Monday, 20 October 2014

Tele Photo Lenses

Lenses with focal lengths longer than that of Normal (approximately 40degree angle of view) are called tele photo lenses. Generally lenses which have a focal length of 70mm or more are termed tele photo lenses. Remember that focal lengths mentioned in this article are all for full frame sensors and if you camera has a crop sensor then you need to factor that into the equation.

Tele Photo Lenses
Tele Photo Lenses

Types of Telephoto Lenses

Short Telephoto Lenses (Focal lengths from 85mm - 135mm)

Short Tele Photo Lenses
Short Tele Photo Lenses

Short telephoto lenses comprise focal lengths from 85mm to 135mm; they are normally very compact and lightweight lenses ideal for handheld shooting of portraits and candid shots. The short tele photo focal length is the most preferred focal length for shooting portraits as it brings out the best proportions in a human form.

Medium Telephoto Lenses (Focal lengths from 135mm - 300mm)

Medium Tele Photo Lenses
Medium Tele Photo Lenses

Lenses with focal lengths from 135mm – 300mm are termed as medium telephoto lenses, they are more expensive and bulkier compared to short tele photo lenses and are commonly used to shoot action and sports.

Super Telephoto Lenses (Focal lengths from 300mm+)

Super Tele Photo Lenses
Super Tele Photo Lenses

Super telephoto lenses are the ones with a focal length greater than 300mm, they are mostly used by professional wildlife photographers and also by some sports photographers. They are very specialized piece of equipment and so they are very expensive and also weigh much. One will need super heavy duty tripods and specialized tripod heads like the gimbal heads to make the most out of these heavyweights. However they lets you get as close to the action as possible without intruding your subject’s private space and putting your life at risk. Super tele photo lenses are also used for astrophotography.

Why use a telephoto lens?

A common misconception most beginner photographers have about telephoto lenses is that are just for capturing subjects at a distance. And are only to be used in situations where you can’t get physically close to the subject. While this is one of the major advantages that a telephoto lens gives the photographer, the ability to photograph objects from a distance, it is the control of perspective that is the decisive factor. The distance from which you shoot your subject changes the perspective of your photos. Tele photo lenses lets the photographer normalize the size and distance between near and far objects, thereby making the depth of field look much shallower.

Telephoto Lens and Perspective

The narrow angle of view provided by telephoto lenses helps normalize the relative size and distance when comparing near and far objects. Meaning even though nearby objects actually appear larger in reality; when viewed through a telephoto lens both nearby objects and objects that are much further appear of similar size. This effect is known as "foreshortening" or "perspective compression". It is to be noted that normalizing the relative size too much would  make the scene flat and uninteresting as human eyes generally expect closer objects to appear little larger.

A telephoto lens could also make the distance between objects appear compressed. Meaning they can make objects that are physically miles apart to look as if they are on the same plane. A much powerful tool if one needs to emphasize the number of objects, or to enhance the appearance of congestion.

Another common misconception about telephoto lenses is that they affect the perspective, however just as we discussed in case of wide angle lenses, perspective is only affected by the distance from the camera to the subject. Normally when shooting with a tele photo lens one is much further away from the subject which does affect perspective and not any peculiarity of the lens as such.

Shooting Far Away Subjects

With its very narrow angle of view a telephoto lens enables the photographer  to bring small and distant objects closer, thus making it possible to photograph candidly without the subject being aware of the camera, which could significantly alter its behavior. This is useful especially for candid portraits and also when shooting wildlife. Telephoto lenses also let the photographer selectively compose his/her frame so as to make simple and focused compositions. The power to exclude what is not required in a frame presents unlimited creative potential to the creative mind.

Shooting Landscapes with telephoto lenses

We all grew up hearing that "a wide angle lens is for landscapes" and "a telephoto lens is for wildlife”. The logic behind this is that wide angle lenses exaggerate the sense of depth and spaciousness is an important quality of landscapes which makes wide angle lenses the perfect choice for landscape photography.

However it is to be noted that very powerful and effective compositions can be made with the "inappropriate" type of lenses. Telephoto lenses compress the sense of depth and so to use them to shoot landscapes require adopting different techniques. Remember in case of tele photo lenses, less is more, keep your compositions simple, cut out the seemingly unimportant elements and concentrate on the most visually striking elements thereby adding impact. A common telephoto technique to improve the sense of depth is to compose the scene so that it's comprised of layered subject matter at distinctly different distances.

Focusing and Telephoto Lenses

While using telephoto lenses, it is of utmost importance that you focus on the chosen area with pin point accuracy. The longer the focal length the more accurate your point of focus needs to be. The primary reason for this is because when shooting with telephoto lenses you will be working with much shallower depth of field, and the magnification of the lens also enlarges the out of focus area thereby increasing blur in those areas. 

Telephoto lenses are easier to work with the focus and recompose technique as one is shooting at a distance from the subject chances of errors are less. Preferred technique of most photographers is to use the central autofocus point to achieve focus, lock the focus (by keeping the shutter button half pressed) and recompose before you press the shutter fully down.

Combating Camera Shake

The longer the focal length the shorter the exposure time required to get a sharp shot. Camera shake is more pronounced with longer focal lengths and to reduce it you need to either use faster shutter speeds or hold your camera steadier or a combination of these.

One might need to use a larger aperture (if the lens used permits it) or increase the ISO of the camera. The compromise is with a wider aperture one loses depth of field and with a higher ISO setting there will be more noise in the images. One could lean on a stable object or use a monopod or a tripod to make the camera more stable.

Telephoto lenses and depth of field

Telephoto lenses do not have less depth of field. If you are magnifying your subject by the same amount both telephoto and wide angle lenses will give you the same depth of field. Telephoto lenses have a reputation of producing shallow depth of field, however it is due to the fact that while using tele photo lenses, people magnify their subjects more and they also shoot from further away thus the subject ends up filling more of the frame and so this higher magnification is what causes the shallower depth of field. As telephoto lenses enlarges the background in relation to the subject, It also does enlarge the out of focus regions in an image (bokeh) thereby giving the appearance of shallower depth of field.

NEXT: Macro Lenses