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Tuesday, September 1, 2009

Do I Need Permission?


Commercial Vs. Editorial Uses • Sharp To The Edges • Extended Macro • TILT!

Labels: How-ToColumnTech Tips
Sharp To The Edges
Q
I understand the concept of depth of field and use small apertures to increase that portion of the photograph that’s in focus. However, with close-up photography, such as a flower, most of my photographs end up with the outer portions out of focus. I’m using a long lens mostly. I know that I can pull back and get more of the flower in focus, but I lose detail when I do this. Do you have a solution on how I can increase the “width of field” to improve my still-life photographs?
R. Fisher
Via the Internet

A From your question, I surmise that you’re using a telephoto lens that wasn’t designed for macro photography, perhaps adding extension tubes to enable you to focus closer. This combination will often exhibit good sharpness in the center, but less resolution at the edges when used for close-up macro photography. Note also that a characteristic of better-grade (more expensive) lenses and extenders is a greater range of sharpness to the edges. Even so, a better choice would be a macro telephoto lens, such as a 200mm or 180mm macro. These lenses have what we call a “flat field” rendition. The image is especially sharp from edge to edge.

By its nature, using a telephoto for macro means you have less depth of field to work with. To extend the range of depth of field, use a compositing technique with software called Helicon Focus (www.heliconfocus.com) or a new Blend Mode, Auto-Blend Layers, found in Photoshop CS4. From a tripod, take several captures, moving through the image from foreground to background, manually refocusing for sharpness at each plane, overlapping the areas of sharpness from image to image. The software will combine these “slices” into one sharply focused image by retaining all in-focus elements and discarding those that aren’t sharp.

Extended Macro
Q
I’m looking for more magnification from my Canon EF 100mm f/2.8 macro lens. Can I use a 1.4x or 2x tele-extender with this lens?
K. Kilsch
Via the Internet


A The 1.4x and 2x tele-extenders won’t physically mount directly to the EF 100mm lens, and Canon doesn’t advise you to do this. But there’s a way around it. Place a 12mm or 25mm EF extension tube between the extender and the lens. The result will be slightly increased magnification due to the extension tube and either 1.4x or 2x magnification from the tele-extenders—the equivalent of a 140mm or 200mm macro lens. With mid-range ƒ-stops like ƒ/11, the quality will still be excellent.

You’ll be giving up a few things. The autofocus will function but won’t be accurate, hence, unusable. Exposure will be best determined by taking a test shot and using the histogram on the back to determine what, if any, fine-tuning is needed.

At this magnification, flash is a necessity; the best options are Canon’s MR-14EX or MT-24EX macro flashes.

TILT!
Q
Since I’ve switched from 4x5 to a digital SLR, I miss the view camera’s ability to control the plane of focus. I know you can buy tilt/shift lenses, but they’re expensive and come in limited focal lengths. With a view camera, you can control the focal plane not only by tilting the lens, but also by tilting the film plane. Has anyone thought about making a D-SLR with the ability to tilt the sensor for a similar effect? That should work with all your lenses. (I know the image circle of a D-SLR lens is too small to allow shifting the lens up and down, but tilting should work.)
S. Hinch
Via the Internet

A There are still a few photographers out there who don’t want to give up the perspective controls and the amount of data offered by large-format systems. Digital scanning backs for medium- and large-format cameras are very expensive and relatively slow. Those who have switched to medium- or small-format digital usually embrace the tilt/shift lenses offered by Nikon and Canon. At this time, there are no digital cameras with a moveable sensor, but who knows what’s coming next?

There are alternatives. Zörk (www.zoerk.com) makes a pro shift adapter that attaches to other makers’ lenses. It has a range of tilts and shifts, but, as you mentioned, most lenses don’t have an image circle large enough to accommodate significant lens movements. Zörk also offers a medium-format enlarging lens (80mm) that works well with D-SLR cameras. Or, dust off your 4x5 view camera and replace the ground glass with an adapter from Fotodiox (www.fotodiox.com) that allows you to attach either a Canon or Nikon D-SLR to the back. The result won’t be as sharp as a tilt/shift lens, and you’ll be limited to the focal lengths that you own for your large-format camera.

My preference is to extend the useful range of the available tilt/shift focal lengths (Canon offers four and Nikon three) by combining them with tele-extenders. I have on many occasions added the 1.4X or 2X tele-extender to the Canon 90mm tilt/shift with excellent results. The lenses are expensive, especially the latest versions from Canon (17mm and 24mm), but are well worth the investment for serious landscape and architectural photographers.

For information about upcoming seminars and digital-imaging workshops, visit www.georgelepp.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.georgelepp.com.

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