I'm not talking about the NHL playoffs here. Really, I'm not. I'm promoting what is considered to be a dinosaur in today's photographic world. Back in the day -- not so long ago, really-- the USA made the bulk of their little photographic gadgetry, especially things like filters and the metal adaptors that fitted them to your camera. At one time, not all cameras had screw threads in front of the lenses, and there were no "standard" front diameters like there are with SLRs. Whereas now we have 49, 52, 55, 58, 62, 67mm, etc. filters, years ago there were only what are known as Series Filters. A Series filter was given a designation as IV, V, VI, VII, VIII, or IX. Each progression of the Roman numeral designation meant a larger diameter filter. For example, Series V filters are 30mm across, Series VI are 40mm, and Series VII are 50mm. You could find an adaptor that fit your lens, and the Series filter merely fit into the adaptor with a screw in retaining ring holding it in place. The beauty of this scheme is that you could own a bunch a different adaptors that used whatever diameter filter you needed. Some adaptors snapped over your lens, some have bayonet mounts, and some are standard filter-ring diameters that we are accustomed to using today. You could also find lens hoods that used the Series designation.
The reason I am bringing this up is that although I have been using these filters for some time, lots of people know nothing about them. If you are using vintage cameras with odd front filter diameters, then the Series filters are a great thing to know about. For the most part, they are no longer being manufactured, but if you attend any photo show, you'll see some. Those circular Kodak filter boxes that are an art deco yellow and black are a giveaway that there is probably a series V, VI, or VII filter inside. I also recently picked up several hundred (thousands?) of the filters and the adaptor rings from an estate. Amazing...
Series VI filters are great for rangefinder cameras, and Series VII and VIII are especially useful for SLRS. You can find + and - diopters, 25A red filters, yellow filters, diffusion, and more commonly, color correction filters. With a few metal adapter rings and some commonly-used filters, you'll have some very useful tools available to you. I'll post more about them later this week.