A BG filter (AKA blue green filter) does not look blue green to a full spectrum camera. BG filters do not add a "color cast" to a photo when used on a full spectrum camera,
BG filters remove "color cast", they return the camera to natural visual color.
BG38 or BG40 are the best ones to use for the truest visual color in most cases.
In fact, Baader UVIR-Cut filter looks too red, it has more of a "color cast" than do BG38 or BG40, on my Nikon cameras,
and most people with other brands of cameras say BG38 and BG40 look the most natural.
The problem with Baader UVIR-Cut is that it has a more red version of the visual range than does BG40, for example.
BG40 is more true to natural visible than Baader UVIR-Cut is, in my comparison tests.
Here is the blue to red visible scale:
More blue < S8612 - BG39 - BG38 - BG40 - Baader UVIR-Cut > more red
(S8612 is a BG type filter) (BG38 and BG40 look best to me).
Use what works best for you, but that is the tendency I have seen with that list of filters (blue to red).
In my tests, BG40 is maybe the closest out OOC natural visible filter for my UVIR cameras, compared to a stock camera.
With either the UVIR-Cut or the BG40 you will still need something stack with them the cut the visual at or above the 400/415/420/435nm point, because even the UVIR-Cut doesn't cut above 400nm,
it leaks some UV.
Some comparison tests I did:
https://www.ultravio...__fromsearch__1
In my opinion, the best combination is
U-340 2mm + S8612 2mm on the flash (or U-340 2mm alone on a Nichia 365nm LED torch),
BG40 2mm + KV418 on the lens for a UVIR camera.
You can replace the lens stack with a variety of other filters, some may work all alone as one filter only,
but that is the lens stack I use most of the time for UVIVF. You can use GG glass, like GG420, GG435, however if you get close to something you may get fluorescing GG, so be aware of that.
KV418 is not that easy to find and is expensive, and Ulf and Jonathan have tested some other candidates for that.
Ask them or search for that.
The same lens stack may be used on stock cameras.
If your flash is leaking the ~700nm~ Red/IR range, then you will have a mixture of true visual fluorescence + reflected visual red.
You may like that look, but don't be fooled about what it actually is, that red is not florescence, or at least not all of it, and you can't tell how much is reflected or fluorescence unless you remove the reflected red.
Edited by Cadmium, 19 November 2019 - 12:09.