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| Lowest flash power & Continous Light http://paulcbuff-techforum.com/viewtopic.php?f=8&t=4879 |
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| Author: | Keano12 [ Wed Nov 25, 2015 11:16 am ] |
| Post subject: | Lowest flash power & Continous Light |
I know a well known portrait photographer who shoots all natural light or if light isn't available he uses a continuous light. He said he feels like he's cheating because it's so simple and his strobes just sit there. I have a 500w strobe already I use a lot. But for shooting in a very large aperture for dof indoor recreating that window light look would I be better getting a continuous light? I could even turn up the shutter speed or does the AB/Einstein in its lowest power still greater then what a continuous light could get turned down? I used a ND but it does affect color and harder to focus. |
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| Author: | Technical Support [ Mon Nov 30, 2015 12:13 pm ] |
| Post subject: | Re: Lowest flash power & Continous Light |
Comparing flash to continuous is a little tricky. Partly because one is instant and one is a function of time. Additionally, you potentially have color temperature differences to contend with. So, an E640 has a range of 640Ws to 2.5Ws. Output is not rated in Watt-seconds, but lets run with that idea for now, as that is how many people understand it. The same amount of light is produced if you shoot at 1/250s or 1/8s. Now, the model lamp is a 250W bulb (max). If you take a 1 second exposure, you are capturing 250Ws of light. One second is a little long, so lets do 1/100s. You are now capturing 2.5Ws of light (250W divided by 1/100s= 2.5Ws). So, assuming the same efficiency, a 250W model lamp at full and a 1/100s shutter speed produces the same amount of light as and E640 at minimum power. However, remember how we said brightness is not measured in Watt-seconds (or Watts)? That is because a Watt is a unit of energy consumed, not a unit of brightness. Different kinds of lights have different effeciencies. That is how you get a CFL bulb that is equivalent to a 60W incandescent, but only uses 10W of power. With the same total amount of energy used, Xenon flash is about 40% more efficient than a halogen bulb. So, what you get at 2.5Ws of flash would require 3.5Ws of incandescent light (IOW, use about 1/60s to 1/80s shutter speed instead of 1/100 in the example above). With that said, many users use the modeling lamps in our lights to match the desired aperture values, and/or to match the ambient light levels that flash could easily overpower. Also, ambient light levels indoors are typically similar in color to the model lamp (~28,000K or less) rather than the flash output (5200-5600K). |
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| Author: | jbr51 [ Mon Dec 14, 2015 11:22 pm ] |
| Post subject: | Re: Lowest flash power & Continous Light |
(~28,000K or less) That is some seriously cool/blue light. Or perhaps just a typo. |
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| Author: | Technical Support [ Tue Dec 15, 2015 9:55 am ] |
| Post subject: | Re: Lowest flash power & Continous Light |
Technically, I am correct, as I did say "or less". ;) But, yes, I did mean 2,800K. |
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| Author: | Keano12 [ Wed Dec 23, 2015 4:04 am ] |
| Post subject: | Re: Lowest flash power & Continous Light |
Thanks for that info. If using the modeling light and the mini battery what is the max usable modeling light power instead of the 250w? Thanks |
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| Author: | Technical Support [ Wed Dec 23, 2015 3:44 pm ] |
| Post subject: | Re: Lowest flash power & Continous Light |
Less than 120W, as there will be some ancillary draw from the flash unit. The less you use, the better. |
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| Author: | Keano12 [ Thu Jan 07, 2016 3:48 pm ] |
| Post subject: | Re: Lowest flash power & Continous Light |
If I use the modeling light set high and take a shot will that affect the shot? Or does it turn off? I'm asking in the case of using a ND filter and need to turn it up but don't want it to affect exposure? Also regarding my original question if I wanted to use the modeling light with the vagabond mini instead of replacing the bulb with a 25w as suggested could I use 150w but keep it at a low setting and have the same battery life? Just curious thx |
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| Author: | Technical Support [ Fri Jan 08, 2016 1:24 pm ] |
| Post subject: | Re: Lowest flash power & Continous Light |
If you have the model lamp set to a very high power and the flash set to a very low power, then, yes, the model lamp can contribute to the exposure. You can set the model lamp to stay on, or switch off during recycle. However, with the nature of incandescent light bulbs, the extinguish times are not necessarily consistent and may affect the output and color from shot to shot. If you plan to use this configuration, we recommend dialing the model lamp down from full power or leaving the model lamp set to not be used as a recycle indicator. The latter will make it consistent, and you can white balance for it. With that said, using a ND filter will drop the model lamp as well as the flash output, so it may not be any more of an issue than without the filters. But, if for some reason the relative intensity between the two change by adding the ND filter, I would still suggest leaving the model lamp set to not be a recycle indicator. |
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| Author: | Keano12 [ Fri Jan 08, 2016 9:15 pm ] |
| Post subject: | Re: Lowest flash power & Continous Light |
Quote: If you have the model lamp set to a very high power and the flash set to a very low power, then, yes, the model lamp can contribute to the exposure. Ah ok what I meant was as the shot is taken is the modeling lamp still on which sounds like it is. Sounds like having it on Tracking is the best option. Since it stays on I don't care about it being used as a recycle indicator. For the ND I could crank up the modeling light to get focus then turn it off for the shotI guess I meant. Thanks |
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