Q I want to take wildflower images with the background thrown completely out of focus. The problem is that my telephoto lens (75-300mm) is an ƒ/5.6 lens, and I fear that it won’t do an acceptable job of making the background nothing more than color. Do I need a faster ƒ/2.8 telephoto to accomplish this technique?
A Three factors come into play when attempting to blur the background behind a sharp foreground object: distance to the subject, focal length and ƒ-stop. The 75-300mm ƒ/5.6 lens will do a great job if you preset the lens to the 300mm focal length and the ƒ-stop to ƒ/5.6 (its widest aperture), then move yourself and the camera away from or toward the subject until you achieve the composition you desire.
The optimum effect would be achieved with a faster lens (ƒ/2.8) and an even longer focal length, such as 400mm. This combination will provide only a very small range of sharpness, so be sure your entire subject is covered. A “perfect” out-of-focus background can be achieved with a lens that features a perfectly round aperture (the opening formed by the iris), so as not to distort the out-of-focus renderings of the background. The distortions caused by the angled perimeter of the aperture in some lenses can be revealed in highlights in the background that take on the shape of the aperture. You can avoid this problem by shooting wide open whenever possible.
A New-Sized Sensor?
Q Do you know if any of the camera manufacturers has considered a D-SLR that would capture the entire circular image of the lens? The manufacturer could certainly make a circular sensor, but it would be large—43.2mm in diameter. And I would surmise that the mirror box and pentaprism would have to be correspondingly large. But all of the lens information could be captured, and the photographer would have the choice of a rectangular image (traditional 35mm format), a square image (à la Hasselblad) or anything in between, including any part (or all) of the circular image that was appropriate. The number of pixels would be huge.
A This is a good idea to improve quality and make digital cameras more efficient, but we need to keep in mind that the quality of the image from any lens falls off out to the edges of the image circle, as does the light. Leica, with its recently unveiled S2, will offer a medium-format-sized camera that looks and feels like a large D-SLR. Its 37.5-megapixel, 30x45mm sensor is 56 percent larger than a full-frame D-SLR sensor. I do like the idea of a square sensor that gives the photographer more creative options rather than being constrained to a set format. But the fact that the circular image a lens provides is just that—a circle—could make it difficult to get good quality at the four corners of the image.
An idea that follows logically is the need for digital projectors that project a square imaging area instead of confining the presentation of still images to horizontal format, which necessarily limits the size of the verticals.
A square format (achieved by increasing the vertical spread, not decreasing the horizontal!) would allow equal sized presentation of both vertical and horizontal images, an option we accomplish easily with slide projectors and transparency film. I occasionally take video in the vertical orientation because the subject dictates that composition; to process it, I rotate it in the computer with video-editing software so it can be shown the way I captured it.
Q This past July 4th, I photographed fireworks using a D-SLR camera. The resulting photos looked like they were taken at sunset instead of full darkness. The longer the exposure I set, the lighter they were. Is this because of Automatic White Balance? Should I have set it to “manual” and chosen “daylight”?
Also, during our vacation this fall, I was worried about being able to charge my camera batteries while we were camping without electricity. I found a device to plug into the cigarette lighter that produces 110 volts, has plug-ins on it and can handle up to 100w maximum power. The inverter worked great and charged my batteries while we drove through Yellowstone and Grand Teton National Parks!
Via the Internet
A It’s not about white balance, but it is about long exposures. The longer exposures picked up the scattered light in the sky. I use this technique to get a lighter sky when doing HDR images with very long exposures; it separates the subjects from the dark background. If you want the pure black sky, you’ll have to use shorter exposures. While this will capture fewer fireworks displays on each frame, you can take several and combine them using a Photoshop blend mode: “Lighter” in older versions and “Lighter Color” in CS4. This technique also works well to combine individual shots of lightning. In either case, if you have a foreground, you’ll need to set your camera on a tripod and capture every image exactly the same way.
Sharing CF Cards
Q I have a CF card with pictures on it from earlier use in a small camera. I used the card in a Canon 20D. The photos are visible on the camera back, but I’m unable to transfer them to my computer using a card reader. A message displays that the card is “unformatted” and asks, “Do you wish to format?” I, of course, said “no” but wonder if there’s any way to get these photos off the card into the computer.
Via the Internet
A It’s not a good idea to use the same card in different types of digital cameras because they’re likely to utilize different file formats. Usually it works out okay, and the computer will be able to recognize the different folders, but occasionally the computer, via the card reader, will reject the data. If this happens, you have a number of solutions.
If you’ve loaded the software that the camera manufacturers provided, the chances of the computer being able to read the imaging formats is far greater. Two examples are Canon’s DPP (Digital Photo Professional) or Nikon’s Nikon Capture NX 2. If you don’t have the software, download it from the manufacturer over the Internet, often free of charge. Another option is to connect each of the cameras directly to the computer and download the images without the card reader interface. The data on the card can be retrieved using an image data-rescue program, such as Lexar’s Image Rescue 3 and WinRecovery Software’s CardRecovery (for Windows) or CardRescue (for Mac OS X), which will convert the files to a common picture format.
Wishing On A Starburst
Q Recently, I made my first attempt at photographing city scenes at night. I went to the local town center where they had a huge lighted holiday display. I shot at ISO 100 and ƒ/16, and most of my exposures were between 5 and 8 seconds long. When I downloaded the photos to my computer, I noticed that almost every light had a 10-point starburst coming from it, both from the decorations and from the streetlights. I used no filters. Is this a normal occurrence with nighttime photos? If not, what would have caused this starburst effect?
A The two causes of the starburst effect are wide-angle lenses (28mm and wider) and small apertures such as ƒ/11, ƒ/16 and ƒ/22. Anytime this combination is aimed at a small, bright light source, you’ll get a starburst. It works with lights at night and with the sun. The secret is to know the effect will happen and use it to compositional advantage. The starburst itself varies from lens to lens, so test yours to understand the likely outcome with each option.
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.