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Normal for 550EX Master?

bens

By bens
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bens

bens

Posted
Posted

Purchased a refurbished 550EX to use as a master with the 420EX.

I'm a neophyte at two flashes, don't have three. Tested the 550EX

with the 420 tonight, found the manual confusing. As far as I can

tell, to vary output between the 550 and 420, I use ratio in ETTL

mode with master automatically as A and 420 set as B, yes? Is there

any other way?

 

Also, when I try to set ratios in manual mode in order to vary the

output between the two, the 550 simply will not set; it just goes

around its setting circuit without ever setting. Is this normal

when only one slave is in use? Or is it a problem for the day I can

afford another slave?

 

Thanks for your help.

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vesa_perala

vesa_perala

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Yes, the only way to set ratios is automatic E-TTL is to set the flashes in different groups. But remember you are not directly adjusting the output of the flashes with ratios, you are adjusting the illumination on the subject, as defined by the metering pattern (AF point neigbourhood with the highest priority).

 

I think 420 can't work in manual mode, not even as a slave, but am not 100% sure. I use two 550EXs and a Sigma EF 500 Super. In manual mode you are not setting actual ratios, you set the output of each flash group.

 

To set the output first set the master flash (make sure the master switch is in "Master" position) in manual (M) mode with the mode button. Then press the sel/set-button until you see a "Ratio" text. By default it is "Ratio Off". When Ratio Off is flashing push the + or - button (can't remember which) to set Ratio On for A:B or A:B:C. After that when you press the sel/set you should be able to set the output level for each flash group (1/1, 1/2, 1/4, 1/8, 1/16, ... 1/128).

 

The rotating order of each setting is a bit messy in my opinion but when you press the sel/set enough many times you should see the Ratio selection.

 

This is from my memory, don't have the flash right here now.

 

regards Vesa

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digitmstr

digitmstr

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If you had two 550EXs you could adjust the ratio even if the flashes were on the same group (A or B) by using the FEC control built into the flash heads. Unfortunately, the 420EX doesn't allow for this. Therefore, the ONLY way to do it is by using the A:B ratio adjustment on the 550EX.
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jim_larson1

jim_larson1

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Pretty much spot on.

 

If the MASTER unit is in "M", then all slaves must be in "M". Since the 420EX does not have "M"anual mode, it won't fire at all. If the MASTER unit was in "ETTL", then you can have a slave in "M".

 

And yes. . .you are not setting power output with the ratio. You are setting EXPOSURE ratio. You can have 1 flash in group "A" and 20 flashes in group "B". If you did. . then you will expect the 20 flashes to group "B" to fire at fairly low power in order to not over expose the subject.

 

You can vary the output of an INDIVIDUAL SLAVE use the slaves unit FEC. If you set at +1, then *that slave* will fire at one stop higher than commanded by the master unit. Note that the 420EX does not have FEC controls. . .so you cannot do this with the 420EX.

 

Note that you cannot add FEC to a MASTER UNIT. If you dial in FEC on the master unit, it will change the FEC on the body and therefore change the exposure for ALL flash groups.

 

All this aside. . .the 550EX and 420EX are powerful when used in combination. Honestly. . . the A/B ratio controls combined with FEC on the body provide all the flexibility you need for great results.

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vesa_perala

vesa_perala

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Jim wrote:

 

"If the MASTER unit is in "M", then all slaves must be in "M". Since the 420EX does not have "M"anual mode, it won't fire at all. If the MASTER unit was in "ETTL", then you can have a slave in "M"."

 

I'm not sure if I understood you 100% (my fault) but with 550EX flashes (or 580EX I believe) you don't need to set the slaves in "M" mode by yourself, they will be set to "M" by the master flash when you set the Master in "M" and take the first photo.

 

Just to clarify.

 

Vesa

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jim_larson1

jim_larson1

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<i>I'm not sure if I understood you 100% (my fault) but with 550EX flashes (or 580EX I believe) you don't need to set the slaves in "M" mode by yourself, they will be set to "M" by the master flash when you set the Master in "M" and take the first photo.

<p>

Just to clarify</i><p>Just to clarify: If they fire. . .at what strength? Full strength? And I don't think a 420EX (which lacks "M") would fire at all.<p> I admit being too lazy to test this on my rig right now.

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bens

bens

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This discussion reminds me of the time twenty eight years ago when I lived in shared housing with a physics graduate student. After trying to explain one of his incomprehensible equations to me, I told him, "Its all Greek to me." "Oh no," he replied pointing, "That is a Roman numeral."
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vesa_perala

vesa_perala

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"...with 550EX flashes (or 580EX I believe) you don't need to set the slaves in "M" mode by yourself, they will be set to "M" by the master flash when you set the Master in "M" and take the first photo."

 

Just to clarify: If they fire. . .at what strength? Full strength? And I don't think a 420EX (which lacks "M") would fire at all.

 

----

 

To clarify: Yes, also I think the 420EX will not fire.

 

The master flash device generates a preflash few (tens) milliseconds before the main flash. The preflash contains information about e.g. the output power level for the slave groups. When the slave receives the preflash information it sets it's output according to that and fires the main flash simultaneously with the master flash device.

 

Clear as mud?

 

Vesa

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jim_simon3

jim_simon3

Posted
Posted
I can't find the article, but Julian Loke wrote a very simple how to do it for wireless EOS flash. I thought it was at the EOSDOC project but I can't find it there. It helps make sense of the whole process. Maybe it is at his own website if he still has one. Julian writes many very well thought out articles.
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