I'm new to manual flash settings. When setting the aperture for fill flash is there a general rule regarding how much to stop down below the metered exposure for regular flash? I do not have an integrated flash on my Bronica so I must set this manually. Also, is a flash meter absolutely necessary or can flash exposure be estimated using guide numbers? If so, how. Thanks

-- Greg Augustine (gjaugie@home.com), May 27, 2001

Answers

Greg, I've read that fill flash can be made from regular flash by stopping down one stop. I have found that I like 1.5 - 2 stops. There is a relationship between guide number, aperture and subject distance to come up with the right amount of flash to dial in. Unfortunately, I don't have the formula in front of me to pass on!

Johnny

-- Johnny Motown (johnny.motown@att.net), May 29, 2001.

How much you under, over, or match the ambient exposure depends on how you want the photograph to come out. To match the ambient light you should use the f-stop that is required for the flash and the shutter speed that the f-stop requires to make a good exposure for the abient light. I don't know if this will help, but I think of it this way; the f-stop controlls the flash and the shutter speed controlls the ambient light.

From there, if you want the shadows to be a bit under the ambient you change the f-stop to a smaller aperture and change the shutter speed to get a correct exposure for the ambient light.

If you want the ambient light to be under exposed, then use a faster shutter speed as long as it is at the sinc speed or slower.

To over expose the ambient light you just need to change the shutter speed to a slower speed.

There are several ways to mix and match the flash to the ambient light. Practice will make you more confortable working with the flash in ambient light.

-- Rick Lang (rickpho@aol.com), May 30, 2001.

Aperture setting for fill flash.

Pro photographers because of their need for speed and repeditive reliability would use a manual flash that has an aperature control on the back that adjusts the cuts off of the flash when there is enough light bounced back to the camera mounted unit from the subject. For portraits set at 2 stops under is a safe bet. If in bright sun light equal to to even maybe up to one stop over, to even out the facial shadows. ie you light the shot to overcome the ambient light. Use the defuser on the head to help soften the on camera effect. of course keep an eye on the background. Light absorbing bushes or dark timbers won't bounce light back like light coloured houshold setings. I use metz 60-1 or 45. If your flash is totaly manual you will have to go considerably slower, but the results will be more consistant and accurate. if you are banging off shot after shot, like a wedding, set your apperature, say f8 and speed at what ever your camera is sync. to. Then play your speed to what ever you need . ie matching inside to light outside the window, just crank up the speed. It's not as compicated as you might suppose. This out line which might bring comment is admitedly rough and ready but with a good lab you will get your shots with out boring the subjects. Shoot now improve later with experience.

-- Greg Pratt (gregpam@ozemail.com.au), June 04, 2001.

guide number max. distance to subject = ------------ aperture

-- Emiel de Grijs (emiel@mailandnews.com), June 13, 2001.

As my previous answer appeared to be messed up a bit I'll format it in a different way. What I was trying to say is that the correct formula for finding the maximum subject-distance by guidenumber is:

max. distance = guidenumber / aperture

My flash has a guidenumber of 35, so when I use aperture F10 the max. distance will be 3.5 metres (using ISO 100).

-- Emiel de Grijs (emiel@mailandnews.com), June 13, 2001.