Ah Roger... read it again:
>No! Watt-seconds is just that. Watts times seconds. It's a measure
That's exactly what I said... allow me to do the math for you:
500 (Watts) X 1 (Second) = 500 watt-seconds
as you so correctly put it, the same as your electricity bill.
Which is less that 250 WS (250 watt lamp burning for one second)
This translates into fewer photons being pumped out (Less energy)
and half as much light
so a 250WS light will require a wider f-stop than a 500WS light
I think my first explanation was a lot easier to understand
>of the amount of energy released. A watt is a rate -- energy per
>second. Multiply that for the duration in seconds to get the total
>energy release. For example, you buy electricity by the Kilowatt-
>hour. But perhaps you mis-spoke. The rest of your commentary seems
>to be correct.
>
>Roger
>
>On Feb 8, 2007, at 11:07 PM, Herschel Mair wrote:
>
>> Hi Lea,
>>
>> The WS (or Joules) specification used in studio flashes is a little
>> misleading.
>>
>> It's really a measure of electricity and not light. One
>> manufacturer's 500WS light may put out much more or less light
>> than another's.
>>
>>
>> It's useful for comparing lights in a single manufacturer though
>> and you can be pretty sure that the Elinchrom 400WS light will give
>> you twice the light output of the Elinchrom 200WS.
>>
>>
>> What you really need is the guide number (GN) with the umbrella or
>> light shaper you will be using.
>>
>>
>> When thinking of watt-seconds, think of "WATTS PER SECOND"
>>
>>
>> A 500W tungsten lamp will give you, let's say, f/11 at 1 second
>> exposure. (500 WS)
>>
>> A 250W tungsten light should give you f/8 at 1 second under the
>> same circumstances (250WS)
>>
>>
>> etc.,
>>
>>
>>
>>
>>
>>
>> Herschel Mair
>> Head of the Department of Photography,
>>
>> Higher College of Technology
>> Muscat
>> Sultanate of Oman
>>
>> Adobe Certified instructor
>>
>>
>>
>> + (986) 99899 673
>>
>>
>>
>> www.herschelmair.com
>>
>>
>> ----- Original Message ----
>> From: lea murphy <lea@xxxxxxxxxxxxxxxxx>
>> To: List for Photo/Imaging Educators - Professionals - Students
>> <photoforum@xxxxxxxxxxxxxxxxxxxxxx>
>> Sent: Friday, February 9, 2007 4:06:00 AM
>> Subject: Re: Elinchrom Studio Set
>>
>> I'd buy it in a hearbeat. Elinchrom is some of the best lighting
>> you can buy.
>>
>> The heads are the lights themselves and 250 and 400 is the watts
>> per second the lights can output. There's all sorts of technical
>> stuff to explain it (and hopefully someone will) but one way to
>> think of it is that it is like a guide number for your studio
>> lights. Basically, the higher the number the more power and the
>> faster recycling time.
>>
>> This will be more than sufficient for studio work though you may,
>> in time, wish to add a third light and softboxes instead of umbrellas.
>>
>> Good for you and good luck.
>> Lea
>>
>> On Feb 8, 2007, at 5:37 PM, Elson T. Elizaga wrote:
>>
>>> I'm planning to buy this set:
>>>
>>> http://www.ebay.ph/viItem?ItemId=150089965064
>>>
>>> What is 250 and 400 in the phrase "2 heads: 1x250 and 1x400"?
>>>
>>> Watts? What do you think of the whole set in general? Is it
>>> sufficient for portraits? Food and jewelry photography?
>>>
>>> I'm not a studio photographer so some things in this area are
>>> still baffling to me.
>>>
>>> I've asked the seller already, but I'd like to get your opinion, too.
>>>
>>> Elson
>>>
>>
>>
>>
>>
>> lea murphy
>> www.leamurphy.com
>> www.whinydogpress.com
>> blog: web.mac.com/leamurphy
>>
>>
>>
>>
>>
>> Food fight? Enjoy some healthy debate
>> in the Yahoo! Answers Food & Drink Q&A.
>
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