|George Lepp photographed this cactus patterned with fine needles and tiny flowers with a Canon EF 180mm macro at 1⁄45 sec. at ƒ/11. Nineteen stacked images rendered the subject needle-sharp from front to back when composited with Zerene Stacker software.|
Q To get more depth of field in my macro shots, I've been using an aperture of ƒ/22. I'm seeing a larger area of sharpness, but the overall image just isn't sharp. I'm using an expensive 100mm macro lens with disappointing results. What's going on?
San Diego, California
A An optical phenomenon known as diffraction is affecting your image quality. The sharpest image is formed by straight rays of light, that is, rays that aren't impeded or bent as they enter the lens and reach the sensor. The wider the lens opening, the sharper the image. The downside of this is that, at higher magnifications, depth of field is minimal; efforts to increase it by choosing a smaller aperture result in an image that's being formed by rays that are bent as they enter the lens diaphragm.
As an example, I often use the Canon MP-E 65mm ƒ/2.8 1-5x Macro lens. At 1x, I can use ƒ/16 and get good results in sharpness. When I extend the lens to attain 5x, I need to open up the aperture to at least ƒ/4 to minimize diffraction, but I get less depth of field. If I use ƒ/16 at 5x, the image won't be sharp at any point. This is a real problem because, at the higher magnifications, I need as much depth of field as possible. The best that can be done with a single shot is to compose the image so the area of sharp focus is positioned to emphasize the message or most important feature.
A total solution is a technique called focus stacking. With the lens set at its optimum aperture, the photographer captures a series of images, moving through the subject and overlapping the depth of field at each position. A post-capture program such as Photoshop (www.adobe.com), Helicon Focus (www.heliconsoft.com) or Zerene Stacker (www.zerenesystems.com) assembles the "slices" of focus into one completely sharp image. The programs miraculously keep the sharp areas of each image in the stack and ignore the out-of-focus areas. Stacking can be used in many photographic situations, from macro to landscape, and it's a technique I highly recommend and teach in my seminars and workshops.
Q I'm into creating time-lapse movies with my DSLR, but I'm having trouble with a sort of flicker in the movie when it plays back. What's causing this, and how do I get rid of it?
A Flicker is a common problem in time-lapse (TL) compositions; it's caused by slight variances in exposure from one capture to the next. Even though your exposure and shutter speed are manually set exactly the same for each capture, the lens diaphragm doesn't open and close precisely the same amount each time it cycles from the preset aperture to wide-open between captures. A better process would leave the aperture closed down to the preferred aperture during the whole sequence, eliminating the opening between captures, but today's lenses don't do that. An older, completely manual lens (when was the last time you saw one of these?) remains at the set aperture between captures. Some TL photographers compensate for this by setting their exposure to the widest aperture possible to minimize the movement of the diaphragm. The drawback to this strategy is that control of exposure and depth of field are limited, and a fast shutter speed is required.
Shutter speeds also are inconsistent by a small percentage; it's more evident with fast shutter speeds. Most TL photographers recommend using a slow shutter when capturing the many images in a sequence.
There's an override solution, albeit a bit risky. Set the desired ƒ-stop, then depress the depth-of-field preview button and the lens release button simultaneously while just slightly twisting the lens to unmount it; this locks the ƒ-stop at the set aperture. Be very careful not to rotate the lens too much because it could detach and drop from the body. Remount the lens securely as soon as the sequence is finished!
If these capture procedures aren't possible or don't solve the problem, look at post-capture correction. Three programs can minimize TL flicker. The most powerful is LRTimelapse from Gunther Wegner in Germany (99 € and up, www.LRTimelapse.com), which works in conjunction with Lightroom to optimize each frame in the TL, correct any abrupt changes in exposure between frames, and smooth transitions between day and night. Sequence, an app for Mac users ($39.95 from the App Store), smooths flicker in postproduction. Granite Bay Software's GBDeflicker ($99, www.granitebaysoftware.com) is designed to work with Adobe Premiere's video assembly app.
The Drive Vs. The Cloud: Updated "Whether" Report
Q You've mentioned before that you're not inclined to adopt cloud storage to back up your images because you're reluctant to relinquish control to a third party, but I'm still struggling with the decision. Isn't cloud storage technically advanced and less expensive?
A The only wrong decision you can make here is no decision: It's truly necessary to back up your images routinely. The only time I've ever lost images was the one time that I attempted to transfer a group from a new external drive to repopulate the internal drive of a new computer. The external drive failed before I accomplished the transfer. It made me so mad that I've never allowed my images to reside in only one location, even for a few minutes, since then.
A few months ago, I wrote in this space about the system of storage and backups I've just put into operation with my new Apple Mac Pro, aka the Trash Can, which has a maximum 1 TB internal PCIe-based flash storage that's dedicated to applications. Nearby, I have shelves of external storage drives—about 30 TB in the form of six Seagate (www.seagate.com) 4 TB and four 3 TB drives that are about two-thirds full. But that's only the front line of storage; two full sets of backups are maintained both on-site and in a safe-deposit box at a bank. At a cost of approximately $150 each for the 4 TB drives and $120 for the 3 TB units at Costco, the entire system of file backups costs about $2,760. Don't panic! Not everyone needs that much storage right away, but be aware that image files are increasingly larger, with worked Photoshop files, hi-def video (4K?) and high-resolution panoramas, to name a few storage hogs.
Another option for mega-storage is a RAID (Redundant Array of Independent Disks) system, which houses several internal drives in a containment system with a controller to either manage the contents as a single unit or designate one of the drives as a redundant backup system for the whole. Drobo (www.droboworks.com) and the Buffalo Drive Station (www.buffalotech.com) are examples of this type of system. My colleague Robert Agli has a multi-drive Drobo as a backup and has had only one of his many drives fail in 11 years.
In addition to the control factor (I worry that a cloud storage company will go out of business, have a failure or be down for a period of time when I need my files), I need the speed of the USB 3 drives (625 MB/sec.) and am looking forward to even faster transfers with Thunderbolt in the future. Cloud-based storage over the Internet is far slower, depending upon your Internet upload options; the fastest speed available to me is 5 MB/sec. While some argue that, even with its limitations, the cloud is more secure than hard drives that can fail, my success rate with drives exceeds expectations; the common wisdom, according to tech magazines, is that 10% of external drives will fail in three years, but that just hasn't happened, and with two backups, it's not an issue.
So what about the cost factor? Let's assume you're an advanced amateur photographer and need about 5 TB of backup for your images. A 5 TB Seagate external backup drive from Amazon goes for around $200. A cloud-based backup from Carbonite (www.carbonite.com) is $100 per year for unlimited space on one computer. If we assume three years of life for the external drives (even though they would last longer), that's $300 for three years of the cloud vs. $200 for your own external storage.
I do see two conditions under which you may want to use the cloud for image storage. If you need enormous amounts of space, the cloud may be a more economical option. And if you want to access your image files from anywhere, the cloud can be a benefit. A readily available cloud option is the iCloud Drive, a new service for Mac users, which offers 5 GB free (not really much help, when the camera's CF card holds 16 GB), or $47.88/year for 200 GB. Google Drive is $119.88/year for 1 TB. These services don't really seem to understand the needs of digital photographers.
I hear a lot from photographers who are frustrated with the amount of computer time and knowledge required to merely keep up with processing and organizing digital image files. But if the images you capture are worth keeping, then they're worth the time to organize and protect in a systematic, reliable way. Just sayin.'
Follow George Lepp's exploits, see his latest photographs and be part of the discussion on his Facebook page: www.facebook.com/georgelepp.