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Quick and dirty guide to manual flash photography?

safdari cyrus , Nov 04, 2009; 12:05 p.m.

I am a large format photographer who rarely deals with flash. In-studio, I use continuous lighting. Now I plan on using a vivitar 285hv flash off-camera with a Canon F1 (new) and a Mamiya 7ii and perhaps a handheld 4x5 life a SuperSpeed -- and I have no idea what to do. I do have a Sekonic flashmeter though. So can someone give me a quick run down, for example for a portrait outdoors espcially involving fill light? Not quite sure how to "balance" the ambient v. flash exposure, and whether this is necessary.
I understand that the synch speed on the canon f1 is 1/90 -- so I have to use shutter speeds that are slower or equal to that. The other cameras of course don't have focal shutters so not an issue there.
So suppose I want to take a photo of a backlit subject. The ambient exposure is ASA 400, 125 at f/16. I am guessing I put the vivitar on full-power manual mode, flashmeter the shadow, and end up with another exposure setting.
Then what?
I'd buy a book but they seem to all deal mostly with TTL flash and digital cameras. Recommendations? And please do not refer me to strobist -- been there.

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Howard M , Nov 04, 2009; 12:14 p.m.

Henry Posner , Nov 04, 2009; 01:19 p.m.

Fill flash with the Vivitar is not complicated. Meter your subject minus the flash, making sure your shutter speed is at or slower than the fastest x-sync speed. Let's say it's f/8 and 1/60th sec. The 285 has concentric dials on the side. One sets ISO and the other selects an aperture. That's usually color-coded. I know it is on the 283. Set the flash's ISO to the same as the camera and select an aperture on the flash that's one stop less than your shooting aperture. in this example you're shooting at f/8,so set your flash to f/5.6. You can do all of this w/out a flash meter. I did for years.

In your example above, my first suggestion would be to switch to ISO 100 if you're shooting individual head-n-shoulders portraits. That'd get you to 1/60th and f/11. Then set your flash to produce f/8.

Henry Posner
B&H Photo-Video

safdari cyrus , Nov 04, 2009; 02:43 p.m.

Thank you Henry
I understand that the dials on the side are basically a quick and easy way of doing guide number calculations.
Two quick questions to help me better understand this:
1- Why is the flash set to one aperture that's less than the cameras? To allow more light in?
2- What about on cameras that have leaf shutters? What's the procedure then?

safdari cyrus , Nov 04, 2009; 02:59 p.m.

Sorry, make Q1:
1- Why is the flash set to one aperture that's less than the cameras for fill flash? Is that because the flash should be set to provide less than the normal exposure?

Henry Posner , Nov 04, 2009; 03:58 p.m.

The flash acts like a fill light while the ambient acts like your main light. The fill is usually one stop less so it moderates the shadows and contrast and retains the three-dimentionality of the face which is not flat.

With a leaf shutter, you can use any shutter speed which means you can set your camera to any shutter speed + aperture combo and if you then select a flash output one stop less than the aperture, you'll have the same results.

I did this all the time with a Bronica ETRS and Metz 60CT1.

Henry Posner
B&H Photo-Video

Tim Ludwig , Nov 04, 2009; 04:05 p.m.

Safdari,

The reason for fill flash outdoors is to bring the shadow detail up to an easily printable range with the highlight detail. You always set your exposure for the highlights with traditional metering and then set your fill flash for an exposure that is less than that of the highlight.

Henry says one stop less, I say at least two less because I think that fill flash that is too close to the same as the highlight range is too bold. Simply put, you see the effects of the flash when you should see only a raising of the shadow value and a catch light in the subject's eyes.

Test both and see which you prefer.

Having said that, I will add that I loathe fill flash. I have never yet seen an example that I feel looks realistic. The primary reason is that it always comes from a tiny light source which produces very bright highlights and very dark shadows. It looks artificial!

So for me, the choice is always either subtractive lighting by using a shade above and to one side of the subject, or the use of a large reflector to bounce a large and soft source of light into the shadow areas of the subject shadows.

By all means, test each approach and see which fits your preferences.

safdari cyrus , Nov 04, 2009; 04:17 p.m.

OK thanks - that seems straightforward enough. So just let me see if I got this: by setting the flash to one or two aperture stops less than the cameras, you're "fooling" the flash into producing less light than the ambient light. I suppose the same result could be acheived by setting the flash on a higher ISO?

Howard M , Nov 04, 2009; 06:42 p.m.

all you're trying to do is fill-in the light and change the contrast between the ambient and flash. if you use the same power rating, it'll look flat and fake. set it to 1-1.5 stops less and you start developing some interesting shape and shadow.

safdari cyrus , Nov 04, 2009; 09:37 p.m.

Thanks I got the concept -- fill light should be 1-2 stops less bright than ambient lite so as to bring out the details in the shadows but not overpower the ambient light or else you end up with flat, boring overexposed images.
But now how exactly do I set a particular exposure setting on the vivitar flash? Please tell me if I am doing it right:
Say my ambient light reading is ASA 400, f/8, 1/250. Taking into consideration that my fastest xsync is 1/60, that comes out to f/16.
OK now If I want the fill flash to have 2 stops less exposure, I calculate i would have to set the flash on f/8.
I set the side dial on the vivitar at ASA 400, and see that f/8 lines up to the red tab.
So I then set the varipower knob to the red setting. Now I should be getting a flash that is equivalent of two stops less than ambient at 1/60. Is this right? Is this how you work it?
==
Oh but somewhere in there I have to take into consideration the distance to to the subject?
This is confusing!


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