Howdy. We need to create a transition between shots, currently in the offline as a dissolve, but with the look and feel of a vintage Hollywood optical print blooming transition. I can put this together manually, but curious if there happens to be a Matchbox or Flame tool or Sapphire that might already have it sorted to start with.
Gemini gave me a quite good answer:
Once I specified that I’m using Flame, it did respond with a couple of MX options.
It’s bullshit that google does not link the AE tutorial they’re clearly stealing from. Those little tricks are the cornerstone of communities like ours. If people don’t come here and ask questions the community dissolves and the state of the art diminishes.
Please post a reference– the dehancer page that is (sometimes?) buried in that google link makes it look like a basic glow effect –and I suspect you’re looking for something nicer.
Boris Continuum has tons of these transitions. Works just like a dissolve on the timeline.
Does Continuum play nicely with Flame? It also seems like it has a lot of other Boris tools in it, like Mocha. Looks quite nice.
Yes. I use it a lot to re-create snap zoom transitions that my offline editors love to use.
Super. Thanks for the tip.
Continuum only works on Mac Flames as an OFX. There’s no Linux version of it unfortunately. 
Ah, I knew there had to be a catch…
awe sorry I didn’t think about that. I’ve been in the mac world for too long.
Sapphire also has the transitions that work on cut points too. Works on Linux. Cant say they’re the same as continuum but there are a lot.
I’m not sure I’m interpreting this correctly, but maybe LS_Airglow and animate your threshold down while exposing plate up?
Actually that’s a good call. Use the “transition builder” and see if there are any good presets for your blooming effect. Also do a post on the Sapphire forum on the BorisFX site or their Discord. Maybe you’ll get lucky and John Dickinson will build something custom for you! 
That sounds to me like an old Hollywood film flash frame where as the film winds down through the gate, it effectively logarithmically increases the exposure whilst the film is still being exposed. So in reality, it’s just X number frames before and after transition or the exposure logarithmically increases inversely relation to the speed in FPS.
I ended up using Sapphire UltraGlow Transition, then did a bunch of downstream fx on top of that. Client is happy, which means that I am a certifiable Genius.