Ornello wrote: The 720 filter is the lightest of the deep filters.
Looking through it at foliage, you can see some effect with the eye alone.
My question is what is the difference in response between the Rollei film and Ilford SFX, and will the SFX film record with this filter?
AFAIK the the Ilford film has extended red sensitivity up to 740nm while the Rollei film goes up to 820nm (I think).
This image on Flickr was taken on SFX with a 720 filter on the lens according to the author, but as you can see, it has a different look from Kodak HIE.