Profoto B1 Air 500 w/s for wide aperture in small studio

[Kat D.]

 

<p >I'm about to commit to the Profoto B1 Air 500 w/s. Have never used strobes. Have read how the light from some strobes can be too bright in small studios for wide apertures. This unit has 7-stop range (7.8 to 500).</p>

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<p >Is my interpretation of this post by Ralph Oshiro about an Elinchrom 500 w/s correct -- that I should be able to go down to f 3.2 at 100 ISO with similar softbox? I would have the Profoto 3' octo or a 2' x 3' rectangular.</p>

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<p >I just wanted to make sure before I order the Profoto. Watts per second is totally foreign concept to me. Thanks.</p>

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<p ><a href="/photodb/user?user_id=6506120">ralph oshiro</a> , Jul 26, 2015; 01:36 a.m.</p>

 

<p>As you can see, a 7-stop range in a monolight is a huge <a id="itxthook5" href="/photography-lighting-equipment-techniques-forum/00dMqW?start=10" rel="nofollow">benefit<img id="itxthook5icon" src="http://images.intellitxt.com/ast/adTypes/icon1.png" alt="" /></a> to being able to vary your shooting aperture, especially if you tend to place your modifiers very close to your subjects. Even though the Dynalite has only a 4-stop range, the cool thing about it is that it puts out a whopping f/20 @ ISO 100 at maximum power, at a distance of 4' using a 3' octa (single baffle, single diffuser).<br>

The Dynalite is my daylight-exterior strobe (mainly because of its HyperSync-friendly, long-tailed t0.5 spec. of 1/675th), so having a true 400Ws of output is a good thing. Now, a more apples-to-apples comparison using an Elinchrom 39" mini-octa (also, with a silver interior), with both its internal baffle and front-diffuser attached, using my 7-stop range Elinchrom strobe:<br>

Elinchrom ELC Pro HD 500 monolight: 500Ws with a 7-stop range (7.8Ws-500Ws): [All measurements at ISO 100]<br>

<strong>• 39" octa @ 4' = f/3.2 @ </strong><strong>7.8Ws [minimum power]</strong><br /><strong>• <strong>39" octa<strong> @ 4' </strong>= </strong>f/6.3 @ </strong><strong>30Ws</strong><br /><strong>• <strong>39" octa<strong> @ 4' </strong>= </strong>f/8.0 @ </strong><strong>50Ws</strong><br /><strong>• <strong>39" octa<strong> @ 4'</strong> = </strong>f/25.0 @ </strong><strong>500Ws [maximum power]</strong></p>

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http://www.photo.net/photography-lighting-equipment-techniques-forum/00dMqW?start=10

 

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[Jochen_S]

<p>A magazine article I checked claimed 9 f-stops power range for the B1 500Ws down to 2 Ws and a metric guide number of 90 with magnum reflector at ISO 100. - Sales adds confirmed the power range and claimed a metric GN of 45 with strandard reflector.<br>

Big questions: will your cameras allow ISO 100? - Mine don't, they start at ISO 160, 200 & 320, some could get pulled to do ISO 100.<br>

Will you really be able to benefit from the Profoto? Its a battery unit. Can and will you haul it around? Will you get along with the capacity? - 90 min modelling light or 220 pops at full power claimed. Do you have Canon or Nikon to use the TTL flash control?<br>

Anyhow you should be able to shoot at least as wide open as Ralph.</p>

[Kat D.]

<p>Hi Jochen....</p>

<p>CORRECTION: I'm so sorry, it's the D1, not the B1, that I plan to buy. I don't think I can alter my post title at this point.</p>

<p>No, I don't need a battery-powered one and wouldn't spend $2000. Also, you are right, I would want more than 90 minutes of modelling light time.</p>

<p>As for ISO, I usually use film, so ISO 100 is no problem there, of course. However, I will also use with my Canon 5DII which does go down to 100 ISO. But thanks for pointing out possible issue re ISO.</p>

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[Bill C]

[Kat] "Watts per second is totally foreign concept to me. "

 

Hi, it's not actually "watts PER second," rather just said as "watt seconds." (We write it as "watt-seconds" but don't

pronounce the dash as "minus.") It's just a term for energy storage, and if you wanted to, you could even convert your AA

battery ratings to watt-seconds. Anyway, all a photographer needs to do, for the most part, is to have a general sense of

how much they might need, and to know that watt-seconds are "linear" (this means that doubling or halving them is

equivalent to an f-stop exposure change).

 

I think that 500 watt-seconds is a pretty good general purpose size for a monolight in the digital world. If you need more,

you can add a second unit - this doubles the power, equivalent to an f-stop. If you want less, reduce the power, and if you

can't get low enough, you can add diffusers, or even neutral density gels over the light. You can even put neutral density

filters on the camera lens, although this dims your view on an SLR camera.

 

BTW, I don't know that specific unit, but whatever Ralph Oshiro says is more than likely right.

[Kat D.]

<p>Hi Bill. Thanks for correcting my "watts per second." I need to read more about all the aspects of strobes. Your explanation of watts seconds is very clear. Thanks. It does sound like the 500 watts second would be good general purpose strobe, and I could pretty easily reduce the power.</p>

[craig_shearman1]

<p>If the strobe dials down to 7.8 ws you will have no problem. Most strobes that I've seen don't dial down anywhere near that low regardless of what their full power rating is. My Novatrons, for example, are 240ws and only have choice of half power or quarter power (120 ws or 60 ws). <br /><br />Even if your strobe doesn't dial down far enough, you can always use a neutral density gel or extra diffusion to take it down to practically nothing.</p>

[rodeo_joe1]

<p>+1 to getting a set of ND filters, but for the camera lens, then you can pretty much use whatever aperture you like. A 3 stop (8x) ND filter is very useful and would let you use ~f/1.4 at 1/32nd power, according to Ralph's figures. Effectively you'd then have a 10 stop range of flash output.</p>

<p>The other advantage of an ND lens filter is that it also cuts down ambient light. 7.8 Joules (same as watt-seconds, but the official SI unit of energy and less ambiguous) is a tiny pop of flash and its colour and exposure could easily be contaminated by ambient studio lighting - unless you work in pitch darkness of course.</p>

[Kat D.]

<p>Craig and Rodeo Joe: Thanks for your help.</p>