How to use the Sunpak Auto120 flash?

One thing I ocassionaly do in digital photography, but never attempt with film photography is taking pictures using flash. Dad has a Minolta XG-E with a Sunpak Auto120 flash. Put some fresh batteries in it, and the thing still fires


I know this is not a TTL flash, so I have to learn the old school way.
Well, I'm still figuring how to use this (cannot find the manual on the internet).
Assuming I'm using a 100 ASA film, and if lens is set to f/4, then I get this 5m distance. But 5m of what?
Flash range? Or distance between me and subject?

By setting the flash to “auto” - see the front of the flash you have the option to select manual or auto, set your camera to manual then select f4.0 & shutter speed to any setting at or below the flash synchronisation speed. The flash exposure will be correct for all camera/flash to subject distances from 0.5m to 5metres... however, you do need to know what the ambient exposure reading is so as to control and/or balance the flash and ambient exposures!

Not using the flash auto function and your camera on manual the correct exposure aperture is the distance between the flash and subject divided into the flash guide number - which, in this case it looks to be about 20. Thus, depending on how far you are away from your subject in metres simply divide that distance into 20 and set your aperture to match the answer. i.e. @ ISO 100 - f8.0 @ 2.5m or, f5.6. @ approx 3.5m

Be aware though that if the ambient lighting exposure requires a higher exposure - aperture/shutter setting than the planned flash aperture/shutter speed setting and you choose to go with the flash setting, you will in all probability over expose your shot. Working with flash in low light conditions is somewhat more straight forward! There are plenty resources available for you to access which will facilitate your understanding or working with flash in a non-TTL environment. Good luck!

PS. The guide number will vary depending on the ISO speed of the film being used! A higher speed means a higher guide number and slower film a lower guide number!

Ozxplorer posted before I hit reply, and I'm sure he understands it better than I.

Basically, for Manual mode, the dial shows you what f-stop to use for how far away the subject is. This should give you good coverage from the flash. So, for something 5 meters away, f 4 should give you adequate illumination, and from your picture, f 11 would be good for a subject 2 meters away.

The red line shows what should work if you switch it to Auto mode. In this case auto mode will automatically adjust the flash intensity for a subject anywhere between 0.5 and 5 meters away. The photocell on the front of the flash (likely inside that hole surrounded by the green oval) will detect light bouncing off the subject to determine how much light it will give.

Make sure you set the camera's shutter speed to it's flash sync speed (likely the only speed on the shutter dial with a different color).

The basic principle for these types of strobes is fairly common, so you can get a general idea from most manuals. I don't see your model on butkus.org, but here is a general listing of manuals available there:
http://www.butkus.org/chinon/flashes_meters/sunpak_flash/sunpak_flash_units.htm

Some have sliding selectors instead of dials, some have 2 auto modes, but they all function similarly. The gx24 and 311 from the butkus link should give you a good idea.

For clarity, the suggestions above are in reference to ASA/ISO 100 film.
The auto-exposure function will still work between 0.5 and 5 meters for film with a different speed, but when you turn the dial to that speed you will note that the red Mark will line up with a different aperture setting - use the setting indicated rather than f/4.

-) there are two guide numbers, the metrical and the imperial, based on the very length unit applied
-) old european flashes had their guide number based on ASA 50 not on ASA 100
-) manufacturers of modern flashes base the guide number on the tele setting, whereas the classic setting was for an illumination for a 35mm lens

Keep that in mind when reading flash descriptions.