How can one understand the power output of Mono lights in practical terms? Does one 250W/s monolight power out put equals that of 1 250W GE bulb?
I am asking because currently I use a 500W GE bulb attached to a 12" reflector for my studio Portraits and wonder if using a 1000W/s mono light will give double the power; hence double the shutter speed.
Placing my light 2-3 foot away from the subject gives about 1/60, F5.6 @ ISO 400, give or take +/- .3. So if I use a 1000W/s mono light will I be able to use ISO 200 at the same setting, or perhaps those lights are super efficient and can just blow away a 1000W bulb for example?
Canon Flash
As for the Canon 580EX flash or 430EX I can't find their power output anywhere? are they evaluated differently to mono lights for example?
AC Units
What are AC strobe units? I see them listed in BH under their own category, but can't figures how they differ from monos?
They are different measurements, so you can't make a direct comparison of W vs W/S any more than you can between miles and miles-per-hour. This site will explain the differences: LINK Studio flashes are not typically rated by f/stop or guide number because the choice of modifier which alters the area the light covers will change he output. But if you look at this page on the same site LINK and click the "Product Specs" button at the bottom you'll find charts which show power in terms of w/s and f/stops with various modifiers for that brand which sold directly and is very popular with beginners. Even the AB400 (160 W/S) model there would be more than adequate for your needs in comparison to your hot lights, but the AB800 model (320W/S) is the more popular choice. I have a set of four AB800s and from a distance of 3ft with a medium softbox attached a single AB800 light measures f/22 at ISO at full power and f/4 at minimum power. FYI - when flash is used shutter speed does not affect exposure.
Hot shoe flashes are rated by guide number (GN) . A Canon 580ex has GN 190 feet / 58 meters. The GN is determined by measuring output a distance of 10ft with a meter set to ISO 100, then multiplying the f/stop by 10. Thus a 580ex with GN = 190 (when zoomed to 105mm setting) will produce f/19 at 10ft.
"Mono" is simply term for the type of studio flash in which each flash tube has its own power pack up on the light stand, vs the older original designs where one floor mounted power "Pack" is used to power 1-4 flash heads on the stands via high voltage cables.
In practical terms if one uses hot lights the concerns are long exposures, noise in the blue channel, roasting the subjects, and catching the house on fire. In practical terms if one uses just about any type of flash the only concern is having too much power in some situations.
cgardner wrote:
......... But if you look at this page on the same site LINK and click the "Product Specs" button at the bottom you'll find charts which show power in terms of w/s and f/stops with various modifiers for that brand which sold directly and is very popular with beginners......
......... FYI - when flash is used shutter speed does not affect exposure.
A very big thanks for your help! The links were great. Two questions though:
1. I noticed in the second link that the mono lights output was listed in "real" and "effective" the former being higher. Since I can't find this with other mono light brands what is the difference between those two ratings?
2. Is shutter speed set to a constant like 1/200 for example?
1. I noticed in the second link that the mono lights output was listed in "real" and "effective" the former being higher. Since I can't find this with other mono light brands what is the difference between those two ratings?
Ignore the "effective" rating. If you see a rating listed as "real" or "true" or no qualifier at all, use that to compare with others.
Watt seconds refers to the energy capacity of the capacitors used in the flash--the total amount of energy it stores for a maximum-power flash. Some flash systems are slightly more efficient than others so you can't draw an exact comparison, but that's the only universal rating for comparison we have to use (a joule is equal to a watt second, btw).
Generally, you can consider flash units within 50 watt seconds of each other to be equal.
2. Is shutter speed set to a constant like 1/200 for example?
Yes. Sometimes a camera requires a slightly slower sync speed (maybe 1/2 stop slower) than its rated maximum with studio electronic flash, especially with accessory wireless triggers. But the shutter speed is kept constant in use--you vary exposure by varying the aperture, the flash power setting, or the distance of the flash from the subject.
