Lens Filters: Which filters do photographers actually need?

In Gear by Pete LaGregor

A 10-stop filter allowed me to use a 60 second exposure here to blur the waves crashing against the shoreline, making it look like an eerie mist.

What filters do you need and how do you figure out what size is best? These are certainly questions that many new (and some experienced) photographers, who have never used filters, ask all the time. It can get a little complicated but it really just comes down to a couple that you really need.

I'll explain what each of these filters do, which ones you really need, and how to make sure you are getting the right filters for your camera.

UV Filters

These are the filters that frequently come as part of an add on package from the camera store when you purchase your camera or lens. This is a piece of old technology that has long since been obsolete but is hanging on for dear life, mostly because it helps to pad the profit margins of retailers.  UV filters originally were used with film.  Film is typically split into different layers for red, blue, and green.  The blue layer was quite sensitive to ultravoilet light.  However, even before digital cameras, most film being produced had to a large degree overcome that problem. Today's digital cameras have completely eliminated it through the use of internal filters that block UV and infrared light. What does all this mean? It means that UV filters are completely useless as far as image quality goes.

In fact, in many instances with light sources either within the frame or slightly out of frame, a UV filter can cause or increase lens flare. This is a result of there being an extra piece of glass in front of the camera for light to bounce between before being captured with the sensor. Add to this the problem of less expensive (ie cheap) UV filters causing a decrease in sharpness and contrast and why would anyone ever use one?

The reason most people use a UV filter is protecting their lens. But even this seems to be less helpful than once thought. A quick internet search as to the efficacy of UV filters in protecting lenses will show you testing indicating that a lens with a UV filter on it may not be any more protected than one without. This has a lot to do with the fact that the front element of your lens is much more resilient than you think and, in fact, stronger than the UV filter. So any force that would damage the lens, will most likely go right through the UV filter with little resistance and harm your lens regardless.

If you are really concerned about scratching or dropping your lens then the ideal way to prevent that is a solid lens hood.  As opposed to a UV filter, a lens hood has the added bonus of preventing some lens flare as opposed to making it worse. If lens dropping is really a concern, get insurance on your gear. It's more expensive but you know it works!

Bottom line…you don't need a UV filter.

Circular Polarizer

A Circular Polarizer has two pieces of glass that rotate to adjust the strength of polarization

If you ever had “polarized” sunglasses, then you have experienced the effects of a circular polarizer. The lens filter type consists of two pieces of glass connected together and rotated independently to adjust the amount of polarization. In practical use, you simply just look at the image either in the viewfinder or on the screen and rotate the polarizer until it looks the way you want.

This is a must have accessory for any photographer.

A circular polarizer can be used for a number of things that can help your photo. Most importantly, the effects it can have on your image are difficult or impossible to recreate through software editing.  Incidentally, they are not called circular polarizer filters because of their shape. It refers to the method of polarizing occurring. Older film cameras used “linear” polarizing filters but these prevented the use light metering and some type of autofocusing.  So now, they are obsolete and rarely seen for sale. You should make sure any polarizer you buy is of the circular type, but you're unlikely to find too many linear polarizers for sale.

A polarizer can reduce glare from shiny things like water or leaves.  The first time you use a polarizer you may be surprised how much glare come off of objects you shoot every day. Vegetation is particularly shiny without a polarizer. A properly used polarizer will result in richer, deeper, and more realistic colors when shooting objects that might otherwise cause a glare from the sun or other light source.

A polarizer here removed some of the glare off the rocks and also darkened the scene just enough to allow a 1.3 second shutter speed to blur the flowing water.

They can also mitigate or eliminate reflections off of water. While there may be times when you want to shoot a reflection, there are also many instances where removing the reflection creates a much more interesting photo. One common example is a shallow lakeside with interesting looking rocks or other features below the surface. If there is a reflection from the sky then you will have difficulty capturing an image of what is below the surface. However, with a polarizer, you can make the water crystal clear, allowing you to photograph what lies below the surface.

Polarizers also tend to make blue skies a darker, richer blue. Although, you have to be careful not to go too far with this or else you risk losing a realistic look. Also, when shooting the sky with a very wide angle lens and a polarizer, you may end up with a sky that in not the same color throughout. This is because a polarizer's effect varies based on the angle of the sun in relation to the subject and when you are shooting very wide you are looking at sections of sky that are being affected to varying degrees. When shooting with a very wide lens, it may simply be better to take the filter off.

Check out the article Six Tips for Using a Polarizing Filter to learn more.

Neutral Density (or “ND”) Filters

ND filters are really just sunglasses for your camera. They let less light into the lens. There are a number of uses for this and can probably be the topic of its own article.  By decreasing the light coming into the camera, you have more control over shutter speed, specifically, you can shoot at slower shutter speeds so that you can get the look that a slower shutter speed gives you.

ND filters are a valuable and very useful tool. 

ND filters let you accomplish shots that would not otherwise be possible. This could be a smooth silky looking waterfall, clouds blurring to create leading lines across the sky, or choppy water blurring to give the appearance of being perfectly still. They are even sometimes used by portrait photographers so that they can use a wide open aperture in bright daytime conditions.

ND filters come in a range according to how dark they are. This is commonly measured by how many stops (in shutter speed, aperture, or ISO) you would have to adjust the camera settings in order to have a proper exposure as compared to without the filter. Filter companies use different ways of expressing this (which can be very confusing to those new to ND filters).  Some make it easy and just say the number of stops but others use increments of 0.3 for some reason. In other words a 1-stop filter would be 0.3, a 2-stop would be 0.6 and a 10-stop would be 3.0. It's important to do a little digging to make sure you are buying what you want.

An ND filter made it possible to use a 15 second exposure to smooth out the water to really contrast with the jagged branches sticking out.

Another consideration to make when choosing an ND filter is whether it gives the resulting image a color cast. This is more of a concern in the stronger filters such as a 10-stop. Generally, if you are shooting in RAW then you can correct this in Lightroom, however, it just makes everything a little easier when you can see what the image really looks like right there on your camera without having to switch white balance every time you put the filter on or take it off.

If you want to learn more about ND filters check out these articles right here in Improve Photography

Graduated ND Filters

These are simply filters that are ND filters on half and clear on the other half. They come in different variations which range from gradual to more sharp transitions from the ND half to the clear half. These filters are used for a situation where one part of your image is brighter than the other (such as the sky and the ground in a landscape image).

The downside to these is that they are really only useful when you have a perfectly flat horizon. If there is anything sticking up, like a mountain or tree, it is going to get darkened right along with the sky. These filters are another holdover from the film days and scenes with a broad range of brightness are more aptly dealt with by bracketing your shots and blending them together using software like Photoshop.

What Size Filter?

This is an easy one. Every lens has a filter diameter or thread size. This is measured in millimeters (“mm”) just like the focal length. Don't get these two confused.  If you are looking at an online store, you can usually find this information where the other specifications are listed. You can also usually find this number either in your instruction manual for the lens or on the lens box. I have always found it simple to just search the internet for “What is the filter size for _____ lens?” Google usually knows where to find the answer.

So does that mean if your lenses have different size thread, you need to get all different size filters? Absolutely not! It is very common for photographers (or at least the smart ones) to get a filter that fits their largest diameter lens (or even plan ahead to lenses they intend to buy). Once you have one large enough for your largest lens, you can get these cheap little accessories called step up rings. They are essentially adapters to let you put a larger diameter filter on a smaller diameter lens. Since the filter is larger than the lens opening, it will not block the image in any way. If you follow this method, you can use your budget for one quality set of filters and just a few step up rings rather than spending a fortune on filters of various sizes or sacrificing quality to get more of them.

Keep in mind this doesn't really work the other way.  You can't put a smaller filter on a larger lens with a step up (or down) ring. It would block the lens.

Square Filters (and Filter Systems)

What about those square pieces of glass you might see some landscape photographers using? They are filters too. Typically, these are ND and Graduated ND filters but there are square polarizers out there too (although it can sound confusing since technically its a square circular polarizer). Although it is more typical to have a standard polarizing filter either in front of or behind the square filter holder so that it can be adjusted independently.

The square filter holder system is attached to the lens though adapters sized to match your lens.

 

The benefit of this type of filter system is that you do not need to screw it on and off. You can either slide the square filters in and our or, in the case of most holders, simply snap the holder off, compose and focus your image, then snap it back on. This can be a huge time saver when working with very strong ND filters because you likely won't be able to see anything in the viewfinder when its attached.

These are the type that I use primarily and love them, however, it is certainly a user preference. Many amazing photographers use exclusively screw on type filters, so figure out what style works best with you and go for it. There are many good holders out there by companies such as Lee Filters, Cokin, Breakthrough Photography, and even a very inexpensive version by a company called The Filter Dude.

You will need both the holder and square filters to use this system.

So what do you really need?

So let's get down to the real question here. What do you really need? Well, like most questions in photography, it really depends on what you are doing. Landscape photographers will tend to need filters much more than portrait photographers (although a 1 or 2-stop ND can come in very handy for a portrait photographer shooting outside).

My recommendation would be to make sure you have a polarizing filter first. This will help in any kind of photography and even can act as a 1-stop ND filter as it blocks just about that amount of light, so it is useful and versatile. The next step would be to get an ND filter. Here is where you have to decide what you will be using it for the most. If you want to turn waves into a mist effect like my photo above, then you want a stronger ND such as a 6-stop or 10-stop. If you don't really shoot landscapes and primarily shoot portraits, you may want a 2-stop or 3-stop. Skip the 1-stop because your polarizer can do that. If you are unsure then a 6-stop ND is a great choice. It can get you those cool landscape effects and still probably give you the benefits that a portrait photographer needs from an ND filter.

A great starting combo is a circular polarizer and a 6-stop ND filter. 

There are a number of companies out there selling filters. B+W, Lee, Tiffen, and Breakthrough to name a few. The prices range from kinda cheap to hundreds of dollars. I would recommend checking out the offerings from Breakthrough Photography. They consistently come up as having the best quality and (for ND filters) the least color cast, even on the stronger NDs like the 10-stop.

If you want to learn more about filters in general, check out Episode 19 of the Tripod Podcast, Filters and Filter Systems.

I would love to hear from everyone out there about their thoughts on filters. What works for you? What kind of creative uses have you found for various types of filters? What style of filter system do you prefer and why?


About the Author

Pete LaGregor

Pete is a portrait photographer in New Jersey and specializes in Family Portraits, Senior Portraits, and Personal Brand Photography. You can also find him on Pinterest.