Urgent question regarding manual camera and flash without external light meter

[shimelle667]

I am a college senior enrolled in my beginning photojournalism class. I am shooting a photo essay about a burlesque troupe (so they perform mostly in dark bars and the like). Until now I have only worked with outdoor light so I have always used the light meter in my camera. Tonight is my first night to shoot one of the shows, and I need to use a flash. I don't have an external light meter, and I don't know how to correlate the F-stop with the external flash, since my light meter doesn't read it. I tried figuring it out from my textbook, but it's too confusing, and I don't have manuals for the flash or camera because they belong to a friend who doesn't know how to use them, and the show is in a few hours. I don't want to waste a bunch of film and come up with nothing useful, so if anyone can help shed some light on this (oh, whoops...sorry for the pun) I would greatly appreciate it!!

 

[Big Mike]

What 'type' of flash is it...and is it 'dedicated' to the camera? Is it a Canon flash on a Canon camera, for example?

Is it maybe an Auto thyristor flash? Does it have an 'eye' so that it can read the light and meter itself...based on the setting you set on it?

If it's just a flash that is not dedicated to the camera...and is not an auto thyristor...then you make have to calculate the exposure manually. You will need to know the Guide Number of the flash. For example...the GN may be 100 feet. To get the exposure (aperture), you would get (or estimate) the distance to the subject and divide the GN by the distance. So with a GN of 100 feet...at 10 feet, the aperture should be F10. (I think that's right :scratch: )

 

[mysteryscribe]

Auto stobes work by giving you a zone for a given f stop setting... you set your camera on a particular fstop from the flash's calculator.... It then adjusts the light output to make that fstop with every flash so long as you stay within the distance perscribed on the caluculator..... If there is no caluclator like that you have a manual flash not many manual flashes around these days

Thyristor is the charging circuit to save the battery and extend the life not for calculations.

The Manual calculation is flash output (ie guide number) devided by the distance in feet equal fstop or gn/distance=fstop.


That's how we had to do it all the time when I first started. Without the thyristor circuits we had to carry 510 volt battery packs around as well.

The above is for non dedicated strobes. The camera makes the calculation for dedicated strobes but my guess is you dont have that or this wouldn't be an issue it would be in your camera manual.

 

[shimelle667]

it's not a dedicated flash. It's just a random flash and a camera. A friend tried to explain the gn/d= f equation, but I am still confused. I don't know the guide number. There are different settings on the flash, all of which I don't understand. On the front of it there is a blue dot, a red dot and an "M" and I don't know which one of those I am supposed to set it on. Also, there is thingy (I am sorry for using the word thingy, I am usually much more articulate) that I am supposed to set the ISO (which is 400). I am still puzzled. I am sorry.

 

[mysteryscribe]

You have an auto flash

each color represents a setting. Somewhere on that flash there is a fstop that corresponts to each of those colors that is what you set your camera to



the fstop will vary with the iso of the film so set it first.
there is somewhere on the flash a calculator that will work it all out for you


Set the iso on the dial you have

then find the color that that will give you the fstop closest to what you want f8 or even 5.6 is a good indoor setting for misc work. Dept of field will be adaquate if you focus fairly close

let me know if you figure it out but start with iso 400

then see where the colors are you can use either one as long as you set the leaver or switch for the same color.. The switch or lever is for the actual sensor. the calculator tells you what to set the camera on.

You can also set it to M which is manual that is the gn/d=fstop thingie. If you get frustrated and want to go that route set everything on m and find the ten feet fstop from the calculator and do the algebra 10ft x fstop = guide number.... with only two zones I would guess the gn to be around 90 but do the math