Telephoto lenses have long reaches and are great to ‘bring the subject closer’ to achieve detailed, frame-filling photographs. They can be tricky to use and there’s a huge range of lenses available. Here are six tips and hints to get the best out of your lenses.
Prime lenses – these are a fixed focal length and for wildlife 300mm to 500mm or longer work very well. They are fast (have wide apertures) and sharp (can resolve fine detail). They can also be very expensive and heavy.
Zoom lenses – these have the flexibility of getting a frame-filling shot or a wider composition that shows the subject in its habitat and can be particularly useful for when the subject moves nearer or further from the camera such as birds in flight. Typical zoom ranges are 70-200mm, 100-400mm and 150-600mm. Many have a variable aperture through their zoom range: my 100-400mm lens has an aperture of f4.5 at the 100mm end and f5.6 at the 400mm end. Some zooms have a constant aperture throughout their zoom range but these are more expensive than the more affordable variable aperture lenses. The image quality can be almost as good as a prime lens – you might be hard pushed to tell the difference and they are lighter.
Teleconverters – teleconverters or extenders go between the camera and the lens to multiply the focal length by, typically, 1.4x or 2x. Other magnifications are available but these are the most common. They don’t add much weight and are reasonably small and are an affordable way to make your lenses more flexible. They can work very well with prime lenses and with high quality zooms but the image can be degraded a little. I use a 1.4x with my 100-400mm zoom with some success but the 2x can make the image too soft. Not all lenses are compatible with them so check before you buy. The downside to using them is a loss of light and a slower auto focus. A 1.4x teleconverter reduces the light falling on the sensor by 1 stop and 2 stops with a 2x. If you are shooting at f5.6 that will become f8 with a 1.4x and f11 with a 2x. Beware that some cameras may not auto focus beyond f8.
Support the lens and camera – Some telephoto prime lenses can be hand-held and most zoom lenses are light enough to do without a tripod. When using a big, heavy lens, especially at lower shutter speeds, a tripod is all but essential. Choose a high-quality tripod that will easily cope with a heavy payload of camera and lens. A flimsy tripod will vibrate and wobble. You will also need a tripod head which sits on top of the three legs and into which the camera/lens is mounted. Gimbal heads are great as are ballheads. I have recently ‘converted’ from a gimbal to ballhead. When properly set up the camera/lens is balanced on the tripod and seems ‘weightless’ in use. Long telephoto lenses usually come with a foot mounted on a collar that fits around the lens. It is this that is mounted in the tripod head rather than the camera so as to protect the camera’s lens mount. Consider using a monopod. This can be easier and quicker to use than a tripod – it is lighter and usually does not have a dedicated head. I mount a camera/lens directly to a monopod.
Steady as you go – telephoto lenses amplify small camera movements as well as subject movement so it is essential to employ good technique when taking the picture. If hand-holding support the lens with your left hand and tuck your elbows against your body and ‘tighten up’. Take a deep breath and hold it – this stops your chest moving and helps keep the camera steady. Squeeze the shutter rather than stab at it. If using a tripod or monopod press the back of the camera against your face and drape your left arm over the lens to dampen any vibrations. Some tripod heads have a little hook on the underside. This can be used to hang your backpack to add more stability. I keep a small cloth bag which I fill with rocks, clods of earth or half-bricks etc. Hanging a weight in this way really helps to dampen vibrations. I often use spikes on the end of the tripod legs when on soft ground in a wood or meadow rather than the standard rubber feet. A fast shutter speed is essential to freeze action and to overcome camera movement. As a rule of thumb use the lens focal length to determine the slowest shutter speed to use: 1/300th second with a 300mm lens and 1/500th second with a 500mm lens etc. It generally needs to be faster than this to freeze wing beats: 1/2500th second is a good starting point. Image stabilisation should be used, too. This can be incorporated in the lens or the camera body. It’s a high-tech system that either shifts lens elements or the actual camera sensor to help compensate for small accidental camera/lens movements. It will not compensate for subject movements.
Calibrate for pin-sharp accuracy – telephoto lenses and wide apertures make for a wafer-thin depth of field so it is essential that the focus is where you want it to be. Slight variations in manufacture of the lens and camera can result in a lens focussing a little in front or behind where you expect. For instance, if a bird is sideways on and you focus on the eye but the folded wing is sharp and the eye is blurry the lens is focussing in front of where you expect and the auto focus needs adjusting. Mirrorless cameras don’t have this potential problem because they use the actual imaging sensor for focussing but DSLRs use a separate sensor dedicated to this important task. Most DSLRs have an AF calibration feature in their menus to correct for this. It’s straightforward but a little time-consuming. I use a special target to calibrate the auto focus. Essentially you focus on one particular point and then see how far off your focus might be and make the appropriate adjustments. Here’s a link to the process, and you can use a clearly marked ruler set at an angle instead of a special target, copy and paste the entire line into your browser:
There are lots of other resources on YouTube and the Web, too.
This is a basic guide to using telephoto lenses. If you have any questions just drop me a Facebook message via Ealing Wildlife Group and I’ll do my best to help.