Filters – Special Effects and More

 

Photography is, a lot of times, a matter of creativity. In this article I'll walk you through the main filters available with some tips and hints on the subject.

 

Contents:

1. what is a filter?
2. how is it attached to the camera?
3. what kinds of filters are there?
4. ultra-violet filter
5. polarizer
6. ND filter
7. diopter
8. infra-red
9. color filters
10. teleconverter
11. special and creative filters
12. Quality
13. summary

 

 

1. introduction – what is photography? Aiming a camera at a subject and pressing the shutter allows the camera to capture the light-waves that are reflected or emitted from the subject. Through the use of filters we can become selective of the specific wavelengths of light that the camera will absorb from the subject, thus allowing us to manipulate an image recorded to our satisfaction.  In this article I will explain and demonstrate the different types of filters and optical lenses.
2. A filter is designed to allow the camera to absorb specific wavelengths of light and to filter out the other wavelengths that that the photographer does not wish to record. This enables the photographer to achieve certain effects that he could not have achieved without the use of the filter, thus expanding the limits on creativity in his/her photography. A lens differs from a filter in that it changes the optics of a photograph and has no effect on the types of wavelengths that are filtered through to the camera.
3. Most compact digital cameras have no threading on the lens for the filter and need an adaptor to attach the filter. Adaptors can be fitted on to all cameras, and even if the manufacturer does not produce an official adaptor for a specific camera, there are many companies that with take on this task and create an adaptor that can be fitted on a tripod. This problem does not exist in SLR cameras, because most lenses have threading or a slot in the rear of the lens in the larger focal lengths. Most filters have threading on both sides, so one filter can be connected on top of another, though the fewer the better.
4. There are many different kinds of filters for all demands and the variety is enormous: ultra-violet, ND, infra-red, color filters, polarizer and the list goes on. Even if these terms don’t make much sense to you now, they will soon. The cheapest company for filters is Cozo, but there are more expensive and better quality products by B+W, Hoya, Tiffen and many others.
5. Ultra violet filter (UV filter)- This filter's primary role is to protect the camera’s lens system. It is relatively of low cost and it prevents direct damage to the lens in case the camera is hit. it prevents dust and other dirt from entering the lens ( I had a most unpleasant experience of this kind). In addition, the filter blocks ultra-violet light- thus reducing, even if minimally, the effect of haziness (there are UV filters that are designed specifically to reduce haziness). Because the primary function of the filter is protective, it is prudent to leave it attached to the camera almost always, and thus it is important that it be of high quality.
6. polarizer- The function of the polarizer is to enable the photographer to control the reflections from non-metalic objects. Use of the filter creates dark hues in the sky, emphasizes the contrast in clouds and other bright objects, and augments color saturation. The polarizer is built out of a “sandwich” of 2 rings, and the rotation of one lens in relation to the other ring determines the effect on the photograph. In order to achieve the maximal effect of the reflection you need to capture them in a 30 degree angle. When photographing the sky, it is recommended to shoot at a 90 degree angle to the sun. The filter diminishes the amount of light that enters in one stop. The polarizer is an expensive filter, relatively speaking. How does this filter works? Good one, well the answer is this – reagular light is unpolarized and so the light waves travel in all planes (horizontal, vertical and so on). You can imagine the polarizer filter as countless tiny vertical slits that only let the vertical light-waves through and block all the others. So when light reflects from a non-metalic it becomes partially polarized and that affects the image due to the filter.

7. Neutral density filter (ND filter) – This filter decreases the amount of light that is passing through it in an equal manner, without affecting the colors or wavelengths filtered, but just the amount of light. There are many kinds of ND filters, each measured by its strength. Some filters decrease only one stop worth of light (meaning, half the amount of light), and some decrease the light filtered by 3 or 4 stops. The filter allows the photographer to work with long exposures in broad day light, to open the aperture fully in camera that have limited shutter speed, to use film in high speed in day light (we don’t have that problem with digital) and so on. In addition, there is a gradual ND filter that is half transparent and half blocked, so the photographer can capture sunsets in a way that the ground is not under-exposed while the sky isn’t burnt. The ND filter is relatively cheap, but if you're looking for higher quality – again, money talks

 

8. Close-up Lens -  This lens’s job is to allow the lens to focus on much closer objects than the usual limits.. The photographer can achieve magnificent macro shots with these kinds of lenses. If you wish to expand your knowledge of macro-photography, I wrote a separate guide on the subject in this website. The lenses are measured by numbers that represent their strength. +4 lens will be stronger than a +2 lens and so on and so forth. The photographer can stack the lenses one on top of another, thus summing up their strength. For example, a +4 and a +2 together will be equal to a +6 lens. The price of these lenses is not expensive, and a set of 3 lenses +1, +2 and +4 costs about 40$. A B+W deopter with a +10 strength like I have costs about 100 US$.

9. infra red filter (IR filter) – the spectrum of light is much wider than what the human eye can perceive. The infra-red filter blocks all other wavelengths except the IR spectrum and that is why the filter looks black to us. When a photograph taken with the IR filter is processed in color, it doesn’t look very impressive. But when it is transformed to a black and white photos, the sky is black, the vegetation looks snowy white and even the most recognizable places seem foreign. In a film camera the photographer needs to load IR sensitive film and in a digital camera the photographer needs to make sure that the sensor is sensitive to the IR spectrum and to which wavelengths within that spectrum. In most cameras there is an IR filter that prevents the IR wavelengths from ever reaching the sensor. This built-in filter can be removed, but I wouldn’t recommend messing with it. There are filters for different wavelengths, starting from 650 nm up to 1000 nm. For example, the G3 camera that I had could perform with wavelengths of 720 nm and the Nikon D70 that I now have can perform more or less within that range. Even though the D70 is less sensitive to IR that the G3, it is still more sensitive than other DSLR cameras, like the Canon ones. Because the IR filter blocks most of the light from entering the camera, there is a need for long exposures of more than a few seconds even in mid-day. Some cameras are more sensitive and don’t require such long exposures. The Infra-red filter is expensive, and costs about 100$. It is recommended to read the IR photography article for further information.

10. color filters – these filters block all of the visible spectrum range except one color, which is allowed to pass through to the camera. In a color photograph the use of the filter will make the entire photo look the same color, which isn’t very impressive. But when you switch to black and white mode, everything becomes much more interesting. A red filter will create an illusion of very dark sky and very bright clouds, everything that is red will look white.  In the black and white mode, the color filtered (different color every time, depending on the filter) will appear white and its opposite color will appear black since it is filtered entirely. One should know that a similar effect can be accomplished by manipulating the color channels in photo-shop.
11. teleconverters – How many times did you express out loud the suspected profession of your lens’s mother when you were trying to photograph an object that was too far away? I know I did more than once or twice. It makes no difference what the range of your zoom is, you’ll always want more. That is the reason for the existence of a line of lenses that duplicate the focus , and thus the range of the camera. For example, if a compact camera can reach a zoom of 140 mm (in comparison to film), and this range, naturally, isn’t enough, a x2 teleconverter will increase the camera’s range to 280 mm (that sounds better). And vice versa, if the wide end of a compact  camera reaches 35 mm, and that too isn’t enough, there is a x0.7 teleconverter that allows me to reach 24 mm focus, which is more impressive. The prices of teleconverters is high and they cost about 250$. In SLR cameras increasing the focus length does not come without a price, because increasing the focus means reducing the aperture accordingly. For example, F/2.8 70-200 mm with a x2 teleconverter will give us a focus length of 140-400 mm with a F/5.6 aperture.
12. special and creative filters – There is a variety of filters that were created to satisfy artistic demands of the photographer and for a dramatic effect. For example, a “star” filter which is a glass with tiny slots across it that create an illusion of a stars out of every light source in the dark. Another example is the “fog” filter, which creates an illusion of fog in every photo. There are many more creative filters that are designed to add that extra kick to a photograph.
13. The quality of filters – All glass allow only part of the light through, and reflects the rest of it. Some have 10% reflection and higher quality glass has 95%, but to achieve even higher quality – special coating is needed. And here comes the different letters: MC, HMC, SMC and other variations while the first is Multi Coated and the rest are Hyper and Super. The difference is how many layers of coating can be found on the glass, the more the better.
14. summary – As we have discussed, the filters that exist and are available for use are numerous and varied, and each filter allows us to take the photo as we picture it in our minds. If you master the art of working with the right filters you could achieve those special views of life that exist only in photographs.

 

 

Yours truly,

Roie Galitz

 

 

 

 

All rights to this article and photographs in it are reserves for Roie Galitz www.galitz.co.il