PhotonJohn Blog

The Digital Photo Pro posting The Digital Lens Revisited asks the question

In a world of marketing buzzwords like “optimized” and “designed for digital,” what’s really going on behind all the hype?

Here are some highlights from the posting. Read the posting for much more detail.

Crop Factors

If you use a 20mm film lens to project an image on a sensor that’s 16×24mm, it will behave like a 30mm. This is because the sensor is 1.5 times smaller than a 35mm piece of film, which is 24×36mm. To maintain a 20mm focal length, you’d need a lens with a focal length of 13mm. D-SLRs with sensors even smaller than 16×24mm will need even shorter focal lengths because the magnification factor is even greater

(Credit: Digital Photo Pro)

Chromatic Aberration

Because lenses disperse the different colors of light, it causes them to focus at different points (Fig. 3). Telephoto lenses and wide-angles with an inverted-telephoto design are especially prone to this phenomenon.

(Credit: Digital Photo Pro)

Ghosting and Flare

Canon’s Westfall explains, “One of the big differences between a digital SLR and a film camera is the fact that you’re using this image sensor with usually a low-pass filter in front of it. And it’s a shiny surface. So if you’re using a lens that isn’t optimized for an image sensor, there’s a risk—depending on which lens—that there will be some internal reflections that bounce back and forth between the image sensor and the element in question, which could be any element in the lens.

“What we’ve done over the last seven or eight years now is to work on developing coatings and make sure that the shapes of the individual lens elements are such that the flare and ghosting are minimized or eliminated.”

(Credit: Digital Photo Pro)

Bottom Line

At the end of the day—beyond all the technical details of why and how—it’s about quality. What are the best lenses for your camera, either the one you own or the one you rent when you go in the studio or out on location? What will get you the best possible images when you snap the shutter? No amount of editing will ever make up for lack of quality at the moment of capture.

Lenses designed for digital capture have many advantages over analog lenses, to be sure. Not in every case—there are exceptions, as we mentioned. But there are some good reasons why everyone is making them now and why you should consider using them if you haven’t already.

…John

The Digital Photo Pro posting Turbo’d Image Sensors updates the image-sensor technology story (See Image Sensors).

Today’s state-of-the-art image sensors are bigger, more powerful and capable of delivering better images than anything that came before. Manufacturers like Canon, Nikon, Olympus, Pentax and Sigma are putting out the most technically advanced models ever, and at their hearts are these new CMOS and CCD chips.

(Credit: Digital Photo Pro)

(Credit: Digital Photo Pro)

ABOVE: A CCD image sensor requires much more in-camera circuitry than a CMOS sensor. Each additional processing element draws power and also generates heat, which can contribute to increased noise, particularly in long exposures. As more pixels are crammed onto a sensor, these issues become ever more important.

(Credit: Digital Photo Pro)

The sensor is one of several microchips in a modern D-SLR. This high-horsepower Olympus sensor relies upon a similarly high-horsepower AF system to be able to capture the image at its fullest potential.

The posting calibrated my head when it pointed out that a single pixel is approximately 1/100th the size of this period.

…John

The Adobe white paper Non-Destructive Imaging: An Evolution of Rendering Technology is an interesting read.

With the rapid adoption of raw photography in commercial as well as amateur circles, the basic concepts of non-destructive imaging are increasingly important. But non-destructive workflows are not new. In this paper Peter Krogh leads you through a detailed outline of these evolving rendering technologies, and describes their relevance to every digital photographer.

SO WHAT IS DESTRUCTIVE IMAGING?

You might be tempted to ask, why destroy your photos? Aren’t you supposed to make them better? The word destructive is not referring to destruction of the photo’s goodness, but rather destruction of the original data in the image.

So while you may make a photo “better” by lightening up shadow detail, you may do it in a way that destroys the original information. This paper concentrates on ways to adjust photos without losing the original information.

The author makes a good case for using catalog-based Parametric Image Editing (PIE) software such as Adobe Lightroom. It enables generating an unlimited number of renderings of a photo. Rendering changes are stored in a catalog, applied to the previews, but not necessarily touching the original file.

Catalog-based PIE software that is integrated with a rendering engine can create these derivative products even more efficiently than non-rendering cataloging software. It’s frequently desirable to do a bit of touch-up to the image files on the way to output. Having that ability within the same program that groups and sends files to output lets the user integrate picture selection and image editing in a streamlined way.

I relied on iView MediaPro cataloging program (now Microsoft® Expression® Media) before Adobe lightroom was available. It has limited if any PIE capabilities.

…John

Just what is a GigaPan? It’s a device capable of capturing multi-gigapixel , explorable panoramas with most off-the-shelf digital cameras.

(Credit: Global Connection Project)

Check it out at the Global Connection Project.

I like doing panoramas using a Panosaurus mounted on a tripod.

(Credit: Panosaurus)

Combining high dynamic range imaging (HDRI), super-resolution (SR), and pano, is a winner, and time consuming. SR increases pixel count by 2x in each direction.

Using these technologies, I’ve created ((8 Megapixel camera) X (2x height) X (2x width) X ((4 pano panels) - (1 panel for overlap and cropping))) =~ 92 Megapixel image.

Here is a sample that has been cropped and optimized for the Web.

(Credit: Mary Telford, Fiber Artist)

Not bad for a Canon 350D.

I’d like to use a GigaPan to speed up the process and include more pano panels. Unfortunately, the GigaPan doesn’t yet support D-SLRs, so I’d probably use a Canon G9.

…John

The Kodak Thousand Nerds blog posting by John Compton and John Hamilton discussed how the new and improved digital camera Color Filter Array 2.0 sensor works.

Kodak has been working to improve sensor performance - so that image sensors can make better use of the light that comes through the lens. And after several years of work (involving a whole team of Kodak scientists), earlier today, Kodak announced a new image sensor technology that addresses this need directly, giving image sensors a 2x to 4x increase in sensitivity - the equivalent of one to two photographic stops.

Bayer Pattern

Sample pattern for new KODAK Technology

Unfortunately this promising technology will take some time to get into the consumer camera market stream.

…John