Flash Recycle Time Between "M" and "ETTL"

When I shoot using my 580EX in ETTL mode, I noticed that the flash recycles almost instantly for the next shot. When shooting in the "M" mode, though, the recycle time is much longer, especially in 1/1, and improves in speed with the ratio of 1/2, 1/4, 1/8, etc.

Correct me if I'm wrong, but my guess is that ETTL has a faster recycle time because it's light output isn't as much as in M mode as it emits just enough to cover the distance from the flash to the subject?

Also, if you need to shoot fast, then having the flash set to M mode is out of the question because of its slower recycle time?

E-TTL can use a lot of power, or very little.
Manual flash can use a lot of power, or very little.

Recycle time depends on the amount of power used, regardless of how it's controlled.

Dial your flash down to 1/128 power in Manual mode, and you can shoot "machine gun style" 'till your CF card is full.

Curtis N wrote in post #5512755
E-TTL can use a lot of power, or very little.
Manual flash can use a lot of power, or very little.

Recycle time depends on the amount of power used, regardless of how it's controlled.

Dial your flash down to 1/128 power in Manual mode, and you can shoot "machine gun style" 'till your CF card is full.

That makes sense. Likewise, shooting at a very fast shutter speed also recycles the flash fast due to less light being used, right? It seems like the max shutter speed of 1/250 is enough to recycle the flash pretty fast for my need of shooting violin and piano recitals. I'm getting much better results shooting in M flash setting than E-TTL....

Shutter speed doesn't matter (as long as you're not in HSS mode). The flash is faster than your shutter.

Aperture and ISO do matter. f/4 and ISO 400 will require only 1/16 as much light as f/8 and ISO 100.

Curtis N wrote in post #5512967
Shutter speed doesn't matter (as long as you're not in HSS mode). The flash is faster than your shutter.

Aperture and ISO do matter. f/4 and ISO 400 will require only 1/16 as much light as f/8 and ISO 100.

Okay, thanks for clarifying this for me. I hadn't realized the role of ISO and the aperture on flash output even though that ought to be obvious!

Hmmmm.... I like learning something new.

Thanks!

Shooting on Sunday I used my 580 on camera and in ETTL mode. It took noticeably longer to recycle than when I use it off camera at full power. I always use fully charged batteries.

Wow. Just wow.

Given fresh batteries the flash charge time is proportional to the amount of light the flash put out. If you put the flash in M 1/1 it's going to take the max recharge time. If you put it in ETTL you're VERY unlikely to use a full charge, so it'll be a lot quicker to recharge.

Martin, you're saying that it's quicker to recharge when used off camera at full power than when used on the camera in ETTL? I don't believe that's possible, given fresh batteries each time. If they were the same set of batteries and you used it off camera at full power then by the time the flash was on the camera cycle time will be longer.

Well, all I can say is a shoot I did the weekend before, I used my 3 flash guns, The 580 on full most of the time as main light. There were 2 of us jointly taking pics using the same set of lights. Between us, we took over 300 pics at times with barely a second between shots. No missfires occured even just before the 1st set of batteries died.

Shooting this Sunday in ETTL, there were many missfires with shots a couple of seconds apart. The only thing I can think is that the preflash may be draining a little more power.

So your 580EX firing full power in manual recharged in one second?

Martin, before you FRY your flash, read your owner manual carefully about the number of consecutive flashes before you need to let your flash rest, to dissipate heat. Somebody on POTN fried a couple of flashes before wising up!

Dont's start fires with your flash!!!!

martinsmith wrote in post #5514315
Well, all I can say is a shoot I did the weekend before, I used my 3 flash guns, The 580 on full most of the time as main light. There were 2 of us jointly taking pics using the same set of lights. Between us, we took over 300 pics at times with barely a second between shots. No missfires occured even just before the 1st set of batteries died.

Shooting this Sunday in ETTL, there were many missfires with shots a couple of seconds apart. The only thing I can think is that the preflash may be draining a little more power.

There's no way you can take consecutive full power shot with a barely a second between shots unless you were using an external powerpack in addition to the internal batteries of the 580EX! I didn't see you mentioning that (unless I missed it). Were you?

I'm with everybody else on this - a one second recharge on full power manual just isn't going to happen without an external battery pack. Somebody must have slipped in and adjusted something while you weren't watching.

A slightly off topic, but for those of you who own one, what's the external battery pack that you'd recommend?