Confused about WattSeconds. . .

I've read here many posts about WattSeconds and Lumens and guide numbers and such, but I'm trying to convert this in my head to f/stop and shutter settings. There are many choices, but folks here generally seem to be so favorably disposed to the bees and their service, I'll likely get a complete system from them.

Seems most folks settle on the 800's as best all-around choices, so I'm guessing in most home studios the 1600's are overkill. Can some of you bees owners tell me what a typical setup with a couple of 800's would give you in terms of ISO and exposure settings -- don't forget power settings on the bees.

I've been lurking for quite a while and I'm trying to sort out a system to get in my head right now.

Thanks! What a great forum this is. The amount I've picked up here in a couple short months is pretty amazing considering I never used a digital camera before about November!

John

I haven't done any testing recently with my 'Bees, but if you look at the detailed specs on AB's web site they show you f-stop settings with various "modifiers" (umbrellas, softboxes, etc.) in a way that can really give you what you need.

In a small studio, I feel the 800's (approx 320 wattseconds) will provide plenty of light. They do in my setups.

I have one 1600 (in addtion to two 800's) and plan to get more 1600's, as I intend to use them for large-group location shots - such as at class reunions, etc.

Well, I have one B800 and a reflector. At 1/4 power I get ISO 100 1/125 f8. Still learning, but this one B800 seems plenty for me right now. Wouldn't mind another for a hairlight and BG light, though.

These were taken with a single B800. For both, the camera was at:
24-70mm @ 52mm
1/80 sec, f/3.2
Mode: Manual
ISO: 160

In one image, the bee was bounced off the back wall and ceiling of my garage studio at about 3/4 power and there is a large pannel to control fill. In the other, the bee was at about 1/4 power and being shot through a large translucent pannel, again with another pannel to control fill. Hope that helps.

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Thanks, that helps a lot. Many of you are not shooting at full power, and as I suspected, for my purposes, the 1600s would likely be overkill.

Preesh!

John

The joker in the deck about watt/seconds is what occurs when you need smaller f-stops for more depth of field or have to move the light farther from the subject. To gain 1 f/stop you have to double the watt/seconds. If you are shooting head and shoulders portraits with the light just a few feet away from the subject at f/4 you need very little flash power. But every time you double the distance from the flash to the subject you lose 2 stops of light. And if you need f/11 to get enough depth of field to photograph a group of people plus have the lights 20 feet from the group, all of a sudden you may require 1600-2400 watt seconds. So for someone shooting a variety of situations more powerful heads make the most sense.

>>So for someone shooting a variety of situations more powerful heads make the most sense.<<
Technically speaking, a 'more powerful head' will output no more power if its power supply (capacitor) cannot store more power to put thru the head! This is certainly true when the head and the power pack are two separate items. Of course, many who use monolights (like Alien Bee) are referring to a 'more powerful unit' that has a larger power supply integrated to a head capable of supporting more power put into it, and that causes the monolight to put out more light.

>>WattSeconds and Lumens and guide numbers and such, but I'm trying to convert this in my head to f/stop and shutter settings.<<
There is no way to directly convert watt-seconds to f/stop. And it takes computations to convert lumens (which is a measurement of light output in ALL DIRECTIONS and does not factor reflector efficiency, light modifiers that may be used, etc.) into anything meaningful in phototgraphy.

>>The joker in the deck about watt/seconds is what occurs when you need smaller f-stops for more depth of field or have to move the light farther from the subject.<<
chtgrubbs makes good comments that lean professionals to seek units which can be regulated easily in power output, and up to about a 6 f/stop range of adjustments in what unit often can achieve with switch positions on power supplies, etc.

In separate power supplies that support multiple heads, 500 w/s power supply with two heads (250 w/s per head) is a very reasonable size for portraits where you want to be able to use larger aperture for limited DOF. Depending upon what ISO you set, and what light modifiers you do/don't use, etc. it still might require the use of ND filter over the lens to limit the light striking the sensor and use of a wide open aperture.

I use the Speedtron 2400 wattsecond packs, but ususally I combine 2 heads into one pack for 1200 ws per head. Back to physics class: A watt second is one watt per joule per second. The more watts in that one joule in that second the brighter the light will be. A lumen is the initial amount of light produced. I believe you are measuring lumens through the light meter.

Now packs. Like said in the post, you can buy packs up to 4800WS, but the more wattseconds you have the more expensive they are. Also, the faster the capacitor rechargers, the more money they will be. For a home studio I doubt you will need more than 1200 ws. The reason I am saying 1200 is for the reason, the more heads you plug into the pack the more times power needs to be distributed. So if you have 2 heads, the efficency of the pack reduces to 600ws per head. If you have 4 heads 300 ws per head. If you have just 2 heads get an 800 with a fast recycle rate.

Hope that helped.

What seconds?

Hey, this is a great discussion, and continue if you're having fun! I got what I originally needed a long time ago, though. I hear what you are saying about WS not converting to f/stops because of distance, and electronic factors and such. I wasn't really interested in the technical discussion, but asked for practical reasons.

What I was wondering was what kind of exposures were folks getting in a smallish, home studio using different sized bees, and I determined the 800s would likely fit the bill for me. I'm not going to do big group shots. I'm at a stage in life where, although not immune to budgetary restrictions, I can afford to do things like buy 1600 units rather than 800 units without obsessing over it so much. But since I do not have unlimited funds, I don't want to spend on capacity there's a 98% chance I'll never use.

At any rate, continue if you're having fun, but I didn't want anyone thinking the original poster needed further information. I ask a lot of questions around here, so I don't want to waste anyone's time.

The depth of knowledge around here is fantastic, though. Isn't the Internet wonderful? Sitting near Philadelphia in the US, I can have a question answered by a professional photographer in the UK or Australia. I hope I never stop taking that for granted.

John

John, you may have read this elsewhere, but this is something to consider. The 'Bees all use the same modelling light. You can replace the standard 100-watt household bulb with a 150-watt Philips Halogena (about $4 at Home Depot), which I highly recommend. The problem is that if you use a mix of, for example, B800's and B1600's, the modelling lights become less useful in determining how shadows will look in the photograph. That's because the modelling lights don't represent the different power levels between the different models.

If you don't plan to use the lights outside your own studio where you will want more power, get all B800's. That way the modelling lights are proportional to each other (from light to light) the same as the flash tubes are.

Skip,

I had read that, and I'm building a notes file. Thanks for reminding me about the 150-watt Philips Halogena, I had read that, but forgot to mark it down. I've been lurking for a while, and I'm trying to determine my kit. I'm leaning toward the 3-light Alien Bee kit, but I may just get the lights piecemeal and buy some accessories from AB and others elsewhere. They give a discount on building your own package based on number of lights.

I had determined to get all the same, 800s. My budgetary constraints are I don't need to get a 400 to save a couple bucks if I know I want 800s. If I'd use them, I'd get 4 lights or go 1600. But my lurking and home studio needs have me convinced a 3-light 800 setup will likely work well. I've also read good things about the Stellar kits, as well.

I'd love more practical tips like you just posted, by the way. I'm just not personally interested in the math of the watt seconds, lumens stuff. Thansk again to all of you.

Back to physics class indeed: Ws = J

This link might be helpfull to shed a little light on the subject. (scroll down to below the table)

I've mainly used umbrellas, as i've not bothered to figure out how to get the soft box together yet. With B800s at ISO100 I get between about F8 and F12, depending how I set things up. They're plenty powerful enough for me.

That sounds plenty powerful, Tim. I'll either be working in the garage or the basement. More working room in the basement, but higher ceiling in the garage.

About umbrellas--the bees kit I'm looking at comes with a 48-inch Translucent White “Shoot-Thru” Umbrella and a 32-inch Silver/White Reversible Bounce Umbrella. They make larger and, apparently, I can mix and match components in my own "kit" and get the same discount. Should I get the next larger size of each of these umbrellas, or are these adequate.

I'm not sure, but I suspect that since the lights will likely be close to my subjects the sizes are OK. In a larger studio I'd want larger umbrellas, correct? If I understand it correctly, as the ratio of the umbrella diameter / distance to subject shrinks, it behaves more like a point source with harsher shadows. The larger that ratio, the softer the light.

Thanks.

John

P.S. Now that I'm onto this, what about getting a larger reflector for one of the lights? Anyone used their "beauty dish" or 11" reflector? Is their "spill kill" better with umbrellas for softening the light?