Google+ Followers

Thursday, June 5, 2014

Essentials of Photography - Part III, The Eye of The Photographer

Note:  This is another in a series of articles meant for my Photo Club to help us learn about Photography

Compiled from many sources by John D. Roach
with all images by me

In this lesson, as mentioned in the previous one, we will take a close look at perspective and how it can be used as a composition aid.  Our article will point out a how a few key filters can help you control light and compose pictures that would otherwise not be possible, before, finally offering some thoughts framing, camera angle and other ways to add strength to a composition.

Perspective & Lens Coverage

There is a misconception with many photographers, even among the most experienced photographers, that the choice of lens you use determines the perspective of the photograph – for sure this is not correct or true.

Perspective is a function of the distance between the camera, the subject and the background. If these distances remain the same it does not matter whether you shoot with a short focal length (wide-angle) lens, or a long focal
length (telephoto) lens, because the perspective will always be the same – what changes is the angle of view. If you use a short focal length (wide-angle) lens more of the scene will be included in the viewfinder frame of the
camera, compared with using a long focal length (telephoto) lens, because the former has a wider angle of view than the latter. If the focal length of the lens is doubled the area of coverage of the frame is halved, assuming the
camera to subject distance remains constant. For example, if you use a focal length of 18mm and then change to a focal length of 40mm the area of coverage is reduced to almost half of what is was, provided you shoot from the

same camera position.  The same would be true if a subject shot from the same position at 100mm and again at 200mm.  These are not perspective changes.



Chicago at 18mm



Chicago at 40mm




Building at 100mm


Building at 200mm


Perspective changes when the distance between the camera and the subject changes. If we use another example and shoot a picture with a focal length of 100mm, and then double the distance between the camera and the subject and shoot another picture with a focal length of 200mm, the subject will appear to be the same size in each shot but the perspective will look very different. The longer focal length offers a narrower coverage of the background compared with the shorter focal length, even though the magnification of the subject is the same in both pictures.


Bootsie at 100mm



Bootsie at 200mm
Distance from subject doubled


Therefore if you want to maintain the same image magnification but include less of the background, use a longer focal length and increase the distance between the camera and the subject, conversely, if you want to show more of the background use a shorter focal length and reduce the camera to subject distance. Whenever you consider a composition start by deciding how much of the scene you want to include and then choose the focal length and

shooting distance accordingly.

These effects can be put to good use. By photographing a subject at close range with a wide angle lens it will appear larger than normal in relation to other elements in the scene that are further away from the camera. You can exploit the extended depth of field offered by wide angle focal lengths, and use the hyper focal distance technique to ensure the main subject and the background are both rendered sharply, or alternatively you could use a wide aperture (small f-/number) to limit depth of field and isolate the subject with the differential focus technique, as discussed in Lesson 2.

Equally, you can use the characteristics of a long focal length lens to magnify a subject that is further away from the camera, whilst restricting the amount of the background that is included in the frame. This has the opposite
effect on the perceived perspective, as the subject and background appear to be closer together than they actually are; an effect often referred to as "compressed perspective”.  See these to cityscapes:



Cityscape at 18mm


Cityscape at 38mm


Cityscape at 86mm


Filters

Do traditional optical filters have a place in digital photography given that it is easy to emulate their effect with powerful image enhancement applications such as Adobe Photoshop, and a little skill?  Yes and indeed!

This question can be answered simply that getting as much right in camera remains an imperative; equip yourself with a few key lens filters, and not only will you find this task relatively straightforward, but you will also save yourself precious hours that would otherwise be spent trying to correct and enhance your digital pictures with a computer. If you shoot on film, particularly transparency film, the arguments for using filters are even more compelling, since they are often the only means by which you can control light to record your vision.

Why Use a Filter?

It is pointless using a filter just for the sake of it, because at the risk of stating the obvious most filters will change the way that a film, or sensor “records” or captures” light. Therefore, it is important to consider, in the same manner as you would choose a focal length, or lens aperture to convey your perception of a scene to the viewer, whether filtration is appropriate, and if so which filter(s) is required. We recommend if you are shooting with a digital camera only three types of filter are required; polarizing, neutral density, and graduated neutral density (see below).


A filter can do one or more of the following:

  • Control exposure to all or part of the frame area
  • Change the overall color or tone of the image
  • Adjust the color balance of the image significantly sometimes
  • Reduce or increase contrast (one of the key ways to enhance the scene
  • Create a visual effect which may make the scene different

Photography is all about making decisions and it is essential that among these you analyze what if any aspects of the scene you are photographing you would like to change and why. In other words you have to decide what it
is that you are trying to achieve. To this end it seems that the art of good filtration is that its use should not be obvious. Used well, filters should enhance and compliment a photograph not detract from it!

UV / Protective Filter:

A question heard regularly concerns the use of ultra violet (UV) or
Skylight filters, and whether they should be left on a lens at all times. The
issue of reducing the effects of UV light, particularly prevalent in bright
sunlight, and at high altitude, which can cause a 'cool' blue color cast to
occur is no longer relevant since most modern films and digital sensors
have very little if any sensitivity to UV light.

The other justification given for keeping such a filter attached
permanently to a lens is their value in protecting the front element from
physical damage. Some manufacturers make filters from coated optical
glass that does not influence the transmission of any particular
wave-lengths of light. These protection filters can be useful, particularly if
you shoot under difficult conditions, for example in abnormally high
levels of dust or moisture, when you are likely to clean the front of the
lens far more often, which increases the risk of inadvertently damaging
the front element. In these circumstances consider keeping a protection filter in place, and I usually leave one on at all other times as well; after all that is what they were designed for. However, remove the protection filter whenever shooting directly in to a strong light source such as the sun at sunrise or sunset, as the surfaces of the filter can cause internal reflections within the lens that reduce contrast and flare spots. Always use a lens hood whenever possible to protect the front of your lenses from both physical damage, and extraneous light.

Filter Systems:

Quality should be your first consideration when it comes to selecting a filter. I have never understood the rationale behind spending a considerable amount of money on a high-grade lens to then go and stick a cheap filter in front of it but some photographers are apparently prepared to do so. Then they have the temerity to complain their pictures show the effects of optical aberrations and unexpected color shifts. Welcome to the real world – good quality filters are expensive!

Top quality glass, or resin filters are expensive since their production requires the same high-grade materials, exacting methods of manufacture, and tight quality control as a high quality lens.



So what are the attributes of a good filter?

  • The quality of the raw material is important – regardless of whether the filter is made from glass or resin.

  • A filter should be absolutely neutral in color (unless it is designed to change color in a specific manner).

  • To maximize light transmission a filter will usually benefit from being coated, or multicoated.

  • The thread of the filter mount or mounting ring should be made from a suitably durable metal to prevent it being deformed with use and causing problems by binding in the filter mount thread of the lens.



Filter Systems – Round or Square?

Filters come in two distinct varieties, either round types that attach directly to a lens via a circular mounting thread, or slot-in types that require a dedicated filter holder, which attaches to the lens by means of an adapter
ring. The former type are quite adequate if all you require is a filter that produces a uniform effect across the entire frame area; however, this type should be avoided if you need any form of graduated filter, which has an
effect that changes between one side of the filter and the other. The round screw-in type graduated filters almost invariably have the area of transition positioned across the center of the filter, where it is likely to be least useful.







Typical Filter Assembly on Camera Lens


A slot-in filter system is more flexible, particularly if you have a range of lenses with a variety of different sized filter threads, as you only need one of each filter type and use adapter rings of different diameters that fit into a dedicated filter holder to attach the filter to the lens. The great advantage of this type of filter system is that the filter can be moved up and down in the holder, and rotated to align the area of transition of a graduated filter with precision.

If you wish you could keep an adapter ring attached to each lens, which allows you to change just the holder and filter(s) between different lenses, improving handling, particularly when you need to work quickly. For maximum flexibility, particularly with lenses that have a wide angle-of-view, it is best to opt for slot-in type filters of a sufficient size to prevent vignetting (the cut-off of light in the corner of the frame), generally, this means they
will need to be about 100mm wide.

Carrying filters, even a small collection, will require some thought if they are to be accessible and well protected at the same time. The best solution for the circular screw-in variety of filter is to stack them all together and then fit screw-in metal end caps to form a 'tube'. The larger slot-in style of filters are usually supplied in a slip-in case and are best kept in these but if you want to reduce bulk, filter wallets capable of holding multiple filters, are produced by several manufacturers.

Filter Types - Polarizing Filters

The polarizing filter is without doubt the most useful filter of all for outdoor photography, regardless of whether you shoot color, or black and white, on film, or with a digital camera.

Known popularly for their ability to deepen the color saturation of a blue sky a polarizing filter can also be used to boost other colors in a scene under virtually lighting conditions. Their principal disadvantage is that they reduce
light transmission by up to 2-stops (2EV). A polarizer can help you in two ways: it can either reduce the effect of light scatter that would otherwise cause a loss of contrast or color saturation, or alternatively reduce/remove
the effect of reflections from a non-metallic surface such as glass, or water.



Scene without Circular Polarizer




Scene with Circular Polarizer #1



Scene with Circular Polarizer #2


A good example of light scatter is that blue sky referred to earlier. As light from the sun enters the upper atmosphere it is scattered by air molecules,which causes its regular, uniform wave pattern to be interrupted. This scattering process, a reflection, reduces color saturation but a polarizer removes many of these 'scattered' waves by only allowing light waves in a specific orientation to pass through it. This effect is strongest when the filter is at 90ยบ to the direction of the light. So, if the afternoon sun is in the West sky the polarizing filter will achieve the deepest blue when it is facing North, or South. The effect is reduced progressively as the filter is turned to an angle of either 0-degrees, or 180-degrees to the sun. However, you do need to take some care if you use a lens with a very wide angle of view, as it is possible to record the variation in the degree of polarization across the sky area (see example picture). As a general rule of thumb the effect can manifest with any lens that has an angle of view greater than 70-degrees (i.e. a focal length of 28mm on the 35mm film format / 18mm on the APS-C format digital sensors).

Another effect of light scatter that we see commonly is the random reflection of light from foliage, which produces a bright sheen and masks the vibrancy of its color. Again, the wave pattern of light striking such surfaces is interrupted but the polarizer will prevent many of the resultant scattered light waves from passing through, so the sheen is removed and colors appear more intense.  

As an illustration of a polarizing filter’s effect on a surface reflection consider what happens if you look down into a pool of water; you normally see a series of reflections and rarely see much below the surface. As a light wave strikes the surface, part of it enters the water and is bent (refracted) while part of it is bounced back (reflected) off it. A polarizer helps to cut out much of this reflected light, whilst the refracted light travels in to the water to illuminate what lies beneath.  Compare both the water and the sky in above three images.

Finally, it is important to consider the difference between a linear, or circular type polarizer; a circular polarizer has an additional, very thin layer of material coated on its surface (it worthy of note that with cheaper filters the
quality of this coating can leave something to be desired with the result that they can cause color shifts) that induces a 'phase difference' in the light.  This additional layer enables these filters to be used with the TTL metering and auto focus systems of modern cameras, which rely on an internal polarization process to distribute the light to their metering and focusing sensors (a standard linear polarizer produces a light that can often conflict
with these systems).

Neutral Density

As photographers we rarely complain about having too much light, especially when we want to use slow (low ISO) film, or low sensitivity settings with our digital cameras, to maximize image quality. However, there
are occasions when reducing the amount of light passing through the lens is desirable. In these instances a continuous neutral density (ND) filter is the solution. Most filter manufacturers offer ND filters in a variety of strengths
(density).

Experiment with a slow shutter speed in an attempt to emphasize motion but in bright conditions this can be difficult, especially with digital cameras that have a base sensitivity setting equivalent to ISO200 film. Consider a situation where you wanted to show motion blur in a person running.

Typically, to achieve a reasonable amount of motion blur would require a shutter speed around a 1/30 second. However, apply the 'sunny f/16' rule of thumb, which states that with a lens set to f/16, the shutter speed required for 'correct' exposure of a subject in direct sunlight under a clear sky is the reciprocal of the ISO value, the exposure would be 1/200sec f/16; there would be no chance of recording any motion blur in these conditions. By fitting a 3-stop (x8) ND filter on the lens the exposure is reduced to 1/25 at f/16, providing a usable shutter speed and an aperture value to create the motion blur effect.


Image without Filter


Image with .3 ND Filter


Image with .6 ND Filter


Image with .9 ND Filter


Neutral Density Graduated

A graduated filter is 'clear' on one side and introduces an increasing neutral density effect across its width, as the density of the filter changes from no effect to the full quoted effect at the opposite side of the filter.
Why do we need graduated ND filters? In many scenes, particularly when shooting outdoors, it is not uncommon to encounter very high levels of contrast (the range of brightness between the darkest shadows and lightest
highlights); a typical situation is a bright sky above a dark foreground, where the difference in light levels can be equivalent to as much as 10, or 12-stops.  Film and digital sensors have far less tolerance to such an extreme range of brightness than our eyes, which are capable of adjusting to various intensities of light very quickly. The dynamic range of a film, or digital sensor (its ability to retain discernible detail in shadow and highlight areas) is typically no more than 5-stops with most transparency films, while most digital sensors and negative films have a slightly wider dynamic range, around 7-stops. The graduated ND filter allows us to reduce the contrast range of the scene by reducing the transmission of light from the brighter areas.

Generally, graduated ND filters are available in similar densities as the continuous variety of ND filter, and two different rates of transition between the clear and ND portions, usually described as 'soft' or 'hard'; the 'soft' transition is less abrupt than the 'hard' variety. The latter are used in situations where the boundary between the light and dark areas in the scene is well defined such as a bright sky above a dark foreground, and the boundary is a straight horizon. More often we encounter scenes where the boundary is less well defined; elements in the composition intersect the line between the light and dark areas, making it more difficult to disguise the edge of transition in the filter. In this situation use the 'soft' graduation variety.

The type of lens you use will also influence the choice between "soft" and "hard" graduation; the extended depth of field offered by an extreme wide-angle lens used at a small aperture can make the edge of transition in the filter appear too obvious, so use a 'soft' graduation to reduce this risk. At focal lengths up to around 135mm graduated ND filters work well; however, the limited depth of field of longer focal lengths diffuses the effect of even the most abrupt (hardest) transition in a filter to a point where it is of no practical use. 




Image without filter




Image with .3 GND Filter





Image with .6 GND Filter




Image with .9 GND Filter



Image without filter



Image with .3 GND Filter



Image with .6 GND Filter



Image with .9 GND Filter


Positioning a graduated filter does take a little practice to ensure the edge of transition is in exactly the right place, and is not apparent in the final shot. Trying to do this while looking through the viewfinder whilst the lens is wide open at its maximum aperture is not easy, especially with 'soft' graduated filters. If your camera has a depth-of-field preview button, close the lens down to a moderate aperture (around f/8) whilst you adjust the filter's
position. Do not close the lens down too far (f/11, or less) as the viewfinder image will be too dark for you to see what is going on.

Note: A high quality ND graduated filter is just that – neutral, and will not induce any shift in color but be wary of the so called 'grey' graduated filters produced by some manufacturers, as these are anything but neutral and introduce all sorts of unwanted color casts. Unless you are content to have strange, unexpected colors affect your photographs avoid these filters at all costs!

Variable Neutral Density Filters:

Essential these filters do the same as the Graduated Neutral Density Filter or the standard Neutral Density Filter however as the Circular Polarizer these filters thread onto the lens and have the capability of being manual adjusted to achieve the exposure effect sought for control light.  They are especially useful to manage effect of both water and sky since as already discussed with the other filters the shutter speed will be increased or decreased based on the amount (density) of the lighting control offered by the circular turns of the filter.  Here are examples at various turns of the filter wheel from minimum to maximum effect of untouched images:










Note:  These nine (9) examples can not be easily described in terms of the number of stops as is true with Graduated Neutral Density Filters, however, with practice the Variable Filter offers flexibility without having to change filters to give similar effect.  Please notice the variations in how light is controlled and the ultimate effect on the image.  While aperture may stay constant, the shutter speed has dropped or increased varying amongst to create a different feel as well as effect within the images.  Practice and you will see what I mean.


Framing

Apart from applying the guides to composition discussed in Lesson 1, and using the tools of composition discussed in Lesson 2 and the first part of Lesson 3, how you frame the subject has a fundamental affect on a the way it is depicted and thus, ultimately, the success of the picture (see following example).



An Example of Framing
This sort of boring building becomes
a little more interesting with framing


Camera Angle

The camera position you adopt in relation to the subject is probably the most influential decision you make when composing a photograph; after all it will not only determine which part of the subject and scene will be visible in the photograph but also establish how the viewer perceives the subject.

A high camera angle can create a sense of elevation, as the viewer looks down on the subject as though they had a high vantage point. For example, in a landscape picture this can heighten the sense of depth in a shot, as the viewer's eye is lead away toward the horizon. A low camera angle will emphasize the height of a subject, if you use a wide-angle lens and tilt it upward any vertical lines in the frame will appear to converge together
toward the top of the frame.  See the following examples:







Three Examples that show effect of Angle of Camera


Shooting Detail

All too often, particularly when we are confronted with a familiar scene there is a temptation to shoot a picture that encompasses all the elements it contains by adopting the "get it all in" approach. By taking a little time to study the familiar we can often find alternative pictures, an approach I call "seen in a scene" – by isolating a small section from the whole scene, whether it is a detail of a large subject, or an independent element with in the
overall scene it is often possible to create a new and refreshing view of the familiar.  Wide Angle effects a far different view then the compressed view:



Wide Angel View



Compressed Telephoto View


Juxtaposition

By enclosing two, or more specific and autonomous elements with in the edges of the viewfinder frame, you create an immediate relationship between them, particularly if you compose with care to eliminate any potentially
distracting elements to concentrate the viewers attention on the main subjects.



Examples of Juxtaposition of elements in the image


Another aspects of the composition to consider include using the points of intersection (power points) when the frame is divide in to thirds or fifths, and aligning the key elements on a horizontal, vertical, or diagonal line with the frame area.


Graphic Elements

In Lesson 1 we discussed the use of compositional tools such as the rule of thirds, and leading lines but as important as these are a composition can be strengthened even more by framing to include a strong geometric shape, such as a circle, square, or triangle within the frame. For example, including a circle in a rectangle adds significant interest to a composition. The graphic shape can be either a naturally occurring shape in the subject, created by the shapes of the elements that make up a scene, or by the patterns of light and shadow in the scene. The skill is to study the subject and look for these graphic elements; quite often they can be made most effective by cropping in closely to emphasize them.  Study the following five (5) examples:



Natural Flow




Natural Graphic



Repeating Pattern and Flow




Angular Flow



Contrasting Patterns


Frame in a Frame

Using a naturally occurring frame to frame the main subject is another effective method for successful composition. This can be done in one of two ways; either the framing object extends to the edge(s) of the viewfinder frame, or by using an element in the scene to create an independent frame around the main subject but show both it and the framing element in the context of the scene. Regardless of the approach you use the "frame within a frame" adds depth to a picture giving the picture more a of a three-dimensional quality.


Frame in a Frame


Shooting Silhouettes

Reducing the main subject to a graphic shape that lacks any color, or texture is a very powerful compositional tool, as we see the form of the subject in conditions of high contrast against the background.

Silhouettes can be found in any situation where the main subject is back lit (i.e. the light is coming from behind the subject), and often the most effective silhouettes occur when the subject has a well-defined shape (remember you are unlikely to be able to see any detail in the subject when it is reduced to a silhouette) and the background is uncluttered. 

Probably one of the easiest silhouettes to shoot is a subject against a sunrise or sunset sky, when the low angle of the light provides direct backlight. Fog and mist conditions can also lend an extra dimension to shooting a silhouette, as the light is diffused reducing the contrast to create a softer, gentler mood to the shot. You do need to take care though, because if the fog, or mist is too dense the contrast will be too low and the effect of the silhouette is weakened; in these conditions make sure you get closer to the subject.

Whenever you shoot a silhouette do consider the proportion of the silhouette to the overall area of the frame; too much solid black will dominate the picture, weakening the appeal of the contrasting color(s) of the background.
Likewise, do not forget the "rules" of composition I have discussed in this course, placing the silhouette on a point of intersection (power point) of a frame divided in thirds or fifths is still just as valid.

Exposing for a silhouette is straightforward provided you remember that any large area of solid shadow in the frame is likely to influence the TTL metering system of your camera and result in over-exposure, particularly
if you use a multi-segment, or center-weighted metering pattern. There are two solutions, either meter from the background without the subject to be silhouetted in the frame, or use a spot meter to take a reading from a
specific area of the background. My preferred method is to set the exposure manually but if you use an automatic exposure mode it will be necessary to either lock the exposure value for the background, or apply an appropriate level of exposure compensation.  See the following examples:




Thus concludes our third in our series on Composition and various techniques for creating more compelling images.  Go practice.

Final and Fourth Installment in our Essential of Photography — The Photographic Eye Series will be about light and time.  Stay tuned.

  John D. Roach, June 5, 2014


References:

New York Institute of Photography Pro Photography Courses
Several BetterPhoto Courses Material on Composition
Perfect Picture School of Photography and Bryan Peterson Books
Digital Photography School and Nikonians websites among others