This question has to have been asked and answered time and time again but for the life of me I can't find anything on the subject. I apologize if this has been answered before. Anyway, is there any resource that describes using modern batteries in vintage flash units that used flash bulbs? I have an Argus C3 with flash unit thats been sitting in my collection for a while and I did some work getting it back to prime condition and I'd really like to take this out and use it with some flash bulbs in the flash unit. Now I know nothing about batteries or battery equivalents. The battery compartment of the flash unit appears to take 2 batteries the size of modern C batteries. Is the solution so simple that I can just use modern C batteries?? I don't want to damage anything so I've not tried putting modern batteries in the unit yet. If someone could let me know what batteries I can use and what bulbs I can use in the flash unit it would be very much appreciated. Thanks!