Using Filters in B&W Photography
- Exposure Compensation
- Popular Filters
- More Extreme Filters
- What About Overcast Skies?
- Use With Digital
- Neutral Density Filters
- The Ubiquitous UV
- Other Thoughts
You might wonder why someone would use a colored filter when shooting black and white film or the Leica M Monochrom. Simply, it changes the representation of colors that the film captures. Remember, your image is not black and white until it's actually recorded by the film. A colored filter will alter colors as seen by the lens and affect how they're recorded by the film. A general rule of thumb is that a filter will lighten colors similar to its own, and darken those opposite (as seen on a color wheel):
|Filter||Factor||EC||Description of Effects||Lightens||Darkens|
|Green||4x||+2||Lightens foliage and darkens skies somewhat. Pleasing skin tones in men||Yellow, yellow-green, olive, greens||Blue, violet, magenta, red, maroon|
|Yellow||2x||+1||Darkens skies slightly and increases contrast with clouds and reduces haze. Pleasing skin tones in women||Yellow, Chartreuse, Olive, Red, Pink, Orange, Lime Green||Blue, Violet, Purple, Lilacs|
|Orange||2.5x||+1 1/3||Stronger effect than yellow and may darken sky considerably||Yellow, Chartreuse, Olive, Red, Pink, Orange, Lime Green||Blue, Violet, Purple|
|Red||8x||+3||Produces very dramatic skies, darkens foliage and reduces haze||Reds, pinks, magentas, browns, yellow, orange||Blues, greens, cyan|
|Blue||4x||+2||Increases effect of haze, gives misty, foggy feel and obscures distant details||Blue, Violet, Purple||Yellow, Chartreuse, Olive, Red, Pink, Orange, Lime Green|
|UV||1x||0||Absorbs UV radiation and will reduce distant haze or fogginess|
Filters for black and white photography are available in a broad spectrum of colors, but primarily cover from yellow to orange with green and red on either end, which tend to be a little more specialized. There's even a blue, but its use is a bit of a specialty. Naturally, any filter that's not clear - will absorb some of the light.
All filters except perhaps a clear UV or Skylight filter will incur an exposure penalty as they absorb some of the light. Perhaps obviously, the darker the filter, the more you'll have to compensate. Generally this is in the one to three stop range, with yellow being the lightest and red the darkest.
Filter factors are generally listed as x2, x4, x8, etc. What this means is that they transmit 1/2, 1/4 or 1/8 of the light, respectively. In the photographer's mind however, this doesn't translate into exposure calculations as well as stops. It's therefore easiest to think of them as 1, 2 and 3 stop filters, respectively.
These filter factors assume the use of an external, or handheld meter. You'd take your meter reading and apply the necessary exposure compensation. But what about cameras that meter through the lens (TTL)? Generally, you can accept the meter reading as the camera suggests. The one filter that you need to watch out for is the red filter - you'll need to add about an extra stop of compensation (e.g. adjust exposure manually, dial in a +1 exposure compensation or cut the ISO in half). This depends on the meter's color sensitivity however and it would be best to verify with a handheld meter to ensure the most accurate exposure.
Perhaps the most common filter is the light yellow. This filter will generally darken blue skies and increase the contrast of clouds slightly and helps to cut down haze. It's also good for people and portraits, especially women - as it mellows out freckles and skin blemishes (for men you'd more commonly use a green filter). Being such a light color it only incurs a one stop exposure penalty. This is a filter you might very well leave on your lens all the time, instead of a UV if you shoot primarily black and white and if you're looking to buy just one filter - this would be a good choice.
If you prefer a slight bit more contrast, you can go with a yellow-orange or orange filter. Very similar to yellow, but progressively darken the sky and bring out the clouds even more, for example. People start to get a little ghostly towards the orange end however. Great for landscapes without overdoing it. These usually incur a 1 - 1 1/3 stop exposure compensation.
While the green filter mentioned above isn't as popular it does have its uses; it darkens certain skin tones and generally gives a more "outdoorsy" tan look. Not just good for shooting portraits of men, but also used in landscape photography as it darkens skies only somewhat, but lightens foliage. A green filter typically incurs a two stop exposure compensation.
More Extreme Filters
Some filters are just considered extreme. Perhaps the most notable example is the red filter. It darkens blue skies and foliage the most; often rendering them dark gray to black. The separation of clouds is very high in contrast and dramatic. If you really want to take it to the next level, use a polarizing filter as well - which will almost ensure black skies and brilliant white clouds. One scenario where the red filter is more useful is in shooting architecture, especially when set against the sky. Great separation, with strong details especially at distance as it reduces haze. Red bricks and clay roof tiles are lightened. Not so good for people as it tends to wash out the skin, making for a rather ghostly, ethereal look. Then there's the exposure compensation typically required, which is about three stops.
Blue filters generally aren't used much in black and white photography, but they can be useful. Generally they reduce contrast but are great for enhancing haze which makes for a misty, foggy feeling that obscures distant details somewhat. Great for use by the seashore or in the mountains to add depth.
What About Overcast Skies?
Unfortunately, overcast skies generally tend to be rather boring, whether shot in color or black and white. You might wonder if there's a filter that would help spice things up a little. Unfortunately, overcast skies are a mostly neutral gray, containing equal amounts of red, green and blue components. So no matter the filter color, it will have little if any effect. On such days it's best to include as little of the sky as possible. On the bright side, no pun intended - is that the lighting on such days is very soft and even, and of low contrast. It's like having a giant softbox overhead. Great day for portraits, for example.
Use With Digital
What about shooting black and white with a digital camera? Unlike true black and white film, digital cameras capture your image in full color and aren't actually "black and white." The camera takes your RAW/DNG image and converts it to black and white in-camera, producing a JPEG. You're better off converting to black and white during import or post-processing, where you have more control over the exact effect and simulating a particular filter is a preset found in most applications. So leave the filters for shooting film.
The exception to this, is of course the Leica M Monochrom. This camera, despite being digital - behaves much like traditional black and white film. The sensor lacks the traditional bayer filter and only sees luminance information. This allows you to use any of the color filters discussed here with this camera, and behave just like they do with film! As with film, the most popular choices are yellow, followed by orange and red... With increasing effect, respectively.
Neutral Density Filters
There are a class of filters called neutral density which by their very nature have no color at all - but a neutral gray of varying density, or darkness. These are used to reduce the light hitting the film (or sensor) equally across the spectrum. Most commonly used to slow down your shutter speed down to capture flowing water in a more natural way. They're also useful to reduce or eliminate moving objects from your scene, such as people or cars. Though you'd normally have to stop down a fair bit as well to get a long enough shutter speed. Another use for neutral density filters has more to do with the aperture - allowing you to shoot fast lenses at or near wide open for depth of field effects. This allows you to more easily separate your subject from the background, or give you that wide open bokeh effect, which is all the rage these days. Finally, you can use them to reduce your effective film speed. If you're out shooting on a bright day and only have ISO 400 speed film with you - a neutral density filter can effectively slow it down to ISO 200, 100 or even 50 (.3/2x, .6/4x or .9/8x). Here's a convenient conversion table:
|Density||Light transmission||Filter factor||Exposure compensation|
What about gradiated neutral density filters? These are fantastic for landscape shooting, primarily to reduce the brightness of the sky above the horizon, for example. They're even available in various color gradations besides neutral gray. Cokin made these popular in the 80's with a variety of them, including a simulated sunset filter. Their use on rangefinders however, is very limited and not very practical. Unlike an SLR where you can see through the lens and at the shooting aperture - you cannot do this on a rangefinder. Therefore, it's practically impossible to align the filter properly except by bracketing a few shots and hoping for the best. If shooting digitally, at least you can get instant feedback via the LCD but it's still a hit-or-miss affair. Best to leave these for SLRs, then.
The Ubiquitous UV
One filter that just about everyone has heard of is the UV filter, or its close relative, the skylight filter. These filters are often used as "protective" filters for lenses. That is, they're essentially clear and serve to keep dirt and fingerprints off the front element of your lens. Whether this is a sound strategy and one you should follow is one of those questions for the ages in photography. Points could be made both for and against until the end of time. If you're going to use one, make sure it's of the highest quality (though this can be said for all of your filter choices).
The UV, or ultraviolet filter absorbs light in this area of the spectrum - where haze generally falls. This is most evident at higher altitudes such as in the mountains, or at the seashore for example. The effect is rather slight in any case. There is no color to these filters and they require no exposure compensation.
Skylight filters on the other hand, are slightly warm in color - though light enough that they require no exposure compensation. These filters are typically used when shooting color film under cloudy skies or in the shade. For black and white use, they have little benefit and if you're looking for a protective filter - stick with a UV.
What if you have a UV/IR filter from use with the M8? When shooting black and white they'll have minimal effect and could potentially be used as a protective filter so you don't have to remove and install them all the time when switching bodies - though you should really consider removing them or using a regular UV when possible. With color film however, effects can vary and will generally lead to odd color shifts and therefore must be removed.
What size should you get? One approach is to buy the biggest filter thread size among your lenses and any step-rings necessary to adapt them to your smaller sized filter threads. The downside is that fitting a lens hood may become difficult, if not impossible. And if your sizes cover quite a range, perhaps impractical. Another approach is to just buy filters for the largest of your most commonly used lenses and go from there. A good size might be 46mm for example. Quite common in the M system and shared by many lenses. Another good size would be 39mm, which is also very common. The downside is that 39mm is about as small as it generally gets, so you wouldn't be able to use them with larger lenses. It would be better to go the other way and use a step-ring. It all comes down to which lenses you shoot most often with.
How do you store them? Commercially available filter pouches and wallets are great - but unfortunately cater to the SLR crowd mostly, where the filter sizes are generally larger, often much larger. What good is a pouch that can hold 82mm filters when your largest typical size might be 46mm? They also tend to consume a fair bit of space in your bag. One great solution are stacking caps. Basically one male and one female threaded cap. You screw your filters into each other, stacking them. Then screw on the stacking caps to either end. They offer fantastic protection and the smallest packing size possible. The downside is that in order to get at a filter, there's a bit of screwing around involved...
What manufacturer is good, or bad? Generally the best filters are made by B+W, Heliopan and the higher-end Hoya line (e.g. Pro One, HD, etc.). B+W and Heliopan filters are excellent filters in the regard that the frames are made of brass, lending a solid feel to them and helps to prevent binding. The glass is made from the highest quality optical glass and the multi-coatings extensive. Though any high quality, multi-coated filter will do generally. Avoid no-name and store brands and those you can find on eBay for next-to-nothing at all costs. They're no bargain.