Series Filter Size Data
This is data that I have collected from various places on the Internet. Some of these I have verified, but many of the larger sizes I have not, so please use this as a general guide with the understanding that it *could* be wrong.
| IV = 20.6 mm |
| 4.5 = 25.5 mm |
| V = 30.2 mm |
| 5.5 = 35.9 mm |
| VI = 41.3 mm |
| VII = 50.8 mm |
| 7.5L = 57mm |
| VIII = 63.5mm |
| 8.5/5.5L = 74.8 x 5.6mm |
| 8.5/8mm = 74.8 x 8mm |
| IX = 82.6 mm |
| 93 = 93mm |
| 103 = 103mm |
| 107 = 107 mm |
| 119 = 119mm |
| 125 = 125 mm |
| 138 = 138 mm |
Using Series Filters
In order to use Series filters, you need to have an adapter ring and either a retaining ring or a lens hood. The adapter ring slips over the end of the lens typically, but I have seen some that screw into threads. This adapter should be the same diameter as the lens you wish to use it on. There are prongs that can be *slightly* bent in or out to adjust for size, but don't count on being able to use more than a millimeter or two at most larger than the lens diameter. These often come with a retaining ring already, but you should always ask first as the retaining rings are harder to come by all by them selves than the set.
Once you have the adapter and retaining ring, you use the filters that match the Series number of the adapter you are using. For example, a 22mm diameter Series V adapter ring uses Series V filters, not filters that are 22mm thread size. Series VI adapters use Series VI filters, and so on. These filters often have a letter designation rather than a number, like modern filters, although some do have a number designation. For example, a Yellow #8 is often labeled 'K2'. When I have time, I plan on posting a chart showing the modern filter number for the older letter designations.
These filters drop into the adapter rather than screw into threads, and they are held in place with either a retaining ring or a lens hood. Both retaining rings and lens hoods carry the same Series number (Roman numeral) as the adapter ring they will fit, so be sure to match up the proper size if you get them separately. Alternatively, you can use modern filters with Series adapter rings by using a step-UP ring, which are designated by a Series number then a thread size. For example, the proper ring to use when stepping up from Series VI to 58mm would be called "Step Up ring Series VI - 58mm". Be sure to get step-UP rings, as step-DOWN rings will cause vignetting in most cases (darkening of the edges of the frame).