Tuesday, November 9, 2010
Make Your Best Black-And-White
B&W: Where To Start • Histograms In All The Right Places • Diffraction Ratings • Enhancements • New Film Scanners
B&W: Where To Start
Q Many articles in OP suggest software programs to try for converting color images to black-and-white and discuss how to fine-tune the converted images. In your opinion, what’s the most beneficial starting point for capturing an image you intend to output in black-and-white: color or black-and-white?
A The best place to start, no matter what your intended output, is with a RAW-format, well-exposed, sharp color capture with controlled contrast. The more quality information you’ve captured, the more you can do with it. Why limit your options by capturing in black-and-white? If your camera has a black-and-white mode, you can use it like a Polaroid, but make your final exposure in color and in the RAW format. Any digital color capture can be converted to a quality black-and-white image file. There are lots of ways to make that conversion. Photoshop, of course, can make the switch while offering many processing and filter options. Another excellent program I use is Nik Silver Efex Pro (www.niksoftware.com). The software adjusts grain and emulsion sensitivity to match your choice of 18 different popular black-and-white films.
Histograms In All The Right Places
Q Is it possible to access an image’s histogram or information obtained from it after the images are downloaded into your PC? Such info would help a great deal in separating your good images from the ones that belong in the recycle bin.
Via the Internet
A The histogram is an important tool for digital photographers because it displays the range of tonal values in an image and alerts you to possible under- and overexposures. You can refer to the histogram on the LCD on the back of your camera for use in making exposure adjustments in the field. But the histogram is also, as you note, extremely useful during evaluation and post-capture processing of your photographs. The histogram that displays on the back of your camera and the one that comes up in Photoshop, Lightroom or most other post-capture editing software are essentially identical for any particular image. If your software doesn’t offer the histogram, you need to upgrade! A well-exposed photograph presents a histogram with data that doesn’t stack up against either wall of the graph; pixels displayed on the far right (whites) or far left (blacks) of the histogram have no detail. Alterations to exposure (such as bringing out detail in highlights and shadows) that you make as you work on your images will change the histogram. That’s another reason to work only on copies of your images and to save your “keeper” digital files in their original form.
Q I quickly found that if I stop down the aperture on my new upgrade lens much beyond f/11, there’s a significant loss of image sharpness. I use a tripod for all landscapes, so I surmise that diffraction is the problem. Are there diffraction ratings for individual lenses at various apertures?
Via the Internet
A Diffraction (distortion of the light rays entering the lens) is amplified at smaller apertures, causing significant loss of sharpness. It’s frustrating because we often choose smaller apertures to increase our depth of field, or in-focus range. While particular lenses may vary, most lenses gain sharpness as they’re stopped down two to three stops from the maximum ƒ-stop (ƒ/2, ƒ/2.8, ƒ/4, etc.). At ƒ/11, the sharpness should be excellent; there’s a small amount of compromise in sharpness at ƒ/16, but this coincides with a significant increase in depth of field. At ƒ/22 and higher, diffraction becomes a major detriment to image detail.
Due to individual variations, photographers should spend some time testing their own lenses to determine the point of maximum sharpness and depth of field for each one. It’s good to know this before you head out to the field! One source to use for lens comparisons is Photozone; it’s an excellent site with a vast array of lens tests online (www.photozone.de).
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