Filter Holder
To
me, the ideal situation, as far as filters are concerned, is to have one size filter
that will fit all of the lenses that I use.
The contraption at the left allows me to do just that. Shown is a 52mm red filter (Nikon size) on a 120mm Apo Symar.
A funny thing about large format lenses is that the rear element is more consistent in size than the front. For me 52mm does the trick.
Each lens board has two spring devices which hold the filter against the rear element and inside the bellows, where it is less prone to flare. The down side is that I must focus with the filter in place - for optical reasons....really not that big of a deal.