Quick Answer

For most narrative work, start with the 3-stop ND (0.9) as your everyday filter, add the 6-stop (1.8) for bright exteriors and shallow depth of field, and keep the 1-stop (0.3) for subtle exposure control. If you want to soften highlights and skin tones, pair any of these with the Black Mist 1/4 drop-in.

Why Drop-In Filters Beat Screw-On ND

NiSi Athena full-frame prime lenses feature a built-in drop-in filter slot, which means you can swap ND strengths without changing the lens or adding a matte box. This keeps your rig compact and speeds up on-set changes, especially when you need to adapt between indoor and outdoor lighting.

Because the filter sits behind the lens elements, it also reduces the risk of flare or reflection compared to front-mounted filters. The lightweight aluminum frame and optical glass construction keep image quality consistent across the set.

Understanding ND Stop Differences

Each stop of ND halves the light reaching the sensor. A 1-stop filter (0.3) is subtle—useful for opening your aperture slightly or slowing the shutter in moderate light. A 3-stop (0.9) is the classic all-rounder, giving you control in most daylight scenes. A 6-stop (1.8) is the heavy hitter, enabling wide apertures in bright sun or long exposures for motion blur.

The full-spectrum neutrality of these filters means they are designed to deliver true-to-life color without a color cast, which is critical when you're matching shots across a set of primes.

Black Mist: A Creative Add-On

If you often shoot portraits or want a dreamy, cinematic look, the Black Mist 1/4 drop-in is a valuable companion. It diffuses highlights and softens fine details like wrinkles and blemishes, adding a subtle glow to your footage. Unlike ND filters, it doesn't change exposure—so you can use it on its own or stack it with an ND for combined effects.

Keep in mind that stacking filters can introduce slight vignetting or internal reflections, so test your combination before a critical shoot.

Decision Rules for Choosing Your ND Stop

  • Shooting in mixed or moderate light?: Start with the 3-stop (0.9) ND. It gives you enough control to shoot at wider apertures in most daylight conditions without over-darkening your image.
  • Shooting in bright sun or want motion blur?: Choose the 6-stop (1.8) ND. It reduces light by 6 stops, letting you use slow shutter speeds or wide apertures even in harsh sunlight. If you only buy one filter and often shoot outdoors, the 6-stop might be your priority.
  • Need only subtle exposure control?: The 1-stop (0.3) ND is your pick. It's perfect for slight adjustments, like opening your aperture one stop in bright conditions or fine-tuning your shutter angle.
  • Want a soft, cinematic look?: Add the Black Mist 1/4 to your kit. It softens highlights and skin imperfections, and you can stack it with an ND for combined control and style. Test stacking to avoid vignetting—use a lens hood or check your frame edges.

Filter Options at a Glance

Who Should Choose Which Filter?

Best for

  • Narrative filmmakers who need a versatile everyday ND—choose the 3-stop.
  • Run-and-gun shooters who want to adapt quickly between indoor and outdoor—consider the 1-stop for subtle changes.
  • Portrait and beauty videographers who want a flattering, soft look—pick the Black Mist 1/4.

Not for

  • If you only shoot in controlled studio lighting, you may not need an ND at all—skip the ND and use the Black Mist for style.
  • If you're on a tight budget and can only buy one filter, the 6-stop is more limiting in low light—opt for the 3-stop for broader use.