Glad to hear you got the filter Graeme!
I used a 720nm filter on several of my lenses since most of mine use 77mm filters it was flexible, here is a few notes in regards to using that filter.
1. it’s like a 20 stop ND, so a tripod is needed.
2. because it’s so dark, shutter speeds get very long, so you can’t use it really if it’s windy out at all. Also if it’s getting dark it was very hard to use, Often a 30 second exposure wasn’t long enough and the shadows got a magenta cast.
3. so it works best during the day while it’s still pretty bright.
4. Hot Spots are a real thing, they are worse the tighter your aperture is, so you will want to shoot at f4, f5.6, maybe f8. Some lenses are worse then others, so you will want to try a few of them to find out which of your lenses don’t have a hot spo
5.The IR light doesn’t focus well on the edges of your frame, so you will find the edges are often soft while the center is sharp.
I used my IR filter for almost a year before I decided to just get a camera converted to 590nm IR (the Ir coloring I prefer).
I can’t wait to see some of your IR photos.
