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FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 27 May 2007 (Sunday) 17:52
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Flash f/stop question.

 
DayHawk
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May 27, 2007 17:52 |  #1

I got a question for you light experts.

in alot of threads ive read, they are explaining lighting in f/stops, now ive allways just dialed in what I though was ok(got 2 digital lamps and one analog) never worked in f/Stop's with my lamps.

so my question is this:
what do I do to make the main light (as an example) f/8.0 and so forth? do I measure each lamp individually with my meter?

and if yes, what f/stop do I need to go after for my camera setting, the main light? or just all the lights combines in one reading.

I am abit confused by this, thanks in advance

- Nick


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airfrogusmc
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May 27, 2007 17:54 |  #2

DayHawk wrote in post #3276240 (external link)
I got a question for you light experts.

in alot of threads ive read, they are explaining lighting in f/stops, now ive allways just dialed in what I though was ok(got 2 digital lamps and one analog) never worked in f/Stop's with my lamps.

so my question is this:
what do I do to make the main light (as an example) f/8.0 and so forth? do I measure each lamp individually with my meter?

and if yes, what f/stop do I need to go after for my camera setting, the main light? or just all the lights combines in one reading.

I am abit confused by this, thanks in advance

- Nick

I always set my camera for the main light.




  
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DayHawk
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May 28, 2007 04:49 |  #3

/bump, need some help guys! :)

- Nick


Canon xt rebel 350D

Canon 70-200mm f/4L
Canon 50mm f/1.8 MK II (Nifty Fifty)
Kit lens
Lowepro mini trekker AW
5 in 1 reflector, full body size
Speedlite 580EX + Lumiquest softbox
A day dreamer of the 85mm f/1.2L

http://www.nphoto.dk (external link)

  
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WilliamL
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May 28, 2007 06:40 |  #4

Now DayHawk by no means am I an expert on this really for from it.. but I set the camera to the main light.. say f8 and then I work to get the other lights 1 to 2 stops lower.. hope this helps...

and yes I check each light individually


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DayHawk
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May 29, 2007 05:52 |  #5

That is just what I mean though, how do you know if your light is at f/8? do you turn up and down on the lamp until your meter measures f/8?
my lights are in digital numbers, they go up to 6.0 max in 0.1 excrements ( I know I didn't spell that correct :) )

- Nick


Canon xt rebel 350D

Canon 70-200mm f/4L
Canon 50mm f/1.8 MK II (Nifty Fifty)
Kit lens
Lowepro mini trekker AW
5 in 1 reflector, full body size
Speedlite 580EX + Lumiquest softbox
A day dreamer of the 85mm f/1.2L

http://www.nphoto.dk (external link)

  
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EOS_JD
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May 29, 2007 06:58 |  #6

What meter are you using?


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tfiorda
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May 29, 2007 07:07 |  #7

DayHawk wrote in post #3284524 (external link)
That is just what I mean though, how do you know if your light is at f/8? do you turn up and down on the lamp until your meter measures f/8?
my lights are in digital numbers, they go up to 6.0 max in 0.1 excrements ( I know I didn't spell that correct :) )

- Nick

Nick,

Use any meter that is a flash meter. I use the Sekonic 558R but I think their flash meter is a 338, but any flash meter will work.

Then, you meter the light when you fire the strobe/flash and look at the meter reading. If you are looking for an f/8 light and your meter says f/4, then you need to increase the intensity of the light (brighten) by two stops. Keep doing this until you obtain your desired f/8 reading. Each light manufacturer is a bit different so I cannot give you exact numbers on your lights to change, but this is they way to do this. BTW, this is for the main light.

If you are using more than one light, i.e. a fill light, also you would want that light to be 1 to 2 stops less light to give a nice modeling to the subjects face.

Background lights work in the same way. Also with the backgound lights, you can start to control the intensity and color in your backgrounds by either making them higher or lower in stops than the main light.

Hope this helps,

Tony...




  
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jr_senator
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May 29, 2007 08:45 |  #8

airfrogusmc wrote in post #3276245 (external link)
I always set my camera for the main light.

I do a good bit of multi-flash shooting and I also set for the main light.



  
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DayHawk
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May 29, 2007 09:01 |  #9

that answered my question quite nicely tfiorda, thank you!

so I am guessing when I meter each individual light ( I use 3) I need to turn the other one's of to get an accurate metering?

- Nick


Canon xt rebel 350D

Canon 70-200mm f/4L
Canon 50mm f/1.8 MK II (Nifty Fifty)
Kit lens
Lowepro mini trekker AW
5 in 1 reflector, full body size
Speedlite 580EX + Lumiquest softbox
A day dreamer of the 85mm f/1.2L

http://www.nphoto.dk (external link)

  
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FlashZebra
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May 29, 2007 09:59 |  #10

What is a "digital lamp"? What is an "analog" lamp?

Enjoy! Lon


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DayHawk
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May 29, 2007 10:05 |  #11

londuck wrote in post #3285414 (external link)
What is a "digital lamp"? What is an "analog" lamp?

Enjoy! Lon

lol I might have called it a lamp, I ment strobe :)

- Nick


Canon xt rebel 350D

Canon 70-200mm f/4L
Canon 50mm f/1.8 MK II (Nifty Fifty)
Kit lens
Lowepro mini trekker AW
5 in 1 reflector, full body size
Speedlite 580EX + Lumiquest softbox
A day dreamer of the 85mm f/1.2L

http://www.nphoto.dk (external link)

  
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Titus213
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May 29, 2007 12:13 |  #12

Check out this article. It explains a different technique than that suggested here. I used this last shoot and it was dead on.

http://super.nova.org/​DPR/Ratios/ (external link)

I would suggest that the combination of the fill and the key on certain areas of your subject could lead to over exposure if just the key measurement is used.


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Big ­ Mike
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May 29, 2007 12:23 |  #13

I'm no expert...but what I would do, is to use the meter to set the main light to what you want (say F8 ). Then turn off that light and measure the other lights, one at a time, to get the ratio that you want (say F4 or F5.6)

Then, once the ratios are set, take a reading with all the lights firing and use that as your shooting aperture


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steveathome
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May 29, 2007 15:17 |  #14

Big Mike wrote in post #3286241 (external link)
I'm no expert...but what I would do, is to use the meter to set the main light to what you want (say F8 ). Then turn off that light and measure the other lights, one at a time, to get the ratio that you want (say F4 or F5.6)

Then, once the ratios are set, take a reading with all the lights firing and use that as your shooting aperture

As said above
Take your final reading with dome pointing to-wards the lens with all strobes firing, should you wish to reduce the total lighting to suit the required aperture, you lower the output equally of each unit.

This is why I like the Elinchrom D-Lites as this task is made very easy with their digital power control. Very accurate and consistent.

Edit
If you don't have that control over your strobe output aim to set you main strobe to about 1/3 stop less than your required aperture, once the ratio's have been set on the fill etc, you may find it will come closer to your required aperture when all fired together.




  
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Roy ­ Mathers
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May 29, 2007 15:29 |  #15

DayHawk wrote in post #3284524 (external link)
That is just what I mean though, how do you know if your light is at f/8? do you turn up and down on the lamp until your meter measures f/8?
my lights are in digital numbers, they go up to 6.0 max in 0.1 excrements ( I know I didn't spell that correct :) )

- Nick

You certainly did spell it correctly, but it's the wrong word - you meant 'increments' (Look up 'excrements' in the dictionary:lol: )




  
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Flash f/stop question.
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