Avoiding pre-flash with 5D

[Philip Freedman]

Can anyone tell me which modern Canon flash units are compatible with my 5D and

will allow me to switch OFF the pre-flash and if necessary use an older

exposure metering mode? I find that many people blink from a pre-flash at

exactly the moment when the shutter opens.

 

Any help appreciated

Thanks

Philip

[r.rajamani]

See this post where there is a custom function on the 550 to use it in manual mode to avoid preflash.

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=004uWR

Why not use a Canon flash to have the best of both worlds, have a pre-flash or disable it when you need to.

[thierry nguyen cuu - nomad]

<i>which modern Canon flash units are compatible with my 5D and will allow me to switch OFF the pre-flash</i>

<br><br>

 

The 580EX allows you to turn on (ETTL II) or off (M or Multi mode) the preflash

[picturesque]

Any auto thyristor based flash will have no pre-flash. However, most are not compatible (meaning being able to communicate with the camera) with the camera bodies. A Metz 54MZ has both ETTL capability as well as auto thyristor, and the new 580EX II will as well. Probably one of those is your best bet, although there are limitations with the auto thyristor part working in automated camera modes such as AV, TV or P, and if you go with auto thyristor/no communication flashes, you have to remember about the maximum flash sync speed (camera won't remember for you) and you will not have focus assist as well.

[steve_dunn2]

<p>If you switch off the pre-flash, you are guaranteeing that you will have to use an older metering method; the 5D, as with all remotely recent EOS DSLRs, supports only modern (E-TTL family) flash metering. Without body-based flash metering, you have three options:</p>

 

<ul>

<li>Use a flash which has an automatic flash metering sensor, as became common in the 1970s-80s. The only current Canon flash unit which meets this requirement is the 580EX II. The older potato-masher 480EG also has an automatic flash metering sensor.

<li>Go back farther in time and do the guide number calculations yourself. You'll need a flash which can be fired in manual mode, either at full power or at reduced power; I believe that would be (roughly from newest to oldest) 580EX II, 430EX, 580EX, 550EX, 540EZ, 430EZ, or 420EZ. I'm not entirely sure about the last couple; they were discontinued over a decade ago.

<li>Work like studio pros and use a flash meter.

</ul>

 

<p>Another possibility is to use FEL. The pre-flash is fired when flash metering is done, which is normally immediately before the exposure, when you fully depress the shutter release button. But if you use FEL, flash metering is done when you use the FEL button, so you can warn your subject that the first flash is not the real picture (so that they don't break pose), hit FEL, wait a second or two, then hit the shutter release.</p>

[digitmstr]

You can use the 550EX in Manual mode.

[digitmstr]

You can also use a Vivitar 283, for example or get the new 580EX II.

[jbq]

Use FEL and you'll be fine

[bobatkins]

You can't turn it off and maintain atomatic flash metering. E-TTL requires a pre-flash and is the only auto mode.

 

If you set the flash to manual, there's no preflash, but you'll have to figure out what flash settings, aperture settings and distances give you the exposure you want.

 

FEL makes the preflash happen when you do the FEL metering. If you then shoot while the internal metering is held (10 seconds?), you'll just get one flash.

[awindsor]

Philip,

 

You are not using second curtain sync are you?

 

Bob,

 

Of course you cannot maintain E-TTL metering without the preflash but you can use an auto-flash and still get metering without a preflash. The Canon 580EX II allows for on-flash auto flash metering.

 

Omega,

 

The 430EX and 550EX also allow you to use manual flash to disable the preflash but the poster was interested in flash metering.

[bobatkins]

Yes, the 580 EX II allows that, though at $500 it's still a bit on the pricey side.

 

Personally, I use a flash meter.

[chrisjb]

As said you can use FEL, in 6 yr of DSLR in our pix in niteclubs restuarants and bars its been most effective, rarely get sleepy or closed eyes. also as we use center focus point can meter with accuracy where you want to. eg: directly from a neutral face or tone. of course the new 580EX2 looks promising, up to now we`ve used Metz as an alternetive in some stuations.

[jim_larson1]

I have heard that the ETTL preflash can cause blinking problems. Primarily, however, I have heard this to be more of an issue in multiflash setups.

[awindsor]

That was why I asked about the settings. I have personally never experienced blinking humans with an E-TTL flash triggered by direct connection but there seem to be a few exceptional individuals for which this happens. It is a much bigger problem with wireless set-ups since the preflash phase is much longer - the more groups the worse the problem.

 

I have seen birds blink with direct flash (and hummingbirds can actually leave the frame!) but I can switch to manual for fill.

 

Alistair