Today I took my 580EX and a light meter to see if I could understand how the 580EX actually works. I did this in the shade late in the evening and off camera so I could see how the compensation worked using ETTL comparing the background while using EC on the flash .
My dedicated meter may be damaged, but if not, I came to these conclusions, which I do not know if they are correct:
--ETTL: The FC on the flash from -3 to +3 is only one full stop.
--Manual: The flash works like any low powered strobe, but weaker and less control, from 1/64th to full power.
Also:
If my meter is not damaged, it was giving me some very erroneous results. For instance, it was calling for up to two stop increased exposure, which then blew the image totally. This was when I was using it as a incident meter, not as a reflected meter. When used as a reflected meter, the readings were the same, or nearly the same.
Is it possible that the external meter can't for some reason read the 580's flash correctly when in incident mode?
Can anyone with a dedicated meter test this using the 580EX in either manual or ETTL with FC?
Full Version: 580EX Flash question
QUOTE (dwdallam @ Apr 29 2008, 08:06 PM)
Today I took my 580EX and a light meter to see if I could understand how the 580EX actually works. I did this in the shade late in the evening and off camera so I could see how the compensation worked using ETTL comparing the background while using EC on the flash .
My dedicated meter may be damaged, but if not, I came to these conclusions, which I do not know if they are correct:
--ETTL: The FC on the flash from -3 to +3 is only one full stop.
--Manual: The flash works like any low powered strobe, but weaker and less control, from 1/64th to full power.
Also:
If my meter is not damaged, it was giving me some very erroneous results. For instance, it was calling for up to two stop increased exposure, which then blew the image totally. This was when I was using it as a incident meter, not as a reflected meter. When used as a reflected meter, the readings were the same, or nearly the same.
Is it possible that the external meter can't for some reason read the 580's flash correctly when in incident mode?
Can anyone with a dedicated meter test this using the 580EX in either manual or ETTL with FC?
My dedicated meter may be damaged, but if not, I came to these conclusions, which I do not know if they are correct:
--ETTL: The FC on the flash from -3 to +3 is only one full stop.
--Manual: The flash works like any low powered strobe, but weaker and less control, from 1/64th to full power.
Also:
If my meter is not damaged, it was giving me some very erroneous results. For instance, it was calling for up to two stop increased exposure, which then blew the image totally. This was when I was using it as a incident meter, not as a reflected meter. When used as a reflected meter, the readings were the same, or nearly the same.
Is it possible that the external meter can't for some reason read the 580's flash correctly when in incident mode?
Can anyone with a dedicated meter test this using the 580EX in either manual or ETTL with FC?
What light meter are you using ?
Your tests are something I've been meaning to try. I have a Sekonic Flasmate and a Sekonic 758DR, so will test on my 580ex with both, maybe on the weekend.
Mark
I use a 580ex and 430ex with pocket wizards as a small lighting kit (strobist style) and generally set them to manual and work from there. Sometimes I do meter them to get a starting point and find that in manual they meter just fine.
You say you tried this outside to meter your speedlites. Working with exsiting ambient light really changes how you set your flashes. You either need to use the meter so that the shutter speed is so far beyond ambient so no ambient affects the reading or test indoors.
Outside manual lighting is never full strength as a meter would tell you unless you want to overpower the ambient light. I generally work by setting lighting for outside a stop less or more depending on how much I do or don't want dominant flash to fill flash.
You say you tried this outside to meter your speedlites. Working with exsiting ambient light really changes how you set your flashes. You either need to use the meter so that the shutter speed is so far beyond ambient so no ambient affects the reading or test indoors.
Outside manual lighting is never full strength as a meter would tell you unless you want to overpower the ambient light. I generally work by setting lighting for outside a stop less or more depending on how much I do or don't want dominant flash to fill flash.
QUOTE (John Schweikert @ Apr 30 2008, 02:20 AM)
I use a 580ex and 430ex with pocket wizards as a small lighting kit (strobist style) and generally set them to manual and work from there. Sometimes I do meter them to get a starting point and find that in manual they meter just fine.
You say you tried this outside to meter your speedlites. Working with exsiting ambient light really changes how you set your flashes. You either need to use the meter so that the shutter speed is so far beyond ambient so no ambient affects the reading or test indoors.
Outside manual lighting is never full strength as a meter would tell you unless you want to overpower the ambient light. I generally work by setting lighting for outside a stop less or more depending on how much I do or don't want dominant flash to fill flash.
You say you tried this outside to meter your speedlites. Working with exsiting ambient light really changes how you set your flashes. You either need to use the meter so that the shutter speed is so far beyond ambient so no ambient affects the reading or test indoors.
Outside manual lighting is never full strength as a meter would tell you unless you want to overpower the ambient light. I generally work by setting lighting for outside a stop less or more depending on how much I do or don't want dominant flash to fill flash.
That sounds on the right track them. My shutter speed was not quite fast enough to take out all the ambient light, but within one stop I think. However, why would ambient light affect the meter reading when the meter is set to flash?
My light meter is a Sekonics L308 series.
Your meter is likely reading the pre-flash from the 580EX which it uses to calculate exposure. The pre-flash happens just a moment before the actual full power flash, almost invisible to the eye, but the meter will read the pre-flash and miss the full power flash that actually makes the exposure.
An external light meter will only work with the 580EX if you are in manual mode.
An external light meter will only work with the 580EX if you are in manual mode.
Sheldon has a great point. On the auto/ettl setting there will be apre flash. On manual no pre flash, it acts like a small studio flash.
When doing meter readings outside, even with the meter set to flash it will pick up ambient light to include in the overall reading unless you set the shutter speed higher than an ambient reading to reduce or eliminate that as a factor to getting a good flash reading. That's just how the meters work and how you do mixed light meter reading.
When doing meter readings outside, even with the meter set to flash it will pick up ambient light to include in the overall reading unless you set the shutter speed higher than an ambient reading to reduce or eliminate that as a factor to getting a good flash reading. That's just how the meters work and how you do mixed light meter reading.
QUOTE (Sheldon N @ Apr 30 2008, 12:32 PM)
Your meter is likely reading the pre-flash from the 580EX which it uses to calculate exposure. The pre-flash happens just a moment before the actual full power flash, almost invisible to the eye, but the meter will read the pre-flash and miss the full power flash that actually makes the exposure.
An external light meter will only work with the 580EX if you are in manual mode.
An external light meter will only work with the 580EX if you are in manual mode.
QUOTE (Sheldon N @ Apr 30 2008, 01:32 PM)
Your meter is likely reading the pre-flash from the 580EX which it uses to calculate exposure. The pre-flash happens just a moment before the actual full power flash, almost invisible to the eye, but the meter will read the pre-flash and miss the full power flash that actually makes the exposure.
An external light meter will only work with the 580EX if you are in manual mode.
An external light meter will only work with the 580EX if you are in manual mode.
yeap! I been there!
QUOTE (jorgedelfino @ May 1 2008, 02:09 AM)
yeap! I been there!
I'll try, again, using full manual mode and see what I get.
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