Hi Geordie, "M" is for manual flash, which means you get full output, so you have to expose via the old guide number method. Blue is for auto exposure with a shorter range so that you can stop down more, and red is farther (better for bounce) but you have to use a wider aperture. If I remember correctly, with ISO 100 film, blue gets you out to 20 feet at f/4, and red gets you out to 40 ft at f/2. On the back, set the film speed on the adjusting part of the scale, and that will show you what aperture to use. Blue line for the blue mark on the front, and red line for red mark on the front.
If this doesn't make much sense, it's probably because it is way past my bedtime. :-) I'm pretty sure that I have a PDF version of the manual for this flash if you would like me to email you it off list. I'll look. William in Utah. Geordie wrote: > > Hello, > > I was wondering if anynone might be able to help me with my flash. > > I bought a Vivitar thyrisistor 2800 flash awhile back, and I don't have > instructions for it, and I conveniently forgot what its functions are. > > On the front of the flash there is a three position switch, where the three > choices are: Blue Dot, "M", Red Dot. > > On the back there are red and blue lines pointing to certain apertures on > the flash exposure chart. > > I'm a bit confused on how to use the functions, and until I drag my butt > down to the used camera shop to find an instruction manual, I was hoping > someone might be able to enlighten me? > > Any help would be great! > > thanks > > geordie > victoria, bc > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
