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Filter Systems 101: Everything You Need To Know About The Different Filter Systems

Filters are what is going to turn your photos from good ones into great ones.

This is a technical summery of the different systems, if you want to read more about how, when and why to use them check out this other resource I’ve written that includes a section on best practises when using filters then come back here after. There are 2 main types of filter system. Circular systems and square systems, and they are pretty much what they sound like.

Circular Filter

Circular Filter

Circular filters are round and screw onto the end of your lens meaning you will have to buy the right size filter for each lens you have.

Square Filter

The Square Filter System

Square filters on the other hand have to be attached to the end of your lens using a special bracket. The advantage of using this system is you don’t need to buy different size filters for each different size lens. Often you simply put the bracket onto the end of which ever lens you are using and slide the square filter into the bracket and your ready to go. You’ll maybe have to get adaptor rings for different sized lenses but they aren’t expensive and that’s much better than having to buy a whole new set of filters.

When it comes to square filters you can’t beat the Lee System. They have a huge range that includes every type of filter you can imagine and their quality can’t be beaten.

Now we’re clear about what the differences between the two systems are, let’s talk about specific filters and which ones fall under each category.

Polarizers

Arguable the most important filter you should have because it’s pretty much the only filter who’s job can’t be replicated in post processing or using a built in function on your camera. Using a polarizer cuts out glare on top of water (or from most shiny surface really) and adds saturation & contrast. It’s this ability to cut out glare though that makes it such a powerful tool, and you can’t achieve this in any other way. There are main 2 types of polarizers; linear polarizers and circular polarizers. 



For travel photography the type you will need almost all of the time is a circular polarizer filter (CPF). A CPF screws onto the end of your lens and can rotate in order for you to adjust the amount of polarization you want. Getting a round rotating CPF will mean you can use it at the same time as other filters such as neutral density filters & graduated neutral density filters, which we’ll get onto now.

Neutral Density Filters

Neutral density filters, or ND filters for short, are dark pieces of glass that stop some light getting into the camera. You can get a number of different ‘strength’ ND filters but the most common are 3 stop, 4 stop, 6 stop and 10 stop. ‘Stop’ refers to how much light they cut out, the higher the stop number, the more light they cut out.

Different ND Filters

Different ND Filters

The main reason for ND filters is to block out light in order to achieve a slower shutter speed and in-turn blur movement. Below you can see the affect of using a ND filter with a slow shutter speed on moving water.

Long Exposure The longer the shutter speed, the more ‘stops’ of light need to be cut out. Either circular or square filter systems are great when it comes to ND filters.

Graduated Neutral Density Filters

Like normal ND filters, graduated ND filters reduce the amount of light getting into the camera but this time the glass gradually goes from light to dark.

Different ND Graduated Filters

Different ND Graduated Filters

Why might you want this? Well because it allows you to do things like darken bright skies while leave the bottom half of the frame fully exposed. This is particularly handy in landscape photography when shooting a sunset for example, as the dynamic range between the bright sky and dark foreground can be difficult to expose for. Without a graduated ND filter the sky would either be over exposed or the foreground would be way underexposed.

You can overcome this problem without the use of filters by taking an HDR photo (taking 3 different exposures of the same scene and combining them in a post processing program like Lightroom) but many photographers prefer to do it manually using graduated ND filters, mainly because it saves time in post afterwards and also because we love taking photos as photographers, not sitting behind a computer having to do lots of editing to make things look good.

Another reason why graduated ND filters are a good idea is because you can combine them with other filters at the same time such as a normal ND filter and get a perfectly exposed long exposure shot. There are a few different types of graduated ND filters but the 2 main important ones you should know about are hard edge and soft edge. A hard edge means the filter will go from dark to light more suddenly and won’t gradually fade from one to the other. Great for when you have a scene with a fairly straight horizon, for example looking out to sea.

ND Hard Grad

ND Hard Grad

A soft edge means the filter will gradually fade from dark to light. Best for use in mountainous scenes where the horizon isn’t such a straight line. This way you won’t see a dark line cutting off the tops of some of the mountains.

ND Soft Grad

ND Soft Grad

Normally square filter systems are the best for graduated ND filters because they can be slotted into a filter holder and depending on where the horizon is in the frame, the filter itself can be slid up or down to line it up with the under/over exposed parts of the photo.

UV Filters

Probably the least important filter these days. Modern cameras and lenses are pretty good at not letting UV light interfere with photos. Back in the days of film cameras it could cause the developed photo to have a slight blue haze in it as film can be sensitive to UV light. It’s not really necessary now but some people still like to include them in their filter kits mainly for the purpose of protected the lens glass.

I personally don’t bother with them because I’m very careful but I can understand why people do use them. After all, spending $30-$50 on a UV filter to protect a lens that cost 100’s if not 1000’s of dollars does make sense. Accidents do happen I guess. If you’re going to use a UV filter to protect your lens then obviously a circular UV filter is best so you can just screw it onto the end of your lens and leave it there for added protection.

Finally… A Filter Pouch

After you’ve kitted yourself out with a nice selection of filters it’s a good idea to get yourself a nice filter pouch to hold them all in. It keeps them protected and nicely organised so that you don’t have to fumble around looking for the one you need. Filter Pouch Think of it as your emergency photography survival kit. I always think mine looks like an emergency survival kit anyway. You pull out this little bag and in it you have everything you need to turn a good photo into a great one.

Thanks for reading!

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Charlie Gardiner
Article by Charlie Gardiner

Charlie, originally from the UK but currently based in Spain, is a travel photographer and the founder of World of Travel Photography. For the last few years he has been making a living from his travel photography which has enabled him to see more and more of the world. Check out his Instagram and Twitter accounts below to follow his latest adventures.

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