In the film era a vast amount of filters was needed to alter the colours, the temperature or to add certain effects to the photos. In digital photography many of these filters have become pretty much useless as they can be recreated in post processing with the added bonus of more control over the effect without any disadvantages.
But there are also some useful filters which can’t be fully recreated in post processing and still have a place in digital photography and these are the ones I’m going to talk about.
Update 09/27/2016: at Photokina 2016 in Cologne I checked out all the big filter manufacturers and have updated some sections accordingly. I am also working closely with NiSi filters now – not just because I think their filters offer the best quality – but because they listen to their customers and I hope to be able to help them develope the first holder I find nothing to complain about 🙂
The polarizer is by far the most powerful filter out there. It can affect polarized light in the ways of strengthen or weaken it. This may sound a little cryptic, but I will try to give some examples what that means in practice.
Reflections and the sky
Both shots were taken with the exact same camera settings and have undergone the same post processing, only the polarizer setting is different.
Reflections mainly consist of polarized light, so a polarzier has great effect on these. Furthermore you may also change the appearance of the sky by using this filter. Polarizers only work (well) at certain angles, so standing directly in front of a shop window you will have a hard time eliminating any reflections. Stay there about 30° to the window and you may be better off. Rainbows also consist of polarized light, so you can either emphasize or eliminate them.
With ultra wide angle lenses you may also run into some problems as the field of view of these lenses is so great that the polarzier might show different effects in different parts of the image.
The ability to eliminate the reflections on wet foliage and rocks is invaluable for me in nature and landscape photography. Without the reflections photos look way more saturated and clean.
In this photo I used the polarzier to eliminate the reflections of light on the wet rocks and also the reflections on the water, so the stones beneath surfaced and made the photo way more interesting:
You shouldn’t chimp on a polarizer. As the good ones are quite expensive it may be a good idea to buy one for the lens with the biggest filter diameter and use in on the other lenses with step-up rings. I can recommend the Hoya HD Polarizers*, which I have used for many years now.
Update: There are also manufactures like NiSi or Singh-Ray now offering “Landscape” or “Warming” polarizers, which have some additional effects on certain colors. I will try to get my hands on one of these and post a comparison here as soon as possible.
Neutral Density Filters (ND)
Neutral density filters give the ability to use longer exposure times during daylight. This is effective for shooting waterfalls which will turn into mist or clouds to create the impression of movement in the sky. These filters come in different intensities ranging from 0.3 Stops to 15 Stops and even more. The most common I use are 6 and 10 stop ND filters.
Update: almost every manufacturer is now also offering stronger ND filters: Lee a “Super Stopper” 15-stop ND* filter (exposure time x32.000), Hitech the Firecrest 13* (x8.000) and 16-Stop* (x64.000) ND filters and NiSi a 15-stop* and the “Black Hole” 20-stop ND* filter, the latter increasing your exposure time by the whopping factor of 1.000.000 (2^20) which will only be useful in real bright environments, as a 1 second exposure will become a 12 day(!) exposure. It can be used to shoot landscapes wide open with a long exposure time under very sunny circumstances though.
Strong ND filters can also have a strong colour cast. When it comes to 10-Stop ND filters I have thoroughly used myself the Lee Big Stopper (100mm), the Hitech Firecrest 10-Stop ND Filter (67mm) and the NiSi 10-Stop Nano-coated ND Filter (70mm) which are all made of optical glass, not resin. The Lee filter has a very strong blue cast, which can be corrected in post, but your images will look very blue on the camera display. The NiSi and the Hitech filters show almost no color cast but the Hitech filter unfortunately lacks a foaming to prevent straylight getting in between holder and filter (this seems to be only true for the 67mm system thoug, the 100mm Hitech Firecrest series seems to feature such foaming).
For the following shot I used a 10 Stop ND filter (the Lee Big Stopper*) which leads to a 1000 (2^10=1024) times longer exposure:
Nowadays you can also buy so called “Vario ND Filters” where you can change the density. This sounds like a good idea at first sight but I would strongly advise to avoid these things (except for maybe filming). They consist of two contorted polarizers so you might encounter the effect of a polarizer which you can’t control (and may not even want) and setting a distinct density value is next to impossible.
Graduated Neutral Density Filters (GND)
These filters have a gradient and come in the types of Soft Edge, Hard Edge and Reverse and also have different densities. Even with the high dynamic range of modern cameras sometimes a GND filter makes sense, just take a look at the title photo with the blown out sky.
In the following example I first took a shot without a GND, the sky is blown out in many areas. To balance the exposure I used a 3 Stop (0.9) Soft Edge GND filter:
For starters I would recommend getting a 0.9 Hard Edge and a 0.9 Soft Edge GND filter*. This gives you quite a lot of options without spending much money on not needed filters. Especially stay away from sets which include 0.3, 0.6 and 0.9 GND filters. The 0.3 is utterly useless, you can correct these small amounts in post.
Slot-in filters or Screw-in filters?
Most common are the screw in filters. For polarizers and ND filters these work quite ok, in case you want to use GND filters better invest in a slot-in filtersystem, as you want to be able to move the horizontal line with these.
A few years ago slot-in filtersystem were really quite expensive, luckily there are some more (decent) manufacturers now so you have more options than I did. You also need adapterrings for mounting the filtersystem first. These rings have to fit your lenses’ filter diameter.
So in case you are interested in a slot-in filtersystems read on.
Which is the right size for a Slot-in filter system?
First you have to decide which size is the right one for you and your lenses, as these slot-in filter systems come in different sizes:
67 mm (Hitech, Cokin A)
70 mm (NiSi)
75 mm (Lee Seven5, Haida 75mm)
85 mm (Hitech, Cokin P)
100 mm (Lee 100mm, NiSi 100mm, Hitech, Cokin Z, Haida, Singh-Ray)
145 mm (Fotodiox Wonderpana)
150 mm (Lee SW150, Haida, NiSi 150mm)
165 mm (Hitech Lucroit)
180 mm (NiSi, to use Canons 11-24mm 4.0L at 11mm without vignetting)
There are probably some more and of course I haven’t used all of them myself (but seen many while holding workshops).
In case you want to use filters with lenses like the Nikon 14-24mm 2.8G, Samyang 14mm 2.8 and Tamron 15-30mm 2.8 you need 145 mm or more. To use Canons 11-24mm 4.0L black cornes due to the filter holder you even need a huge 180mm syste.
For other full frame lenses (including something like a 16-35mm 4.0) a 100 mm system will suffice.
In case you don’t need filters for your ultra wide angle lenses or you are using smaller lenses like the Zeiss Loxias oder Leica-M lenses even one of the smaller systems will do the job.
Are there any other differences?
One of the major differences is the incorporation of the polarizer. With the Lee System you can either buy a 100 mm slot-in polarizer or mount an 105mm polarizer in front of the slot-in filters. Both options have their pro’s and con’s:
The slot-in polarizer can even be used with some 12-16mm lenses without vignetting issues but you can’t turn GND filters and the polarizer independently. With a polarizer up front you can do that but will probably encounter black corners due to vignetting with lenses wider than 21-24mm.
The NiSi V5 100mm and the 70mm system as well as the overhauled Haida 100mm System all incorporate a very slim polarizer between the lens and the slot-in filters. Both manufacturers implemented a little wheel to turn the polarizer even when mounted alongside square filters.
Hitech now uses a similar mechanism in their new 100mm Firecrest holder, but I found it to consist of too many, mostly plastic parts.
There are also differences when it comes to the quality of the filters. Resin scrachtes more easily than glass but is less prone to break.
When it comes to GND filters there are solid-colored filters and filters with just a very thin dark surface. If the latter caught a scratch it becomes pretty much useless.
The Cokin filters often show nasty color shifting which is not even across the spectrum so can’t easily be corrected.
The Hitech filters (epecially the newer Firecrest series) are usually quite good, but combining 2 or more GND filters may lead to color shifts as well.
Update: I found that with my 67mm Resin Hitech GND I get nasty green color shifts in the corners when used on the Zeiss Loxia 21mm 2.8 (might happen on other wideangle lenses, too). The Hitech Firecrest GND made of optical glass don’t show this behaviour, but all seem to be one stop weaker than stated (many amazon reviews claimed it, nevertheless I bought a 0.9 GND which was in fact merely a measured 0.6 GND), this is one of the reasons I am now using the NiSi 70mm system personally.
Lee and Singh Ray are pretty good but also pretty expensive.
Haida filters have great value when it comes to ND filters but I have no experience with GND filters from this manufacturer.
What’s in my bag?
For my Nikon full frame DSLR lenses I was using the Lee 100mm System* which consists of a 105mm screw-in polarizer*, a 100mm Lee slot-in polarizer*, a 10-stop ND filter (Lee Big Stopper)*, a Lee 0.9 GND Soft Edge*, a Lee 0.9 GND Hard edge* as well as an 0.6 Reverse GND by Hitech* (which I rarely ever used) all stored in the MindShift Gear Filter Hive*. As of today I might go for the NiSi V5 Holder* or the Haida Holder* (which both offer a rotatable slim polarizer between lens and square filters) instead of the Lee Holder.
For my A7 cameras I was using the 67mm Hitech Holder*, a 77mm Hoya HD Polarizer*, a 6-stop Firecrest glass ND, and a 0.9 Soft Edge GND* as well as a 0.9 Hard Edge GND* which fits all together in the great Mindshift Gear Filter Nest Mini*.
(see reasons above why I am not using this setup anymore)
For my A7 cameras I am now using the 70mm NiSi holder* (which already includes a polarizer), 6-stop and 10-stop* nano-coated NiSi ND filters and my beloved 0.9 Soft Edge GND* as well as 0.9 Hard Edge GND*. To have some more space I also settled for the Lee Seven5 Pouch*.
With this setup I can use a polarizer in conjuction with a GND and ND with the Loxia 21mm 2.8 (if you turn the holder by ~45° you may get dark corners) as well as the Voigtlander 35mm 1.7 and 50mm 1.5, the Loxia 85mm 2.4 and even the Voigtlander SL 180mm 4.0 APO-Lanthar.
For the Voigtlander 10mm 5.6 I now also have a lens specific 150mm holder (see review for more information). Due to it’s big size it is not something I carry around all the time, yet can yield astonishing results:
Here you can find some of my photos where I used filters on flickr.