“The Myth and Magic of the “Super Telephoto Lens”
Most photographers (especially those with an affinity for nature photography) “long” for a longer lens! Those looking on as we use our telephoto “cannons” imagine that the big glass is an immediate fix for glorious, in-your-face shots of wild animals, sports close-ups, or even intrusive images of unsuspecting celebrities! So many times I have heard people remark that “you must get great shots with a lens that big…”
It is easy to assume that once you own a telephoto lens, the great shots just jump onto your memory card, and that no subject is too far away for a great image. Unfortunately, like many other endeavors, quality super-telephoto photography is not as simple as it appears, and the award-winning images do not come easy! The “big guns” do, however, help the shooter make images possible that cannot be obtained any other way. The “special effects” made possible with a Super Telephoto Lens (STL) makes using them addictive!
I hope to share some insights on the use of super-telephoto lenses: the advantages, pitfalls, and tips on maximizing the images you can get using these tools. Hopefully, what I have to say will shorten the “learning curve” of those just getting into this type of fascinating photography, and encourage others to give it a try!
First, we should define what exactly a super telephoto lens (STL) is. Most would agree that lenses of 400 millimeters or greater would qualify as a STL. Zoom lens incorporating this focal length in their range would also be considered such. The major camera manufacturers offer lenses up to 600 or 800 mm, and 1200 mm lenses are even available on special order (and of course, exorbitant prices!). “Angle of view” is the best way to describe a STL’s effect on the subject. The more millimeters you have, the narrower the angle of view captured by the image sensor.
One of the biggest myths about using an STL is that the photographer can easily fill the frame with a subject, no matter how small, or how distant. One of the quickest lessons one learns when beginning to use an STL, is that the subject size is never as large as one would expect. Most bird photographers, for example, ALWAYS want a longer lens, especially for shooting small birds! For example, imaging a sparrow-sized bird with a 500 mm lens requires a distance of 20 feet or less for a frame filling shot, and that‘s with a sub-35 mm format digital camera body! An experienced bird or wildlife photographer learns how to get as close to the subject as possible (without stressing or disrupting the subject’s behavior) in order to get the best image possible.
This leads to another myth: that images posted online or in print are framed as they were in the camera. Most frame-filling images of birds and wildlife have been cropped, and some HEAVILY, before being shown to others. It is a rare occasion when an image does not need cropping to some degree. The high-resolution sensors of the latest digital SLRs allow lots of cropping in while retaining excellent quality. Of course, the original image must be exceedingly sharp and well exposed to stand up to heavy cropping.
This is helpful when the shooter wants to isolate a subject, either from its background, and/or from other competing objects. This effect communicates the subject to the viewer more clearly, and often with great impact! The STL is a great tool for removing distracting elements from the image, useful also in portraiture in many cases. The STL either excludes distractions outside of the small angle of view, or blurs them out with its characteristically shallow depth of field, which is the range of sharpness front to back in an image.
Sparrow was shot from my truck window with a beanbag support. Bird was about 20ft. away The f/3.5 aperture allowed for the background to be less of a distraction. Image was cropped.
An explanation of the digital magnification factor is in order at this point. Most digital SLR image sensors are smaller than the 35 mm image size of the past. This means that less of the image projected by the lens appears in the image produced by a digital SLR. This has the effect of cropping the image in the camera, and resulting in a larger subject size in the frame than would be produced on 35 mm film with the same lens. Most digital sensors cause the subject to be magnified by 1.5 times that on film. A 400 mm lens becomes equivalent to a 600 mm lens when attached to a typical digital SLR! This is a great advantage for wildlife or sports shooters who always yearn for a closer view.
The extreme subject magnification comes at a cost, however. One of the largest obstacles to overcome when a quality image is the goal with an STL is image blur due to lens movement or vibration. Subject movement during the exposure is also more of an issue when using an STL. The higher the magnification of the subject, the more image blur can be a factor. One of the most frustrating aspects I have found when reviewing my STL images, are the number of “deletes” due to subject blur. Image stabilization technology in many of the newer STLs does combat image blur significantly, but only that caused by lens movement. A fast shutter speed is still necessary to freeze subject movement. Raising the ISO setting of the camera or using a larger lens opening (aperture) is often needed to allow for these faster shutter speeds, especially when shooting in low light.
The ability to use a large aperture (or lens opening) has another wonderful advantage in using a quality STL. The most sought after (and expensive) STLs are those which, have a relatively large maximum aperture. Typical consumer grade telephoto lenses have moderately small maximum apertures of f/5.6 or smaller. Higher-end models have maximum openings of f/2.8 to f/4. In fact one of the reasons a seasoned photographer uses an STL (beyond subject magnification) is to isolate the subject from a busy, messy, or distracting background. “Opening up” the lens to a large aperture is a crucial advantage when, for example, a beautiful bird is surrounded by jagged twigs and branches which would distract the viewer from enjoying the details of the bird. Large aperture STLs can create a creamy background blur, which softens the background and accentuates the subject.
Fox and Kit were about fifty feet away! I was able to capture them with my 400mm lens – no tele-converter here. Cropped in post processing.
Several accessories are useful, if not essential, in the use of an STL. First and foremost, a very sturdy tripod is a must when using a telephoto lens for any length of time. Sure, “grab shots” can be made hand holding an STL with image stabilization making this more possible than ever. Still, for the best results and most comfort, a quality tripod with the right “head” is indispensable.
I would guess that one of the most common errors leading to poor photo quality with an STL is using an insufficient tripod. It is not advisable to try “getting away” with an STL on your “everyday” tripod. Most tripods used with standard-range lenses will not provide enough rigidity or stability for an STL, due to its weight and high subject magnification. Several characteristics make my list for an appropriate tripod for your STL:
1. Do not plan on raising the center post, as this compromises the steadiness of the tripod. The legs should be long enough so that, fully extended, the lens sits at least at eye-level without raising the center post.
2. The width of the legs where they touch the ground should be at least the same as the length of your rig, if not wider.
3. Be sure to use a head that matches the oversized tripod. A large ball head is very popular.
4. Aluminum legs work fine, though carbon fiber is noticeably lighter and somewhat more rigid.
5) Generally, the fewer telescoping sections a tripod has, the more stable it will be.
Also, for the best stability of the lens, the proper setup, stance and grip on your rig will be important to avoid subject blur due to lens movement.
First, take the time to set your tripod legs to the most comfortable height. You should be able to look through the viewfinder with out either stooping or tiptoeing. You will need to adjust the length of the legs periodically depending on where your subject is located, as well as the often-tilted landscape you are shooting from.
The positioning of your arms and hands will make a noticeable difference in the steadiness of the lens. Your right hand will of course be gripping the camera body. Your left hand should support the lens. I find that, by first balancing the rig on the tripod, then placing my left hand on top of the lens directly above the tripod head, gives me good lens stability. Your face should also be pressed firmly against the back of the camera. Avoid “punching” the shutter button. Instead, apply light constant pressure, gently releasing the shutter to avoid movement of your rig.
Using a STL can generate exciting images not possible with shorter lenses, if used properly. I hope that these tips will help those just trying out super-telephoto photography, and perhaps even a seasoned long lens shooter may have learned something from what I have shared. Be forewarned, however: STL shooting is definitely addictive. Give it a try!