What body(ies)/lens(es) are you planning to use the filter with?
I am a user of the Tiffen Black Pro Mist 1/4 strength. The Black Soft Glow is similar, though I haven’t used one. The main difference between the two seems to be the slight contrast/highlight reduction and halation the Pro Mist gives, whereas the Soft Glow softens the overall image without decreasing contrast and highlights.
What look are you after? If you’re after cinematic roll off, light source halation, skin softening, without being over done, skip the Soft Glow (my opinion) and go with a Black Pro Mist (or other Pro Mist to suit your taste). The effect that filter has is very positive in my experience.
As for strength, I have found 1/4 to be a good balance between just enough and not too much. 1/8 has minima effect in my opinion and is a bit of a waste of money. I have a 1/2 that I use at times, which can be a bit too much. I wouldn’t even touch the 1,2, or 3 unless I absolutely had a cinematic effect I was after for a specific purpose. If that was the case I’d consider either stacking a pro mist with a smoque filter or just using the smoque on its own. For general everyday use the 1/4 strength is hard to beat. I use it on everything. New lens- new filter for it. Now, I am after the cinematic moody look, so your mileage may vary, but even if I’m not after that ‘look’ for an image the 1/4 strength is hardly ever a negative to the overall final image.
I use a Tiffen 1/4 BPM with an FD 55 1.2 SSC, Tokina Opera 50 1.4 FF, RF 70-200 4 L
I use the Tiffen 1/2 BPM with an EF 16-35 2.8 L IS II USM, Pentax M 50 1.4 SMC, Pentax M 100 2.8 SMC. (I’ll probably add a 1/4 for these bc 1/2 can be too much.)
Bodies are R6 Mark II, 5D, T3, Pentax K-50.
Hope that helps at least give you an idea.
