Good morning Jerry! Thank you for the kind words, I will try to live up to them, although I would really like to immediately lower everyone’s expectations. I have been up most of the night with insomnia, as usual. I am also taking 5 kinds of pain meds, so right now I am struggling to remember how to spell my name … ;>)
Before I get started, I am going to make an assumption that James is not trying to stop motion, but rather to shoot at a wider aperture to get the depth of field and bokeh that he is looking for? He mentions using neutral density filters, which of course affects both the flash and ambient. No real help there in stopping motion.
Luckily I think paul_jones and others have supplied most of the answers already.
The older Pocket Wizard Max are supposed to sync up to 1/500 of a second with a leaf shutter. The limit is due to propagation delays with the radio signal. As Paul mentions though, if you shoot at 1/800 and clip part of the t0.1 flash tail, you are not losing a lot of power. In fact, the newer Pocket Wizard Mini’s use that as part of a strategy to sync at much faster speeds with a focal plane shutter (up to 1/8000 with Canon), but that will just make my head hurt more right now until we get the basics down ….
[blockquote]
The MultiMAX is designed to sync cameras and flash units at
shutters speeds up to 1/250th for most focal plane shutters (35mm)
and 1/500th for most leaf shutters. Some camera and flash
combinations are capable of fast sync speeds up to 1/1000th. The
MultiMAX (set for RECEIVE mode) is capable of operation at these
speeds in Fast Mode.[/blockquote]
If you look at the “Sunny 16” rule at ISO 100, your exposure for ambient light at 1/800 will be at f/16->f/11-f/8->f/5.6. If you want to overpower the ambient by, say, 1 stop, you need to be able to reach f/8 with the modifier and pack you are using. (ISO 50 will give you 1 stop lower of course, if you have it.)
It will be easier to reach that using a relatively efficient modifier, like a Para. You could also use something like a PAR reflector or a Beauty Dish, or even something like a softbox if you are willing to work a little more closely.
From the Broncolor specs, a Para 220 at 3200 Ws and 10 meters (33 feet) will give you 32 8/10 when used in focused mode.
So to get to f/8, ambient + 1 stop, you need 32 8/10->32->22->16->11->8 = 3200->1600->800->400->200->100 Ws with something efficient like the Para.
That is at 10 meters! You can get the same settings with the Para 220 defocused at 4 meters. Or with the Beauty Dish or Pulsoflex 100x100 softbox at 2 meters. If you apply the inverse square law, you will need 200 Ws at 3 meters, 400 Ws at 4.5 meters, etc.
On my older Broncolor Pulso A4 (precursor to the Grafit – I didn’t have a Grafit handy), I can set a t0.1 time of 1/500 at 1400 Ws (8.
, 1/1000 at almost 800 Ws (7.9), and 1/2000 at 400 Ws (6.9) That should be plenty of power to overpower the sun at a reasonable distance.
By using a bi-tube head – attaching both sides of the flash tube to the same pack - I get 1/500 seconds t0.1 at 1600 Ws (9.0), 1/1000 at 1400 Ws (8.
, and 1/2000 at 800 Ws (7.9)
Those are pretty respectable power levels, at decent flash durations. Remember that Bron uses t0.1 times, where everyone else usually quotes t0.5 times. A 1/1000 second t0.1 time is roughly equivalent to a 1/3000 second t0.5 time!
Also, If you “clip” a t0.1 time with something like a 1/800 sync setting, you are losing much less power than “clipping” a t0.5 time. Per paul’s comment above, you are certainly losing less than 1/4 stop if the 1/800 exposure contains the peak of the flash and clips the trailing tail:
This Bron brochure has a graph of the t0.1 and t0.5 flash pulses on page 8. I lost my pro version of Adobe Acrobat somehow through automated updates, can’t cut and paste the graphic.
http://www.bron.ch/_data/bc_do_bs_grafitaplus_en.pdfSmaller on camera flash units can achieve much shorter flash durations, but their output is pretty limited for larger scenes, or for use in any kind of large modifier to get studio quality lighting.
Cheers! My head hurts, need to sleep.
Best,
Michael
