FAQ

B+W Filters for Still Photography

1. I love your filters. Can I buy them from you?
2. What information is necessary to order a B+W filter?
3. Why does B+W use brass rings?
4. How can I tell if my filter is Multi-coated?
5. What is the difference between a Linear and a Circular Polarizer?
6. What is a Kasemann Polarizer?
7. What makes B+W Polarizers better than other brands?
8. Where does B+W get its glass?
9. Are there any filters offered by B+W that B+W does not make?
10. Does B+W have slim filters for wide-angle lenses?
11. Now that I know the filter factor for my filter, do I ever have to take another meter reading?
12. I want to shoot infrared. What do I need to know? 
13. Why are B+W filters more expensive than most other brands?
14. Are B+W filters more important when using large filters or for small filters as well?
15. How old is the B+W filter company?
16. Does B+W make an adapter that allows a filter to screw onto a different size diameter lens?
17. What is the best way to clean my B+W filter?
18. Can I leave the filter on my camera all the time?
19. Should I buy UV or Skylight?
20. Are filters necessary at all for taking pictures?
21. What does the multiplying factor mean?
22. Can I attach several filters on top of one another?
23. Are digital filters different from "normal" filters?
24. Why should I buy a B+W Filter?
25. What are the transmission curves for your filters?
26. What are the differences between F-Pro, Slim, and Wide-Angle filter mounts?
27. How can I tell if my unknown polarizer is Linear or Circular?
28. How many stops of light do your neutral density filters reduce?
29. What filters do I need to shoot IR images?

1. I love your filters. Can I buy them from you?

We are the distributor of B+W filters and generally don't sell direct to the end user.

You can buy our products through any authorized B+W dealer. Even if they don't have what you want in stock, they can order it for you. We ship most orders within 24 hours of receiving them, excluding weekends and holidays. Your dealer can also confirm price.

2. What information is necessary to order a B+W filter?

In buying a filter, two items of information are important.
For one thing, the filter type, and for another, the accessory thread size on the front of the lens.

You can find the right filter for you in our filter section

For information about the required filter size, check your camera/lens manual, or with the manufacturer of your lens.

IMPORTANT: The most important information is the thread diameter and thread pitch. A table showing available sizes and types can be found here.

3. Why does B+W use brass rings?

Aluminum rings will often bind to the aluminum housing of the lens. Brass won't bind to aluminum, making it the superior choice for filters.

4. How can I tell if my filter is Multi-coated?

If your filter says "multi-coated" on it, then it has a multi-coating.

If it says "MULTI RESISTANT" or "MRC" it has our current multi-coating.

The term "MULTI RESISTANT COATING" refers to the latest in multi-coating technology from B+ W. Each side has eight layers with the outer layer consisting of a multi-resistant coating that repels dust and water. The cleaning of filters with this hard, water-repellant system of coatings has become considerably easier. (See FAQ: What is the best way to clean my B+W filter?)

If your filter does not have any of these designations, then it does not have a multi-coating on it.

Certain information is engraved on every filter. These data have to do with diameter, filter type, or type number, and when required, the multiplying factor and details regarding the coating.

If it is a photo filter, then in many cases it has a single coating on each side (= B+W Standard). Filter types like trick, as well as infra-red and strong grey filters, are not coated. Additional details may also be found on the B+W Complete List.

Note: The quality of the coating (i.e., the components of each layer and the order of the layers) is most important, not the number of coatings per side. B+W uses only top of the line coatings for higher transmission, with fewer coats per side. In addition, if a B+W filter has this coating, it will say "MULTI RESISTANT" or “MRC” on the filter itself, as well as on the packaging.

5. What is the difference between a Linear and a Circular Polarizer?

A Circular Polarizer is a Linear Polarizer with a 1/ 4 wave plate retarder added to the back of the polarizer foil. Circular Polarizers are necessary when using an SLR that has a beam splitter which is used for internal light meter reading. The beam splitter polarizes light and depending upon the position of the polarizer, you may cause double polarization and therefore result in inaccurate meter readings. Circular Polarizers are also necessary for auto focus cameras.

TIP: In any case in which linear polarizing filters suffice, circular polarizing filters can also be used, but not the other way around.

A detailed description of the physics of the way linear and polarizing filters work can be found at: http://www.schneiderkreuznach.com/pdf/filter/p17.pdf

Linear polarizers are also referred to as Top polarizers on our web site and in our literature.

6. What is a Kaesemann polarizer?

Kasemann was an independent company that manufactured some of the highest quality polarizer material in the world. B+W Filter/Schneider purchased the company in the mid 1980's.

The quality of the material is uniform and neutral in color. In addition, the polarizer is edge-sealed and guaranteed against separation. Moisture from humidity will destroy the polarizer material and edge sealing protects the material. Kasemann Polarizers are available in Linear and Circular.

7. What makes B+W Polarizers better than other brands?

The neutral color of B+W Polarizers assures you that there will not be any color shift when using our polarizer filter. B+W polarizers have an high extinction ratio which increases the effectiveness of the polarizer.

8. Where does B+W get its glass?

Most of the glass comes from Schott, the finest German glass manufacturer. Exceptions would be our diopters, prisms and cross screen filters which utilize high-quality optical glass. Also, B+W Softar filters are supplied by Zeiss and are made from acrylic.

9. Are there any filters offered by B+W that  B+W does not make?

Yes, some of the special effects filters. B+W has them made to its specifications. For example, as stated above, B+W Softar filters, which are made from acrylic, are supplied by Zeiss.

10. Does B+W have slim filters for wide-angle lenses?

Yes! They were introduced at Photokina '96. B+W Slim-line filters are available in sizes 49mm through 105mm with single coated (both sides) glass. They are also available with MULTI RESISTANT COATING (MRC) in sizes 49mm through 105mm (UV from 49 to 127 mm). Slim polarizers, both single coated and MRC, are available in sizes 49 through 82. They do not have a front accessory thread to avoid vignetting with lenses as wide as 17mm in 35mm format. Some report success with lenses as wide as 16mm. Shoot a test with your specific lens to confirm. Most are supplied with a slip on lens cap.

The height is only 3 mm, in the case of rotatable polarizing filters 5 mm.

11. Now that I know the filter factor for my filter, do I ever have to take another meter reading?

Yes! Filter factors are useful to estimate the optical density of a filter across the entire visible spectrum, but they are just generalizations. A filter might have a filter factor of 2, meaning that half the light that enters the filter never makes it out, but every scene is different and requires a meter reading to determine correct exposure. A filter might pass about 60% of red and blue light, but only pass about 25% of green light. It measures as a filter factor of 2, but if you photograph a head of lettuce, it will be underexposed by a stop. Always take a meter reading to be sure you are getting a good exposure.

12. I want to shoot Infrared. What do I need to know?

Before we get in to a detailed explanation, there are a few facts that need to be explained about light. Our eyes see a certain portion of the electromagnetic spectrum. The energy in this spectrum that has wavelengths from about 400 nanometers (billionths of a meter, abbreviated as nm) to 700nm we see as the colors of the rainbow (blue to red, respectively). The region of the electromagnetic spectrum from about 700nm to about 1200nm is known as the Infrared region. Our eyes can't see wavelengths longer than 700nm, but certain types of film can!

In order to take pictures of the Infrared region, you need to use a film that is sensitive to the energy in this region, commonly referred to as Infrared film. You also need to keep most, if not all, of the visible light from reaching the film, as it will overpower the Infrared image. A filter such as the B+W 092, 093, or 099 filter does this.

Things to remember:

Infrared radiation focuses at a different place than visible light. Look at your lens for a red dot on the focusing ring, this is where you set the focus to take sharp Infrared images. It is also impossible to compose the scene with the B+W 093 Infrared Black filter on the lens since no visible light gets through. Our B+W 092 Dark Red filter lets a little red light through so that you can compose the scene through the lens with the filter attached.

Meter readings are mostly useless with Infrared since most meters only read visible light. You will have to shoot test rolls to determine your filter factors with different filter and film combinations.

We offer many different Infrared filter types to accommodate both black & white and color Infrared films.

13. Why are B+W filters more expensive than most other brands?

First, most of our filters are mounted in brass rings to prevent the filter from binding to the aluminum housing of the lens. Second, our filters are manufactured the same way fine optics are made, they are cut ground and polished on state-of-the-art computerized machines. Also, most of our filters are made from Schott glass where the color is dyed in the mass. B+W tests each filter for flatness and parallel thickness which assures you of the accuracy of our filters. In addition, we have an interferometer and a scanning spectrophotometer on our premises.

14. Are B+W Filters more important when using large filters or for small filters as well?

It doesn't matter whether the filter is large or small. Using the highest quality filters will assure you of better photographs.

15. How old is the B+W Filter company?

B+W was founded in July, 1947 by Walter Biermann and Johannes Weber. In 1985 B+W merged with Schneider Optik of Bad Kreuznach, Germany. Schneider Optics, Inc. is the exclusive distributor for the United States for B+W filters.

16. Does B+W make an adapter that allows a filter to screw onto a different size diameter lens?

Yes. B+W makes step-down/up adapters that allow a large filter to screw onto a smaller diameter lens and vice versa. An adapter that combines a 105mm filter with a 100mm diameter lens would be a step-down adapter since it steps from a larger filter down to a smaller diameter lens. An adapter that combines a 95mm filter with the same lens would be a step-up adapter.

17. What is the best way to clean my B+W filter?

The first step is to use a camel hair blower brush to remove any loose dirt, grit, etc. from the glass. Then use a cotton swab, Kimwipe, or WHITE KLEENEX brand (no additives) moistened with a name brand lens cleaning solution or original Windex. Never wipe the filter with a dry "wipe", and NEVER pour the solution on the filter itself. Use a gentle circular motion and work from the center of the filter to the ring and lift off in an upward motion against the ring. NOTE: The above is fine for B+W single-coated and MRC-designated filters. If your B+W filter has multi-coating of the older type (non MRC), it would be best if the filter were handled by a Schneider technician.

IMPORTANT : When cleaning your optical devices, always follow the manufacturer's directions.

18. Can I leave the filter on my camera all the time?

Filters with which an image is visibly corrected (e.g., polarizing or conversion filters) or through which an image is to be deliberately changed (e.g., special effect filters such as diffusion filters) should not be left on the camera, but mounted only when specifically required. In practice, two types of filters which have proved to be reliable can be left on the lens permanently, and which also serve as ideal protection for the front lens. These are the UV- or Skylight filter.

19. Should I buy UV or Skylight?

The UV filter blocks intrusive UV radiation which otherwise could cause a lack of sharpness. The contrasts are heightened, and unpleasant fog is avoided. The UV filter is used with color-reversal (slides) and black and white / color negative films, and in digital photography. In order to avoid blue cast or to achieve a warmer image, the Skylight filter is used for color slides.

The Skylight filter (KR 1.5) absorbs the excess blue which is present in daylight, and thus produces a warmer color tone. At the same time, it blocks UV rays, and reduces the haze around distant objects.

Both filters are exceptionally well suited as protection for the front lens, and can be left permanently on the lens.

20. Are filters necessary at all for taking pictures?

In order to achieve more brilliant results with your pictures, filters are indispensable. They solve a multiplicity of problems. A UV- or Skylight filter blocks UV components (UV filter) and hinders blue cast (Skylight). On a vacation in the mountains or at the seashore, they are an indispensable companion. Both filters can be permanently left on the lens and are ideal protection for the front lens. Polarizing filters help produce stronger colors and suppress distorting reflections. Color filters prevent color distortion. Filters for black + white film help achieve greater contrast. Light reduction is achieved by neutral grey filters. The invisible is made visible by the infra-red filter. Small subjects look quite large with the close-up or macro lens. Trick and supplementary lenses enhance the creativity of the photographer and allow compositions which would be simply impossible without them.

Filters increase individuality and creativity.

And in digital photography?

In digital photography, despite a plethora of comprehensive image-processing programs, filters are still needed.. Image data which are lost when taking the picture cannot be reproduced later on the computer, e.g., in connection with reduced reflections with polarizing filters. Precisely in the area of digital photography, it is important to use filters of excellent quality, such as those which B+W produces.

In particular, the enormous resolving power of the lenses of digital cameras requires the highest optical quality.

Almost every filter holds back a part of the light (absorption) by virtue of its monochromatic character. This loss of light is compensated for when taking the picture by a corresponding increase in the exposure. The required correction value is called the multiplying factor or the filter factor. The factor itself is indicated on every B+W photo filter. The factor can also be found in your brochure.The multiplying factor is not a constant; rather, it varies according to the lighting conditions and the kind of film. As part of the filter information, the factor most used for daylight is given. Depending on the situation when the picture is being taken and on individual preferences, it is always possible to adjust these values. Of course, instead of increasing the exposure time, the aperture can be increased to obtain the necessary amount of light.The factor does not mean increasing the diaphragm or the exposure time by the value indicated. When the indication is 2x, this does not mean, as is so often assumed, that the diaphragm or the exposure time is to be changed by two steps. IMPORTANT : The exposure time measured without the filter must be multiplied by the filter factor! If, for example, the exposure time is set at 1/500 sec, the correct exposure time with a multiplying factor of 2x is now 1/250 sec. In practice, the exposure correction is usually converted and the exposure adjusted by means of the diaphragm. The following table shows the conversion of the most important filter factors to stop values.

Amost all cameras today have a built-in light meter. The multiplying factor is then automatically included in the calculation.

22. Can I attach several filters on top of one another?

Filters can be combined. This is of importance, e.g. in connection with polarizing filter and Redhancer, close-up lenses of different strengths, (e.g., NL+1 with NL+3 equals NL+4), or grey filters, in order to allow for intermediate steps. This also applies to experiments in the area of trick and effect filters.

IMPORTANT : When combining filters, the filter factors must be multiplied and notsimply added together!

More than one filter of the same category should not be used. It makes no sense, e.g., to mount black + white contrast filters, such as a red and a yellow, at the same time, since only the strongest filter (red), will have any effect. In order to maintain picture quality, not more than two filters should be mounted on top of one another. With short focal lengths, it should be kept in mind that vignetting can occur.

23. Are digital filters different from "normal" filters?

With digital cameras, new and, in particular, smaller thread diameters are constantly coming onto the market. In this camera segment, silver-colored mounts are in demand. B+W has expanded its product line by including the diameters in question, and the result was the B+W Digital Pro filter series. This filter series is offered in a brushed chrome finish. The filter glasses correspond to those of "normal" photo filters.

The B+W Type 486 UV-IR CUT filter (Transmission curve) can be characterized as specifically a digital filter. This interference filter blocks the UV and IR components which interfere with the electronic photographic medium.

24. Why should I buy a B+W Filter?

As far as filters are concerned, B+W's competence is unique. In over 50 years of manufacturing experience, we have developed first-class know-how. A B+W filter stands out, especially because of its excellent optical and mechanical properties. B+W has a very widely differentiated product line with the most varied filter glasses and diameters. After outstanding quality, for B+W, customer satisfaction and service have the highest priority. The B+W team would be happy to answer any further questions you might have. B+W sets the standard in the photo filter sector.

25. What are the transmission curves for your filters?

The transmission curves for B+W Filters can be found here.

26. What are the differences between F-Pro, Slim, and Wide-Angle filter mounts?

Please refer to the following PDF.

27. How can I tell if my unknown polarizer is Linear or Circular?

You need to start with a polarizer that is known to be linear.

1) Hold the known linear polarizer in one hand about 8" from your eye.
2) Hold the unknown polarizer with the other hand about 12" from your eye so you can see through both filters.
3) Rotate the unknown polarizer while holding the known polarizer fixed.
4) Turn the unknown polarizer 180 degrees to look through it in the other direction.
5) Determine Results:
   - If the results are almost opaque with the unknown filter facing in both directions, the unknown polarizer is linear.
   - If the results are almost opaque in one direction and a color shift in the other direction, the unknown polarizer is circular.

28. How many stops of light do your neutral density filters reduce?

ND.3 (101) = 1 stop compensation
ND.6 (102) = 2 stops compensation
ND.9 (103) = 3 stops compensation
ND1.8 (106) = 6 stops compensation
ND3.0 (110) = 10 stops compensation

http://www.schneideroptics.com/info/handbook/pdf/B+WHandbook10_11.pdf
NOTE: ND filter types (113) and (120) are discontinued.

29. What filters do I need to shoot IR images?

First, make sure your camera is IR compatible.

A simple test for this is to aim a TV remote into your lens and take a photograph of it – if you see the red dot, then you stand a more than good chance of getting IR images out of your camera. Digital sensors or chips are IR sensitive by nature and so camera manufacturers install an IR blocking filter in front of the sensor to absorb excess IR. However, some of these filters perform better than others and that’s why a simple test will determine your camera’s capabilities.

Once you have determined that your camera has a certain level of IR sensitivity, you will then need to purchase either a B+W 092 or B+W 093 filter in order to shoot IR images.

The 092 filter appears dark purplish when held to a light source and blocks visible light up to 650 nm, transmits 50% up to 700 nm and over 90% transmission from 730 nm to 2000 nm. The 093 filter blocks the entire visible spectrum yielding much more dramatic results and looks completely opaque to the naked eye. It’s transmission only begins to exceed 1% at 800 nm rising to 88% at 900 nm.

With either filter, experimentation will be the key to achieving the kind of results you desire. Exposure times will be long and you may need to set your camera on a black and white capture mode but once you become familiar with the procedure, a whole new world of imaging will appear before you!