If you buy one filter, buy a circular polarizer. It is the only common filter whose effect genuinely cannot be reproduced in editing — it removes reflections off glass, water and wet leaves, and deepens a pale sky, by physically filtering the light before it reaches the sensor. The second one worth owning is a neutral density filter, and only if you shoot video or want long exposures. Everything else is optional, and one popular category is close to pointless on a modern camera.
A filter is a disc of glass that screws onto the front of your lens and changes the light on its way in. That is the whole concept. What matters is which changes are optical — and therefore impossible to add later — and which are just colour adjustments you could have made in two seconds on a slider. Film photographers needed a drawer full of filters because the colour had to be right in the camera. Digital shooters need two.
The four types, and what each actually does
CPL — circular polarizer
A polarizer blocks light waves oscillating in one orientation and passes the rest. You screw it on and physically rotate the front ring, watching the effect change as you turn it. Three things happen. Reflections off non-metallic surfaces — a shop window, a car windscreen, the surface of a lake, the sheen on wet foliage or glossy packaging — reduce or disappear, letting you see through into the water or the window. A hazy blue sky goes deeper and the clouds separate from it. And saturation in foliage and paint increases, because you have removed the white glare sitting on top of the colour.
None of that is recoverable in software, because the reflection and the thing behind it are the same pixels once the shot is taken. The costs are real though: a polarizer eats roughly one to two stops of light, the effect varies with your angle to the sun, and on a very wide lens the sky can darken unevenly across the frame. Our CPL filter ranking goes deeper on which glass to buy.
ND — neutral density
A neutral density filter is sunglasses for your lens: it cuts the amount of light evenly across all colours without changing them. It exists so you can use a slower shutter speed or a wider aperture than the light would otherwise allow.
For video this is not a luxury, it is the fix for a specific problem. Natural-looking motion in video comes from a shutter speed around double your frame rate — 1/50s at 25fps, 1/60s at 30fps. On a bright day, that shutter speed at your lens's nicest aperture massively overexposes, and your only options are stopping the aperture down (losing the background blur you wanted) or raising the shutter speed (which makes motion look stuttery and video-ish). An ND filter solves it by removing light rather than changing a setting. For stills, an ND is what turns moving water into silk and a crowd into a blur.
Variable ND
A variable ND is two polarizing elements that rotate against each other, giving you a range of strengths in one filter instead of a bag of fixed ones. The convenience is enormous for video, where the light changes between shots. The catch is that at the far end of its range you can get an X-shaped dark cross across the frame, and because the mechanism is polarizing, it brings some of a polarizer's side effects with it. Good ones restrict their range specifically to avoid the cross. Our ND filter ranking covers the trade-off in detail.
UV / protection
The honest answer: a UV filter does essentially nothing optically on a digital camera. Digital sensors have UV-blocking built into the filter stack, and the haze-cutting effect that mattered on film is not a thing you will see. People still buy them as a sacrificial sheet of glass in front of an expensive front element, which is a defensible reason — a $30 filter is cheaper to replace than a lens. But understand it as insurance, not as an image improvement, and buy decent glass if you use one, because a cheap filter in front of a good lens adds flare and softness for no benefit at all.
How to pick the right size
Filters are sold by thread diameter in millimetres, and it is a property of the lens, not the camera. Look at the front of your lens barrel or the inside of the lens cap for a number after the ø symbol — 49, 52, 55, 58, 62, 67, 72 and 77 are the common ones. A 67mm filter fits any lens with a 67mm thread and nothing else. Two consequences: buy the size for the lens you actually use it on, and if you own several lenses, buy for the largest and use a cheap step-up ring on the smaller ones rather than buying the same filter four times.
The four types at a glance
| Type | What it changes | Light cost | Can software do it instead? |
|---|
| CPL (circular polarizer) | Removes reflections off glass, water and wet foliage; deepens a hazy sky; cuts glare | About 1-2 stops | No — the reflection and what is behind it are the same pixels |
| ND (fixed neutral density) | Cuts light evenly across all colors so you can use a slower shutter or wider aperture | Exactly its rating | No — motion blur and depth of field are baked into the exposure |
| Variable ND | The same, across a range, by rotating two polarizing elements | Adjustable within its range | No, with the caveat of an X-cross at the extreme of the range |
| UV / protection | Essentially nothing optically on a digital camera; acts as sacrificial glass | Negligible | There is nothing to do — buy it for protection or not at all |
The four picks, and what each listing is
| Pick | Type | Published specs | Buy it when |
|---|
| K&F Concept True Color CPL | CPL | 28-layer multi-coating, optical glass in a slim frame, sold in every common thread size | First, before any other filter |
| Hoya Digital Slim Filter Set II | CPL + ND16 + UV | Three slim multi-coated filters with a storage case, common thread sizes | You would rather buy once and find out what you reach for |
| Hoya Variable ND II | Variable ND | ND3-ND400, roughly 1.5-9 stops, high-grade optical glass, premium coatings | You shoot video and the light changes between shots |
| Urth ND Filter Kit | Fixed ND set | ND8 / ND64 / ND1000, three filters plus a case, no variable color cast | Stills and long exposures, where optical purity wins |
Specs are as published by each manufacturer and linked in Sources; prices beside each buy button are live and date-stamped. We have not tested these filters in a lab.
What to buy, in order
First: a circular polarizerin your most-used lens's thread size. It is the filter that does something nothing else can, it works for both stills and video, and good ones are not expensive. The K&F True Color CPL ranked first above is the one we point people at because its coating is tuned to avoid the colour cast cheap polarizers add.
Second, if you shoot video: a variable ND. The moment you want a shallow depth of field outdoors at a proper shutter speed, there is no alternative. If you only shoot stills and want the cleanest possible result, a set of fixed NDs is optically better than a variable one and cheaper per stop — that is the case for the Urth fixed set ranked fourth.
Third, optionally: a starter set. The Hoya Digital Slim Set II ranked second is the cheapest sensible way to own all three categories at once, since it bundles a CPL, an ND16 and a UV. It is the right purchase if you would rather buy once and find out which filters you actually reach for than research three separately.
Four mistakes worth avoiding
Stacking filters. Every piece of glass adds reflections. Two or three stacked on a wide lens also physically intrude into the frame and vignette the corners. Use one at a time.
Buying cheap glass for an expensive lens. The filter becomes the weakest optical element in the path. Flare, ghosting and softness all come from poor coatings, and you paid for a lens specifically to avoid those.
Leaving a polarizer on permanently. It costs you one to two stops of light at all times, which you do not want indoors or at dusk, and its effect is actively unhelpful on some subjects — a polarized rainbow disappears, and so does the attractive sheen on a freshly-painted car.
Forgetting the thread size.Measure before you order. The number is printed on the lens barrel and on most lens caps, after a ø symbol.
Do filters still matter now that software is so good?
Two of them do, for one reason: they change the light before it is recorded. A polarizer removes a reflection, which means the detail behind it is in the file — software can only edit pixels that already exist, and a reflection and the thing behind it occupy the same pixels. A neutral density filter lets you use a shutter speed and an aperture that would otherwise be impossible, and motion blur and depth of field are both baked into the exposure.
Everything else has largely moved into the editor. Warming and cooling filters, colour correction, graduated filters that darken a sky, soft-focus filters — all of those are now sliders, and doing them in software is non-destructive and free. That is why this page ranks four filters rather than fifteen. If your goal is better-looking video rather than better-looking gear, the lighting you put in front of the camera will change far more than anything you screw onto the lens, and your shutter and aperture settings matter more than both.
A note on cleaning and storage
A filter is a lens surface and deserves the same care: blow dust off before wiping it, never use household glass cleaner, and keep it in its case rather than loose in a bag where it collects grit. The cleaning kit guide covers which tool suits which surface. A scratched filter is worth replacing immediately — unlike a scratched lens, it costs very little to fix.
