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Filter threads and step-up rings

By OneProGear · Published · Updated

Every screw-in filter has to match the thread size printed on your lens. Learn where to find that number, how magnetic filters save time, when a step-up ring lets one large filter fit several lenses, and when a matte box is the better route.

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  1. Read the ø, not the focal length

    The ø number is the diameter of the screw thread at the front of your lens, in millimetres. It has nothing to do with focal length. Two 35 mm lenses from different brands can have completely different thread sizes. Look on the lens barrel, around the front glass, or inside the cap.

    If a product page does not mention the thread size, as can happen with long zooms like the Sony FE 100-400mm, check the lens itself or the maker's spec sheet.

    Common sizes on photo and hybrid lenses are 49, 52, 55, 58, 62, 67, 72, 77 and 82 mm. Cinema lenses often have a 95 mm front or no thread at all, and take filters through a matte box instead.

  2. Match the filter to your thread size

    Once you know your size, pick a filter made for it. Examples from SmallRig:

    • 52 mm: the MagEase magnetic VND (1–5 stops), polariser and 1/4 black mist. These click onto the Universal Magnetic Filter Adapter Ring, which screws into a 52 mm lens.
    • 67 mm: the Attachable VND (1–5 stops), polariser and black mist, which fit the Universal 67 mm Magnetic Filter Adapter.
    • 77 mm: the 77 mm MRC VND and 77 mm MRC CPL, which screw straight onto a 77 mm lens.
    • 82 mm: the 82 mm UV and VND Filter Kit.

    A CPL (circular polariser) cuts glare and reflections. Black mist softens bright highlights for a filmic look. If your lens is 77 mm, the 77 mm VND fits with nothing else. If it is 67 mm, pick the 67 mm VND. Do not buy an 82 mm filter for a 77 mm lens unless you also get a 77–82 mm step-up ring.

  3. Magnetic systems: one ring, many filters

    Magnetic systems like MagEase (52 mm) and SmallRig's attachable 67 mm range work in two parts. A thin adapter ring screws onto the lens once and stays there. Filters then snap on and off with magnets. You can swap from a VND to a polariser to a mist filter in seconds, without unscrewing anything.

    The part that actually grips your lens is the adapter ring: the 52 mm Universal Magnetic Filter Adapter Ring, or the Universal 67 mm Magnetic Filter Adapter, which comes with a threaded adapter.

    Phone cage adapters, such as the 67 mm magnetic adapters for iPhone 16 and iPhone 17 Pro Max cages, are a separate system. They hold 67 mm filters on a phone rig, not on a camera lens. Keep phone and lens parts in separate pouches.

  4. Step-up rings: one big filter for several lenses

    A step-up ring is a thin metal ring. One side screws into your lens; the other side takes a larger filter. For example, a 72–77 mm ring lets a 77 mm filter sit on a 72 mm lens. Many photographers buy one 82 mm VND and a small set of step-up rings, so a single filter covers every lens in the bag.

    Always go up in size, never down. A step-down ring (large lens, smaller filter) causes dark corners in the picture, called vignetting.

    When you shop, check both numbers: the lens side must match your lens, and the filter side your filter.

    Do not confuse step-up rings with matte box adapter rings. The SmallRig Adapter Rings Kit, for example, adapts 52, 55, 58, 62 and 86 mm lens fronts to a 95 mm matte box clamp. It is made for a matte box, not for screwing on a larger filter.

  5. The matte box route: clamp-on, not screw-in

    A matte box is a hood that sits in front of the lens and holds filters in slide-in trays. It suits cinema lenses, which often have no filter thread.

    SmallRig's 95 mm CPL and VND kit with rod clamp, the clamp-on ring kit (80 and 85 to 95 mm) and the 4 × 5.65 in cinema ND filters all belong to this route. The Adapter Rings Kit lets a photo lens with a 52, 55, 58, 62 or 86 mm front fit the 95 mm clamp. The 95–114 mm threaded adapter ring is also a matte box part.

    Cinema 4 × 5.65 in filters do not care about thread size. They care about the tray size in your matte box. Do not try to tape a 77 mm screw-in VND inside a 95 mm matte box.

  6. Choose the right variable ND range

    ND filters are rated in stops. Each stop halves the light. ND2–ND32 means 1 to 5 stops, which is what the 52 mm MagEase and 67 mm attachable VNDs cover. The magnetic 67 mm VND ND64–ND400 covers 6 to 9 stops.

    As a rough guide, 1 to 5 stops handles shade through to normal sunlight when you shoot video at 24 fps with a 1/50 shutter. 6 to 9 stops is for harsh sun, or when you want a very wide aperture in daylight. Two filters with two ranges usually beat one very wide-range VND, which is more likely to show a dark X pattern or a colour shift.

    A VND is built from polarisers, and so is a CPL. Stacking a CPL on a VND can cause that same X pattern. Use one or the other, or a CPL and VND made to work as a pair, like the 82 mm kit or the 95 mm rod-clamp kit.

  7. Caps, hoods, and a 30-second check

    An adapter ring or step-up ring often means your original lens cap no longer fits. Get a cap in the filter's size. A bayonet lens hood may not fit over a thick VND; the 67 mm attachable VND is about 9 mm thick, for example.

    Before a shoot, do a 30-second check. Screw the adapter onto the lens gently and make sure it sits flat before the last turn tightens. Then click or screw on the filter. If a ring feels stiff or crooked, stop and restart. A cross-threaded ring can damage the thread on your lens, and that costs far more to fix than a ring.

    Check in this order: the size on the lens, then the filter, then the cap. A 77 mm VND on a 77 mm lens needs no ring. The same filter on a 72 mm lens needs a 72–77 mm step-up ring.

What you need

  • The filter thread size printed on your lens (for example ø52, ø67, ø77 or ø82)
  • A filter in that size, or a larger filter plus a step-up ring
  • A lens cap that still fits once the filter or ring is on
  • For cinema lenses: a matte box with clamp-on rings instead of screw-in filters

A variable ND filter is a dark filter you twist to cut the light, so you can keep a normal shutter speed in bright sun. It only helps if it fits your lens. The number that matters is the size in millimetres on the front of the lens, usually beside a ø symbol. Buy a filter in that size, or buy a larger filter and a step-up ring.

Read the ø, not the focal length

The ø number is the diameter of the screw thread at the front of your lens, in millimetres. It has nothing to do with focal length. Two 35 mm lenses from different brands can have completely different thread sizes. Look on the lens barrel, around the front glass, or inside the cap.

If a product page does not mention the thread size, as can happen with long zooms like the Sony FE 100-400mm, check the lens itself or the maker's spec sheet.

Common sizes on photo and hybrid lenses are 49, 52, 55, 58, 62, 67, 72, 77 and 82 mm. Cinema lenses often have a 95 mm front or no thread at all, and take filters through a matte box instead.

Match the filter to your thread size

Once you know your size, pick a filter made for it. Examples from SmallRig:

  • 52 mm: the MagEase magnetic VND (1–5 stops), polariser and 1/4 black mist. These click onto the Universal Magnetic Filter Adapter Ring, which screws into a 52 mm lens.
  • 67 mm: the Attachable VND (1–5 stops), polariser and black mist, which fit the Universal 67 mm Magnetic Filter Adapter.
  • 77 mm: the 77 mm MRC VND and 77 mm MRC CPL, which screw straight onto a 77 mm lens.
  • 82 mm: the 82 mm UV and VND Filter Kit.

A CPL (circular polariser) cuts glare and reflections. Black mist softens bright highlights for a filmic look. If your lens is 77 mm, the 77 mm VND fits with nothing else. If it is 67 mm, pick the 67 mm VND. Do not buy an 82 mm filter for a 77 mm lens unless you also get a 77–82 mm step-up ring.

Magnetic systems: one ring, many filters

Magnetic systems like MagEase (52 mm) and SmallRig's attachable 67 mm range work in two parts. A thin adapter ring screws onto the lens once and stays there. Filters then snap on and off with magnets. You can swap from a VND to a polariser to a mist filter in seconds, without unscrewing anything.

The part that actually grips your lens is the adapter ring: the 52 mm Universal Magnetic Filter Adapter Ring, or the Universal 67 mm Magnetic Filter Adapter, which comes with a threaded adapter.

Phone cage adapters, such as the 67 mm magnetic adapters for iPhone 16 and iPhone 17 Pro Max cages, are a separate system. They hold 67 mm filters on a phone rig, not on a camera lens. Keep phone and lens parts in separate pouches.

Step-up rings: one big filter for several lenses

A step-up ring is a thin metal ring. One side screws into your lens; the other side takes a larger filter. For example, a 72–77 mm ring lets a 77 mm filter sit on a 72 mm lens. Many photographers buy one 82 mm VND and a small set of step-up rings, so a single filter covers every lens in the bag.

Always go up in size, never down. A step-down ring (large lens, smaller filter) causes dark corners in the picture, called vignetting.

When you shop, check both numbers: the lens side must match your lens, and the filter side your filter.

Do not confuse step-up rings with matte box adapter rings. The SmallRig Adapter Rings Kit, for example, adapts 52, 55, 58, 62 and 86 mm lens fronts to a 95 mm matte box clamp. It is made for a matte box, not for screwing on a larger filter.

The matte box route: clamp-on, not screw-in

A matte box is a hood that sits in front of the lens and holds filters in slide-in trays. It suits cinema lenses, which often have no filter thread.

SmallRig's 95 mm CPL and VND kit with rod clamp, the clamp-on ring kit (80 and 85 to 95 mm) and the 4 × 5.65 in cinema ND filters all belong to this route. The Adapter Rings Kit lets a photo lens with a 52, 55, 58, 62 or 86 mm front fit the 95 mm clamp. The 95–114 mm threaded adapter ring is also a matte box part.

Cinema 4 × 5.65 in filters do not care about thread size. They care about the tray size in your matte box. Do not try to tape a 77 mm screw-in VND inside a 95 mm matte box.

Choose the right variable ND range

ND filters are rated in stops. Each stop halves the light. ND2–ND32 means 1 to 5 stops, which is what the 52 mm MagEase and 67 mm attachable VNDs cover. The magnetic 67 mm VND ND64–ND400 covers 6 to 9 stops.

As a rough guide, 1 to 5 stops handles shade through to normal sunlight when you shoot video at 24 fps with a 1/50 shutter. 6 to 9 stops is for harsh sun, or when you want a very wide aperture in daylight. Two filters with two ranges usually beat one very wide-range VND, which is more likely to show a dark X pattern or a colour shift.

A VND is built from polarisers, and so is a CPL. Stacking a CPL on a VND can cause that same X pattern. Use one or the other, or a CPL and VND made to work as a pair, like the 82 mm kit or the 95 mm rod-clamp kit.

Caps, hoods, and a 30-second check

An adapter ring or step-up ring often means your original lens cap no longer fits. Get a cap in the filter's size. A bayonet lens hood may not fit over a thick VND; the 67 mm attachable VND is about 9 mm thick, for example.

Before a shoot, do a 30-second check. Screw the adapter onto the lens gently and make sure it sits flat before the last turn tightens. Then click or screw on the filter. If a ring feels stiff or crooked, stop and restart. A cross-threaded ring can damage the thread on your lens, and that costs far more to fix than a ring.

Check in this order: the size on the lens, then the filter, then the cap. A 77 mm VND on a 77 mm lens needs no ring. The same filter on a 72 mm lens needs a 72–77 mm step-up ring.

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Buy this as a kit

Ready-made run-and-gun filmmaker kits. Swap any part or change quantities on the kit page.

Compare the run-and-gun filmmaker kits →

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