By Joe Kashi, for the Redoubt Reporter
This week, let’s review the best affordable lenses and match them to the various best-buy cameras that we considered last week. So, without further ado, let’s do the numbers.
As with our camera value discussion last week, we’ll take separate looks at lenses in the lower cost, midrange and upper-price brackets. Choose wisely. Before making any purchase, compare professional reviews of all affordable lenses that fit your needs. Because different lens review websites use different criteria to evaluate lenses, try to stick with the same website, if possible, so that you’re comparing apples with apples.
From my perspective, the three best lens review sites are http://www.slrgear.com, http://www.photozone.de and http://www.lenstip.com. Each of these sites measures a lens’ ultimate resolution using the preferable MTF50 method, which combines contrast and resolution.
Avoiding optical defects
To recap our more-extensive optics discussions over the past few weeks, high resolution of fine detail, good internal optical contrast and avoiding “flare” are the most important quality criteria when choosing a lens for digital photography.
Avoid lenses prone to “flare,” the internal reflections and ghost images that can occur when light from a very bright light source, such as the sun, directly strikes a lens’ outer glass elements. Good optical contrast and minimizing flare are controlled by applying a high-quality “multicoating” to every air-glass surface of the lens during manufacture.
For similar reasons, avoid older lenses designed for film photography; their rear elements cannot suppress the much brighter reflections from the camera’s polished digital sensor.
Resolution, contrast and controlling flare are the three most important lens quality criteria because any image problems caused by these defects cannot be fixed after the fact. Post-processing in Photoshop can’t add detail that your lens didn’t capture in the first place and can’t fix the bright spots and ghost images caused by flare.
Other “defects,” such as distortion, vignetting and most chromatic aberration are not deal-breakers, because they can be fixed afterward by post-processing in Photoshop or Lightroom.
A more expensive lens is not necessarily better and can easily cost more than your camera. Similarly, the best values, and often better image quality, can often be found among good quality lenses with a smaller maximum aperture, like f 3.5 or f 4.
So, do you really need a really expensive lens? Expensive, highly touted lenses will not make you a better photographer, nor turn boring and mediocre images into something worth hanging on a museum wall.
Top-end optics are probably most useful to pros and other serious photographers who already have the technical knowledge and “eye” to use them to best advantage. So, before loading up on expensive gear, first upgrade your technical knowledge and determine what additional optical capabilities you actually need.
Often, more careful use of existing lenses provides sufficiently improved image quality. For example, almost all lenses work better at particular zoom and aperture settings, usually short to medium focal lengths and aperture settings in the f 5.6 to f 8 range, depending on the lens.
A bit of experimentation, along with examination of the charts and graphs that accompany good lens reviews, may show a range of settings where your existing lenses perform well. Those same charts and data also help you compare lenses and decide whether an expensive new lens really makes enough difference.
Prime or zoom lens?
There are two broad types of lenses, variable-magnification zoom lenses and fixed, single-magnification “prime” lenses. Each has advantages and disadvantages.
When making comparisons, remember that a lens’ effective magnification is higher on digital cameras compared to 35-mm film. That’s because digital APS-C and Four-Thirds sensors are smaller than a 35-mm film frame. Nikon, Pentax and Sony users should multiply a lens’ focal length by 1.5, Canon users by 1.6, and Olympus/Panasonic Four Third-users by 2 to get a lens’ comparative 35-mm magnification equivalent.
Everyone is familiar with zoom lenses and we value their ease of use. Zoom lenses, though, tend to be larger and heavier. Their overall resolution of fine detail and optical contrast are often lower than equivalent prime lenses because a greater number of optical compromises are inevitable when designing lenses that must perform reasonably well over a broad optical range.
Prime lenses are often sharper, smaller and lighter but less convenient. You’ll need to physically change lenses when a different magnification is required, possibly exposing your sensor to dust. Good prime lenses tend to be rather expensive. Buying a complete set of high quality primes can cost a few thousand dollars.
Many experienced photographers prefer using prime lenses and the compositional discipline that their use requires. As digital photography matures and users become more sophisticated, there’s some shift away from zoom lenses toward primes. Recently, camera manufacturers have introduced many prime lenses newly designed for digital photography.
If you take many close-up “macro” photographs, then you likely own at least one prime lens, your macro lens. The “macro” features of most zoom lenses are not very sharp and suitable only for casual use.
Macro prime lenses are usually very sharp from center to edge, not just at close-up distances but also in normal photography. Because it’s much more convenient to use a longer focal-length lens when shooting close-up, most prime macro lenses have a longer-than-normal focal length and often do very well as a short telephoto or portrait lens. Shorter focal length macro lenses make excellent, and very sharp, normal range prime lenses.
Third-party vendors Sigma and Tamron make very high-grade prime macro lenses that fit most camera brands. These third-party lenses are usually sharpest at medium lens apertures. Sigma’s 70-mm f 2.8 macro lens ($500) is so sharp that it’s used as a reference against which to compare other lenses. Sigma also makes a 50-mm macro lens ($370) but I believe that the 70-mm version is preferable because of its extreme sharpness and usefulness as a short telephoto or portrait lens.
Tamron’s 90-mm f 2.8 macro lens ($400 to $450) is nearly as sharp. Tamron’s 60-mm macro lens ($500) has a very bright f 2 aperture and is likewise very sharp except at the extreme corners. Tamron frequently provides $50 to $100 mail-in rebates and actually pays those advertised rebates promptly.
Olympus makes a series of very sharp prime macro lenses that fit Four-Thirds and Micro Four-Thirds (M43) cameras from both Olympus and Panasonic. Because these lenses were originally designed for Olympus’ pro digital SLR cameras, you’ll need an Olympus MMF-2 adapter ($165) in order to use these fine lenses in autofocus/autoexposure modes on current Olympus and Panasonic Micro Four-Thirds cameras.
Among the Olympus macro lenses, the 50-mm f 2 ($500) is superlatively sharp. As with the Sigma 70-mm macro, Olympus’ 50-mm macro is so good that it’s used as a standard reference against which other M43 lenses are compared. Olympus’ 35-mm macro lens ($200) is nearly as good but quite a bit less expensive.
Olympus recently announced a 45-mm f 1.8 prime macro lens for M43 cameras but it’s not yet shipped and no data is available. Panasonic makes a similar 45-mm macro lens but I consider it to be overpriced at $705 compared to the Olympus offerings. The only minor inconvenience with current Olympus prime macro lenses is the need to use the MMF-2 adapter with them.
Major camera vendors make both gems and clunkers in this group of lenses and price is not a good guide to optical quality. For example, Zeiss’ 50-mm macro costs nearly $1,300 but shows decent quality only after stopping down by three complete aperture stops. Nikon’s 105-mm macro ($950) is adequate but not nearly as sharp as Nikon’s less expensive 60-mm (under $470), which is quite a bit sharper and should also work well as a short telephoto and portrait lens.
Nikon recently introduced a 40-mm f 2.8 ($280) and initial reviews suggest that it’s very sharp. At that price, the new 40-mm lens is an excellent value and probably the macro lens of choice for nonprofessional users. It should also work very well as normal focal lens for daily use.
All of Canon’s macro prime lenses are very good when used correctly but again, price does not give a good measure of quality. Canon’s much more expensive 100-mm f 2.8 L macro prime lens ($980) is only slightly sharper than Canon’s less expensive “non-L” version of the same 100-mm lens ($570). Canon’s 60-mm f 2.8 macro prime lens is nearly as sharp as the L version except for some slightly lower resolution on the left edge. At $430, it’s a much better buy.
Pentax currently sells two newly designed macro prime lenses that are extremely well-constructed and very sharp. I often use Pentax’s 35-mm f 2.8 Limited series macro lens ($580) as my normal lens for regular day-to-day photography. It’s small, light and an excellent all-around lens on a Pentax K-5 or K20d.
Pentax’s 100-mm WR macro ($619) is not only a fine macro lens but also a compact, excellent and weather-resistant medium telephoto lens. It’s considered to be as sharp or sharper than the much more expensive Canon 100-mm L macro prime lens.
Next week, we’ll look at other prime lenses for interchangeable-lens cameras before moving on to zoom lenses.
Local attorney Joe Kashi received his bachelor’s and master’s degrees from MIT and his law degree from Georgetown University. He has published many articles about computer technology, law practice and digital photography in national media since 1990. Many of his technology and photography articles can be accessed through his website, http://www.kashilaw.com.