THE B&W VIEWING FILTER
Susan and I have used a Zone VI B&W viewing filter for years. This nifty little round device not only shows you the relative tonal relationship between different areas of a scene, it also acts as a framing device.
Zone VI 4×5 Viewing Filter
So, what is a B&W viewing filter? In reality it is a Wratten #90 monochromatic filter. The gel version of these filters are available from the usual photographic suppliers. They are a gelatin filter and fragile. Several companies manufacture monochromatic viewing filters. Tiffin has a version for B&W, but we prefer the Zone VI filter. It is rugged, mine is over 15 years old and still going strong. The fragile filter is mounted between glass and encapsulated in a round molded plastic enclosure. The filter comes with a cord so it can hang around your neck ready for use at any time.
So, what does the B&W filter really do? What it does not do is turn a scene to B&W. The filter shows you the approximate tonal relationship between different areas of a scene as recorded by B&W film. It will show you if there are any mergers of tone within a scene. For example, the filter will show you if a building will tonally merge with the sky, thus indicating the use of a filter to darken the sky for separation. It will also give you a good idea of how different colors will look in B&W. I have found that nice little green moss on a tree trunk will merge with the bark and disappear. The viewing filter will show you this with just a glance. Once you get used to using this handy, yet simple little device, you will not want to be without it.
The Zone VI version also serves as a framing device. The 4×5 version has the same proportions as a 4×5 or 8×10 negative. By learning to hold the filter at the correct distance from your eye, you will soon be able to approximate what focal length lens is required on your camera for a specific framing.
One other thing, the filter forces you to close one eye to use. Remember, the camera has only one lens, one view, one perspective. You may be surprised, but try closing one eye while you are looking at a possible photograph. You just may quickly learn that once you remove the 3-D effect of using both eyes, the photo just may not work. Try it!
This is just another tool. It may work for you, maybe not. The only way to really know is to try it. The Zone VI B&W Viewing Filter is no longer manufactured, but you see them used all the time. Check the Internet. This just could become a regular part of your equipment complement.