Fill flash

[Mike Wilde]

Originally Posted by MattKing

Mike:

Don't you mean that you set the flash to expect the camera lens to be set to f/4, rather than f/8?

If the flash thinks you are using f/8, won't it put out twice the light needed for f/5.6, not half the light needed?

Matt

Of course. I wrote this as I was about to head out the door to take the family canoe tripping for the weekend, and had about a zillion other thoughts of what - did I have to still do/had forgottong/etc. on my mind.

The other confusing factor is sometimes I set up my Speedo blackline studio flash rig outside and use ambient light as the overall fill. 2400w/s at less than a few metres away from the flash head with this setup is usually brighter than the sun. It works wonderfully when I am shooting a group portrait and need a bit more depth of field, because the ortho sheet film I have a stash of is lith, and when processed for continous tone work this equates to and effective EI of around 6, and then there is a bellows factor to deal with at times with some subjects as well.

[c6h6o3]

You didn't say whether you were using TTL flash or not.

But with my Hasselblad 503cxi, I take an incident reading of the ambient light with a hand held meter and close the aperture 1/2 stop down from that reading. I then set the TTL flash setting on the camera to double the film speed. (i.e. 800 for Portra 400 VC). The exposures are invariably perfect.

This will only work, however, if you have control over both the flash and the aperture separately and the flash is being metered through the lens.

[John Koehrer]

Originally Posted by ajuk

I think the lens cap test was conclusive, with the cap on it came out full blast, without it didn't.

Ooooh, that's what you meant. Just never heard it called the lens cap test.

[ajuk]

I made it up, thought it was self explanatory. Anyway I think I messed up because I didn't use slow sync.

[rob champagne]

I thought you wanted fill. Fill needs one or two stops less than ambient so it affects only shadows and not highlights. If you just want balanced then slow sync will help but with your subject having highly reflective white dress, then I don't think it will work as well as you think it will because the flash will push the highlights up as well.
So for fill you want flash with -2 EV compensation. That way the dress won't be blown out like it is in your first shot.