Our Dark CPL filters are a high-quality processed 2-in-1 combination of grey and CPL filters. The round filter glass is set into a particularly sturdy titanium ring, which withstands even the largest variations in temperature, so that the filter itself does not become stuck. Thus our Dark CPL filters are ideally suitable for use in outdoor photography. That is ideal because both conventional ND filters and normal polarisation filters like CPL filters are primarily needed to create atmospheric and optimally exposed pictures with strong contrasts and intense colours and without reflections on non-metallic surfaces in landscape photography. The high-quality Gorilla® glass also provides protection against dirt and optical distortions and guarantees a high degree of light transmission. The high-quality filter glass is rounded off by several layers of our so-called Luminance Coating. This guarantees the highest degree of colour neutrality without colour casts despite its neutral grey hue. In addition the coating protects the filter glass against scratches. Our special inspection process, which exceeds customary benchmarks and standards in the sector, guarantees that all of our filters are manufactured to a consistently high quality level. The so-called “engineered & quality controlled in Germany” principle of quality assurance, which is based on the AQL standards, was expanded by many control mechanisms and lower tolerances.
Everything about the Rollei Dark CPL filters
- Two filters in one – modes of action of grey and CPL filters
- Operating principle of ND filters
- Operating principle of CPL filters
- Areas of application & advantages of Dark CPL filters
- Dark CPLs in various ND strengths (optical density)
- What should you look for when you are purchasing a Dark CPL filter?
- The special Gorilla® Glass
- Luminance Coating finish
- Engineered & Quality Controlled in Germany – quality assurance
Two filters in one – modes of action of grey & CPL filters
The special feature of our Dark CPL filters is the combination of two different kinds of camera filters in a high-quality screw-on filter - 2-in-1 (ND + CPL), so that you only have to screw one filter on instead of two. Whereas grey filters, which you can obtain in the most diverse optical densities, are characterised by the even neutral grey hue on their entire surface, CPL filters (polarising filters) provide for a particular polarisation of the light, which intensifies the blue of the sky and the green in our plant world, while reflections from non-metallic surfaces are filtered. This effect cannot be imitated even by means of digital image processing. Just as the long exposure cannot be achieved without ND filters. Thus, both CPL and ND filters are indispensable for modern DSLR & DSLM photography.
Owing to CPL filters, for example, you can “look” through reflective or mirroring disks and water surfaces, whereas ND filters, depending on their strength, make long-time exposure possible during the day as well even in strong sunlight. This can be necessary in order to capture movements in your subjects, to let water surfaces appear to be velvety smooth or in order to have moving objects like humans and cars disappear from architectural photography or from urban scenes by means of extremely long-time exposure. In addition, so-called moving light can be captured with ND filters, e.g. the well-known trails of light on roads or motorways.
Operating principle of ND filters - briefly explained
ND (neutral density) filters consist of filter glass with a neutral grey hue. Due to darkening, which varies greatly based on the ND value / strength in the optical density, the light that hits the imaging sensor is decreased by specific f-stop reductions in the case of Dark CPL filters and by up to 10 stops in the case of the ND1000 + CPL variant. Thus you can work with long-time exposure in daylight as well in order to achieve the aforementioned effects like velvety smooth water surfaces, moving light or the disappearance of people from scenes of urban architecture. With respect to the neutral grey hue, the special thing about Rollei is that the darkened filter glass guarantees the highest degree of colour fidelity nevertheless by means of the Luminance Coating whereas other ND filters frequently produce images with a blue, green, or red tinge.
Therefore, ND filters make it possible to extend the exposure time without changing the aperture or ISO value, e.g. for larger apertures in daylight. Already with a light ND filter you can take photographs even in the midday sun with an aperture of 1.4. The darker it becomes the longer the extension of the potential exposure time. Most frequently they are used to prevent over-exposure and for shooting blurring effects or flowing waters are used. In the process, the adjusted strength of the ND filter depends on the aperture used, the lighting conditions and the desired periods of exposure.
Operating principle of CPL filters - briefly explained
[Translator’s note: Sek. = sec. Min. = min. and Std. = hours]
The CPL filter (circular polarisation filter) is besides the grey filter the second camera filter, which is part of the basic equipment of professional and amateur photographers, particularly for travel and landscape photography. While the ND filter extends the possible exposure time, a polarising filter filters complementary polarized light. To put it more simply, complementary polarized light is thus a question of reflections e.g. the reflected blue of the sky in the water or in the leaves of a tree. Thus the colours of the object, upon which the focus is, appear richer and the attention of the viewer is guided in a purposeful manner. At the same time it emphasises contrasts, e.g. the white of the clouds in the blue sky. Also it removes unwanted light reflexes on non-metallic surfaces such as plastic, wood, glass, pelt or skin. That doesn’t just make it popular for landscape photography, but also for product photography.
Dark CPLs - ranges of application & advantages
Rollei’s Dark CPL filters now combine the operating principles of both filter types described above in one filter glass. Thus, they can be used for all the ranges of application of ND filters mentioned and for obtaining the following effects:
- Velvety smooth surfaces of flowing water
- Blurring effects & double images
- Moving light (illumination of night photographs, e.g. trails of light from car headlights)
- Long exposure times during the day
- Depiction of non-visible movements (e.g. cloudscapes)
- Architecture photography (filtering out of people and cars)
- Landscape photography (e.g. flowing water, cloudscapes)
- Storm photographs during the day
But owing to the combination with the circular polarising filter more additional effects are produced, which could have been achieved previously as well, by combining an individual CPL screw-on filter with an ND plug-in filter. But you always had to carry many individual filters around with you to achieve this.
- Polarising filters intensify the blue of the sky and the green of the plant world.
- They suppress unwanted reflections on non-metallic surfaces.
- They make it possible to look through reflecting glass panes and reflecting water surfaces and to take photographs through them.
Therefore, the Dark CPL filter not only saves space in your photography equipment but also saves time spent attaching it to the camera lens. In this way the operational readiness and response time is reduced and this is just ideal for spontaneous subjects and subjects in motion. The best idea is to use your Dark CPL filter in combination with one of our Rollei tripods. In that way no subject will really escape you anymore.
An overview of the advantages of the Dark CPL filter:
- Less bulk & weight in your luggage
- Faster operational readiness
- More economical than the purchase of individual filters
- The highest degree of colour fidelity & light transmission
- No optical distortions
Dark CPLs in different ND strengths
Which Dark CPL filter should I buy?
Dark CPL ND1000 Filter - 10 grey filter aperture stops make even the roughest surfaces smooth and velvety soft. You obtain so-called “super-soft effects” with these ND filters.
In addition they guarantee relatively long exposure times even in the brightest sunshine.
Dark CPL ND64 Filter - 6 grey filter aperture stops are the all-rounders of ND filters. They are ideally suitable for fast flowing water and subjects with velvety smooth water surfaces. It is the happy medium if you wanted to acquire only one grey filter for starters.
Dark CPL ND8 Filter - 3 grey filter aperture stops are suitable for use when there is little daylight. In addition, the subjects are in fact still surreal and soft compared to ND64 or ND1000 filters but are definitely closer to filterless reality.
Overall you should have different ND strengths available as filters, in order to be able to react flexibly to all possible outside factors, different quantities of light and exposure times.
What should you look for when you are purchasing a CPL filter?
The criteria specified here actually apply in general for any purchase of a filter for your camera lens. Our Dark CPL filters fulfills all of these criteria optimally.
- The filter glass – a neutral grey darkened filter glass should guarantee colour neutrality nevertheless and prevent optical distortions. We ensue this by means of our special finish - the so-called Luminance Coating and the high-quality Gorilla glass, which we use for the manufacture of all of our filters. Because apart from the technical requirements for photography, filter glass should also be durable. Our multi-coated Gorilla glass is very sturdy, protects against contaminants such as mud and is scratch-resistant. Thus, even under somewhat rougher and more hectic treatment Rollei’s Dark CPL filters maintain their optical characteristics.
- The diameter – naturally, the filter of your choice should also be compatible with your lens diameter. Our Dark CPL filters are available in all of the common diameters from 49 mm to 82 mm.
- The socket - the socket should guarantee that the filter remains dimensionally stable especially even at extreme temperatures such as during outdoor photography in the polar region or in the desert, for instance. Dimensional stability goes hand in hand with accuracy in size. If this is not guaranteed, then over time the filter could no longer fit on your lens or sit in the thread properly. Our titanium socket prevents this effectively and guarantees accuracy in size at the same time - even at extreme temperatures and during variations in temperature.
- The coating -- as already clarified in the section about filter glass, a high-quality filter glass should have multiple coatings. Our special finish - the Luminance Coating - fulfills all the requirements in this regard, which are demanded of authentic professional filter glass. In every case it should prevent reflections in order to guarantee high-contrast, reflection-free images. Because the combined CPL filter certainly can filter mirror images and reflections on non-metallic surfaces. However, even it is powerless against solar reflections. Our filters are finished using the so-called multi-coating process. Here, several thin metal salt layers are deposited by evaporation on the filter glass in a vacuum. Besides, by means of the coating our filter glass also becomes scratch-resistant, provides supplementary protection to the lens and guarantees absolute colour fidelity.
- Consideration of the choice of subject & lighting conditions - if you do not intend to acquire Dark CPL filters immediately in all available ND strengths, you should plan what you would like to photograph before your purchase. Which Dark CPL filter should I buy?
The Gorilla glass of the Dark CPL filters
Rollei relies on Gorilla glass ®* for its high-quality filter series. Thus, that is also the case for the new Dark CPL series. So they are not only extremely weather-resistant but also don’t lose their optical characteristics due to careless or markedly rough treatment. For this, true expert knowledge is used. The trick happens on the molecular level. For this our filter glasses take a bath in a boiling hot alkaline solution. Thus, a precisely planned exchange of ions, which doesn’t only protect the raw material better against mechanical pressure but also clearly counteracts cracks and scratches due to increased surface tension, begins. This, by the way, is additionally reinforced once again by our Luminance Coating, the finish on our Dark CPL filters. Even in the event of profound damage the coating prevents further splintering on the edges.
Gorilla®* glass is already innately, particularly translucent and distortion-free. The specific kind of glass guarantees that these outstanding optical characteristics are not impaired by contamination in outdoor use or by damage.
The American company, Corning Inc., can look back on more than 160 years of experience in the production and coating of special kinds of glass and lenses. Therefore Rollei dark CPL filters can be manufactured from just 2-mm thick Gorilla®* glass and effortlessly meet all quality requirements that we apply to Rollei professional filters with a particularly low weight.
Luminance Coating – multi-layer finishing of the Rollei Dark CPL filters
Reflections can lend an entirely individual look to photos or can completely ruin them. Some of the possible reflections are already filtered out by the integrated polarisation filter function of our Dark CPL filters. However, no CPL filter is also equipped to combat light reflections from the sun.
Furthermore, many photographers would like to use reflections as a purposeful stylistic device, e.g. for product photography or on other occasions. In order to use these optical effects purposefully, you must make sure to prevent their random occurrence. For this, Rollei is now relying on a special treatment that it developed itself for our particularly high-quality filter glass. In the process, it has always been our primary aspiration to ensure that extreme light transmission and colour fastness are not impaired.
The specialised process is based on completely precise Rollei specifications, adherence to which is constantly examined, and. which can also lead to the refusal of complete deliveries. This coating is also ideally suited for the already extremely resistant, neutral and brilliant Gorilla®* glass of our Dark CPL filters and also protects the latter against scratches.
Thus, as a professional photographer or a discerning amateur you benefit doubly. You don’t have to worry about possible reflections when you are choosing a location and can also fully rely on the impressive weather resistance and robustness of the additionally coated Rollei Dark CPL filters made from Gorilla glass®* even in extreme situations. Even bad knocks or unintentional contact with objects make amazingly little difference to the coated, colour-neutral filter glasses.
The optical tolerance values do not leave any leeway for quality defects. The colour curves of the glass must behave absolutely homogeneously within the range of from 400 to 800 nm. Otherwise they cannot bear the Rollei name. You can add reflections, colour deviations or special effects afterwards. The image material represents a neutral, reflection- and distortion-free basis for your creative ideas.
Quality assurance - Engineered and Quality Controlled in Germany
At Rollei we understood early on that quality is not a unique event, but a continuous process, which must be improved again and again and adapted to the desires of customers and the possibilities of the technology. It is only in this way that we can ensure that the high-quality characteristics of our Dark CPL filters that are promised by us are not isolated cases but without exception every filter glass meets the relevant requirements and the expectations raised. Therefore we introduced an unusually strict quality management system, which continuously guarantees the high quality of our Dark CPL filters. This quality management strategy documented as “engineered and quality controlled in Germany” involves different procedures and basic conditions that far exceed customary specifications in the sector.
The particularly high-quality Rollei Dark CPL filters for professional photographers and discerning amateurs include optical characteristics, which could not be guaranteed at the same time if there were lower quality guidelines. Especially due to the unprecedented 2-in-1 combination of CPL + ND requirements, which cannot do without an outstandingly high level of continuous, precise quality control. Therefore all criteria must be fulfilled at any time during our inspections, which are carried out several times from manufacturing to delivery. Compromises in one discipline would also immediately have an adverse effect on other aspects. If a criterion is not fulfilled on any part of the supply chain, this leads to withdrawal of the complete batch. Consequentially, the approval of new production samples is also exclusively in the hands of the Rollei filter specialists.
However, series production does not mean a loosening of expectations for Rollei under any circumstances. Relentless quality control according to the AQL (acceptance quality limit) principle is performed before delivery of the production batches: If a precisely calculated quantity of products examined by random sampling falls through the cracks, the whole batch does not receive approval.
The delivered filters must then pass yet another final examination at Rollei once again in accordance with the strict AQL specifications before the products may be finally delivered to retailers and end customers.