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How do you know what power to set your strobe at?
  
 
Orlov
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p.1 #1 · p.1 #1 · How do you know what power to set your strobe at?


I'm new to studio lighting. I am looking to do studio photography and I was just wondering how you know what power to set your strobe at? I know you can use a light meter to set your cameras speed, but how do I know what the optimal power setting on my strobe should be for the particular object? I have an Einstein from pcbuff.

Thanks in advance for your knowledge.



Nov 28, 2013 at 01:50 AM
gregfountain
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p.1 #2 · p.1 #2 · How do you know what power to set your strobe at?


Set the light meter to measure output at a given shutter speed. I set my camera in manual mode at 1/160th. I have a 5D3 so 1/160th seems to be optimal sync speed for my Elinchroms. I set the aperture at f/8, and then use the meter to adjust the main light to f/8 (by changing the output of the strobe until the meter registers f/8 in shutter speed mode, which measures for aperture). Depending on your lighting scheme and the ratios you want, you adjust the other strobes from there. Usually this results in your secondary strobes set for a faster f-stop, or lower strobe output.


Nov 28, 2013 at 02:05 AM
blob loblaw
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p.1 #3 · p.1 #3 · How do you know what power to set your strobe at?


it's a bit of an involved question.

i'll give you two scenarios:

1. you have a picture in your mind first. you want shadows and depth of field to be a certain way.
You would pick your distance of light->subject for the shadows, and you would pick your f-stop on the camera for DoF.
The shutter speed will control the ambient light.
Once you set that up, you then use a light meter to set the power of the strobe to complete the equation.

2. you have a requirement to shoot outdoors and to have both sunshine and blue sky show up as well as to have the subject lit with smooth light from your strobe. you would set up your f-stop and shutter to meter for the sun and the sky, then you would power up the strobe until the subject is lit correctly and that would vary as well, whether the sun is behind or in front.

there are many more examples in a book called 'Light Science and Magic'



Nov 28, 2013 at 02:13 AM
myam203
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p.1 #4 · p.1 #4 · How do you know what power to set your strobe at?


If you already understand the function of the aperture on a lens, it's no different with flash. Simply think of adjusting the power on your flash like adjusting the dimmer on a light.

Pick an aperture that will give you the look you want (i.e. shallow DOF at f/2.8 and bigger, sharp all over at f/8 and smaller) and adjust the power on your flash until things look good. Technically, a meter will nail it, but you can certainly get a good idea of your exposure just by eyeballing the LCD or checking your histogram.

Adding ambient light into the equation complicates things a little, but in a nutshell, it comes down to choosing an ambient exposure that gives you the look you want, with an aperture that isn't too small (or large) for your flash to expose properly and a shutter speed that doesn't exceed your camera's sync speed (often 1/250 or 1/200).



Nov 28, 2013 at 03:58 AM
BrianO
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p.1 #5 · p.1 #5 · How do you know what power to set your strobe at?


Orlov wrote:
...I know you can use a light meter to set your cameras speed...


Just to clarify: you adjust your strobe to your camera's aperture, not the shutter speed.

Since the flash pulse from a strobe or speedlight is faster than the highest sync speed of the camera, shutter speed is irrelevant with regard to the strobe. If you were in a totally dark room you could set your camera for 1/200 second or for 2 hours, and the exposure would be the same.

Since one rarely shoots in a totally dark room, you do need to take the ambient light into account when choosing a shutter speed, but a flash is a flash is a flash.



Nov 28, 2013 at 05:56 AM
Michael White
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p.1 #6 · p.1 #6 · How do you know what power to set your strobe at?


i use a meter or i set it a what i believe is a setting that will allow me to change the setting either up or down.


Nov 28, 2013 at 07:59 AM
_SBS_
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p.1 #7 · p.1 #7 · How do you know what power to set your strobe at?


For what I shoot in the studio (Art Jewelry) I find a light meter usually gets in the way as many of my "subjects" are made from a wide and wild variety of materials that all respond to light differently. I'll just make an educated guess at first, take the shot, then adjust the lights accordingly, then take another shot.

At first this took a bit of time, but now I can usually nail it either right away or after one adjustment. Just practice a bit and you'll "feel" what the right setting is (or close to it).

BTW I'm not against light meters, just unnecessary for what I tend to shoot to pay the bills.



Nov 29, 2013 at 05:58 AM
BigIronCruiser
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p.1 #8 · p.1 #8 · How do you know what power to set your strobe at?


Although light meters will get you in the ball park, keep in mind that the aperture in each lens/camera combination may not match your meter. As an example, my 85 1.4 matches my light meter exactly, but using my 70-200 VRII with the same aperture value will result in images that are underexposed by nearly 3/4 stop. Nikon could probably re-calibrate the aperture on the lens, but it's not worth the hassle and expense.


Nov 29, 2013 at 07:04 PM
gladivs
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p.1 #9 · p.1 #9 · How do you know what power to set your strobe at?


You can also use a grey card to tune the exposure.

Make your best guess at aperture/power settings. Take a photo of the grey card, completely filling the frame, in the place the subject will stand. If the histogram is a spike in the middle, you have the right power/aperture combination. If the spike is to the right - it means you are over exposed and reduce the power. If the spike is to the left, it means you are underexposed so increase the power.




Nov 29, 2013 at 09:36 PM
kenyee
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p.1 #10 · p.1 #10 · How do you know what power to set your strobe at?


If you have an Einstein, it's a no brainer to get the Cybercommander and a CSXCV...you'll get remote power control and a light meter.

If you can tether your camera to your computer, you can just try different lighting until it looks good to you (the rear LCD can look right but be wrong, so that's why you should tether to your computer).



Nov 30, 2013 at 02:50 PM
 

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jefferies1
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p.1 #11 · p.1 #11 · How do you know what power to set your strobe at?


I shoot a lot of portraits so I have a look I want but modify it depending on
the look of the person and how the image will be used. I always set the light to capture that look. Decide on how much DOF you want. I prefer a bit shallow for portraits so my go to is F4. Face and nose is in focus with ears a bit soft. Next is how much room light do I want to allow in the image. If I want room light, say from a window or lamp then a slow shutter. If I want to block it out then a faster shutter but not faster than the camera can handle or you get black edges in the image. I usually go to 160 sec. ISO as low as I can go so set at 100 most of the time. Then how many lights. Start with one and adjust by eye or with a light meter to get you close.
Using the shallow DOF I usually keep my strobes near the lower side of the adjustments. From adjustments range of 1-60 maybe a 20-25 is all I might need. Now add a second light or reflector if required for the look you want. When exposure looks good I custom WB so I have a neutral starting point.

For the first few do a test show and view in computer on a corrected monitor. It takes time to tell if exposure is good from the camera screen until you have some practice.

You can also use a white/black /gray card to help decide if exposure is correct. Adjust till the white is just one stop bright and is blinking ( too bright of highlights) and then move down from there. The black should look black and white have texture showing.

Many suggest a washcloth because it has texture. If it is too bright the texture is gone. Means you just ruined a wedding dress portrait. Correct texture will be seen on the screen. Got to keep the texture showing. It all comes back to personal style.



Dec 11, 2013 at 11:35 PM
atwl77
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p.1 #12 · p.1 #12 · How do you know what power to set your strobe at?


My approach is to decide the approximate aperture/DOF to use first -- this is usually around f5.6-8 for portraits, more for products. Then using a light meter, I will adjust the main light's power until I get the desired f-stop.

From there I decide what are the roles of the other lights (if any, such as fill, hair light, rim light, etc), and decide what power to use based on the ratio against the main light (e.g. I usually go for 1-stop difference for rim light, maybe 1-3 stops for fill depending on how soft/hard I want the shadows, etc), and use the light meter adjust the power to achieve that desired f-stop.

Finally a take one final, combined light meter reading to determine the overall exposure, and see if I want to fine tune any further.

It sounds like a lot of work, but actually I use a bunch of Canon 600EX-RT speedlights with the ST-E3-RT transmitter so I can easily enable/disable flash groups and manually set power on each group with the transmitter; all the while sitting at the subject's position to take the light meter reading.



Dec 12, 2013 at 11:21 AM
BrianO
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p.1 #13 · p.1 #13 · How do you know what power to set your strobe at?


atwl77 wrote:
...decide what power to use based on the ratio against the main light ...maybe 1-3 stops for fill depending on how soft/hard I want the shadows...


I assume you mean how light/dark you want the shadows to be (contrast ratio), not how hard/soft (transition quality). The latter is a factor of the size of the light, not its brightness.



Dec 12, 2013 at 05:38 PM
Kisutch
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p.1 #14 · p.1 #14 · How do you know what power to set your strobe at?


Use your LCD screen for instant feedback, go nuts and see what you like. I tried to read a bunch to learn lighting, but it only gets you so far, and a lot of the stuff doesn't really make sense until you start doing it.


Dec 12, 2013 at 09:17 PM
Sid Ceaser
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p.1 #15 · p.1 #15 · How do you know what power to set your strobe at?


Orlov wrote:
I'm new to studio lighting. I am looking to do studio photography and I was just wondering how you know what power to set your strobe at? I know you can use a light meter to set your cameras speed, but how do I know what the optimal power setting on my strobe should be for the particular object?


By learning. With time, and experience and shooting.

I think your question is a little open-ended, which is okay considering you aren't used to controlling artificial lighting.

Before turning your lights on, think about what *you* want out of the picture. What look, or effect do *you* want the portrait to have? Shallow depth of field perhaps? Then you'll want to keep the strobe at a low power so that you can shoot with a larger aperture. Want everything sharp and crisp? Then you will want to the strobe to have more power so that you can get good sharp depth.

Start slow. Start simple. Take baby steps. You can't just set a light up and set it to some magical setting that will make everything-across-the-board look good. That isn't how it works.

First figure out how you want the image to look, and then start from there. Refine your questions so that you can incrementally work through the process.

Cheers,
Sid





Dec 15, 2013 at 08:12 PM
papageno
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p.1 #16 · p.1 #16 · How do you know what power to set your strobe at?


Get a decent book on the subject and study it. this is as complex a topic as you want it to be; it's asking a lot for someone to distill everything they know into 350 words that will immediately and precisely be workable for you.

Get the book and do things; then ask for specific advice....



Dec 15, 2013 at 08:46 PM
cordellwillis
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p.1 #17 · p.1 #17 · How do you know what power to set your strobe at?




papageno wrote:
Get a decent book on the subject and study it. this is as complex a topic as you want it to be; it's asking a lot for someone to distill everything they know into 350 words that will immediately and precisely be workable for you.

Get the book and do things; then ask for specific advice....


THIS!!! /\

Problem is people junp on the net expecting instant one liner answers. The several answers given here proves that it's more to it.



Dec 16, 2013 at 05:47 AM
swoop
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p.1 #18 · p.1 #18 · How do you know what power to set your strobe at?


4 is the best setting that many professional photographers use.


Dec 17, 2013 at 05:20 PM
gfinlayson
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p.1 #19 · p.1 #19 · How do you know what power to set your strobe at?


Buy a flash meter. Your shutter speed will be limited to the flash sync speed of your camera - you can go slower if you want to include a bit of ambient light. Your ISO setting will depend on your aperture and how much lighting power you have available, but I'd recommend going with your camera's base setting for the cleanest files. Your main variable is the aperture - dial in your shutter and ISO values to your meter and measure a test flash from your model's chin with your meter pointed at your key light. Adjust aperture/flash output to get where you want to be. Lots of people say a meter isn't needed with digital - I disagree. The LCD on the back of the camera is useless at determining whether the exposure is OK and the in camera histogram is based on the in camera JPEG which depends on camera settings. With a properly calibrated flash meter, your exposure will be correct first time, every time.

I'm relatively new to studio lighting (<1 year) and have learned to use a flash meter properly. I don't ever miss an exposure now. I may choose to vary the exposure from the meter for creative reasons, but my starting exposure will always fit within the histogram.



Jan 05, 2014 at 11:00 PM
hondageek
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p.1 #20 · p.1 #20 · How do you know what power to set your strobe at?


If the photo is too dark, turn the strobe up. If it's too light, turn it down. There is no right answer. I hope I don't sound like a smart-ass, but that's pretty much how it works.


Jan 06, 2014 at 01:34 PM
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