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Home >> Learning >> e-Book on Photography Table of Contents Photography e-Book Chapter 10 - Filters Filters come in two main variants, those for protection and those for effect. The vast majority falls under the effect category but first let us discuss the protection issue. This is a topic that is among the most contentious issues, such as Nikon versus Canon or film versus digital, as there are those who see no reason to use a protective filter except in the extreme cases and those who think protection is a wise investment. I fall in the latter camp and believe protective filtration is a good thing. Okay, filters will degrade the image quality by a certain degree because light has to travel through another optical element. Lenses are designed and optimized for the number of elements in the design and filters, no matter how good add a non-optimized addition to the lens. There are those who claim to be able to see the difference between filtered and non-filtered images. Unless we are talking about flare, these people must have eagle eyes to able to see such differences, just as they are likely able to count every last hair on a gnat's ass from 5 feet away. Folks, a high quality filter from B+W or Heliopan is not going to inflict enough meaningful, real world differences that you are going to be able tell except in certain circumstances. The use of a lens hood will eliminate most flare situations but if flare is still a problem, it is quite fast and simple to remove the protective filter, shoot the scene then replace the filter back on the lens. Better yet use your hand or type of shade to block the flare from hitting your lens. Okay, I lied; there is another condition that would allow differences to be seen. The most commonly used protective filter is the clear UV filter and when shooting in higher elevations where there is actually enough UV for the filter to do its thing, you will receive a clearer image than if you had not used a filter. In most other shooting applications the UV filter is of no consequence except as protection against drops, knocks, and bangs to the lens. The idea is very simple, let the filter absorb the drops and bangs and protect your lens' front element from potential damage. John Shaw is a well-known landscape photographer who sees no point to using filters for protection and that is fine. He buys and uses his own equipment so he can do what he wishes with his lenses just as I buy my equipment and choose to protect them. Let me put it this way, if you drop your $1000 lens on the rocks and if the brunt of the impact is absorbed by the front element, you are out that lens until it is repaired and no warranty that I know of, covers that type of accidental damage (your insurance will replace the lens if it is beyond repair though, another reason for insurance - get some!) Your front element will probably cost you a pretty penny, more than a $50 UV filter. Would you rather be out $50 or would you rather pay $200 or more for a front element replacement. I actually have no idea what a front element would cost for a typical $1000 lens but my own experience with Nikon Canada's repair service leads me to believe it would be grossly expensive. I bought Nikon's one-ring 80-200mm f2.8D AF lens used and during my time with it, pressed the little silver button used to select between AF and MF (auto and manual focus) modes too hard once. The button fell inside the lens structure between the exterior casing and internal lens element casing. This very simple repair, which in no way altered the optics of the lens or the quality of images it took, cost me over $200 plus tax. No parts were required, just labour so you can imagine the cost of replacing the front element plus the exorbitant labour costs. Now if you are a big time pro, you just note it in your expense column and write the repair off but for amateur photographers, the costs come out of pocket. Another contentious issue about filters is the quality of the materials used for the filter. When this topic comes up Cokin is usually mentioned as the filter company with questionable products. After all, how much sense does it make to put a $30 plastic filter in front of a $1000 plus lens? Despite the marketing terms describing Cokin filters as being made from "C39 organic glass", it is still a plastic filter and will be scratched if the user is not careful with them. Does it make sense? Does it make sense for Daryl Benson to put his reputation on the line by owning and using some 50 odd Cokin filters to create his images? Does it make sense for Singh Ray to produce and market specialty filters that fit Cokin's P system holders - including some inspired by Daryl Benson and Galen Rowell? Does it make sense that Singh Ray also uses similar plastic materials for some of their widely respected filters? Or how about Hi-tech and Lee using "organic" materials, read plastic, in their respected filters? Push comes to shove and I will prefer using a high quality glass filter from B+W over a plastic Cokin filter but I am not losing sleep over it and Cokin filters offer a very affordable way to build a collection of filters, especially for those that are seldom used, such as my four-point star filter. Additionally, when using certain types of filters, the rectangle makes more sense than the screw on circle. Graduated Neutral Density filters work best when they can shift up or down to match your composition of a scene. With a round GND, the filter dictates the composition. Plastic square or rectangular filters are also more impact resistant then glass, much lighter, and far more compact. Daryl Benson uses a CD wallet to store his square and rectangular filters and I have copied his suggestion myself. The case fits easily in one of the larger pockets of my Domke vest and does not add much bulk at all. Try doing that with 50 round glass filters sized to cover 82mm diameter lenses. Now having boosted Cokin in your eyes let me reveal some concerns others have with them. Cokin filters are suppose to cover up to 82mm diameter lenses in the P series - ignore the Cokin A series as they are far too small for any worthwhile photographic purpose - and they fit in holders that can accommodate up to three filters. If your penchant is for wide-angle shooting, you will likely find that the Cokin P holder is too deep and causes vignettes (semi-circle shadows in the corners of film). Solution, hack the holder so it can only accommodate one filter. Ultra wide-angle lenses may still vignette though and will require the use of an over-sized filter system such as Cokin's X-Pro or Lee filters. Cokin ND and GND filters are not "neutral" in color cast and Cokin admits as much by calling these filters "gray" filters instead of neutral - the graduated color filters are obviously not "neutral". Galen Rowell eschews Cokin filters because of their lack of neutrality and the insinuation of a mauve colorcast in the gray segments. Other users such as Daryl Benson and Dale Wilson consider this as a bonus and certainly, their images are no less impressive than Galen Rowell's. Different strokes for different folks. There are some filters I prefer to use as round, screw on types, such as polarizers. However, the square or rectangular filter system compatible across format types would be a very nice investment to make if the costs are not too high for you. A single, large round polarizer can be used with step-down rings but in the field, fumbling around with step-down or step-up rings can be a pain. The filter system approach would be to use individual adapter rings for each lens and simply mount the holder onto the adapter ring. Filters can be slid in and out as required for the effect desired. You want to warm up that scene AND use the polarizer, go ahead and slide them both in. Oh, you wanted to enhance the scene for some hyper-saturated colors, go ahead and do so. Now, when you start mounting or inserting in multiple filters, this is where the degradation of the image can occur and just because your Lee or Hi-Tech filter system can accommodate six or more filters does not mean that you ever should. Be judicious with your filter use and this goes for both glass and plastic filters. An annoyance with filter systems and step-up rings is that leaving these rings on for maximum convenience makes them inconvenient to use when you do not wish to use filters and want to use a lens hood. A work around this is to buy a collapsible rubber hood for the step-up rings or to use combination filter holder/hoods. Lee is the company I look favorably on for their system approach to filters and because they have a wonderful hood that is self-supporting (meaning no guide rods under the filter, adding weight and bulk) and allows for up to three filters to be inserted (the hoods come in one, two, or three slot configurations). You can buy a combo hood/holder for the Cokin P system or for Lee's larger 4x4 inch series. You cannot cross rotate the filters without the use of additional filter holder but again, why would you want to add the option for another three filters? Filter Brands
Why is brass such a big deal? It is more expensive than aluminum and many lenses' filter threads are made from aluminum too. When aluminum and aluminum meet, the bond between the two can be very difficult to disengage even when the threading of the filter is not overly tight. The use of two dissimilar metals prevents the tight bonding between two of the same metals. Note, although B+W is known for using brass in their filter mounts, B+W does make a line of slightly cheaper filters using the same glass but in aluminum mounts. Be sure to request the brass mount B+W filters otherwise you will encounter the bonding problems with your lenses. In the image of the B+W filter above, the red markings indicate where a thin retaining ring is located to secure the glass element in the filter casing. Something that Hoya filters lack, causing them to have loose glass elements in their filters, especially in the smaller sizes. Schott glass is a big deal among the cognoscenti because this is the glass Zeiss uses for their highly rated lenses (probably Schneider too). Apparently, the ultra expensive Zeiss 300mm f2.8 lens for focal-plane shutter Hasselblad bodies are all made from a single block of ultra high quality Schott glass and once that block has been used up, the 300mm f2.8 will be discontinued. Heady stuff for those who can afford it, last known price is $25,000 US. B+W and Heliopan use Schott glass for most of their filters but note that B+W also uses plastic for certain types of filters too. Hoya is probably the largest filter maker in the world and is widely available in most photo stores. I have not tried their top of the line Super Hoya Multi Coated (S-HMC) filters but have tried their mid-level HMC line of filters and frankly, I am not impressed with the quality. The mechanical build quality of Hoya HMC filters are not reassuring for long term use as many samples of HMC filters do not wholly secure the glass element. The glass can be moved around whereas B+W filters are completely secure. I would hope that the expensive S-HMC filters have superior build quality and integrity. Hoya glass also seems to be vulnerable to dust and dirt attraction. Cleaning Hoya filters will often result in a haze coming over the glass with streak marks being left. The haze and marks do go away after a few minutes but my B+W filters have never exhibited such tendencies. I chalked it up to poor quality glass but I came across a photo mailing list post that may explain why Hoya filters have such tendencies. The plastic containers that Hoya filters come packaged in degrade over time and expel gas. This gas is exposed to the glass element and causes it to exhibit the haze and streaks. The longer the filter has been in the package, the more likely the filter will suffer. This would explain why a few of my Hoya filters seem fine with no problems from cleaning and why others are such dogs. If you live in the US, THK USA will replace a filter if it turns out to be a very bad sample for haze and streaks. The use of filters The use of filters can affect the tone or mood of an image and add a bit of pizzazz and drama to an otherwise dreary scene. Be judicious and ensure your technique is unassailable, including shooting in good light. Good light can often negate the need to use a filter except in certain circumstances. There are only a few filters that most photographers should not be without. The UV filter, as mentioned earlier, is popular as a general protection filter but does have its uses in higher elevations to cut down haze and produce a clearer image. There are special and much stronger UV filters available from most of the major brands such as B+W and Hoya. Warming filters have a slight pinkish, amber, or salmon tone to them to help add a bit of warmth to scenes with excessive blue tones, such as shady areas or overcast conditions. The Skylight filter is probably the most popular one used by consumers but not often used by serious photographers. In between the clear UV and the warmer 81A, the Skylight probably gained its popularity by default, as many stores will give away cheap ones with lens sales. When I bought the Nikkor 24-120mm lens, the sales clerk tossed in a Hoya Skylight filter as a freebie incentive (yes, sometimes I can be bought so disgustingly cheap but I made sure to get the price of the lens down to a more palatable amount for me). I would not otherwise bother with a Skylight filter and would rather go straight to one of the 81 series warming filters. 81 series of warming filters come in six different strengths and the second and third ones, the 81A and 81B, are the most oft used. The 81A is a key filter to own in your filter arsenal as it provides the Goldilocks, just-right amount of warmth to most scenes and only when in deep shade would the 81B be required. Using the higher strengths is not generally required for most situations unless you work in excessively blue-toned scenes. Some photographers love the 81A so much they use it as their standard protection filter too.
Notice in the two examples above how the color balance changes the flowers with the use of a warming filter. Original non-filtered shot at left and filtered at right. The red arrow points to the very obvious change in the "tone" of the patio rocks behind the flower. Polarizers A polarizering filter is another key filter to own and for many, it is THE filter to own over all others. Most know of the traditional use of polarizers to induce a rich, dark blue sky into a scene but this use can be over done in today's world of super saturated films.
There are a number of special effects filters with polarizer-like attributes such as Cokin's popular BY 173 (blue and yellow) but strictly speaking, these filters are not true polarizers, as they do not cut out reflections in scenes. On intriguing way to see if a filter claiming to be a polarizer is in fact so, is to rotate the filter over a prism or rainbow. If the prism or rainbow disappears as you rotate the filter then it is in fact a polarizer. You need not chase down a rainbow for this effect, as a garden hose spraying water in sunlight will create a mini rainbow for you to test this out. I did this with the BY 173 and a water fountain that was creating some rainbows and found out that it was not a true polarizer, as the rainbow never disappeared from sight. I believe Cokin no longer markets their dual color filters as polarizers now. A polarizer with a red filter is how to achieve deeply dark skies in black and white images while keeping the clouds pristinely white. A red filter already creates a contrast between the blue sky and clouds by darkening the sky but a polarizer maximizes the effect for a very dramatic look. The polarizer is indeed a valuable filter to own and be sure to buy one that can be fitted on all of your lenses. If your largest lens is 77mm in diameter, buy a 77mm sized polarizer and use step-down rings with your smaller lenses. If you use a filter system such as from Lee, be prepared to pay some big bucks for a square 4x4 inch filter. Good polarizers do not come by cheaply but you need not spend huge dollars on B+W/Zeiss Kaeseman polarizers. Your camera system will dictate the choice of polarizer too. Polarizers come in two flavors to accommodate manual focus or auto focus systems, linear for the former and circular for the latter. Linear polarizers can be quite good in price but be wary even if you do own and use a manual focus system. Some manual focus cameras come with spot meters or can be equipped with one such, as my Bronica SQ-Ai with a prism finder. These spot meters still use similar technology as auto focus systems so you may still have to spring for a circular polarizer. Linear polarizers can cause auto focus systems to stop working because they cut out the contrast required by the AF system to work and lock focus. Circular polarizers have an extra component to them that allow the polarizer to work its effect while allowing AF systems to work properly. Since I have both systems, I bought circular polarizers to use with my lenses and will continue to do so for future filters. Graduated Filters Graduated neutral density filters are another important part of the landscape photographer's kit. They provide an opportunity to balance out the light values of foreground and background in a scene. GND filters come in hard or soft gradation options with the hard version having half of the filter clear with an abrupt start to the ND portion of the filter. The soft version has the half clear portion too but the ND portion has a gradual level of density until the top portion provides the rated amount of density. You will often see these hard and soft GND filters in a range of colors for different looks and effects, one of the more popular being the orange fake sunset or the super-saturated blue skies. The typical use for GND filters is for landscape scenes with light backgrounds and dark foregrounds. You would first take a reading for the foreground and compare it to a reading for the background to ensure that the difference in exposures is within the range of your GND filter. The recommended first GND filter to buy is the two-stop version but stronger densities can be purchased and some companies such as Singh-Ray can even custom make filters for your needs. After taking a reading of the foreground and background and being satisfied your GND will be beneficial for the shot, slide the filter in and adjust according to the horizon line or closest alternative. You need not just use a GND for horizontal shots as some users utilize GND filters successfully for diagonal shots too. The result of the GND should be to provide you with detail in the foreground and background scenes. Slide films (the overwhelming choice of landscape photographers) have about a five-stop exposure range between the deepest blacks to the whitest whites. Wherever or whichever part of the scene or subject you choose to be your middle value will have a plus and minus two-stop range between going black or going white. If the difference between the foreground and background is beyond this exposure range, the film will not be not be able to record the details in the exposure extremes. Even if the scene is within the range of a GND filter, many photographers are caught without one and have to make a choice between exposing for the highlights, the shadows, or a mid-range exposure. In the days before Photoshop, you chose one or the other and hoped to tweak the film in the darkroom. Nowadays, you can take two exposures, one for the background and one for the foreground and merge the two scenes digitally to obtain a digital GND effect. Read more about this at Michael Reichmann's Luminous Landscape web site. Thus far, I have mentioned the clear protective UV, the 81A, the Polarizer, and the GND filters. These are the basic filters every photographer should have in their kit and will often times be the only filters required in a photographer's kit but there are a many more filters available and can be bought and used according to the photographer's requirements.
Soft Focus Filters
The soft focus filter, popular among wedding and portrait photographers for the dreamy look induced onto the image. I am rather hesitant to recommend these filters despite owning several (B+W and Cokin). Of the ones I own, I tend to use the B+W Soft Focus #1 most but the Cokin has a look to it that can also be attractive. Why do I hesitate to suggest them, because you could create your own with a minimum of fuss or expense. If you have an old clear UV filter no longer being used (like some of those blasted Hoya HMC types) you can smear some Vaseline on it and create a center-hole filter for a modest vignette effect. I personally do not prefer to have an old filter messed up with Vaseline that can mess up my other equipment in the bag and some of you may not have an old filter to abuse in such manner. No need to worry but there may be a slight fuss here because you need to raid your own, your wife's, or girlfriend's pantyhose drawer and "liberate" an old pair for the good of your photographic abilities. A black or white pair works best and all you have to do is wrap the old hose tightly over the lens and take the shot for a soft focus effect. If you have some fine scrim material, that will also work too but again, black or white works best, as other colors will add their colorcast to the subject. If your wife really objects to you taking a pair of scissors to her favorite panty hose and if you are too manly to buy a cheap pair from the drugstore, and if you already own a Cokin P system, perhaps buying a $30 Cokin diffuser filter would be less troublesome. The idea of a soft focus lens is rather perverse as we intentionally try to wreck all that those fine German or Japanese optical engineers have produced in their super sharp lenses. Unfortunately, Father Time is not kind to facial blemishes and wrinkles and if you want to get in good with the mother-in-law, you better learn to take some attractive portraits. Today's lenses are much sharper than necessary to capture a face effectively, hence the Vaseline, the Zeiss Softar, and other myriad methods to soften the effect and add some glow to the subject. However, spending several hundreds of dollars on a Zeiss Softar is not tops among most photographers' must-have lists, or even a mere $100 for a B+W Soft Focus #1 (77mm size in Canada). The ideal is to try to capture details with subtlety without the loss of resolution as often accompanies soft focus lenses, my B+W Soft Focus #1 included. The B+W approach is concentric rings around the filter's glass element to induce a soft look. The Zeiss Softar approach is to use many smaller circles or lenses on the main surface of the plastic element. Having never used a Zeiss Softar nor desiring to own one for a measly $500 CAN, I can offer no comment as to which technique is superior. Interestingly enough Hoya has a soft focus filter that seems to copy the Zeiss Softar technique for far less. Aperture will play a role with most soft focus filters with smaller apertures having less effect than wide-open apertures. The Zeiss Softar is apparently aperture independent for its effect. Filters for Black and White Films Filters for B&W films differ from color as for obvious reasons you are affecting shades of gray instead of color. For example, when taking shots of scenes with significant sky content, B&W film will have a difficult time trying to reveal any differences between the blue sky and the clouds. Blue skies and white clouds have similar contrast and while color films can certainly tell the difference between the two if your chosen exposure allows it to, B&W films cannot tell the difference and you will often be left with a featureless white or gray sky. The use of colored filters will provide the contrast required to separate the clouds from the skies. Yellow is the mildest B&W filter to start with and many B&W photographers never venture out without it being the standard filter for their lenses. As you move to orange, green, and then red, your contrast increases. The ultimate is to use a polarizer with your deep red filter for black skies and white clouds. Of course, just ensure you have a tripod to shoot that minus five-stops scene as a deep red will rob three-stops and a polarizer robs another two. The color of the filter will also affect the gray tones in your scene according to the color wheel of complimentary and opposite colors.
Sorry for the short thrift on B&W filters but I do not have much experience with B&W films so can offer no example images.
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Correspondence & About this website Copyright © 1998-2008 Edwin Leong |
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There
are several brands of filters on the market and most offer decent products.
Among the camera brand companies, Nikon seems to have garnered consensus
praise as being among the best but their selection of filters is quite
low and the filter sizes are obviously limited to Nikkor lenses. B+W
and Heliopan are also considered top-notch filter brands for their use
of German Schott glass (part of the Zeiss group) and brass rings instead
of aluminum. 
B+W
Soft Focus #1 filter at right - concentric circles is part of the design
to soften highlights and reduce contrast
