ND Filters - Square vs Round

[felix5616]

I am planning on using Haida Pro ND filters for blurring motion on my Fuji GFX 50S camera and 23mm Lens. The filter thread is 82mm. Haida Pro ND filters are available in slim 82mm round filters and 100mm square and 150mm square format with holders and adapters. What are the pros and cons of direct thread circular filters vs square filter formats?

[Wayne Fox]

I would say main advantage of direct thread is smaller size and no light leakage behind the filter.  Maybe easier to use a shade to keep glare off if the lens isn't too wide.

Advantage of square for me,  the holder typically can handle multiple filters such as a split ND which can be useful, as well as one set of filters can be adapted to multiple lenses. I use the filters on 3 different camera systems with a totally of 9 different filter sizes.

[felix5616]

makes sense, thanks

[Rand47]

Also, if your use-case if primarily “intensional camera movement” (ICM) during exposure, you may want to consider a screw-in variable density ND filter.  Even though I have a full Wine Country filter system for long exposure work and grad ND use, I also carry a screw-in variable ND for doing ICM work!

Rand

[Conner999]

Screw ons: no light leaks, more compact in case, metal rim adds some protection if dropped, etc.

Square: quick & easy - can add/remove, experiment with strengths, etc., quickly, especially if using multiples. Can integrate with hood (using Lee hood) easily, few filters across many lenses. Cons are glass ones can break easily and more room in case needed for holde and possibly hood. Risk of light leaks, but easily fixed with strip of gaff tape, etc.

[SrMi]

In addition to everything mentioned:

Depending on the camera and ND strength you may need to remove the filter to focus. That is done quicker with a slide-in than with a screw-in.
IMO, a slide-in system (square filter) makes the system more fragile when walking around with it on.