Speedlight/Alienbee and high speed sync question !?

Question

I have a Canon Mark 5D II. The manual says that the highest sync speed for a non canon flash is 250. I use an alien bee 400 in my "studio" and find that it needs to be at about 1/125 shutter speed to avoid having the nasty curtain burn !
I am pretty inexperienced outside of the studio with flash, I almost always just shoot natural light in the evenings before the sun goes down to avoid harsh light. I agreed to do a friend's wedding pictures and initially thought that I wanted to try to use my alien bee to do her outdoor bridal pictures (and for the ceremony I would use my 430 ex). There will be harsh light for the majority of the posed pictures, and my major concern is that because the shutter speed is "limited" I will have to shoot the pictures at an extremely high apeture the entire time because there is no high speed sync option. I wanted to do photos of the bride in a gazebo at about 3:30 so I assume the sun will be quite harsh and I will run into the high f stop issue. Should I instead choose to use my speedlight that has the high speed sync option so that I can use lower apetures ? Does anyone know if it is at all possible to get high speed sync with an alien bee ?!
In the evening at about 6:10 there will still be sunlight creating shadows, but certainly not as bright as mid-day - would this be a good time to use my alien bee for the bride and groom posed pictures, would I most likely run into the problem of still having a very high F stop at that time of day (the wedding is in september)
At what power should I have my speedlight at to properly fill in shadows for the ceremony photos ? Or the posed bridal photos.

Does anyone use their alien bee in the bright mid-day sun ? Any tips/suggestions

Answer 1

What your encountering with your Alien Bees is flash duration. Flashguns work different to studio flash, they always fire at full voltage then quench the flash to get the expected level of light. This means that at low power levels flash duration can be as fast as 1/50,000 of a second with a powerful flash turned right down, even at full power flashguns have a duration of at least 1/1000th of a second.



Studio flash work differently, when you turn the power down on these, it reduces the voltage across the tube, so flash output gets lower, however when you do this flash duration increases (the exact opposite of a flashgun), with the cheaper end of studio strobes this can be as slow as 1/125th of a second on lowest power and is never faster than 1/1000th of a second on full power. This is done to extend the life of the tube.



What this means is if you set your shutter speed faster than 1/125th of a second your AB's are still pushing out light when the second curtain starts to close, and you'll get second curtain shadow.



This is not a problem in a studio as you can get low ambient levels so longish shutter times won't be a problem, but when your shooting outdoors in daylight you will usually need faster shutter speeds just to control the ambient, something that studio strobes can't work with, unless you get high quality units (read expensive). Speed-lights are much better at blending outdoor daylight to flash than most any studio strobe as the flash duration will nearly always be faster than the shutter speed.



Chris

Answer 2

First, there is no way for you to do hi-speed sync with the A.B's. This function is calculated between the on-board computer and a dedicated flash that syncs up with that same computer.



As far as all the calculations for f-stops and shutter speed, they can't be guessed in advance because the conditions are an unknown and very different in sunlight as opposed to a subdued light studio. F-stops and sync speed are irrelevant when using a flash and the only issues are ambient light and depth of field. A flash freezes the action whether you are at 1/60th or 1/250th. The lower the shutter speed the more ambient light is going to come in so in this circumstance slower is not necessarily a bad thing. The flash is closer to your subject than the sun is and the light from the flash unit will win out as far as lighting your subject goes.



Using flash outdoors is a matter of balancing flash against natural light and the simplest answer to this question is not to over complicate the solution. As long as you are not trying to overpower the sun, the A.B. is probably not necessary.



I just had this circumstance come up a couple of months ago when I did an outdoor drill team shoot on a bright sunny day. ...I let the camera figure it out for me. I synchronized my camera to the flash and set it on aperture priority and shot at f2.8 with my flash on a stand with a shoot through umbrella camera left about 6 feet away and up 45 degrees. The shots were all money, just enough ambient light, a blurred background and no harshness. The fastest shutter speed on my shots was 1/125th at f2.8.



Get either the wireless commander or a long flash extension cord so the flash will work dedicated, put the flash on a stand or have someone hold it, shoot aperture priority at your preferred aperture and let the camera figure the rest out for you. The results will surprise you in a good way.



Again shooting outside is completely different than in a studio, you're not lighting a scene, your balancing with ambient and because it's closer, the flash will win ...unless you are shooting directly at the sun. I would practice, you have plenty of time before the big day.

Answer 3

I am not an alien bee user, but I am a wedding photographer and the situations you describe are very common - but not so difficult as you might imagine.



The 430ex is a decent enough flash. Mount in on camera (yes, really) BUT fit a good diffuser - I use a Garry Fong Lightsphere and let ETTL manage the exposures - I often have to boost the flash exposure, and less frequently, cut it back a few stops. Do this with the camera controls rather than through the flash gun's menu - fast and effective.



Your 5D II will handle most of the light situations without flash - I use a 70-200 f/2.8 and a 50 f/1.4 for a lot of the ceremony and reception, and I prefer reflectors and available open shade to flash outside. Nevertheless, your alien bees would provide you with a good deal of flexibility, and your need for high speed flash is probably more perceived that real. Your flash should not be providing the main light source, just the fill, and for this it will work fine.

Answer 4

Firstly, although your manual may say that the max sync speed is /1250 (I thought it was 1/200 but never mind...), if you are firing your AB's with radio triggers, the actual trigger response may be limiting the max sync speed.



For example, I shoot in a studio occasionally using monolights triggered with RF602's and get my 1/250 max sync speed no problem - when using a friend's PT-04 triggers, I found my max sync had dropped to 1/125 - beyond this I was getting the second curtain appearing (just) in the frame.



Outdoors, at the wedding, it depends how much you want to balance flash & ambient. If you are trying to 'overpower' the ambient daylight & it's bright, you might well have problems as your sync speed will be limited and you will have to stop down. One solution is to use a ND filter which will allow the same flash power/ambient balance, but will allow you to shoot wider (you'll not gain any exposure, but you'll be able to get shallow DOF which is presumably what you want).



Alternatively, rather than trying to overpower the ambient, just maybe drop it by a half stop or so & use the flash to fill in any shadow areas - you'll need less flash power if you're just using it as fill. What power you need for fill depends (of course) on what aperture you'll be shooting at & the flash to subject distance.



This was shot using the sun as key & a 600 W/s monolight as fill;

http://www.flickr.com/photos/deepbluephotography/4897288956/in/set-72157625141716291/

Answer 5

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