his preference for the use of a pan head over a ball head tripod head for his long lens . It made me think how much I have taken for granted the contribution of my gimbaled Wimbelry head to successful in-flight bird photography.

I use the Wimberly to mount a 600 mm f/4.0 Canon lens and would be lost without it.  As much as it helps in obtaining photographs of birds in flight, it gives great peace of mind regarding control of that heavy lens. Before acquiring the Wimberly, I too used a three axis pan head and found that with careful tension on each axes, I could track moving birds but the fear was always that I would lose control of the forward-heavy lens and have it crash against the tripod or even worse the ground. This concern was always a distraction when I was shooting. The beauty of the gimbaled mount is that when properly balanced, the lens/camera assembly simply “floats” with no fear of loss of control.  An added benefit is that it allows swift and smooth tracking of animals in motion in all three axes.

By Way of Introduction

Although I have photographs of me holding a brownie box camera at about the age of eight my serious association with photography began when I embarked on a year-long visit to Africa with my father. He bought me an Agfa Super Silette which I used to document my adventure.  More than fifty years later many of those chromes still exisit today. If I am ambitious, I may post some of them to this blog someday.

Afa Super Silette

I acquired my first SLR in 1966 and shortly after that established a black & white and color darkroom. I spent many enjoyable hours in that “closet” (and quite a few frustrating ones too)  teaching myself the craft of photography.

My attraction to nature and wildlife photography began with my first trip to Alaska with two friends. The hi-light of the trip was our visit to Denali Park where I had my first opportunity to photograph moose, brown bear, caribou and dall sheep.  One of my most vivid memories from that trip was crossing a glacial stream to climb Dall Mountain (appropriate enough) to photograph a group of dall sheep that we had spotted in the distance. We waited as they approached us in eager anticipation of some great images. Our world was enveloped in total silence except for the sound of their hooves on the mountain trail and their munching as they grazed.  While waiting, we enjoyed our own snack of wild blueberries.

The serenity of that place and the anticipation as the sheep approached hooked me for ever.