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05/14/2005 03:34:33 PM · #1 |
Hey everyone,
I have a question regarding the power requirement vs the size and depth of a soft-box unit. Is there a mathematical way to calculate this, or a chart i could check?
I'm planning on purchasing some AlienBees lights (Digibee kit) with 2xB800.
Flash unit stats are as follow:
320 true Ws, 800 effective Ws, 14,000 Ls
5 f-stop power range (full to 1/32nd power)
What size of Softbox would be the most effective for those?
Thanks for the help, i can't quite figure it out.
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05/16/2005 09:15:47 AM · #2 |
| noone's got any idea regarding this?? |
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05/16/2005 09:17:59 AM · #3 |
| If youare planning on Alien Bees contact then and they will be very helpful with letting you know what size soft box to get for them or if you ahve a choice fo softboxes, the correct power for it. |
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05/16/2005 10:31:34 AM · #4 |
Optimal softbox size will depend on what you're shooting (i.e. the subject), and the effect that you want to achieve. The larger the light source is relative to the subject, the softer the light will be. In addition, the closer a softbox is to the subject, the softer the light will be. For this reason, small softboxes are typically used for small object photography or for dramatic lighting of larger objects. Larger softboxes are most often used for people photography.
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05/16/2005 10:58:01 AM · #5 |
There is a way to calculate the lights..its ISO conversions...
Here is a site with the equation...//www.shortcourses.com/how/guidenumbers/guidenumbers.htm
One of the photographers in our group meet up is going to be giving us a lesson or demonstration on this...a wiz at math.....And we thought we would never need to use math like this...
I wish I could help you more I know the frustration...
some of my notes from discussions on this...
11ft-16ft
1 stop less
f 8
distance of light from subject 1.4 x 6 = 8.4
I am totally lost still but perhaps someone will understand. I will take lots of notes and share them when we learn about this and hopefully I will get it.....:)
Message edited by author 2005-05-16 10:59:08.
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05/16/2005 11:11:35 AM · #6 |
More of what you need for the equipment you are getting...it explains more on the watts... The watts is a key factor and the effective Ws, vs the f stop and power range.... I dont know how to fill the equation with those numbers havent got to it yet..
//www.alienbees.com/manuals/bluebook.htm
Ok I think its the guide number that is the most imporntant to figure this one cmon all you math geniouses help please... ..figuring and scratching head..
Message edited by author 2005-05-16 11:17:44.
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05/16/2005 11:21:56 AM · #7 |
In actuality, a 320w/s flash is fairly week in it comes to softboxes BUT the softbox size is more or less irrelevant, what matters is the diffusion media. I use 250w/s heads as fill lights and use 3'x4' photoflex softboxes BUT in order to get some output I took the inner diffuser (there are two diffusers in a photoflex or chimera box) out and only use the outter one, on the 800w/s and 1600w/s units I leave the dual diffusers in.
the sixe of a softbox is more related to the size of the scene you need to light, on a full body shot if you want an even field a 6' box is much better suited than a 4' one.
as an example of my studio set-up using multiple lights and multiple size boxes:
Message edited by author 2005-05-16 11:23:26. |
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05/16/2005 11:29:13 AM · #8 |
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05/17/2005 04:18:51 PM · #9 |
Originally posted by Gil P:
In actuality, a 320w/s flash is fairly week in it comes to softboxes BUT the softbox size is more or less irrelevant, what matters is the diffusion media. I use 250w/s heads as fill lights and use 3'x4' photoflex softboxes BUT in order to get some output I took the inner diffuser (there are two diffusers in a photoflex or chimera box) out and only use the outter one, on the 800w/s and 1600w/s units I leave the dual diffusers in.
the sixe of a softbox is more related to the size of the scene you need to light, on a full body shot if you want an even field a 6' box is much better suited than a 4' one.
as an example of my studio set-up using multiple lights and multiple size boxes:
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That's funny, I use AlienBees B400 stobes (160Ws) all the time for various types of studio photography, normally in medium size (35") octagonal softboxes. I hardly ever have to turn them up over 3/4 power, even for full-body portraits. In fact, I've never used them at full power.
IMHO, the 3150 total Ws shown in your photo would be extreme overkill for the subject in the photo. And, unless you want harsh flat lighting, you should move the softboxes in much closer to the subject. The 250Ws strobes should put out all the light you need.
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05/17/2005 04:27:56 PM · #10 |
"unless you want harsh flat lighting, you should move the softboxes in much closer to the subject" this is a purely subjective comment but so is lighting, the use of multiple sources is also a question of choice depending on the desired results, right?
on the topic of the statement "extreme overkill for the subject in the photo."
you think so?
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05/17/2005 04:56:06 PM · #11 |
Hey Gil
I just did a shoot this weekend at Blah Blah studio. Great place isn't it?!? Loved it!
My shoot was more for "technical use" rather than fashion but both 400 w/s were only at 1/4 power and the 800 w/s (used to light the bg) was at 1/2 power. I was mostly shooting at 1/1000s at f7 or f8. So I'm curious to know what your settings were to need them at full force.
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05/17/2005 05:18:49 PM · #12 |
Originally posted by kosmikkreeper:
Hey Gil
I just did a shoot this weekend at Blah Blah studio. Great place isn't it?!? Loved it!
My shoot was more for "technical use" rather than fashion but both 400 w/s were only at 1/4 power and the 800 w/s (used to light the bg) was at 1/2 power. I was mostly shooting at 1/1000s at f7 or f8. So I'm curious to know what your settings were to need them at full force. |
well first, I never said I used them at full force...it was assumed I did! second when exactly did you shoot at blah-blah over the weekend?, it's a great place to work, now that we have the grid it really helps.
Message edited by author 2005-05-17 17:20:12. |
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05/17/2005 05:33:47 PM · #13 |
Originally posted by Gil P:
"unless you want harsh flat lighting, you should move the softboxes in much closer to the subject" this is a purely subjective comment but so is lighting, the use of multiple sources is also a question of choice depending on the desired results, right?
on the topic of the statement "extreme overkill for the subject in the photo."
you think so? |
Yes, I do. The amount of light shown in your studio photo would be enough to light a good size stadium. :)
But, youâre right; âenough lightâ is a totally subjective thing. I was just trying to point out that, for most subjects anyway; it isnât necessary to have six different lights putting out 3000+ Ws of light. You can get very good results with much less light output by simply moving the softboxes in closer (the inverse square law.) Moving the softboxes in closer also provides the added advantage of a softer, more wrap-around light too.
Try this: put a 250Ws strobe in your largest softbox (w\diffuser panel), and place it close to a portrait subject. Letâs say 3-5 feet away from the person, at about 45 degrees off camera center. Meter the setup and set the lightâs output for a shot at f/8.0 @ 125/sec. Then, take the shot with the camera at those settings. Now, put your 1600Ws light in the same softbox (without diffuser) and place it 12-14 feet away (as in your studio photo.) Again, meter the setup for the same camera settings and take another exposure. Which shot do you think will give you more complementary lighting? Yes, I know that âcomplementaryâ is subjective too, but thereâs also the concept of a âgenerally accepted standardâ when it comes to judging such things too.
BTW, your photo of the woman looks fine to me. J
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