|A finished, retouched, focus-stacked image of a tulip bed in Butchart Gardens, British Columbia, reveals tack-sharp detail from the closest blossom to the back row. Nine images were captured with a Canon EOS 5D Mark III and EF 180mm macro lens, 1⁄250 sec. at ƒ/11, ISO 200, and composited using Zerene Stacker software.|
Images In Bloom
Q I'm using focus-stacking techniques for my macro images and often I get a halo around some sharp parts of the image. Is there a way to prevent this from happening, or at least dealing with it later in my software?
A Focus-stacking is a technique that expands depth of field in an image. To accomplish it, the photographer frames the image, then captures a series of in-focus slices, moving through the subject and refocusing from foreground to background. When composited in focus-stacking software, only sharp areas are retained, yielding an image that's sharp from foreground to background.
One of the challenges posed by focus-stacking captures is that when an object close to the camera is rendered out of focus, it blooms—that is, as it gets fuzzy, the image gets larger. As they grow, foreground elements can interfere with efforts to attain sharp captures of background areas. This effect is emphasized when using a longer focal-length lens or when trying to focus-stack a relatively large area, and can be exacerbated by significant tonal differences between the foreground and background.
For landscape photography, we use focus stacking in situations where there are important subjects in both foreground and background. Think, for example, of a field of spring wildflowers stretching to a backdrop of snow-covered mountains. To tell the whole story, we want both the flowers and the mountains tack-sharp. If a foreground object, such as a flowering bush, obstructs the distant background, the blooming effect may occur: The foreground object becomes out of focus, obscuring and inhibiting sharp capture of the background behind it. Since chopping down the bush after it's photographed is not an option for responsible nature photographers, the best options are to work around the problem. Use a fairly small ƒ-stop (ƒ/16) so that the foreground object doesn't go completely out of focus when photographing the background. Another choice is to change your perspective; position the foreground subject more into the lower aspect of the composition so that it doesn't intrude into the mountain's space.
When focus-stacking captures in macro photography, the possibility of blooming is greater. Although the size of the subject may be very small, the range of focus between front objects and elements at the back of the composition can be large at high magnification. So when photographing the throat of a flower, for example, the nearest parts, the tips of the stamen and stigma, may bloom out of focus and hide portions of the flower's base as it's being photographed. These problems can be solved in post-capture software featuring retouching. Two programs I use that offer this function are Helicon Focus (www.heliconsoft.com) and Zerene Stacker (www.zerenesystems.com). Once the image is composited, areas of sharp focus can be cloned from individual captures to the final composite; in some cases, the cloning required might be quite detailed and take some practice to accomplish well.
|This Article Features Photo Zoom|
A small section of the unretouched foreground shows out-of-focus "blooming" edging the foreground flower. After retouching in Zerene Stacker and minor cloning in Photoshop CC, the problem was resolved.
Pictures By Number
Q When running two or more cameras, how do you set the numbering system on each camera so that duplicate file names aren't assigned when downloading?
A I've had this problem, where two cameras generated the same image file names—and even duplicates from the same camera! It's a nightmare for file management and possibly a risk for inadvertent loss of your images. Truth is, file management diligence begins before capture by understanding how your camera assigns names.
In continuous numbering mode, the camera establishes a folder, beginning with 100, within which captures are numbered consecutively from 0001 to 9999 and then starts over with a new folder (101). The numbering sequence continues as memory cards are inserted, removed and reinserted. In this mode, identical file names will be generated from one camera to another.
However, in Auto Reset mode, the numbering sequence is rebooted each time a newly formatted card is inserted. This means that from one card to the next, identical sets of file names will be generated. I don't recommend this option.
Some DSLRs, such as my Canon EOS 5D Mark III, offer the option of changing the alpha prefix the camera generates. For example, I've set my Canon EOS 5D Mark III to name files with the first four characters MK3_, followed by the 4-digit file number. Some of my colleagues' Nikons have an in-camera renaming capability also; you'll have to find that old instruction book and figure out how to set yours.
No matter what the camera-generated file name may be, best workflow demands that you rename your image files in accordance with your own file plan, with a date, location or subject code, either before you begin to edit, or immediately after, as you save the files.
Going Long And Light
Q I'm headed to Bhutan for a number of months to work as a volunteer, and I must travel light and with minimum gear. I still want to record what's going on. What are my options for cameras and storage? Should I take many cards or backup drives?
A This question comes up often; when we travel to a new and remote location, it's difficult to anticipate what photographic equipment will be needed and even harder to leave some of our favorite stuff behind. Fortunately, in today's age of small, but capable digital cameras, there are a lot of options for traveling light.
In order to carry minimal equipment, meaning no extra lenses or accessories, I would suggest one of the compact, all-inclusive cameras that have a wide range of focal lengths, built-in flash, close-focus capability, and are relatively small and light. A few suggestions (but not all that are available) are the Nikon Coolpix P520 and L830; Canon PowerShot SX50 HS and SX510 HS; Pentax X-5; Sony Cyber-shot HX50V and HX300; Panasonic Lumix FZ70K and ZS35. At less than $450, these cameras have extended zoom capabilities with image stabilization to reach out—some as far as 1200mm. They also capture HD video, as sometimes video tells the story best. Keep in mind that video files do take up more storage space.
Figure out how many cards you might need, and then take more. These cameras use SD cards that are very small and relatively inexpensive, so they're easy to transport, but also easy to lose. Purchase the cards in 32 GB form so you can take lots of images in JPEG format at the best resolution; you want the highest-quality images you can get. The end results will make excellent prints for a wall display and are more than adequate for sharing on social media. If you're taking a laptop along, you can save the images on that hard drive as they won't take a lot of space. I strongly recommend using a small backup drive, as well; you can purchase a very small USB-powered hard drive (runs off the laptop) that will hold up to 500 GB for less than $100. If a laptop won't be available, you can take a self-powered hard drive, such as the Sanho HyperDrive COLORSPACE; it's made for storing images and even has a small LCD screen to check the images. Power may be an issue so make sure you have the right power adapters for the country and that you have at least two extra batteries for the camera.
Cloudy With A Chance Of Storage
Q With ever-increasing image file sizes, I'm rapidly filling multi-terabyte external drives. Has the time come to use storage and backup services in the cloud?
A We used to have stacks of little yellow boxes filled with slides everywhere; now we have stacks of hard drives, and we keep outgrowing them. Time-lapses, videos and high-res composites yield very large files, so storage is a constant concern. You know I'm an early adopter for most technology, but I'm not ready to turn my files over to a third party yet—even if its name were more substantial than "the cloud"—because my images are just too important to me to relinquish control in that way.
My routine, tedious as it may sound, is to keep my digital images on three sets of hard drives. There's an active set at my desk (five 4 TB drives) that's constantly being backed up to a second set at my desk. There's a third set in the safe deposit box at the bank. Once a month or so, I switch the backup set with the bank set. I'm pretty much constantly scrapping and upgrading the hard drives, weeding out and replacing the older, lower-capacity equipment on a regular basis. So, for me, the basic elements of safe image storage haven't really changed that much from the film days. It still requires organization, regular filing, and bigger and safer "file cabinets."
Follow George Lepp's exploits, see his latest photographs and be part of the discussion on his Facebook page: www.facebook.com/georgelepp.