Black background with Wide Av & Flash???

I remember seeing a video where a photographer was doing a portrait outside during the day and he set the aperture as small as possible and then used a flash. The result was that the model was lit up, but the background was completely black.

Anyone know what I'm talking about or exactly how to do this?

I'm going to be honest and say I do not know how but I did accomplish it yesterday by accident. I have a duck statue on my coffee table and was goofing off with my flash and 17-50. I set the ss to 1/250 and the ap to 2.8 at about 5 feet distance from subject. From the angle I was shooting, my backdoor was in the picture and my dog was standing there. I snapped the picture not thinking too much more about it. When I reviewed the picture, the duck was perfectly exposed yet the light coming in the door was completely blacked out.

I believe it has something to do with SS being high enough to allow only the flashes light to affect the picture.

A excellent place to start learning about flash is HERE.

In answer to your specific question...

Measure the ambient light then underexpose by as many stops as needed to make the background black. Then apply flash to light the subject. You'll find full details as you read the site above.

Basically, you are underexposing the ambient light with a small aperture and probably a very fast shutter speed and the lowest ISO.

You then use the flash to expose the subject in the foreground. The flash is fast and generally powerful enough to expose the subject in the immediate foreground despite the small aperture. Generally, the trick is to underexpose the ambient/sky by two stops and compensate with a flash for the foreground subject so that the subject is properly exposed while the sky is dark and underexposed for a more dramatic look.

Very popular these days. I have a feeling in ten years, they may look a bit dated though.

Ok so I have figured out I need to use a small Aperture and a fast shutter speed, so that the background is black and my subject is the only thing lit up. However, my Canon XSI has a limitation that is not allowing me to do this. When I pop my flash up, the shutter speed is maxed at 1/200(even in manual mode). So apparently that SS is not fast enough because the flash will partially light up the background as well. Is there any way to override the 1/200 limit with flash on?

Not without an external flash that supports HSS. Try using your desired aperture with a shutter speed of 200 and the flash down. If the background is black then it is only getting light from the flash. If this is the case then no settings on the camera or flash can change it.

Your only option in this case is to move the subject (and camera) further away from the background. Double the distance and the background will be a stop darker.

Are you shooting indoors or out? If indoors, you can get an off camera flash and use a snoot or other modifier to limit the light from the flash to the subject.

e-k

Ok, thanks for the advice. I just got my camera a week ago and have learned a lot about Aperture, SS, ISO, but really haven't dove into lighting yet.

OK, here is the challenge...(let us assume not a bright sunny day, but an overcast day, so that it is less strenous for the flash!) The Kodak guidelines for exposure stated that on cloudy overcast days = 1/ISO f/8, so ISO 100 = 1/100 f/8. To underexpose for 'black', you need -3EV underexposure (or less), so 1/800 /f8. But you cannot shoot flash at 1/800, unless you use HSS. The problem with HSS is that the output is reduced thereby reducing max distance of the flash as you go faster in shutter speed, with about -1EV of loss for each EV faster than the max X-sync shutter speed. So if you have a flash which permits 20' max distance at f/8, reducing by -2EV in output you now have an HSS flash at 1/800 which permis only 10' max distance at f/8.

Now imagine trying the same thing in a sunny day (1/ISO f/16) and you see that HSS flash is even more severely reduced in max distance at f/16...same flash would be good only to 5' max distance.

slalomx wrote in post #9906246
Ok, thanks for the advice. I just got my camera a week ago and have learned a lot about Aperture, SS, ISO, but really haven't dove into lighting yet.

Yup, you need at least a flash like a Canon 270/430/580, or a third party flash unit that allows for a "High Speed Sync" so that you can use it for faster shutter speeds.

To get blurred background (shooting wide open) there are various ways to do it.

The easiest (instead of HSS) is using neutral density filters to get your shutter speed down to sync speed and then apply a powerful enough flash to expose the subject.

Usually you will be shooting on the shadow side to get the "flash look" while having the blur.

If you shoot outside, in the full sun, and want a blurred background while using flash you won't be able to without reducing the light by 8ish stops (ND) filter. There's a good thread on this subject somewhere with great photos of this effect..

The easiest way to do it is to take photos around dawn or dusk with the ambient being able to be captured at 2.8 and wider with a shutterspeed for 1/250 and below. The BG is exposed and then just use fill flash/off camera to expose the subject.

Want a black BG? Meter to knock down the ambient lighting by 3 + stops (so see what your camera sets this at in AV or TV mode) and then set the flash to get your subject lit.

Watch this video
Same effect you are going for
http://www.youtube.com​/watch?v=rPGg6kBymHo