Experts, need your advice on flash on the slr.

[raytoei@gmail.com]

Hi,

i think i understand fill-filash with an aperture priority flash and camera. i do have additional questions.

Fill-flash: assuming flash sync at 1/100 on the leicaflex sl2.
In a back lit situation where the background is
metered at f8. I should put the flash to f8 and
adjust my aperture accordingly.

Question: what happens if I put the flash/camera
to f16, does it mean the image will come back
looking like night shot where the background is darkened ?

What happens if I put the flash/camera to f4. will the foreground be too dark ? will a half fill-flash at f5.6
be acceptable ?

sorry to ask these basic questions.

thanks

raytoei

 

[mdarnton]

If I read your post right, the way you're approaching it isn't really "fill"--it's using the flash as another primary light source. In your backlight example it sounds like you're trying to light up the backlit subject so that it doesn't look like backlighting, and use the sun as a secondary source, for rimlighting. That's not "fill".

Fill is a secondary light source, minor, to fill in and brighten dark shadows. Starting over, for fill set the appropriate exposure on your camera, then the flash to give a stop or two less exposure, depending on the results you want.

So let's say you have strong side-lighting, and the proper exposure for the lit side is 1/100@f/8. You might want to set your flash to fire for an f/4 exposure (that is, with f8 set on the lens, instead of f/4 the flash will be two stops underexposed), to give a minimal blast to build up the shadows a bit. (Or more realistically, f/4.5 or f/5, since a two stop spread is probably a bit too much, and a one stop spread a bit too close).

 

[raytoei@gmail.com]

mdarnton, thanks! quick question, since the leicaflex sl2 has a sync speed of 1/100, that means for your example to work, if i use a iso 100 film, i just need to follow your instructions. if i were to use an iso 400 film, then the example above would be:

1/100 f16, and to use a fill to the side light, perhaps, use f8 or f11 on the flash while maintaining f16 on the camera aperture.

does that sound correct ?

in the backlit example, my problem is that i may not be able to choose a different time except for the harsh sun at the beach. so if i have the model in the foreground, and the very bright background, the logical thing to do without the flash is to open up 2 stops, but if I do not want to washout the background, i am thinking of using a flash, but at what aperture setting on the flash? thinking this through, it should be the same as the background (f16 typically at the beach) ?

thanks again.

 

[bobbyrab]

My experience, all be it not with Leica flashes. If you set the flash to f8, the camera measures the reflected light and stops the flash when it reaches what it considers to be f8's worth, but this will be affected by both the ambient light and the reflectivity of the subject. So that setting could work or might be completely wrong depending on what you point it at.

If you want to understand flash it's good to try them out with a flash meter to understand what your particular gun does, for example I had three different Metz hammerhead type flashes, with a supposed five stops range of output, but the measured output from all three guns, from the lowest setting to the highest was only ever one and a half stops. they're never quite as good or consistant as they would have you think.

 

[bobbyrab]

On a beach and restricted by a maximum shutter speed, you may struggle to get the flash to show at all if your not working very close to the model.

 

[mdarnton]

Ray, that is right, both times. You might consider whether you want the background a bit lighter or darker,,the effect will be different. Making the background lighter will probably look more natural, if you want natural.

 

[raytoei@gmail.com]

thanks much. best i shoot at iso 100 at the beach.