using 2 580 II and wireless TTL

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33L

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I tempted at making macro flash system.

I am tempted at getting another 580EXII mainly because i need to get a back up for my main unit.

The idea i have is to use one FITP "O" brackets mount 2 flashes (one on an ETTL cord). If i set one to master and to slave and hopefully decent information transmission between the two.

the thing i dont know is how the ETTL works wirelessly. Does flash A(on cord) fire trying to achieve correct exposure? In this sense will flash B just provide too much light as it will fire at same setting. Or isi it intelligent to know that there are 2 flashes and will fire both at a suitable power to create a well exposed image. i.e. half power each for example?
 
(excuse my ignorance)

so you set it to something like 1/2 and 1/2 as planning on having them equal distances, that should prived a good illumination if diffuesed correctly.

Such as the expensive macro rings flashes. i take it setting the ratio you can create some shadows as 1 unit will fire brighter than the other.
 
oh and another thing. the pre flash transmits the information to the other flash. I take it the receiving sensor is behind the red plastic where the focus assist comes from. Does that mean that if i have the flash heads just poking out from the sides of the lens it will not transmit? (think of the same layout of the expensive canon set, not the ring flash)
 
you control the ratio between groups so set one to A and one to B then make A:B ratio 1:1 and they will both put out the same power

I don't know about that one sorry :(
 
It works as you describe. At close distance, you don't need line of sight between the master and slave for reliable operation - should be fine. See handbook.

However, you will have a lot of power for shooting at macro distances with two 580EXII guns. They just can't turn down low enough. I just tried it - with two 580EX guns firing from 6in, I needed f/5.6 to get correct exposure with ISO200. Any higher ISO or lower f/number just over exposes. You'll probably need an ND filter to get that into a more usable range for general macro use.

I use a RingFlash Adapter SIRC for macro, and for ring-flash portraits too. You can adjust the modelling with card or foil stuck on with BluTack - sounds a bit crude but it's easy and works really well. RayFlash is similar :thumbs:

http://www.flaghead.co.uk/pages/ringflash-intro.html
 
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looking at shooting probably f/16 @ISO 100. Its going to be used for 1:1 work.

Curiously i thought about the ringflash. Does it not create shodows with a longer lens. Thinking of the 150mm Sigma macro possibly with extension tubes.

At the moment its probably just a thought. Probably going to get a bracket of FITP and use just one flash with a micro softbox on it.
 
33L said:
looking at shooting probably f/16 @ISO 100. Its going to be used for 1:1 work.

Curiously i thought about the ringflash. Does it not create shodows with a longer lens. Thinking of the 150mm Sigma macro possibly with extension tubes.

At the moment its probably just a thought. Probably going to get a bracket of FITP and use just one flash with a micro softbox on it.
Click to expand...

You'll be fine with that - no exposure problems there. Stick Stofens on them :thumbs: FITP does them for a fiver.

Yes, ringflash does create shadow at normal distances - a unique soft shadow all the way around the subject, if you stand them against a wall. Like a kind of dark halo - plus of course the effect of the light. Examples on the link - I love it for fashion-portraits :)
 
I just did a test with my mates 580 exII and you were right.... not a problem with line of sight at the distances i am thinking of. just to get my head round ratios etc...
 
HoppyUK said:
It works as you describe. At close distance, you don't need line of sight between the master and slave for reliable operation - should be fine. See handbook.

However, you will have a lot of power for shooting at macro distances with two 580EXII guns. They just can't turn down low enough. I just tried it - with two 580EX guns firing from 6in, I needed f/5.6 to get correct exposure with ISO200. Any higher ISO or lower f/number just over exposes. You'll probably need an ND filter to get that into a more usable range for general macro use.

I use a RingFlash Adapter SIRC for macro, and for ring-flash portraits too. You can adjust the modelling with card or foil stuck on with BluTack - sounds a bit crude but it's easy and works really well. RayFlash is similar :thumbs:

http://www.flaghead.co.uk/pages/ringflash-intro.html
Click to expand...

Have you considered using some ND flash gels to power down the flash some more when they are on the lowest power?
 
J4MIE_P said:
Have you considered using some ND flash gels to power down the flash some more when they are on the lowest power?
Click to expand...

Yes, that's an alternative to an ND over the lens. But an excess of power isn't really a problem with the RingFlash Adapter ;)

I guess using EX580 guns for macro is only a potential problem in manual, when you can't turn them down low enough. E-TTL can reduce the power a lot lower than 1/128th.

I should have mentioned that in my post above - those minimum exposure levels were achieved on E-TTL.
 
HoppyUK said:
Yes, that's an alternative to an ND over the lens. But an excess of power isn't really a problem with the RingFlash Adapter ;)

I guess using EX580 guns for macro is only a potential problem in manual, when you can't turn them down low enough. E-TTL can reduce the power a lot lower than 1/128th.

I should have mentioned that in my post above - those minimum exposure levels were achieved on E-TTL.
Click to expand...

The ND gels for your flash gun was aimed at using the flashes in manual, as even at 1/128th it's too powerful so you could put some ND gels over the flashgun to lower the light by more stops.
 
The ratios go between 8:1 -- 1:1 -- 1:8

does that mean for example 8:1 flash A output is 8 times that of flash B.

excuse the ignorance just didnt find the instructions that clear?
 
33L said:
The ratios go between 8:1 -- 1:1 -- 1:8

does that mean for example 8:1 flash A output is 8 times that of flash B.

excuse the ignorance just didnt find the instructions that clear?
Click to expand...

Yes, 8x is three stops.
 
thanks Richard, you have been most helpful.
 
I have revived this thread as got a question that needs answering.

Do light modifiers interupt pre-flash TTL trasnmission. i.e. a diffuser, ring flash.

Idea is have a diffused soruce on main flash and a something liek a hair light to the rear. I am looking at getting my 2nd 580EXII so just covering options.
 
cheers mate. its questions like these that are just not answered in the manual.
 
33L said:
I have revived this thread as got a question that needs answering.

Do light modifiers interupt pre-flash TTL trasnmission. i.e. a diffuser, ring flash.

Idea is have a diffused soruce on main flash and a something liek a hair light to the rear. I am looking at getting my 2nd 580EXII so just covering options.
Click to expand...

Basically no problem, I often do that. Doesn't affect the actual signal, but does spread the light and absorb some of it, so range is reduced. Fine indoors I've found.
 
thanks Hoppy,

I guess another flash coming my way then. :)
 
thanks for the confirmation David, much appreciated - ican safely order some new kit now!
 
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