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Old Aug 18, 2010, 7:43 AM   #11
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378

You should be able to use your 188A, as it's trigger voltage appears to be relatively low.


The flash also offers a non-TTL Auto mode. That allows you to set the flash and camera to match for aperture and ISO speed (the ASA setting on the flash). Then, when the flash sees enough reflected light for the settings being used, it will automatically terminate the flash burst.

Basically, you'd need to set the camera to manual exposure (M on your mode dial) and set the camera and flash to match for aperture and ISO speed (as it's not going to be able to communicate with the camera, other than for triggering purposes). See the "Use of the 188A on other Cameras" section of it's manual for how you'll need to use it on a Canon dSLR (page 17 of this .pdf, which is showing pages 26 and 27 of a manual):


You'll need to stick wiith shutter speeds within your camera's x-sync limit (use 1/200 second or slower) to prevent any banding, and to make sure the flash contriibutes to the exposure.

Depending on the flash settings available, I'd probably try around ISO 400 and f/5.6, setting the shutter speed to around 1/100 second in most indoor conditions. That should give you a reasonably good balance of range and depth of field, while making sure ambient light isn't contributing too much to reduce any ghosting/blur from subject movement. At wider apertures with lots of light coming in through windows in the daytime, you may need to go a bit faster (making sure you stick with 1/200 second or slower). Or, in darker conditions when you want more ambient light, you can try going slower. But, around 1/100 second at f/5.6 and ISO 400 is usually a good bet for most indoor conditions if that gives you the range you need with a flash that small. You should be able to see the range you can shoot within after selecting an ISO speed/aperture combination. The wider your aperture (smaller f/stop numbers), and the higher your ISO speed, the greater your flash range.

Shutter speed has no impact on the amount of flash light seen by the camera if you're within the x-sync speed (use 1/200 second or slower with your camera), and has no impact on flash range. Shutter speed is only used to dial in how much ambient light contributes to the exposure. As long as your settings result in an image that would be underexposed by 2 or 3 stops without the flash, then the flash can freeze the action for you (since the flash burst length is likely 1/1000 second or faster, depending on subject distance, so the subject would only be properly exposed during the short flash burst length, allowing the flash to freeze the action).
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