When and how to use Filters.

[photouser]

Hi everyone,
My name is Mike and my Photographic Genre is Landscape and Macro photography. I am fairly new to this and have 2 questions that has me baffled!!!!
Can anyone tell me the difference between ND Filters and G.N.D filters. My other question is :- In what sequence would I place several filters on the camera lens? i.e. UV-CPL-colored and any other filters that are necessary.
Or does it really matter?
Many thanks in anticipation of all the advice I am going to receive.
Best regards,
Mike

[Mike Buckley]

Welcome to CiC, Mike!

A neutral density filter has the same density throughout the entire filter. It is used to reduce the same amount of light entering the lens throughout the entire area of the scene being photographed. A common use is to allow use of a slow shutter in bright light that produces the milky look of a waterfall when the light is so bright that a slow enough shutter might not be possible without using the filter. By the way, a polarizer filter is one type of a neutral density filter and I often use one for that purpose even when its use as a polarizer is not needed. That explains why I always recommend that a polarizer is the first filter a photographer should buy when shooting outdoors.

A graduated neutral density filter has a changing amount density. It is used to reduce the amount of light entering the lens throughout only a portion of the area of the scene being photographed. As an example, you might be photographing a landscape scene when the sky is very bright but large areas of the land are very dark. You could position the filter so the part that blocks the light is aligned with the sky and the part that blocks no light is aligned with the land. You can buy neutral density filters with hard, medium and soft transitions between the part of the filter that blocks light and the part that doesn't block light. To see several examples, click here.

I never use a UV filter, so I'm not sure about the ideal order for using it. I usually use a polarizer filter by itself, but I can imagine that it would be difficult to turn if it isn't farthest away from the lens in a stack of filters.

[DanK]

An ND is uniform in darkness. A GND is graduated, with maximum darkness at one extreme and none at the other. the latter is often used to darken skies, placing the border between dark and clear near the horizon.

In digital work, there isn't a real need for colored filters, as you can deal with hue and saturation more easily and more flexibly in post-processing.

Re the order of stacking: the best is not to stack at all unless there is a good reason to. Each filter will add its own imperfections. I almost never stack filters. For example, if I have a protective filter on a lens and decide I need a CPL, I take the protective filter off first unless I have no time. It might make sense to combine a CPL with an ND in some cases, but in those cases, I don't think it matters which order you use. If you use a GND, the GND would have to go on first so that you don't end up rotating it when you rotate the CPL.

[Polar01]

Michael I adding a link to the Lee Filter site, I have used them for a number of years. What I suggest is that you look and read the information where you will see the difference between ND and GND filters. It may also help with some of your other questions. I do not suggest that you go with Lee as there are some other brands on the market. I would suggest, that you do not go the buy the cheapest route as they are good enough, well they are not good enough so you end up buying twice.

Cheers: Allan

[Manfred M]

Welcome to CiC, Michael.

You have received some excellent advice, but let me add a bit more.

There are two different types of filters; circular ones that screw onto your lens and rectangular ones that are used in conjunction with a filter holder. If you are thinking of using GND filters, that approach is just about mandatory.

Let's start with the UV filter. I don't want to start another argument, as this can be an emotional topic with some photographers. Strictly speaking you do not need one as every camera sensor has both a UV and IR filter built in on top of the sensor stack. Many photographers (including me) do use them under some conditions (dirty, rain, etc.) to keep contaminants off the lens surface. I own a number of lenses that do not have filter threads and I can't use a UV or clear protective filter with these. If you decide to use a US / clear filter, make sure you remove it before putting any other filter on.

Polarizers come in two types; linear and ciruclar. These describe how they work, rather than their shape. If you are shooting a DSLR, circular polarizers are the only way to go, as linear polarizers will cause issues with the camera's metering and / or phase detect autofocus systems. In mirrorless cameras, the answer is less clear as this design of camera might work with less expensive linear polarizers as well as circular polarizers. Check your camera manual to make sure.

One other issue with polarizing filters is that they can cause real issues with skies, if you are shooting wide angle lenses. Their effect is maximized when the sun is at right angles to the camera, and have no effect when the sun is straight in front or behind you. With a wide angle lens, greater than around 35mm full-frame equivalent, you will see this impact, which is referred to as "banding". Here the sky will go from dark to light and frankly will not look good.

Straight ND filters are used to reduce the amount of light getting through to the sensor. These are generally used to either use a wider aperture than is normally possible under the given lighting conditions so as to give the photographer a shallower depth of field to shoot with or to use slower shutter speeds, which are often used to soften water and / or clouds.

Straight ND filters come in round and square formats. I own both, but many of my lenses use a 77mm filter thread, so these are easy to use. One option is to use step-down rings, which let you mount the lens on one with a smaller filter thread. My experience with these has not been good as getting the filter and filter ring apart can be a bit of a battle. Plastic filter wrenches help here. Also, using filters that have brass mounts rather than the less expensive aluminum ones (on both the filter and step-down ring) can help.

Variable ND filters are also available. I don't use these, but people that do have told me that the inexpensive ones are terrible and the good ones are extremely expensive.

On to GND (a.k.a. grads) filters come in different densities and vary how the gradation between the clear and darkened areas are separated. The graduation can be "soft" or "hard". I will use hard grads when I shoot over water and the horizon line is fairly distinct and will use soft grads for landscapes where there is not defined horizon. I tend to shoot 2-stop and 3-stop grads.
Some people will tell you that they can get the same effect by applying a gradient in post-production. That is sometimes true, but when the sky is extremely bright, I will use my grads to ensure I get a good, clean capture.

The reason one uses rectangular grad is that one can slide them up and down to place the filter exactly where the photographer wants the effect to occur. At times, I will also turn my grads to get the right coverage, for instance when shooting a hilly or mountainous scene or even in cityscapes.

When it comes to square and rectangular olders, there are a number of them on the market. The best ones are usually made by Lee, Formatt-Hitech and NiSi. I own the Lee system as I find it superior to the other two (and I have shot with all three products). The cheap no-name ones, I would tend to stay away from. These devices come in two parts; the filter holder itself and an adapter ring that is mounted on your camera lens and holds the filter holder. One uses a different adapter ring for each lens filter thread size. These systems all take polarizers. The Lee system puts the polarizer farthest away from the camera and the NiSi puts it close to the lens. I did not shoot the Formatt-Hitech with a polarizer so don't know. There are advantages and disadvantages to both approaches.

In terms of stacking filters, I have shot with a ND, GND and polarizer all in a stack, using my Lee filter holders. I don't like stacking round filters because of the previously mentioned problems in getting them apart. If you do use a filter holder, the polarizer's position will be dictated by the filter holder design. The ND (especially if it is quite high density) should be closest to the lens and needs to be checked for light leaks. The GND comes after the ND (farther away from the camera).

[LePetomane]

Good info. Thanks.

[rpcrowe]

You have received some very valid information. One extra bit of information which I may have missed in the above is a recommendation to add a set of filter wrenches to your filter kit. Occasionally screw-in filters may bind and be difficult to remove. This happens more frequently with filters whose frames are aluminum and less frequently with more expensive brass frame filters.

A filter wrench is a cheap and lightweight fix to a jammed filter. It will damage neither the filter or the lens.

Here is just one example from eBay, you can find them less expensively.

http://www.ebay.com/itm/Fotasy-FW-49...oAAOSwLsBZPmP1

The size wrenches you buy depends on the sizes of filters you use.

I regard these wrenches as a bit of insurance. You don't need one until you need it...

[DanK]

Let's start with the UV filter. I don't want to start another argument, as this can be an emotional topic with some photographers. Strictly speaking you do not need one as every camera sensor has both a UV and IR filter built in on top of the sensor stack. Many photographers (including me) do use them under some conditions (dirty, rain, etc.) to keep contaminants off the lens surface. I own a number of lenses that do not have filter threads and I can't use a UV or clear protective filter with these. If you decide to use a US / clear filter, make sure you remove it before putting any other filter on.

Mike,

Just to elaborate a bit on Manfred's point above: the endless debates on the internet tend to focus on the use of UV filters, but as Manfred points out, UV protection per se is no longer needed with digital cameras. For that reason, some vendors sell both UV filters and clear protective filters that do not filter UV. In some cases, you can save money buying the simple protective filters, but for reasons I don't understand, they aren't always cheaper.

Since this has become a more general thread about filter use, I'll add two points. First, Allan said not to go with the cheapest. I agree. More specifically, I would stick with reputable brand names, and look for multi-coated filters, which lessen flare. However, once you get above the cheap ones, don't assume that cost always correlates with quality. For example, consider this review, which shows CPLs from Marumi--a mid-priced brand--right up there with the biggest names. (Marumi became my default after I read that review some years ago.) Second, filters can be problematic when the light source is in front of the camera. You can get more flare, even with a good filter. I often do use protective filters--I have had any number of them ruined by dirt or gunk, often of unknown providence--but I remove them if I have a point source in front of the camera, e.g., in doing urban night photography.

Dan

[photouser]

Hi Guys,
Many thanks for all the advice you have posted me. As I have received quite a few, it will take me a little while to read and digest all the advice. Thanks again. I now know the best place to visit for first class advice on Photography.
Best regards,
Mike

[rpcrowe]

One more addition. Hoya has sold (and may still sell) Moose Peterson Warming Circular Polarizing Filters. These are excellent filters but are really aimed towards film photography. Using a filter like this on a DSLR, especially when using Auto White Balance is counter productive. I have one but, don't use it anymore since, even when shooting RAW (which I always do) correct color balance tends to take some work to achieve...

[Mike Buckley]

It has never made sense to me to use a warming filter of any kind when using a digital camera. That's because the same effect can be so easily achieved by altering the white balance. If the filter is graduated, the same effect can be created by altering the color cast in the desired area of the scene.

[DanK]

It has never made sense to me to use a warming filter of any kind when using a digital camera. That's because the same effect can be so easily achieved by altering the white balance. If the filter is graduated, the same effect can be created by altering the color cast in the desired area of the scene.

I agree. This is just one example of the colored filters that were useful with film and aren't useful with digital. I had some in the old days, when I shot B&W film, but I don't even own any now to fit any of the lenses I use with digital cameras.