AB400 Sync Speed

I have two AB400 and a 350D and 30D. What is the ideal sync speed for this set-up? I have been using only 1/250 but I can't remember where I learned this setting. Any insight to this subject? I use large soft boxes with the inner baffles and have had pretty good results at 1/250th. Any tips???

You should be fine at 1/250 second.

Just run a few test shots. If part of the image frame is cut off, move to a slightly slower speed like 1/200 or 1/160 second.

The softbox, baffles, or any other light modifier will not affect the needed shutter speed.

Enjoy! Lon

I use a 30D and 3 B800's. Whenever I use strobes I work at 1/125s. 1/250s is the flash sync speed for Speedlites but I believe you should be using anything form 1/60 up to 1/125 for mono lights.

Will 1/125th freeze the kids shots as effectively as 1/250th? When I first started out I had a problem with slight blurring from movement of the children??

You should be able to drop your shutter speed a bit but I'm not sure of the answer to your question. Perhaps Lon knows.

hawkfeather wrote in post #2750741
Will 1/125th freeze the kids shots as effectively as 1/250th? When I first started out I had a problem with slight blurring from movement of the children??

If you are taking the images in an area with subdued light, the shutter will not be controlling the subject blur.

The length of the flash pulse, will become your "effective" shutter speed. You can check the pulse length on the Alien Bee website, but it will be far faster than you will need to freeze the motion and likely faster than any shutter speed you have on yoiur Canon DSLR

So, in subdued ambient light, either 1/125 or 1/250 second will be fine, in fact they will give you the same basic exposure.

Remember the above is true only if you are taking the images in rather subdued light, like "normal" house lighting.

Enjoy! Lon

TMR Design wrote in post #2750659
1/250s is the flash sync speed for Speedlites but I believe you should be using anything form 1/60 up to 1/125 for mono lights.

The camera manuals say use 1/125 with large studio flash. The more powerful units have longer flash durations and need a little more time. AlienBees would not be in this category.

If your shutter speed is too fast, you'll know it. The bottom of the frame will be dark.

As Lon points out, it's the flash that stops motion, not the shutter. In a studio environment, any shutter speed fast enough to render the ambient light insignificant but not faster than flash sync speed will work, with no visible differences within this range.