At one time you'd recommended that I could use a Sloan i' filter, reporting it as an Ic filter then putting a comment in: Actual filter used was Sloan i'. I
have done tranforms based on Johnson V and Ic(really Sloan i') and successfully submitted those observations. Thanks for that guidance.
A related question would be; do you think I could do essentially the same thing but substituting Sloan g' for Johnson B? The response curves for Sloan g' and Johnson B look pretty close except that Sloan g' cuts off the shortest 50nm or so (350-400nm) of the Johnson Blue. With the advantage of sharper cutoffs, the Astrodon Sloan g' (Gen 2) also excludes sky glow at 557.7 nm.
I'm just trying to avoid purchasing a $200 Johnson B filter then maybe 6 months to a year later purchasing a $200 Sloan g' when AAVSO fully adopts the Sloan standard.