Reflecting On Reflections
When I photograph small, shiny nature subjects such as minerals, bugs and reptiles, I need to use flashes, but I can’t seem to eliminate the reflections. Do you have any suggestions about minimizing light flares that get in the way of the details I’m trying to show?
Rochester, New York
Specular highlights—the bright spots of light that appear on shiny, irregular-shaped, illuminated objects—are a real obstacle in close-up photography. The required light sources may be larger than the subject itself, exacerbating the highlight problem. The answer to this dilemma is a technique called cross-polarization, which reduces the number of angles from which light rays can enter the lens.
Cross-polarization is accomplished by placing a polarizing filter on the lens and covering each light source (usually flashes) with plastic polarizing material cut from a sheet. Using the guide on the sheet, position the material on the flash; if more than one light source is used, be sure to orient the material identically on each. You can test the cross-polarization by positioning the flash(es) as you will be using them to illuminate the subject, then rotating the lens filter in front of one of the flashes. When the material on the flash goes black (that is, you can’t see any light coming through the combination), cross-polarization has been achieved. In that position, mark the filter at 12 o’clock and remount the filter on the lens with the mark at 12 o’clock. This makes the effect repeatable without a whole new set of tests.
That’s the good part. The problem is that this technique eliminates approximately five stops of light—and you really need light when working close up. I typically use two flash heads of reasonable size (larger hot-shoe type) on a bracket to position the flashes at an angle to the subject of approximately 45 degrees so they both are in the same orientation. Smaller macro flash units can be used if the subject is small and the flashes are positioned close to it. TTL flash mode should give a reasonable exposure calculation, but you might need to make some adjustments. It is important that all of the light recording on the capture comes from the polarized flash heads and not from the ambient light, which is not polarized.
Linear polarizing material of significant thickness and quality are available from the sources listed below. One sheet will last you a lifetime.
Polarization.com. You want their “Linear Polarizer by the foot fully laminated” product at $35 per foot. These are 17 inches wide; 1 foot is all you need.
Edmund Optics. The 3.25-inch Diameter Gray Polarizing Film comes in a two-sheet pack for $29. Contact: edmundoptics.com/optics/polarizers/linear-polarizers/visible-linear-polarizing-film.
Are Tripods Obsolete?
Dynamic range and ISO range are improving with each new camera from the various manufacturers. Do you think that trend will eventually lead to tripods becoming an obsolete accessory for outdoor photographers?
Fast shutter speeds and tripods have a common objective: limiting the softening effect that unwanted motion and vibration have on our images. Advances in digital sensors that improve dynamic range (light-to-dark tonal values) and ISO capability (sensitivity to light) enable high-quality exposures of short duration—a real boon for hand-held capture of action subjects in the field, even in marginal light. The result is the ability to increase shutter speeds, depth of field, and obtain good detail in shadow areas. I’m using these advantages while photographing flying birds and other fast-moving wildlife subjects in situations where employing a tripod has never been very practical. The difference is that now, with the advancing sensor technology, hand-held results are consistently better and the percentage of successful captures is greatly improved.
However, I’m not throwing away my tripods just yet. One of the main advantages of using a tripod is that it allows for deliberate, thoughtful composition and capture strategies. I always use a tripod for both landscapes and close-up work. As long as I’m pushing the limits, as in photographing the night sky, I’ll be making long exposures. When focus stacking for extended depth of field, an exactly matching orientation must be maintained from frame to frame throughout a set of captures, and that means using a tripod, even in my studio. And then there are the supports needed for capturing time-lapses and rock-steady video. I think I’ll be using my tripods for quite some time to come.
I know it’s best to minimize filters on lenses, but the UV filter I use really paid off when I dropped my camera on a rock while hiking in the wash behind my house. The camera and lens survived fine, but the filter cracked all to pieces.
via the internet
While I’ve repeatedly admonished against the routine use of filters due to their degradation of images, I do recommend that a clear, UV or skylight filter be placed on lenses to protect them when photographing in difficult or dangerous environments, for just the reasons you mention. It’s a trade-off between achieving the best sharpness possible and perhaps saving the lens altogether. So when the wind is blowing sand, or salt water is splashing on the equipment, or I’m in unstable or constrained circumstances, I’ll add the safety filter.
Keep in mind that stacking filters exacerbates the loss of clarity, so if you want to add a polarizing filter, ND filter or any other filter, take off the UV/skylight filter. And I caution against adding polarizing filters to lenses of 200mm and longer, because they can affect the focus point of the lens and greatly compromise sharpness. This is especially evident with variable ND filters that actually consist of two polarizers working to cut back exposure. Check these combos out before you get into the field to determine if your longer-focal-length lenses are adversely affected by your filters.
Choosing A Macro Lens
I’m thinking of purchasing a macro lens. There are a lot of choices, ranging from 30mm to 180mm. My question is, if I were to photograph a flower with depth, like a lily, would a 30mm lens or a 180mm lens give better depth of field, assuming you filled the frame identically with the flower and used the same f/stop?
via the internet
The main factor you need to consider when choosing a macro lens is whether you will be using it on a camera with a full-frame sensor, an APS sensor (1.6x or 1.5x crop factor), or a smaller sensor, such as the Micro Four Thirds system (2x crop factor).
The smaller sensors will extend the apparent reach of any lens as a result of the crop factor. A 30mm macro lens on a Micro Four Thirds system camera, for example, will be the equivalent of a 60mm macro lens on a full-frame camera. The difference you’d see between the 30mm macro on an MFT camera and a 180mm macro on a full-frame camera would be significant. The perspective of the 30mm lens versus a 180mm lens would be different, as the telephoto lens (macro or otherwise) would give a much flatter rendition due to compression of the composition. In addition, the 30mm macro would have less working distance from the subject than a lens of longer focal length.
While the depth of field would be nearly identical for two lenses of different focal lengths if the framing and aperture were the same, the overall look of the subject will be different because of the perspective. I do occasionally use a wide-angle lens with a small amount of extension tube attached to facilitate close focusing to give that different perspective, but the idea isn’t to use the lens as a macro optic.
My choice for an all-around macro lens for full-frame cameras is a 100mm macro, or its equivalent for other format sensors. It has great sharpness and a reasonable working distance for general macro work and also for focus stacking on subjects to life-sized. I also have a 180mm macro and the Canon MP-E 65mm f/2.8 1-5x Macro. Each has its place, with advantages for particular projects.
My wife and I are going to Hawai’i for our 55th anniversary and I'm trying to pack my camera gear with the optimum set of lenses to reduce weight. I want to take my Canon EOS 5D Mark IV and my Canon PowerShot SX60 HS (mainly for the long reach). I have a good variety of lenses. What would you suggest as the best combination to cover a wide range of photographic situations?
via the internet
If your spouse is not also a photographer, traveling light and focusing on the celebration might improve your chances for a 56th anniversary trip!
The answer to your question depends on what you plan to photograph, how much weight you’re willing to carry, and what you plan to do with the images you capture in Hawai’i. If you market them outside of social media, or if you are planning to make large prints, you’ll want to take the EOS 5D Mark IV, the sharpest of your lenses, and a wide range of focal lengths. If you’re going to post the images on the internet, make small prints or share them via social media, the lighter SX60 will do the trick. Something in between would be the Mark IV with a wide-to-telephoto zoom such as a 28-300mm. Don’t forget to pack a lightweight tripod for long exposures, time lapse and video. Aloha!