2 500W heads v 1 1000W head

<p>Hi all,<br>

I occasionally need a lot of power to illuminate large interior architectural spaces. I am currently using Phottix Indra 500W strobes which provide more than enough power in the majority of scenarios. But sometimes it's not quite enough power. I will now reveal my ignorance of the physics of light and ask the following. If I directed two 500W Indra's into a large umbrella (bounced light), how might the effects differ from directing a 1000W strobe, which sadly Phottix doesn't currently make to my knowledge, into that same umbrella assuming all lights were shot at full power and assuming the same camera set-up (aperture, ISO, etc)? Would the latter set-up provide more "reach" into a space than the former? Any other differences?<br>

Thanks,<br>

Andrew</p>

 

<p>The power level should be equal, and with a large umbrella, the lighting effect should be similar. It would give you another stop's worth of light, thus providing more reach. You might want to think about renting for occasional needs like this, or venturing into another brand of strobe that has more powerful models.</p>

Hi, I've never done that specific experiment although I've worked with a large number of flash units over the years, doing

quite a lot of studio lighting design.

 

I would say that in principle, all else equal, that a pair of 500 W-s units are going to put out the same amount of light power

as a single 1,000 W-s unit. However, when bouncing two light units out of the same umbrella it seems like you will be

blocking more of the reflected light, so depending on the exact setup I'd GUESS that there will be some slight light loss or

shading part of the scene. If you use a "shiny" (as opposed to "white") umbrella there will likely be some directional effect

on some of the light; I'm guessing that it won't be very significant but you could test for this by using your current flash

unit mounted off-center from the umbrella. You could also use a cardboard cutout to mimic light-blocking of the second flash unit. Again, I'm just making some educated guesses.

 

Personally, I'd avoid two monolights into the same umbrella unless the system was designed for it. As a note, I realize that your units are monolights, so presumably very little power loss in wiring to the flash tube. I'd

change my guesses a little if you had pack-head systems, due to cable losses.

If you can put up with a slightly harder light, then a

silver umbrella can increase light efficiency by up

to 2 stops over a white reflector. Also an opaque white brolly will be more efficient than a translucent shoot-through type.

 

But yes, two 500 W-s heads will put out roughly the

same amount of light as one 1000W-s head.

 

I'm a bit puzzled by your use of the word "reach", implying that the lights are used at a distance from the subject. Distance effectively increases the hardness of light, and is at odds with the use of a brolly to produce a soft source.

 

The usual way to light a large interior space is to use multiple sources and hide them behind architectural features - pillars or the like. So I'd certainly go for more heads (together with radio triggers) rather than just one with more power.

<p>Watt Seconds is NOT an output measure, it is an energy unit (also known as a joule). The efficiency of the flash tube, the circuitry of the power unit, etc. will affect the output amount so you need to know the guide number of the different flashes to see a true comparison. For example, while not a monolight like the Indra, a Speedotron 2401A pack puts out almost 1 stop more light than a Speedotron 2405CX pack</p>

Two seperate lights will more than double...the versatility of your lighting kit.

 

If you really need the ability to put 1000w-s or more into one umbrella and want ro work with battery powered lights and

also have the capability to have TTL and HSS instead of the INDRA system (which I like a lot) there is the Godox AD600B

systems, sold in the USA as the Adorama Flashpoint XPLOR 600 TTL HSS. Adorama just started selling a bi-tube

version of the Flash Extension Head accessory that connects to two XPLOR 600 / AD600B monolight bodies. I also

really like both the XPLOR 600 and the INDRA 500 systems.

<p>Thanks everyone. The application that I have in mind is enhancing and strengthening the natural light coming in through a window by putting a strobe just outside the window for an interior shot. It works like a charm but sometimes I just need a bit more power than 500Ws.<br>

The Indras are great for architectural shoots. Sometimes you just don't need 500Ws so the ability to use flashes with the Odin transmitter is just great. It makes for a very versatile kit.</p>