Strobe (multiflash in one exposure) question

[wavefront]

Hi All,

I've been using the strobe flash function on my 580exII with good success (see below) and am now organizing another strobe shoot where this time my exposure will have to be longer, say 0.5 - 1 second, and I think about 8-10 flashes will be required in that time. That would require a setting of 10-20 hz on the flash, and according to the manual, that means my power will be limited to 1-16 or 1/32th.

However, I will need more power than that as I'll be shooting through a brolly, and at more of a distance from the subject this time. I guess the only way to get more power is to add more flashes, or do you think an external battery pack for the 580exII would help the amount of power, or is the algorithm printed in the manual programmed in to the flash and unchangeable?

If then I add more flashes to get more power , I think I would have to use wireless IR to get them to talk together (I have access to a number of 580's and 430's).

Is this the best way as IR is often less reliable outdoors, or is there a better way using Ettl cable to ensure they all talk? I have a 3m Ettl cable, and wondered if it could be modifed, or what else I'd need?

Any thoughts, or anyone else extensivley played with the strobe function like this?

Ta,

Mark.

 

[HoppyUK]

If you're short on power, the only thing you can do is raise the ISO and lower the f/number. But that's probably the best way anyway - one stop of ISO is the same effective exposure as two flash guns, two stops is like four guns.

A battery pack does not increase power, only speeds up recycling and lasts longer. If you have two flashes together, they won't strobe in sync.

 

[wavefront]

Thanks Hoppy for clarifying the battery thing That helps.

I felt I would need more power, rather than upping the ISO, as I need to consider my ambient light? If I up the ISO, I can only compensate for my ambient levels by increasing my shutter speed right? However, the cycle of action I want to capture will be limited to 1/2 - 1 second, so that is causing problems!! I'm shooting late in the day to keep the ambient low too as the subject will stand out a bit more.

(please correct me if I've slipped up on the basics again!)

So back to adding more flashes? Would they be out of sync as it takes time for the IR beam to comminicate with each flash? How much out of sync would they be - do you think it would be *that* noticeable? I'm assuming if they were out of sync, it would be tiny amounts and the subject wouldn't have moved far in that time, hence on the image they would appear to be in almost the same position ?

What do you think?

Ta,

Mark.

 

[HoppyUK]

Sorry Mark, I didn't really register the E-TTL bit properly and what it means. Didn't think it through. Aplogies.

If you use E-TTL, you can indeed use more than one flash to increase your power, and the E-TTL also keeps them firing in sync I just tried it

And you're right about the ambient thing - if you're fighting ambient light levels then the only answer is power, as obviously anything else like ISO/aperture also affects the ambient by the same amount so the flash/ambient ratio stays the same.

However, with a very long shutter speed as you suggest, almost any ambient light will be a problem. You really need to get that as low as possible, as close to total darkness as you can get.

 

[wavefront]

Thanks

At 8ish last night in a similar type of location I got 1 second at f10 at 100 iso. I was worried I'd be stopping down to f22 or going to ISO 50 or something ridiculous, but quite pleased I have some room for manouvere now so it looks like I should be able to kill the ambient by a couple of stops if I shoot on a similar night

Now it's time to see if I can get the flashes to talk to each other using the IR - need to sit down and draw a little diagram to makes sure all the flashes will be in the line of sight (ish).

Back to the ettl cables - if I connected the first flash to the camera via a long ettl cable - I'm guessing there's no way to then connect another (second) flash to the first / or camera using another cable - I've never seen one allowing you to add extra flashes?

Ideas incase the IR doesn't do it? Did I hear that the new pocket wizards have ettl capability?

Thanks,

Mark.

 

[HoppyUK]

Thanks

At 8ish last night in a similar type of location I got 1 second at f10 at 100 iso. I was worried I'd be stopping down to f22 or going to ISO 50 or something ridiculous, but quite pleased I have some room for manouvere now so it looks like I should be able to kill the ambient by a couple of stops if I shoot on a similar night

Now it's time to see if I can get the flashes to talk to each other using the IR - need to sit down and draw a little diagram to makes sure all the flashes will be in the line of sight (ish).

Back to the ettl cables - if I connected the first flash to the camera via a long ettl cable - I'm guessing there's no way to then connect another (second) flash to the first / or camera using another cable - I've never seen one allowing you to add extra flashes?

Ideas incase the IR doesn't do it? Did I hear that the new pocket wizards have ettl capability?

Thanks,

Mark.

Connect your 580EX to the E-TTL cord and that will act as both a master and also a flash gun. It will control all the other guns

With the ambient light so low you shouldn't have too much trouble getting the optical triggering to work. The trick is to get the master as close to the other flashes as possible, using a long cord. FlashInThePan on here sells a 10m cord for about £40 I think (see advertisers' section).

Pocket Wizards will do radio E-TTL, but they're £200 a pop and you need one for each unit, plus camera.

 

[wavefront]

Hi,

If anyone has a spare moment (and equipment) can you see if you can get a 580exII flash to fire via your pc-sync port on your Canon camera please?

The reason is, I was talking to a friend last night who said he'd got his camera to fire an external 580exII on strobe mode, but via the pc-sync port rather than ettl. He had done it using a 1Dmk3, and certainly has the image to show for it. If my photoshoot can be done via pc-sync, rather than ettl, that would be so much better.

However, my camera won't do it for some reason!! I tried it on my 5Dmkii and old 300D, using both a pc-sync port and hotshoe adaptor. I set my shutter speed to 1s, and the flash to 1/128th power, 10 flashes, at 10hz as it allows you to see 10 distinct flashes for the test, but just can't get it to fire a strobe. Surely it can't be something special to a 1Dmk3?

Let me know if you can get the strobe to fire!!

Ta,

M.

 

[Kaouthia]

If you're short on power, the only thing you can do is raise the ISO and lower the f/number. But that's probably the best way anyway - one stop of ISO is the same effective exposure as two flash guns, two stops is like four guns.

Yes, but that can cause way way way over exposure of the ambient if the flash is only lighting your subject.

I don't know about the Canon flashes, but battery packs on the Nikon SB-900 don't help increase the number of flashes at a given hz rate in repeat flash/stroboscopic mode, so I'd be surprised if it made a difference on the Canon ones.

One thing I've done in the past is to have an SB-900 in repeat flash mode and then setup other SB-900s and YN460-II flashes as optical slaves to bump up the power, but keep them all in sync. The slaved SB-900s were able to act as reliable optical slaves at much higher frequencies (they didn't really start to misfire til around 50hz) than the YN460-II flashes (a few misfires beyond about 15hz), so I would think the Canon flashes would be able to keep up a bit better too.

 

[HoppyUK]

Hi,

If anyone has a spare moment (and equipment) can you see if you can get a 580exII flash to fire via your pc-sync port on your Canon camera please?

The reason is, I was talking to a friend last night who said he'd got his camera to fire an external 580exII on strobe mode, but via the pc-sync port rather than ettl. He had done it using a 1Dmk3, and certainly has the image to show for it. If my photoshoot can be done via pc-sync, rather than ettl, that would be so much better.

However, my camera won't do it for some reason!! I tried it on my 5Dmkii and old 300D, using both a pc-sync port and hotshoe adaptor. I set my shutter speed to 1s, and the flash to 1/128th power, 10 flashes, at 10hz as it allows you to see 10 distinct flashes for the test, but just can't get it to fire a strobe. Surely it can't be something special to a 1Dmk3?

Let me know if you can get the strobe to fire!!

Ta,

M.

It works for me! If the gun is set to strobe and it receives a firing signal, it will strobe away. I just fired two remote 580EX guns in strobe mode via Yongnuo RF-602 triggers from the hot shoe - same as off the PC socket. You need to be in manual, E-TTL off.

The advantage of E-TTL is that it will also trigger a remote gun but if you get a radio trigger that will do it. RF-602 are very good triggers and only £30 a set (from FITP on here) plus no range problems of course that you might get with optical triggering.

 

[Kaouthia]

That's something I didn't think of. I wonder if I can get it to work with radio triggers using an SB-900 in repeat flash mode with the SB-900's sync port going to an RF-602 transmitter, and flashes on the other receivers. Will have to test.

 

[HoppyUK]

Yes, but that can cause way way way over exposure of the ambient if the flash is only lighting your subject.

I don't know about the Canon flashes, but battery packs on the Nikon SB-900 don't help increase the number of flashes at a given hz rate in repeat flash/stroboscopic mode, so I'd be surprised if it made a difference on the Canon ones.

One thing I've done in the past is to have an SB-900 in repeat flash mode and then setup other SB-900s and YN460-II flashes as optical slaves to bump up the power, but keep them all in sync. The slaved SB-900s were able to act as reliable optical slaves at much higher frequencies (they didn't really start to misfire til around 50hz) than the YN460-II flashes (a few misfires beyond about 15hz), so I would think the Canon flashes would be able to keep up a bit better too.

When the OP says he wants more power, I think he means brighter light not more flashes.

That's a cunning method you've got going there John

 

[Kaouthia]

When the OP says he wants more power, I think he means brighter light not more flashes.

Yes, but tricky to get more light from the flashes without also bumping up the ambient at the same time unless you add more flashes.

That's a cunning method you've got going there John

I was trying to find a way to do some stroboscopic stuff without having to buy a couple of dozen SB-900s.

What I was looking at doing was having some people moving rather quickly over a relatively large scene, with the camera static, so would've been tricky with just my three SB-900s, hehe.

I haven't actually managed to do the shoot I'd planned that for (it's arranged, but the date just hasn't come up yet), but once the date arrives, I'm relatively confident I'll be able to do it with a few hundred quid's worth of YN-560s rather than a few thousand quid's worth of SB-900s.

Must test it out with the RF-602s though. If it's even possible going out from the SB-900 sync port to an RF-602 trigger, I'm curious at what frequency it'll start to fail and misfire.

 

[wavefront]

Hi,

Thanks for the help guys, and Hoppy big thank you for testing that out for me

This is doing my head in!!!

I thought after testing everything and every which way of doing things, my flash is a bit broken. However, I just had a thought, and connected my radio receiver to the flash as it also have a pc-sync port, hard wired it to my camera and bravo - my first pc-sync flash!!! Bizarre, as I then move the cable to the proper built in socket on the 580exii and it only flashes once. Repeat connecting the radio reciever pc-sync port and it works again in strobe.

Can anyone help explain this odd behaviour?

What is now strange is the using the same radio receiver on my flash, I then trigger it via my radio transmitter expecting it to work, and the strobe doesn't work again - only one flash?

What is going on?!!!

Do you think my 580exii is somewhat broken?

thanks,

M.

 

[HoppyUK]

Hi,

Thanks for the help guys, and Hoppy big thank you for testing that out for me

This is doing my head in!!!

I thought after testing everything and every which way of doing things, my flash is a bit broken. However, I just had a thought, and connected my radio receiver to the flash as it also have a pc-sync port, hard wired it to my camera and bravo - my first pc-sync flash!!! Bizarre, as I then move the cable to the proper built in socket on the 580exii and it only flashes once. Repeat connecting the radio reciever pc-sync port and it works again in strobe.

Can anyone help explain this odd behaviour?

What is now strange is the using the same radio receiver on my flash, I then trigger it via my radio transmitter expecting it to work, and the strobe doesn't work again - only one flash?

What is going on?!!!

Do you think my 580exii is somewhat broken?

thanks,

M.

Maybe this, which I picked up from www.michaelbass.blogspot.com "The new 580 EX II has a PC sync jack, although it is disabled when the flash is in the hot shoe, so it cannot be used to fire a radio transmitter when still in the camera hot shoe! The sync jack is also disabled when the flash is in Manual-Master mode..."

You mess with these auto-TTL flash systems at your peril! Which does rather beg the question, what's wrong with doing it using E-TTL?

 

[wavefront]

Hi

I was all set to do it in ettl, and that isn't a problem now - I know that works and it's and option.

I just got sidetracked because a friend mentioned using pc-sync that he got to work, and it seemed easier to try and set up as I have quite a few long pc-sync cables and my subject will be quite a distance away from the camera.

I guess I've gone 'off topic' a touch from the aim of my original shoot, to now trying to work out why my flash isn't behaving the same as other people using the same type flash! I do genuinely believe my flash has some sort of fault the the pcsync port after all this testing.

Thanks for that link - I remember reading that during one of my google searches when scratching my head.....strangely I'm having problems when it's off camera, and not in master mode - the pcsync port works to fire 'one' flash, but no more.

Anyway, I think after last night I have a solution, just no better off to understanding why this is happening!

Thanks for your help,

Mark.