Digital Infrared, Part I: Making Images

written by: Lloyd Chambers

Digital infrared photography is far more convenient and practical than film-based infrared shooting, but it remains technically challenging. By understanding exposure and white balance, hot-spots, backfocus, and sharpness, you’ll avoid frustrating trial and error and quickly begin to enjoy excellent results. I’ve been shooting digital infrared for half a decade now, and those years of experience have taught me a great deal. In this article, I share my key discoveries that make shooting digital infrared images a productive and satisfying effort. A follow-up article will delve into post-processing techniques. Infrared is the spectral band beyond deep red, starting at around Read more »


Digital Infrared, Part II: Post-Capture Processing

In part II of this series: Developing the potential of your infrared captures
written by: Lloyd Chambers

Unlike color images, which can satisfy as JPEGs right out of the camera, digital infrared images almost always benefit from post-capture adjustments that bring out their unusual qualities. After all, infrared is “beyond visible,” so there is no right or wrong approach, unlike color photography. To produce compelling images, this post-processing should be done with an open mind for artistic possibilities. Infrared by its nature has no real color or brightness; unlike regular color photography, the human eye offers no guidance as to how infrared should be rendered. On the photo- graphic continuum, visible-light color photography maps most closely to Read more »

Optimizing Photoshop

The Best Software/Hardware Configurations Can Make a Huge Speed Difference
written by: Lloyd Chambers

Ad-hoc and generalized guidelines exist for optimizing Photoshop performance, but relating a particular workload size to memory and scratch volume requirements is usually left as an “exercise for the reader. I will present specific and actionable research into Photoshop CS4 performance on the Mac Pro and MacBook Pro (most of which applies to Windows PCs as well). Processing time can be cut by as much as 80% by appropriate choice of the amount of memory and the speed of the scratch volume, and by some key configuration parameters of Photoshop itself. Compare that to the modest 14% speed difference and Read more »


Balancing Focus for Peak Sharpness in the Presence of Field Curvature

written by: Lloyd Chambers

Careful choice of focus can help or hurt image sharpness. This is a companion article to Zeiss Touit Lenses for Sony NEX or Fujifilm X  (PT Sept/Oct 2013), but the discussion here applies to lenses in general on any camera.  See also Field Curvature in PT Sept 2009. Most lenses exhibit field curvature, which can result in less sharpness than expected across the frame, often in the mid zones or corners.  A typical complaint is “soft corners”, but with many lenses the lack of sharpness is entirely due to focus, not inherent lens unsharpness. Typically, a focus position can be Read more »


Zeiss Touit Lenses for Sony NEX or Fujifilm X

written by: Lloyd Chambers

DSLR users know that “good glass” is necessary no matter the sensor size, and that’s where mirrorless cameras suffer most, with limited lens selection that is often of marginal build quality and too often modest optical performance. Yet demands on optical quality tend to be higher for smaller sensor cameras due to the greater photosite density, at least for similar levels of high quality detail in the same number of megapixels (e.g. 24 megapixels from full-frame vs the smaller APS-C). Enter the Zeiss Touit lens line for Sony NEX and Fuji- film X. The optics in the Touit lenses are Read more »


Field Curvature

How to analyze and work with this ubiquitous lens problem
written by: Lloyd Chambers

Field curvature can make a sharp lens look soft when the wrong assumptions are made. Understanding how sharpness varies throughout the frame will help you get the most out of some excellent lenses that might not test well on flat (planar) test targets. In previous articles, I’ve explored how diffraction and focus shift can lead to images with degraded contrast and resolution. As if that wasn’t enough to think about, another confounding factor is present: field curvature. In the ideal world, a flat (planar) surface would be imaged onto a flat sensor, and a crisp image would result (a “flat field” Read more »


Small Sensor Cameras Make the Grade

written by: Lloyd Chambers

Introduction The fast-paced digital photography market kicked into high gear beginning with cropped-frame sensors (Nikon D1, 1999), and then quickly moved to full frame (Nikon and Canon). But disruption is in full progress, and if Canon and Nikon aren’t careful, companies like Sony and Olympus could eat their lunch. Hugely improved sensor quality coupled with market demand for smaller, lighter and more convenience now drives a move back to smaller sensors, accompanied by an impressive assortment of lenses, including support from stalwarts such as Zeiss and Schneider. No longer are smaller sensor cameras mediocre solutions for amateurs; professional photographers are Read more »


Focus and Practical Depth of Field

written by: Lloyd Chambers

Especially with high-resolution digital cameras, full-image sharpness is limited to a narrow zone even when stopped well down, demanding careful attention to detail for best results. My recent PHOTO Techniques articles have explored how diffraction, focus shift, and field curvature all can lead to blur. The focus shift and field curvature issues can be mitigated by increasing the depth of field, so long as diffraction is held at bay by not stopping down too far. Depth of field means “the zone of reasonably sharp focus,” with the term “sharp” being both arbitrary and ambiguous. The word “zone” is truer to reality, Read more »


Diffraction: Resolution taxed to its limits

Many think a higher f-stop automatically means greater detail; they're wrong
written by: Lloyd Chambers

To fully exploit the sensor resolution of today’s high-resolution digital cameras, photographers must arbitrate the conflict between diffraction and lens performance/depth of field. Understanding how diffraction affects image quality will enable you to extract the best results possible from your camera. Today’s digital cameras offer steadily improving color accuracy, dynamic range, and bit-depth, together with the crowd favorite— ever-higher megapixel counts. Yet actual image detail is constrained by optical performance: overall sharpness and depth of field require stopping down, but stopping down too far degrades image quality due to diffraction, an optical effect that puts an upper bound on resolution. Even worse, Read more »


Field Test: GPS Units from Canon & Nikon

written by: Lloyd Chambers

Canon and Nikon both offer GPS units for both stills and videos. What are the practical aspects of using these units during shooting and what uses and considerations are there for GPS data? Introduction Both Canon and Nikon offer GPS units that can be connected to their respective brand DSLR cameras, with recent-models having built-in menu support with recording options. With both brands, the GPS units are add-on devices that are designed to mount in the hot-shoe of the camera, though both can be mounted to a belt or otherwise with a cable. With the Nikon GP-1 a cable is Read more »