Noir
(Noir)
2
There is a big difference in UI. The SC52 only has the traditional ZL UI (now called G5), the SC53 additionally has G6 and G7 which are fully programmable, you can program any of the 6 slots (H1, H2, M1...) to any of the 12 brightness levels. This is pretty neat because you can program it to your liking, for example:
single click (H1 & H2) set to low levels, press and hold (L1 & L2) set to medium levels and double click (M1 & M2) set to high levels.
or H1 set to low, L1 set to medium, M1 set to high and H2, L2 & M2 all set to max. This way max is always only a double click away.
or put the six lowest levels in the six slots for late night indoor usage (or the six highest modes for outdoor usage).
or set all six slots to the same (safe) medium level. This makes it effectively a single mode light which you then can safely lend to inexperienced users.
or...
Other differences:
SC52 is a bit cheaper (it is currently the cheapest ZL, together with the H52 and H52F), has 14500 support and is brighter with one (but only for a minute, SC5 Mk II is even brighter with NiMH and lasts 3 min), only comes in cold white with low CRI (a deal breaker for me).
SC53 looks (IMHO) a bit better, comes in neutral white (and high CRI) and has the fully programmable UI.
The SC5 Mk. II is also a good option as it is a decent bit brighter than SC53 and SC52 (with NiMH), but it is a little bit larger & heavier and costs more.