Paul C. Buff, Inc. Technical Forum

I did some testing last week of the newly arrived Einsteins and Vagabond Mini Lithium - both quality of light with modifiers as well as stress testing # of flashes and recycle time.

The question is regarding how the lithium battery recovers after a burst. I flashed full power continuously, without a break, triggering by hand upon hearing the ready beep. The number of flashes was less than expected (although more than the Profoto AcuteB 600 I would usually use) and I was wondering if that was due to the nature of hitting it continuously versus a burst of 5, then wait 20 seconds, then a burst of 5 etc.

I've noticed at lower power settings that the Vagabond mini LED status light will drop down during a burst then come back on again. For example at the half power level the 1/2 light will go off but would then recover back on again.

The tests are here:
http://kevsteele.com/blog/profoto-einstein-lighting/

Somebody tell me if I'm wrong or not, but the last image on your review looks like you assembled the PLM on the wrong hole of the shaft...

Look at the images of the PLM and how they're mounted on the site:
http://www.paulcbuff.com/images/product ... t_0111.jpg

Your image here:
http://kevsteele.com/blog/wp-content/up ... _56591.jpg

Appears that you've mounted the PLM on the first hole near the edge of the mount instead of the second hole near the middle of the rod...

If I'm wrong here someone please correct me. I don't know the different iterations between the PLMS so I could just be jumping the gun and perhaps this configuration is correct for an earlier version of the PLM.

There are two hole positions on the shaft, I tested the light pattern on seamless and on a model with both positions. The most pleasing light, even and focused center with smooth falloff is when the Einstein is using the hole which keeps the flash tube farthest from the center of the PLM.

When the whole Einstein/speedring assembly is slid closer along the shaft into the PLM and the second hole for the screw then I see a donut ring or halo of light and uneven shadows. I'll have to look back at the photos - think I'll append the review post to add those shots.

Of course you can adjust to wherever you want on the shaft, one of those holes is the focal point for the parabola.

I have tested Vagabond Mini with Einstein 640 and WL1600 (640WS) several times from full charge to end of battery charge (modeling lamps off).

Results: Einstein 640 = 460 full power shots (640WS) per charge, WL1600 = 550 full power shots (640WS) per charge. All tests done with PW Intevalometer set for one flash per 10 second, non stop from beginning to end.

If you shoot slower than this rate, the number of shots will decrease some because of the quiescent power draw from the flash keeps drawing some battery power.

Also, We typically see about 3.6 Second Full Power recycle time on Einstein and 3 seconds on AB1600. A little oddity with Vag Mini is the initial recycle time is a bit longer than after is has been fired 20 or 30 times . . . a heat sensitivity thing. On Einstein, we tend to see around 4.2 to 4.5 seconds cold, dropping to about 3.6 seconds after it warms up.

I believe Profoto has a fast and slow recycle setting. Battery life is considerably less on Fast than on slow. The specs are buried away in B&H specs.

Thanks for the tests - quite useful.

Shoyriazu, I just updated the comparison with some images I had taken during the tests that show the difference between using the first hole and second hole when mounting the shaft to the PLM.

http://kevsteele.com/blog/profoto-einstein-lighting/
(you may need to refresh your browser to see the new images about halfway down).


Luap: I've done a few more location shoots with the Einstein 640s and am pretty pleased. I did break one of the pyrex domes when the unit on a PLM, 6 feet up a lightstand, tipped over from airplane prop wash before it was sandbagged and the only thing that happened was the dome shattered, flashtube was fine. The $10 replacement dome vs Profoto's $200 dome makes me smile. I'll pick up some spares.

Really nice review

Rob Galbraith has done many tests with Einstein at full power with VML. I spoke with him today and he confirms he gets 450 640WS pops per charge . . . something wrong with the review that indicates 238 pops at 557WS . . . look at the vastly higher number of pops than Profoto at 1/2 and 1/4 power in the review.

Shooting rapidly has no substantial effect on pops per charge, though at the rate mentioned at 557WS it's likely the VML simply temporarily shutdown for heat protection at 238 pops and that there were still another 200 full power pops left. If VML shuts down from overheat it will come back on in around a minute or two. But remember, if the power is interrupted to Einstein you have to turn it back on via the power switch or Cyber Commander "refresh".

Rob also reported that after about 200 battery charge/recharge cycles, the VML was still providing something like 430 full power pops per charge (640WS). The VML battery is rated at approximately 500 charge/discharge cycles to the 70% remaining capacity point.

If the Profoto tested was an SLA battery it's likely pretty much toast at 200-300 charge/recharge cycles.

It sounds reasonable that it was a thermal shutdown from flashing as fast as it could perform at near full power.

This morning I just tested again, this time at full 640WS of power, with a more realistic approach:
ten sets of ten - firing as fast as it could recycle for each set of ten then pausing 2-3 minutes till the next set of ten.

Set of ten
1. 9:41:15 - 57 = 4.2 sec per (cold, these were first flashes)
2. 9:45:27 - 07 = 4.0 sec
3. 9:48:44- 24 = 4.0 sec
4. 9:51:12 - 50 = 3.8 sec
5. 9:53:56- 34 = 3.8 sec
6. 9:56:10 - 46 = 3.6 sec
7. 9:58:04 - 40 = 3.6 sec
8. 10:00:07 -44 = 3.7 sec
9. 10:02:08- 44 = 3.6 sec
10.10:04:19-55 = 3.6 sec

After that, over the course of an hour, firing on average every 13 seconds I was able to get
282 additional (382 total) flashes till empty (empty, not thermal shutdown for sure).

I'm still shy of what you and others see. I've got a shoot this afternoon but I'm going to ask my intern/asst to do some more tests this week.

All of my tests (several) have been 640WS at one pop per 10 seconds, continuously until battery is exhausted. No shut down and yielding 450 Einstein pops and 550 AB1600 pops. Einstein draws more quiescent power than AB, so fewer flashes per charge.

The longer it takes to complete a series, the fewer the pops per charge. But going from 10 seconds per pop average to 13 may be part of the difference between 383 and 450.

Still, 112 600WS pops for Profoto VS what you got for VML and Einstein at 640WS speaks pretty well for VML/Einstein, to say nothing of the higher E640 power and the enormous cost difference, the constant color and extreme flash durations, AC or DC capability, real modeling lamps, Cyber Commander capability and all that.

Then there is the whole sulfated battery thing with Profoto SLA battery.

The longer initial recycle time is being worked on with the inverter vendor but will take a while. VMLs have to lowest failure rate of any of our products, while inverter/battery systems historically have higher failure rates than other products because of the stress they are under.