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Einstein: Power in f/stop vs light meter reading
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Author:  iamjv22 [ Tue Jun 14, 2011 10:51 am ]
Post subject:  Einstein: Power in f/stop vs light meter reading
Hi,

I have the Einstein 640 and uses the Cyber Commander with it.

When I set the light to say, f/11, I was expecting the light meter to read f/11 as well when I trigger the flash, but that's not the case. Can anyone kindly advise?

Many thanks!
Author:  Technical Support [ Tue Jun 14, 2011 11:19 am ]
Post subject:  Re: Einstein: Power in f/stop vs light meter reading
The Cyber Commander has alot of color coding. Yellow is in regards to the light metering.

The yellow numbers and blue bars do not correlate (there is the odd chance where they happen to, but that is purely coincidental). The blue bars correlate to the EU numbers on the right hand edge of the graph.

When in a single channel, and you take a meter reading, a yellow dash will appear in that channel's collumn. This dash correlates to the yellow f/ numbers on the left. The actual reading will appear in yellow at the top center. The dashes let you keep track of the readings from one light to another.

If you are using one light, meter, locate the yellow bar and move the power up or down until the yellow bar is at f/11. When you shoot, the exposure should be spot on.

Using multiple lights is a little trickier, and i will be glad to go over that if you wish.
Author:  iamjv22 [ Tue Jun 14, 2011 12:13 pm ]
Post subject:  Re: Einstein: Power in f/stop vs light meter reading
Thanks for your fast reply!

So just for clarification on what you said re 1 light, which seems similar to what I have been doing: 1) set the power to desired f/stop (say f/11 in this case), 2) meter the flash, 3) see the difference between the desired f/stop and flash, and power up or down. Is this what you mean?

Hmm ... my silly brain keeps feeling they should match up, i.e. when I dial power to f/11, the metering from the CC should read f/11. :-P
Author:  Technical Support [ Tue Jun 14, 2011 1:00 pm ]
Post subject:  Re: Einstein: Power in f/stop vs light meter reading
iamjv22 wrote:
So just for clarification on what you said re 1 light, which seems similar to what I have been doing: 1) set the power to desired f/stop (say f/11 in this case), 2) meter the flash, 3) see the difference between the desired f/stop and flash, and power up or down. Is this what you mean?


You have 1 and 2 reversed. You can meter at any flashpower. Then match the yellow marker up to the yellow values on the left.

The blue indicators show you relative power as well as flash power in EU scale (the white numbers on the right).

Let's say you have your E640 at 320Ws. This is -1f relative flash power (one gray line in the graph) from full, as well it is EU 5.7. If you set this bare bulb at 10' from the subject, you will get an aperture of XX. Put a reflector on it, you will get a higher aperture, place a softbox on it, a lower aperture. Back it off to 20', a lower aperture again. move it in to 5', a higher aperture. Nothing has changed to the power, but the metering will change.

The main thing to remember, is the meter must be used at the subjects position. This will measure the light falling on the subject, not reflected off of. This is in contrast to speedlites, where the camera reads the reflected light coming through the lens and adjusts power to suit the desired aperture. Because light tones and dark tones can throw off reflected meter readings, incident readings are more reliable. Also, with more stored energy and other design characteristics, studio lights cannot adjust as quickly as a speedlite.

So back to the original issue, meter, then set flash power.
Author:  iamjv22 [ Tue Jun 14, 2011 6:45 pm ]
Post subject:  Re: Einstein: Power in f/stop vs light meter reading
Thank you - this helps!
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