Lens Filters - How to expand your photography
So you have been shooting for a while now, you have gotten the basics down and are looking for a way to expand your photography. Well there are many ways to expand , you could get a new body, a new lens, try your hand at a different type of photography or you could look into filters. Filters are a relatively inexpensive way to try different things (at least when compared to a new camera or a lens.)
There are a bunch of filters used in modern digital photography, but still the number of filters used in film photography was a lot greater. The reason is that a large bunch of effects can be done more easily and more inexpensively on the computer such as star effects or double exposure effects. However, there are certain types of filters that cannot be replicated on a computer, at least not yet. Listed below are the most common types of filters still in use in digital photography and when they are used.
No list of filters would be complete without at least mentioning these. Granted these don’t really change the image usually, in fact that’s precisely why they are used, because they don’t change the image and they are inexpensive. These filters are usually used as a way to protect the front element of the lens from scratches or chips. It is a whole lot less expensive to buy a new filter for $20 than it is to send your lens in for repair.
Circular Polarizer Filters (AKA CPL or Circ Pol.)
Image from Singh-Ray Filters
Unlike UV filters, circular polarizers do actually affect your image. The first, and probably the most obvious, is that they darken the image, meaning you have keep your shutter open longer or have a higher ISO to get the same exposure as if you weren’t using the filter. It is much like an ND filter in this respect. The difference between it and an ND filter is that the polarizer….well, polarises the light. This means that it will cut through glare on water, snow or something shiny, but it also saturates your blue and reds much like a good pair of sunglasses. If you are using a Circ Pol in a landscape shot, you will find the sky will generally be a much more vibrant shade of blue.
There is a trick though, if you are shooting with the sun or your light source in front of you and hoping to cut through the reflections in a lake for example, the Circ Pol will be basically useless. The filters are always most effective when your light source (like the sun) is at 90 degrees from the direction you are shooting in.
Neutral Density (AKA ND Filters)
ND filters are similar to UV filters in that the majority of them aren’t used to change the colour or contrast of the light that enters the lens. They are instead used to limit the amount of light that enters the lens. ND filters are categorised by how dark the filter is. Usually listed as how many stops of light they block. For example, a ND filter of 1 stop allows half the amount of light as would be expected to enter the lens should the filter not be used. Similarity, a 2-stop ND filter only allows 25% of the light to enter the lens. Every added stop halves the amount of light from the number previously. This means a 3-stop ND filter lets in 12.5% of the light etc etc.
So how does letting less light in affect your photography? Well, it allows your to have a longer shutter speed or a larger aperture in bright situations. To get a properly exposed image wile using a 1-Stop ND filter, you have to keep your shutter open twice as long. For example, if you weren’t using a filter and your shutter speed is 1/100th of a second, the new shutter speed when using a 1-Stop ND filter would be 1/50th of a second. Whereas if you were to use a 2-Stop ND filter, your shutter speed would end up being 1/25th of a second.
If you were looking for a shallower depth of field though, you would open your aperture more once you have put the filter on. For example, if you were shooting a portrait on a bright sunny day, chances are, if you shot at F2.8 or faster, you will over-expose the image because it cannot have a fast enough shutter speed to stop too much light hitting the sensor. This is another time when an ND filter is handy, depending on how over-exposed the image is, an ND filter of the appropriate darkness will allow you to shoot at F2.8 or lower without blowing out the image.
Light Pollution Filter
Image from Irex Filters
This one has been mainly used by the astro guys for their telescopes. Basically, this filter is designed to let most wavelengths of light through, while severely limiting light of a specific wavelength. That specific wavelength is 580nm which is the wavelength released by sodium lamps. The theory is that the light that most cities use in their streetlamps and therefor the majority of light pollution won’t pass the filter, allowing the camera sensor to see the other colours better. I haven’t seen many reviews of this particular filter but am very excited to see how effective it is in the field. It could make it easier to get star shots or even the northern lights over cities.
Which filters do you like using and which don’t you care for? Let us know and as always, tag your best shots with #inthenameofadventure so we can see them! Don’t forget to sign up for our newsletter either and that way you will never miss another blog article!