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Tuesday, January 1, 2008

Catching Lightning In A Camera

Lightning Trigger‚ Printer Basics, D-SLR Advantages, Zooms Vs. Fixed-Focal-Lengths, Upsizing Files

Zooms Vs. Fixed-Focal-Lengths

I’ve been told that fixed-focal-length lenses are sharper than equivalent zoom lenses. Does this mean I have to buy and carry a lot of lenses to get the sharpest images?
C. Crider
Detroit, Michiigan

The potential of single-focal-length lenses allows for some advantages in the area of edge-to-edge sharpness, but the disadvantage is that you have to change position or lenses to optimally frame your subject, and yoy have to carry a lot of lenses. Most pros rely on zooms for most focal lengths other than extreme telephotos and extreme wide-angles. Today’s zooms are capable of performance very close to individual focal lengths within their range. The limiting factor is photographer technique. By working smartly with a zoom, a photographer can get the best performance from it—use a tripod and an aperture that maximizes sharpness from that lens, usually ƒ/8 to ƒ/16. Keep in mind that zooms are weakest at their maximum aperture and extreme focal lengths.

Upsizing Files

A lot of agencies request a minimum file size of 50 MB (8-bit flattened TIFF) for digital files, which will lead to upsizing the images with software. My guess is that more than 90 percent of images rarely will be printed in larger format than A3 (magazines, books, brochures, ads, etc.), which means the 50 MB file normally will be downsized before use. Theoretically, the quality of the final print will suffer from being upsized and then downsized, instead of being downsized once from native format. Why don’t agencies accept the native format (read a RAW file converted to TIFF) and upsize the file when it’s needed?
Swedish subscriber to OP
Via the Internet

Agencies require images to be submitted in their native capture size at 300 dpi. They don’t want you to upsize files. Top stock agencies that serve commercial clients require photographers to use a D-SLR of 10 or more megapixels and won’t accept images captured with lesser-quality cameras unless they’re to be used editorially. The 50 MB size generally refers to film captures scanned by a quality scanner. The end result from a 35mm image scanned at 4000 dpi is in the 50 MB range.

Agencies want the best-quality file that can be upsized when needed for commercial use and still be downsized for small publications or the web. An image that has been upsized prior to submission won’t render a quality result. Trust me, the agency will know if you’ve upsized (interpolated) the image. Metadata tells a lot about an image.

Other factors the agency is sensitive about are oversharpening and oversaturating in the attempt to optimize the image before submission. Use restraint.

For information about upcoming seminars and digital-imaging workshops, visit www.geolepp.com. If you have any tips or questions, address them to: OUTDOOR PHOTOGRAPHER, Dept TT, George Lepp, 12121 Wilshire Blvd., Suite 1200, Los Angeles, CA 90025-1176 or online at www.geolepp.com.


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