Flash and Meter Questions

[Terry Again]

Hi All,
My Friend has a XD-11 Minolta Camera and I wonder if a Vivitar 2000 Flash I gave her is ok to use with this camera? I have a Sekonic Auto-Lumi ModelL-158 I wonder If Anyone knows of this Compny And Model's Accurate or not? Thanks for any replys!

[Christopher Walrath]

I'm not quite certain what it is you want to know. I am very familiar with the Minny's and the use of a Viv on top. Light meter's a light meter to a point. But what do you want to know exactly?

[Terry Again]

Hi Chris,
Well I wonder with the XD-11 having "programs" if the flash has a too high a voltage in it's circuits as it fires and charges? that what I mean by safe to use being it's a vivitar 2000 a model I haven't heard or seen written about? On the meter I wonder IF it's an accurate piece and most of all is there a place I could go to figure out how to read the scale so once I have the needles match up I know what to set camera to? I have never used a hand held meter before! And I wonder If the Sekonic has a battery? I can't find a switch to shut on-off!! A place to go to find out how they work if there is no battery? I really am concerned about the flash being OK to use on the XD because I gave the flash and hate to mess up a 100 dollar at least camera!! I haven't the money to replace the camera!!
I hope this is clearer?
Thanks for any replys and place to post!!

[John Koehrer]

My excuse is:I have no brain!
Sekonic is still making quality meters. If the front of the meter looks like a honeycomb pattern it is selenium
and has no on-off switch.
There should be a calculator dial on top. Set your ISO/ASA in the window and IF I recall correctly line the needle up with a reference mark in the window. When that's done the calculator gives you a series of f stop/speed combinations any of which are OK to use.

[Chan Tran]

XD-11 is OK to use with flashes with high voltage sync circuit. I have the XD-11 and the dedicated flash Auto 320X and the only thing it does more than a generic flash is that it automatically set the shutter speed to sync speed in A mode.

[Christopher Walrath]

YOUR FLASH GUIDE NUMBERS

You don't need a meter. Consider the following equation.

FSD = gn / av

Where FSD represents FLASH-to-SUBJECT DISTANCE
gn represents a flash's GUIDE NUMBER
av represents APERTURE

The guide number for your flash is 79 feet with a normal lens and ISO100 speed film. (I did a quick search, 79 IS your published guide number)

Let's say your subject is 30 feet away.

FSD-30 and gn-79 so let's put it in, shall we.

30=79/av

30=79/2.63333333333

So in this instance f/2.8 would probably be more than sufficient to illuminate a subject 30 feet distant through a normal lens with ISO100 film.
Figure out your FSD's for each aperture. Run a test roll to find out if all the exposures are comparable in the light values in your subject and you should be good to go.

If using different films (ISO) or length lenses it is simple to transfer this equation through simple modification.

(information on this subject was accessed at Creative Image Maker Magazine for reference in formulating this post. not a shameless plug contrary to popular belief. i had to consult my article as little as i use this info)

[Terry Again]

Hi Chris, So I do a bunch of math and to remember the answers,write them in a book. Always have a way of measuring how far away I am from subject. How do I get an automatic thing going with the flash and the camera? I hope using the Vivitar 2000 and the Minolta XD 11? Anyone out there Know and how? Would a Vivitar 283 work any better to get an automatic snyc'd flash and exposed correct is what I'm asking?
Thanks for reading and any answers,

[Chan Tran]

I don't know about the Vivitar 2000 but a 283 would work fine because you can use it on automatic mode. The 283 has a choice of 3 automatic apertures. All you have to do is to set the lens aperture the same as that on the flash.

[Toffle]

YOUR FLASH GUIDE NUMBERS

You don't need a meter. Consider the following equation.

FSD = gn / av

Where FSD represents FLASH-to-SUBJECT DISTANCE
gn represents a flash's GUIDE NUMBER
av represents APERTURE

I'm still fuzzy on this... We have FSD, GN and aperture... (and ISO, which is an easy variable to employ) Where does shutter speed fit the equation? It seems to me to be an essential part of the calculation. Or is this considered to be an assumed constant, say 1/60 or so?

Cheers,

[Chan Tran]

For flash exposure the shutter speed doesn't matter as long as it is equal or slower than maximum sync speed. Of course unless the ambient light is quite bright or the shutter speed is quite slow to make exposure by ambient light significant. In such case one must meter the ambient light also.
The exposure time for flash is assumed to be shorter than the shutter speed used. This is true in most cases as flashes used to have duration of 1/1000 sec or shorter. Today, many flashes have their duration at full power a bit longer than the top sync speed 1/250 (I believe because today flashes have larger capacitor and charge at lower voltage than older flashes) of most modern SLRs and it does matter a bit.