How do you compare hotshoe to studio flash in terms of light produced?

<p>Obviously hotshoe is better all around...<br>

What is the math to convert guide numbers to ws? Or how can I compare them in terms of light produced that's on a relatively equal playing field?</p>

 

<p>Just use an incident light meter to measure the output ....</p>

<p>what if you're comparing a light you have to a light you don't?</p>

<p>Most studio type units have a published guide number when using a standard reflector. Depending on who makes the hot shoe flash, the GN may be at max zoom for a tele lens or at midrange for a normal. Both are usually optimistic. :(</p>

<p>Both guide numbers assume reflected spill gets to the subject, which is why you get underexposed images outside in the dark.</p>

<p>There is no simple math to convert ws to GN, the conversion depends on reflector efficiency, flash tube efficiency and other factors. Probably no complex math either. :(<br>

WS is the input power to the flash tube, not a measure of light output.</p>

<p>As Lorne said, you need an incident flash meter, everything else is a WAG.</p>

<p>Not a true statement, "Obviously hotshoe is better all around..." I've got a couple of potato masher style that will melt the cases off a SB900. :)</p>

<p> </p>

<p>There is No math. Guide numbers are determined experimentally for a specific light reflector or modifier, and hopefully published by the flash maker.</p>

<p>You can determine Guide Numbe for a flash yourself, with a flash meter, or without.</p>

<p><em>"what if you're comparing a light you have to a light you don't?"</em> - perhaps you need to expain this better ? If you do not have a light ? - how can you compare?</p>

<p>There is no real way to convert Watt-Seconds to a Guide Number without a meter. The WS measure is just the amount of stored power in the capacitors. The output light will vary based on the discharge rate, the reflector used, and any other modifiers.</p>

<p>This guy did a comparison on a few http://newschoolofphotography.com/lighting/22047-strobe-power-comparison.html</p>

<p>(Everyone else posted while I was typing ....)</p>

<p>From a recent thread we concluded that a high-end hot-shoe flash stores about 50-70 WS of energy. But, like the others have said, this is not very useful. Hot-shoe flashes have a very efficient light modifier, and some even have zoom lenses to focus the light to match the lens focal length. Studio flashes have many modifiers, some efficient, some inefficient.</p>

<p>Comparing Guide Numbers is a better way, Paul C. Buff has a nice GN table for various modifiers.<br /> <a href="http://www.paulcbuff.com/output.php">http://www.paulcbuff.com/output.php</a></p>

<p>What is the purpose of the comparison? Application of lighting has everything to do with choices of equipment. </p>

<p>If it is to know whether studio strobes offer more output than a speed-light ... the answer is yes. </p>

<p>If it is to know whether a studio strobe offers more ways to modify the light ... the answer is yes.</p>

<p> </p>

<p>Studio strobes produce way more light than a hotshoe flash, you would need several hotshoe flashes to compete with even a small studio strobe. Again, why do you ask? Hotshoe flashes are more convenient,but what you should use depends on the application.</p>

<blockquote>

<p>Studio strobes produce way more light than a hotshoe flash</p>

</blockquote>

<p>Yes, if you exclude the wimpy 50 WS cheap setups. Unless you have a tiny studio, I wouldn't recommend a studio flash with less than 160 WS.</p>

<p>One thing to think about when comparing, if you want more light, you need to double it to get a 1 stop change in exposure. If you need two stops change you will need four times the light or watt/seconds. a GN change from 80 to 110 is one stop more light, 110 to 160 is also one stop difference.<br>

So this string of guide numbers are one stop apart, 56, 80, 110, 160, 220, 320, 450, 640. The Sunpak 622 is 125ws powerpack, with a GN of 160 with the standard head and a GN of 40 with the ring head. Flash tube type and angle of coverage make a huge difference.<br>

So, based on the efficiencies of a Sunpak 622 flash unit, a GN of:<br>

160 = 125 WS<br>

220 = 250 WS<br>

320 = 500 WS<br>

450 = 1000 WS<br>

640 = 2000 WS</p>

 

<p>Thanks Y'all.</p>

<blockquote>

<p>Obviously hotshoe is better all around...</p>

</blockquote>

<p>This was a bit of a joke, so I hope noone took it too seriously.<br>

thanks for the links, <a rel="nofollow" href="http://www.paulcbuff.com/output.php" target="_blank">http://www.paulcbuff.com/output.php</a> was especially helpful.<br>

For location photography, I'm using a couple of wireless hot-shoe flashes shooting through an umbrella. biggest problem is that the guns keep overheating.<br>

I've seen people use arrays of flashes... like 6 flashes on one stick to get the light, in which case it would be cheaper to get a portable studio strobe. <br>

I'm looking to purchase a couple of einsteins, and wondering how i can best justify it.</p>

Get the Einsteins, try them, and take advantage of Buff's willingness to take them back. They're willing, because you'll

very likely keep them. Great lights.

<blockquote>

<p>I've seen people use arrays of flashes... like 6 flashes on one stick to get the light, in which case it would be cheaper to get a portable studio strobe. </p>

 

</blockquote>

<p>I routinely use two at a time. Cheaper isn't necessarily the reason. I can slave multiple hot shoe flashes and have a lot less weight to carry than with a monolight, especially if you factor in carrying a battery for the monolight.</p>

<p>Eric</p>

<p>@Eric, do you know how roughly how many shots you get, and what your recycle time is. Do you have an issue with overheating?</p>

<p>6 sb 900's at $500 each on one stick? 3 grand! And end up with one light source. Hope they are sponsored by the mfgr and get them free. Great if light weight and portability is the critical factor. Eric, Denis Reggie does the same and sells a bracket that holds 2 strobes, receivers and a battery pack and shoots through a small sbox. More light, lower power settings and faster recycle. When I do use 2 through a shoot-through umbrella, I just hang the second upsidedown attached to the umbrella shaft with a second umbrella/flash holder. </p>

<p>This is what I use. I highly recommend it. No connection to the company other than a happy customer:</p>

<p><a href="http://www.brewerbracket.com/el-doble-dual-flash-umbrella-bracket.html">http://www.brewerbracket.com/el-doble-dual-flash-umbrella-bracket.html</a></p>

<p>I like this because of how it positions the umbrella relative the flashes.</p>

<p>Daniel, I don't know how many shots I get. I change batteries before I really need to. One set has more than enough juice to get me through formal pics at a wedding. I probably use two more sets during the reception, but I'm guessing I could get by on one set. When there's a break in the action, I change whether I need to or not. I'm also not using them for every single shot. Recycle time is measured in fractions of a second. When it approaches a second, I change batteries. I've never overheated my flashes, but I tend to use the flashes sparingly.</p>

<p>Eric</p>

<p>Here's an example of two flashes on one stand, and then another flash on the camera:</p>

<p><img src="http://www.merrillphotography.com/canid/pics/schumann_080802_298c.jpg" alt="" /></p>

<p> </p>

<p>I still do not quite understand why people insist on beating the snot out of their expensive speed-lights to do off-camera lighting.</p>

<p>It'd like sending a kid with a pea shooter to a tank battle.</p>

<p>I get the "lazy" part ... been there, done that myself. What happened is that when the going got tough the speed-lights went on strike ... and it took 15 minutes before I could use them again. By the time I added enough speed-lights to one modifier to take the stress off each individual one so it wouldn't shut down, I was up to $2,000.+ in speed-lights ... so I just got a Elinchrom Quadra which has heads so small I just leave them on their stands, so set up is super fast.</p>

<p>We aren't just talking about a dark wedding reception where you can jack up the ISO and drag the shutter to make it work half-way decent with a speed-light. What about large coverage, or shooting outside with a background and sky lit by a nuclear sun? That happens at weddings all of the time because we are at the mercy of the Bride's schedule. </p>

<p>There are all kinds of very portable 400 w/s mini strobes that are just as easy to carry and set up as a multiple speed-light kit, and they will last you a lifetime without stressing out your speed-lights to the max. Plus, they can be used to shoot other stuff requiring different modifiers.</p>

<p> </p>

<p>I thought one of the reasons for ganging speedlites was the use of high speed sync, which you can't get with most studio strobes. Maybe I'm wrong.</p>

<p>Also, the ability to zoom the reflector in speedlights changes the guide number.</p>

<p>It all depends in the application. More powerful battery powered flashes are also useful. While Einsteins are definitely cool, if you are on a budget, you can buy old Norman 200 and 400Bs, and Lumedynes, and old Quantum Q flashes...</p>

<p>I agree with Matt ... the Einsteins are without a doubt the best affordable lights I've ever used. They're better than some lights that cost a lot more too.</p>

<p>I usually assume that the guide number (which is measured at 50mm, assuming your speedlite maker is on the up-and-up) is about half of the wattseconds you would get. This isn't exact math by any means, but it's close enough to make a purchasing decision. I find that if you're comfortable shooting 400 ISO with a digital 35mm-style camera, speedlites are generally just fine. If you want to shoot at a lower ISO, or you use medium format or something else that basically requires a smaller aperture, than you need some powerful studio strobes.</p>

<p> </p>

<p ><em>"I thought one of the reasons for ganging speedlites was the use of high speed sync, which you can't get with most studio strobes. Maybe I'm wrong.</em></p>

<p ><em>Also, the ability to zoom the reflector in speedlights changes the guide number."</em></p>

<p > </p>

<p >As you know Nadine, HSS significantly reduces the effective output/reach of speed-lights even when ganged ... and places even more stress on the units while draining the batteries even quicker. You can't increase the maximum output level of a speed-light when it is set to manual ... it is what it is. So, it would take a lot of speed-lights set to HHS to put enough light out far enough to mean anything. </p>

<p > </p>

<p >In darker ambient conditions, it is the duration of strobes that determines the light no matter what shutter-speed is used up to the sync speed ... the HSS in effect is a fast flash duration ... by cutting the level of a strobe to half on a 400 w/s box you get a much faster duration but still 200 w/s ... enough light to be effective.</p>

<p > </p>

<p >Some strobe systems have various reflectors to effectively work like a zoom reflector on a speed-light.</p>

<p > </p>

 

<p>Marc--thanks--I just didn't know. Then, I've heard that flash duration with speedlights is different from flash duration with studio strobes. Could that be one of the reasons to gang speedlights?</p>

<p>I know Nadine ... sorting through the different information isn't very easy, when and if you can find accurate information. Plus most specifications do not indicate effectiveness when using a light modifier ... even a simple umbrella configuration let alone a soft-box ... which is where strobes tend to be even better because of the round light configuration. </p>

<p>What I could find (for example) was that the Elinchrom Quadra with an "A" speed head plugged into the B channel outlet can deliver 1/6000th of a second duration at minimum settings ... and about 80 w/s @ 1/3,000th.</p>

<p>A Canon 580 EX-II manually set to 1/2 power equals 1/2,000th of a second duration @ about 35 to 40 w/s ... and 2 heads in tandem @ 1/2 power equals 1/2,000th duration @ 70 to 80 w/s. Four 580 EXs set to 1/4 power would jump the duration to 1/4,000th but the total output would still be about 70 to 80 w/s.</p>

<p><strong>The main thing is available levels of output:</strong> I've seen direct test shots between the Quadra and Nikon SB-900 both set to maximum output using the same Photek Softliter-II modifier at the same distance to subject, with the same camera & lens set at the same ISO ... and the Quadra produced almost 3 stops more light to the subject. A correct exposure using f/8 and the SB-900 required f/20 with the Quadra (or I assume any other 400 w/s kit, like the Norman, Lumidyne, or Quantum 400 w/s unit). </p>

<p><strong>Three stops is a lot when the distance to subject grows, or you are outdoors with a bright background. Or, would allow the use of a significantly lower ISO. </strong></p>

<p>The financials are also pretty revealing: a one head Quadra kit is $1,400. ... about the same as 3 Canon 580EX-IIs not counting the hardware needed to mount them in tandem. 400 w/s verses 210 to 240 w/s output for the same money. </p>

<p>In fact, in many cases commercial shooters use 1,200 w/s units like (among others), the Hensel 1200 Porty L which can deliver @ 1/8,100 duration at minimum settings ... and can put 150 w/s of light out at about 1/3000th ... but, the kicker is the Porty can do 450 pops, and recycles in under 1 second @ 1,200 w/s! Even more pops and a blazing recycle speed @ 600 w/s. Plus you can control the light level remotely for up to 1,000 feet and run them non-stop with no shut downs to contend with.</p>

<p>However, these are expensive units, which is why they are popular as rental lighting.</p>

<p><strong>In the end, applications are the determining factor ... what, when and where you tend to shoot ... and how often. </strong></p>

<p><em>" So, it would take a lot of speed-lights set to HHS to put enough light out far enough </em>to mean anything." <em> - </em>seems like this person does not use the HHS (or FP in Nikon) mode?</p>

<p>How is 20 meters, or 10 meters long enough for portraits ? (66ft, 33 ft).</p>

<p>There is no need to guess, or even no need to shoot test pictures with Nikon SB800/SB900 and Nikon FP compatible DSLR camera. The flash will show max range for you in any mode, any settings.</p>

<p>As an example of day light, partly cloudy day with sun, set D700 to ISO 800.<br>

Set SB800 to iTTL/BL/FP, Set initially shutter to 1/250 FP but in Aperture prioriy it will go faster, and that is OK for FP. Set lens aperture to f=2.8 or 4.</p>

<p>Then remove the flash diffuser dome, and aim the flash head directly, not tilted, not bounced, no reflector, no wide angle panel. </p>

<p>Activate the camera focus, and the flash will get activated, and will tell you efective max FP range in the iTTL/BL/FP mode that is about 20 meters, or can drop down to 10 meters, depending on the sun shine. This distance is usually long enough for outdoor portraits with the sun and the FP mode single flash.</p>

<p>Vary your shooting parameters, and see the max range on the flash, without even taking a picture. Make sure that the flash stays in the iTTL/BL/FP mode.</p>

<p>Since I usually use negative flash compensation (.e.g -1.3EV), the max FP distance is possible between 10 to 20 meters in most day light lighting conditions.</p>

<p>Adding more remote CLS/FP flashes would allow you lower ISO, and more closed aperture, since you could place remote CLS/FP flashes very close to the subject.</p>

<p>For the conditions I mentioned, 1 SB800 flash is good up to 20 meters(66 ft). This distance is also the max effective automaticn flash exposure distance for the iTTL/CLS commanding and the remote FP if any used with SU800. (10m, 33ft with SB800 used as a commander/CLS/FP).</p>