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Tuesday, April 1, 2008

Slicing Up Depth Of Field

Formulas And Focus • Size, Weight And Will it Float? • From JPEG To RAW • Charging Overseas Without A Charger • Bifocal Focus

From JPEG To RAW If you’re shooting with a higher-end camera like a Canon 5D or Nikon equivalent and you’re shooting in JPEG, do you really gain anything by converting the 8-bit JPEG image to a 16-bit one in Photoshop CS3 and saving and editing it as a TIFF file?
D. Blackburn
Los Angeles, CA

When you capture the image in JPEG, it’s an 8-bit file, which means it contains less information than if you had captured it in RAW (usually a 12-bit file). Converting the 8-bit file to a 16-bit one in Photoshop doesn’t add information; if you want the best quality, you must capture in RAW. There’s an advantage to converting a JPEG to a TIFF or a PSD (Photoshop file) before you begin to work on it. As JPEG files are saved, they lose data each time. TIFFs and PSDs, however, maintain their quality and layer structure.

As a side note, CS3 lets you open JPEGs and TIFFs in the RAW converter. This doesn’t add any information or enlarge the file, but it does enable you to use some of the useful tools found in the converter to improve your images.

Charging Overseas Without A Charger
I’ll be travelling to England, France and the Netherlands for 11 days this spring. I have a Nikon D80 and a Nikon D100 and two batteries for each. Should I carry the chargers or hope the batteries will last? Will I need adaptors for the chargers to work in Europe? Are there new security concerns with the lithium-ion batteries?
T. Campbell
Via the Internet

Always carry a charger, even if you think you have enough batteries. Batteries fail. They don’t last as long in cold temperatures. You may end up taking more pictures than you expected. And you can’t rely on finding the batteries or the charger you need in foreign countries. Check your charger to see if it has a dual-voltage capability; if it does, it will say 110/220, meaning it will automatically accommodate either voltage. You’ll need a different plug adaptor in most countries outside the United States. These are easily purchased at travel/luggage stores or online.

Effective January 1, 2008, the TSA prohibits transporting “loose” lithium batteries in checked baggage. They must be secured in separate packaging, or tape must be placed over their contacts. The TSA recommends that batteries and battery-operated equipment be carried in your carry-on baggage. You can learn everything you need to know about traveling with lithium-ion and primary lithium batteries at www.tsa.gov/travelers/airtravel/assistant/batteries.shtm.

Bifocal Focus
I’m having major difficulties adjusting to the world of bifocal lenses as related to photography and computers. I’m going to have to replace my current prescription and am hoping you might be able to give some advice, since you also wear eyeglasses. Contacts aren’t an option, and I have a very strong prescription.

I currently wear bifocals, and have had problems focusing my cameras ever since I had to start wearing them. I got a prescription specifically for the computer work, as I felt that another focusing zone would just create more difficulties. That solved the computer problem, but focusing a camera still remains difficult.
D. Gullickson
Fairbanks, Alaska

Many photographers aren’t aware that the camera viewfinder can be personalized to their vision. The part of your glasses that’s used in focusing an SLR camera is the area that’s corrected for distance. This is usually the largest section of a bifocal lens. With the camera autofocused on a subject, look into the viewfinder through the upper area of your lenses and adjust the diopter until you see a sharp image. The idea is that you know the camera is delivering a sharp image to the viewfinder, so adjust the viewfinder until it delivers a sharply focused image to you.

The close-up section of your bifocals will enable you to read the dials, settings and LCD. I have, like you, a pair of glasses with large lenses dedicated to computer work. I might add, however, that my wife has a tiny set of trifocal lenses she uses for everything from photography to needlework to computers to driving, so perhaps it’s a learned skill!

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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