I'm interested about a circular filter system for (very) long exposure photography, such as the one by Formatt Hitech. However, I'd like to use a square gradient filter; they make a circular one but I don't think it would be as versatile as a square one.

Is there a way of using a square gradient with circular stacked filters?


If your square system works like mine, then yes. My assumption is that your square system attaches via an adapter ring attached to the front of the lens. If wanting to stack a filter in between, you need only find a circular filter designed for stacking (has mounting threads allowing attachment to the lens and to another filter on top of it - this one clearly says in the description that it has threads in front for stacking [https://www.bhphotovideo.com/c/product/1090044-REG/formatt_hitech_fc77irnd3_0_77mm_firecrest_irnd_3_0.html]) and then attach your square system adapter on top of this filter, as opposed to the lens.

In this case, it'll work just fine. However, you'll be pushing the whole assembly out a bit and at wide angles, you may experience more pronounced vignetting.


As far as I know, those square filters are attached via adapter. Only thing that comes to mind is Cokin system, that looks something like that:

enter image description here

You need to read more about benefits of circular vs square systems, I suspect that your assumption of "but I don't think it would be as versatile as a square one" is not based on enough information. if you google "circular vs square filters" you'll find a lot of info.


There's an old saying: "Just because you can do something doesn't always mean you should."

Yes, you can spin a round filter onto a lens and then, assuming the filter has threads on the inside of the front of the filter ring, spin the square filter holder's adapter to the front of the filter and attache the square filter holder in front of the round filter.

Unless you're using a fairly long focal length lens you will almost certainly have to deal with fairly significant vignetting in the corners and maybe even edges of the camera's field of view.

Most 'thin' spin-on filters do not have threads on the inside of the front of the ring, so you'll likely need to use a regular instead of a 'thin' round filter. The thickness of the adapter ring for the square filter holder can also have an effect since it reduces the inner diameter of the front of the round filter's front ring.

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