Quick Summary
- Series filters are an older photography filter system used mainly from the mid-20th century to the 1970s.
- Unlike modern lenses with threaded filters that screw in directly to the lens, series-size filters used a multi-part holder system.
- Series numbers correspond to lens diameters, allowing flexibility across different lenses. For example, Series 9 corresponds to 62-85mm holders.
- Pros & Cons
- Cons: Cumbersome system requiring multiple pieces.
- Pros: Flexibility to use standard filters on different lenses by switching the adapter.
It’s rare to come across series-size filters today. They’re mostly relegated to the vintage category.
This system was an older photography filter system, mostly used in the mid-20th century up to around the 1970s. But if you’re using a vintage manual-focus lens, you might run into the term.
The term “series size” refers to a system to standardize filter sizes for camera lenses. Unlike today’s modern lenses, which commonly use threaded filters that screw directly onto the lens’s front element, many older lenses use a slip-on filter system.
Series filters look very much like the kind of threaded screw-on filters that are common today, but there are some key differences.
Attaching series-size filters
For one, series-size filters don’t attach directly to the lens. They can come in threaded screw-in and slip-on varieties, but in both cases it’s the adapter ring (basically, the holder) that screwed onto the lens.
And that means there needs to be a different way to hold the filter in place. The solution is to sandwich them in place.
For that reason, there are three parts to the system.
- A metal adapter ring slips onto the end of the lens barrel.
- The filter itself slides into the metal adapter ring.
- A retaining ring slides over the filter and attaches to the adapter ring, locking the filter in place.
The ‘Hidden’ Series Filter: On many vintage Nikon lenses, the lens hood itself acts as the retaining ring. You unscrew the hood into two pieces, drop the unthreaded Series filter inside, and screw it back together.
Series filter sizes
The “series” part refers to the sizing. And it means that a single filter might be usable on lenses with different diameters so long as you switch out the adapter ring. So, it’s conceptually the same as using a step-down or step-up filter ring.
Each series corresponds to a range of lens diameters.
The three you’re most likely to run into are Series 7, 8, and 9. The unthreaded glass in a Series 7 filter measures 50.8mm across, and a Series 8 is 63.5mm. There are half sizes as well — Series 7.5 at 57.2mm and Series 8.5 at 74.6mm — which is part of why shopping for one to fit a vintage lens gets confusing.
| Series Number | Typical Lens Adapter Range |
|---|---|
| 5 | 28 – 36 mm |
| 6 | 31 – 47 mm |
| 7 | 44 – 56 mm |
| 8 | 51 – 69 mm |
| 9 | 62 – 85 mm |
As a practical example, a lens might require a Series 9 filter. That adapter ring would accept any Series 9 filter like the one in the photo I’ve included at the top of this page, and it could fit in adapter rings from 62mm to 85mm (the actual glass of Series 9 filters is 82.6mm diameter).
One thing that trips people up: the series number isn’t a measurement. A Series 7 filter isn’t 7mm or 7 inches across — the numbers are just steps in a sequence that was originally worked out in inches. You’ll also see them written two ways, with Roman numerals for the full sizes (Series VII, VIII, IX) and Arabic numerals for the half sizes (Series 7.5, 8.5). And some makers skipped the numbering altogether and used the millimeter diameter instead, which is why a Hasselblad Series VIII filter is marked “Series 63.”
Pros & cons of the series size filter system
The biggest disadvantage of the system is that it’s quite cumbersome, requiring three pieces to be fiddling with.
And to stack filters, you need to add additional retaining rings.
But the biggest advantage of the system is its flexibility. It’s still not as flexible as a newer style of filter holder system. But the series-size system allowed you to keep a fairly standard selection of filters that could be used on different diameter lenses simply by switching out the adapter.
Once upon a time, they were also cheaper. But that’s no longer the case, as series-size filters fell out of favor half a century ago and became vintage gear while replaced by a flood of threaded direct-attach screw-on filters.
Parting words from KODAK
I was amused by Kodak’s take1 on series-size filters:
Although series-size filters are usually cheaper than direct-fitting filters, they do have a drawback. That drawback comes under storage and retrieval. Finding the needed pieces can take as much time as looking for last year’s Christmas decorations. When the sun is dipping below the horizon, and you’ve found the orange filter and the retaining ring but can’t find the appropriate adapter which has burrowed into the bottom of your camera bag, you might not relish your series-size filters any more. If you’re neat and orderly, no problem. If you aren’t, beware.
Lens filter size charts
Assuming you’re using newer lenses that have threads to take screw-on filters, I’ve compiled some lens filter size charts, starting with some of the most commonly used and current lenses.
You can find the corresponding chart here:
- Canon lens filter sizes chart
- Nikon lens filter sizes chart
- Sony lens filter sizes chart
- Fujifilm / Fujinon lens filter sizes chart
- Olympus / OM System lens filter sizes chart
- Pentax lens filter sizes chart
- Sigma lens filter sizes chart
- Tamron lens filter sizes chart
And you can also use step-up and step-down filters if you don’t have the exact size filter on hand.
Notes & References:
- The KODAK Workshop Series: Using Filters, revised edition (New York: Silver Pixel Press, 2000) p.15. [↩︎]
A couple of notes. The Series developed in the 1930s if not earlier. Kodak’s technical guide dated 1940 listed the Series specs for Series V to Series VIII filters.
Many lenses came with built-in Series female threads. Hasselblad Ektar and Zeiss lenses for the Hasselblad 1600F & 1000F cameras came with Series VII filter threads. The Hasselblad C 50mm f/4 Distagon took Series VIII filters as did the Hasselblad SWC & SWC/Mwith the 38mm lens. The Hasselblad lens shades for those lenses were also the retaining ring that holds the filter in.
Leica release the 1st version of the Leicaflex system 50mm f/2 Summicron-R with Series VI filter sizes. Other R lenses used Series VII filters. There are a lot more examples as well.
Some Series filters came with male & female Series threads and just screwed like a MM type filter. Series polarizers all came this way so that you could rotate them to see the effect. Ditto for star & multi-image effect filters. I even have regular type filters in Series sizes with threads. Vivitar made a lot of dual threads Series filters.
Thanks for the information!