Trying off flash and failing - please provide guidance

[iamjediknight]

Hi,

This evening I was attempting to do off flash portrait for the very first time and failed miserably. This is the equipment I used:

1. Canon 50D
2. Vivatar 285 flash
3. Westcott Umbrella
4. Cactus trigger

I set my flash power at 1/4. Base on an ISO of 100, and my subject 10 ft. away from my camera the Vivatar stated my f/stop should be f/5.6. I put my umbrella on the left side of my subject about at 45 degree angle between my camera and the subject.

I guess I don't know what settings my camera should be. I put the camera in Aperture priority mode on f/5.6 and it calculated the shutter speed of 15 seconds because of low ambient light into the room. I thought the photo came out pretty good, but 15 seconds is way too long.

I then tried putting my camera in manual mode and setting lower shutter speeds but the photos were even too dark or very very dark.

I would like any pointers on what I am doing wrong. Could it be how far I have umbrella I have from subject or how high the umbrella is? To be honest here I am just guessing. I have read up as much as I can but I can't seem to find any guidelines on placement of the umbrella other than general angle.

Thanks for any assistance you can provide to a wanna be portrait photographer.

cheers, Scott.

[tim]

Manual mode only when using flash in studio type settings. Umbrellas wastes power so your calculation is irrelevant. 1/4 power with ISO100 F5.6 sounds too low to me, get a flash meter or just try ISO400 and tweak until things look right - increase flash power or camera iso/aperture.

[Milamu'g]

Your umbrella will eat at least one stop of power so changing the aperture from F5.6 to F4 should get you a lot closer to the desired result.
If the photo is too dark there are three basic ways to counter act this;
- turn up the flash power
- bring in the flash closer to the subject
- bring down your aperture value
and the opposite if the photo is too bright.

[Photorocket455]

Your Vivatar calculator is for straight on flash, when using an umbrella or any light modifier set at full power. Without a flash meter you will have to do trial and error.

John

[GenuineRolla]

^^^

You don't need to have it set at full power. Just lower the f/stop if possible.

He could have stayed at iso 100 and since it seems like it was too dark to get any ambient, he should have just shot at 1/100th. Definitely should have tried to shoot at f/3.5 and then go up if needed. If still too dark, up the power of the flash.

[40Dude6aedyk]

Forget about calculations. Just do it. Without the person take some pictures and look at the results. It's that simple. Use some other object than a person. A pillow will work fine.

Set flash on manual. Say 1/1 or 1/2.
Set camera on manual. You've got only 3 things to worry about: ISO, shutter-speed and aperture. So set ISO to 100, SS to 1/200th and aperature to f/5.6. Take notes and take pictures.

If too dark, then you know to increase ISO, open up aperture, and that shutter speed doesn't matter much with flash. You know that aperture changes depth of field, so if you don't want to change DoF, you only have one thing left to change. Change that one thing and take a look. Take notes.

If too light, then you know to decrease ISO, close down aperture and that shutter-speed doesn't matter much with flash. You can reduce the flash output by going to 1/4, 1/8, .... And the comments about DoF apply as before.

Anyways, there's only a few things to try on your pillow before you get your model back in there. It's trivial.

Then once you are "in the ballpark" you can see the effect of light placement. The beauty of digital is that you can see the results of your experiments instantly and without cost. So move your light around. Make your manual adjustments. Take notes and take pictures.

[GenuineRolla]

^^^

You don't need to have it set at full power. Just lower the f/stop if possible.

He could have stayed at iso 100 and since it seems like it was too dark to get any ambient, he should have just shot at 1/100th. Definitely should have tried to shoot at f/3.5 and then go up if needed. If still too dark, up the power of the flash.

[40Dude6aedyk]

You can't mess with aperture without changing the depth of field. f/3.5 might keep an entire head in focus, but it might not. Eyes in focus, but tip of nose out of focus and ears out of focus do not make for a good portrait.

Do the experiments. Take notes and take pictures. Be systematic about it. Learn by doing, not by reading forums.

[iamjediknight]

All,

Thanks for the quick responses. I think part of my problem was that I didn't have the flash hitting directly in the center of umbrella and it was too far away from my subject. I have been using a disney stuffed animal as a test subject.

I have been getting some good shots using f/4, 1/200, ISO 100 with 1/4 power flash. This weekend I am going to play around with various settings to see what I really like best.

I appreciate all the good insightful tips.

scott.

[GenuineRolla]

f/3.5 is more than enough to keep the whole head in focus. It's once you stop down to f/2.5 that you'll really start to notice the shallow depth of field.

[Jim M]

Hi,


I set my flash power at 1/4. Base on an ISO of 100, and my subject 10 ft. away from my camera the Vivatar stated my f/stop should be f/5.6. I put my umbrella on the left side of my subject about at 45 degree angle between my camera and the subject.

cheers, Scott.
The exposure doesn't depend on how far your camera is from the subject. It depends on how far the flash is from the subject. Also, bouncing changes the calculation, as you have already been told.

Also, before you make any judgments from the back of the camera, load the images on your computer and see what they are like. The back of the camera is way too forgiving unless you are skilled at reading histograms. Best bet is a flash meter.

[iamjediknight]

I love the community here! Everyone is helpful and patient with newbies like me.

[Milamu'g]

f/3.5 is more than enough to keep the whole head in focus. It's once you stop down to f/2.5 that you'll really start to notice the shallow depth of field.
That just depends on your focal length and camera distance from subject.

[Jim M]

That just depends on your focal length and camera distance from subject.
I was going to say the same thing, but decided to stay with the light issue.

[Big Mike]

I don't know if someone mentioned it yet...but I'd suggest placing your light as close to the subject as possible. (just out of the frame would be perfect). Firstly, the gives you the softest light and secondly, it gives you the most power (least fall off) so that you have more options in terms of aperture, ISO and flash power settings.

[PhotoJourno]

Using artificial lighting to photograph an object or subject is mostly a matter of personal experience. There is no substitute for your own approximations, experiments, and testing. Direct light, from close or far. Filtered light, via umbrella or softbox. Angled light, in order to manipulate the shadows behind the object or subject.

Though there are lots of useful guidelines, I also am added to the group of those who would rather experiment with an object first, and start getting comfortable with parameters.

[Brett]

I don't think it's been mentioned here yet, but be sure to keep checking the histogram as you shoot, making sure you're at least getting a decent exposure. The LCD on the back of the camera can fool you into thinking you've got everything perfect, when the histogram will show blown highlights or underexposure.