Will a SLR flash...

[GerritSmith]

Hey! I have a SLR Sunpak auto 144 pc flash, it is from my great grandfather, and I am wondering if it will work on a Canon EOS 20D DSLR?
Sorry if this is a stupid question, but I have been wanting to know.

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[Big Mike]

According to THIS PAGE, that flash uses less than 7 volts for flash triggering.
The 20D, I believe, has a safe rating of up to 250 volts...so it shouldn't damage the camera.

A better idea might be to get a wireless flash trigger and use the flash off-camera.

[GerritSmith]

I am wondering if it is compatible. Will it work with a dslr.

[Big Mike]

I'm sure it will fire...but it won't communicate with the camera for auto flash metering (like a modern Canon flash would).

I think that flash uses auto Thyristor technology...so you should have a switch or slider on the flash that corresponds to an F number. So to get the right power out of the flash, you would need to manual match the settings on the flash and the camera.

You could probably search out a user manual for it.

[GerritSmith]

I have the user manual for it, but it does not help much.

[enzodm]

What Big Mike is telling is that most likely you will not ruin your camera if you try it (which is something that may occur with old flashes). So, since you already have it, try it and tell the results. However, to successfully use it for taking good pictures, you most likely will have to learn how to use a manual flash.

[pgriz]

Pretty much any flash will work in manual mode with any digital camera that has a hot shoe or other means of triggering the flash. As Big Mike already noted, a wireless trigger would probably be the best way to get the camera to fire the flash. You'll have to do the math to figure out what power level to use with which f/stop (and at what distance), but that's a pretty basic procedure. The following web site seems to be the go-to site for off-camera flash: Strobist

[GerritSmith]

Thanks!

[O|||||||O]

Does that flash have a guide number calculator on it? Most flashes do, but I couldn't find a picture of anything but the front of it on Google images...

If it does, you don't even have to do the math. Just tell the flash 3 of the variables and it will tell you the 4th one. (ISO, aperture, distance, and power are the 4 variables - you need to know 3 of them to find the 4th one.)