Hi,
Tried side-by-side, but both beams kept blending into each other :(.
Tried outside, but the pics just look black to me :(… Here they are anyway, both lights on high. A tree, about maybe 25 yards away?
SC52:
SC600:
Tried again, with tablet camera in “night” scene (no manual as far as I can tell) and ISO 100?
SC52:
SC600:
I think these are azalea bushes in our backyard, closer than the earlier pics. Both lights on high (and I was freezing outside)…
Much better beamshots. Is the SC600II floody like the SC52? If they are both on high, then the SC600II looks much brighter in those photo’s.
Plus, remember one thing. The SC600 MKII will give you 900 lms for 5 min than step down to 500 for approx 2 hrs on my AW 3100 batteries. The SC52 (my next purchase) will give you 500 lms for just one min than drop to 280 lms for 0.9 hrs. So, output and runtimes put these in two totally different classes. The SC600 is very small IMO but the SC52 would be a true EDC.
You have to remember that our vision doesn’t see double the brightness as double the brightness, a 40% increase looks like only a slight increase unless held side by side.
I have the first gen sc600 and it outthrows and is decently brighter than my sc52, only at range does the sc600 have the edge, and you don’t grab a zebralight for throw 
I’d suggest something throwier unless your looking as a replacement for your sc52.
Although It is nice to have both lights on you to have the same UI sometimes
Yes, both the SC52 and SC600 were/are floody, very similar.
TL;DR - A 900 lumen flashlight is much brighter than a 500 lumen flashlight.
In order to produce an apparent increase of doubling the perceived brightness, you would need as a general rule of thumb four times the light.
The way we perceive brightness is also not linear at all.
Meaning for example that you would not see a 500 lumen light as being as being five times as bright as a 100 lumen. Nor would a 1lumen light appear 900 times dimmer than a 900 lumen light.
The only way you can reliable observe the increase in brightness indoors, without a luxmeter & sphere is not whitewall hunting, but to observe the differences in the diffuse lighting. Up close the hotspot is just too bright and will not reliable convey the difference as well.
So if you're wondering, WOah! Wait!?!?! Is this light really that much brighter. Set down the two lights side by side in a room in complete dark. Turn on one light and point it at the ceiling. Observe how it lights up the side walls, the floor, everything around you. DO NOT LOOK UP AT THE HOTSPOT. Turn it off the light. WAIT for 10-30 seconds, and then do the same with the other light. Repeat a few times.
Most of the time, assuming the tint of the LED is similar, you will be able to easily see that one light is brighter than the other.
Another factor to consider, is that we do not perceive all wavelengths of the visible spectrum in the same way.
What we see in the spectrum is limited to roughly between 390nm to 700nm. (With some variance in sensitivity at the shorter and longer wavelengths from person to person.)
How well you perceive specific colors, can also vary quite a bit from person to person, and affect perceived brightness.
At the same time the our cones correspond only as follow;
As a result, for example, 150mW of 405nm laser light will appear only about as bright as 5mW of 532nm light.
What this means to flashlights, is the difference in tint from one LED to the next, can very seriously impact perceived brightness.
When all is said and done, the only way to truly measure the differences, is with calibrated instruments.
Interesting information, thank you
Ditto.
The SC600 mkII at 900lm is only one visual step brighter than the SC52 at 280lm, and if you compare 900 vs 500 (or 500 vs 280, after step-down) the difference is even smaller. The main thing you get with the SC600 is longer runtime. Great light for use on bike handlebars, though a cheap Convoy S3 would be just as nice for that sort of thing (possibly better, since the S3 is pretty floody).
However, it appears that the SC600 has a somewhat smaller hotspot and more focused beam, so you should get better throw. It would be a definite win for outdoor or distance use, though as CarpentryHero said, it’s not a thrower.
The way I see it, both lights are very nice but it’s a bit redundant to have both. Take your pick — smaller size or longer runtimes — because the overall output isn’t hugely different.
Thanks for taking the time to explain, I already own the SC52 (and love it) so might not worry about the SC600II
Bought my SC600 MKI at least a year ago for $95 and my SC52 at the release for $55.
The SC52 has made my SC600 almost obsolete as it´s almost as bright (on 14500) and much more edc-able.
The clip on the SC52 is really good and the one for the SC600 sucks (imho)…. why couldn´t they just have made it a decent screw-on clip instead…. 
Sure, the SC600 is still a really nice solid light and if I need longer runtime I bring it, but most of the time the SC52 is enough.
Um, I just noticed something on my SC52. It appears to have PWM on the L1 mode (2.7lm).
I thought I was imagining it, but I compared it against other lights and I’m pretty sure what I’m seeing is really there.
So far it appears to only be on the 2.7lm mode, and it’s not very noticeable during use. I just did a quick check by random chance and was surprised at the result. It looks like it has PWM, and the frequency seems similar to my XinTD C8 V3 (which IIRC runs at about 4.5 kHz). I then tried it with an Eneloop. The PWM went away. Put a 14500 back in and the PWM came back.
The easiest way I’ve found to check is to rapidly wave a white business card back and forth through the beam with a dark background behind.
My H51w doesn’t have PWM. My L3 L10-219 doesn’t have PWM. But the SC52 does. And while trying other lights, I found that the JETBeam RRT01 has something like PWM, but instead of a square wave at 2% duty cycle, it seems to use a steady sine wave.
Anyway, just wondering if anyone else can confirm that the SC52 has PWM on L1 with a 14500 battery.