Lee system

[Songyun]

For what focal length are WA adapter and WA shade necessary?

[anchored]

Can't provide an answer for LF lenses (don't have anything really wide yet), but can for smaller format use... perhaps you can get an idea by converting to the format you're using:

With 35mm film cameras, you need WA adapters for 24mm or shorter.
With 6x7 cameras (RB67), you need the WA adapters for the 50mm lens.

Hope it helps some.

[Eugene van der Merwe]

I use a standard 67mm lee filter ring on my 75mm nikkor SW shooting on 4" x 5", and there is still enough room for movement with this combination, only big tilts and swings result in any vignetting.
My filter holder only has two filter slots, but it does have the polarizer attachment ring on the front. Try before you buy may be good idea?

[Songyun]

Thanks Glenn and Eugene, your comments are very helpful.