How to measure exposure when using Manual Flash?

[Gaurav Prabhu]

I'm new to DSLR photography & new to off camera flash photography too. I've a Canon 60D & a Vivitar 285HV. While taking a portrait or any shot, how should one approach setting the camera> I usually first do a check of environment lighting, dial in the exposure into the camera & adjust the power of light accordingly. Any other way to do so?

Recently I was shooting a portrait of a friend at night & so I got a slow shutter speed of almost 4 secs for the cityscape & so my subject had to be still even inspite of flash. So how can one tackle such situations? I've a Tamron 17-50mm f/2.8 lens.

[homank76]

One of two ways comes to mind. You can either use a lightmeter to get the proper reading or do test shots till you get it dialed in.

[Gaurav Prabhu]

Do not own a light meter, I'm already doing it trial & error. Is there any other way around? Some tips to nail the exposure pretty accurately would be handy.

[homank76]

Are you talking about taking the photo above, so that the city lights will be nice and pretty in the picture along with your main subject?

[Gaurav Prabhu]

Originally Posted by homank76

Are you talking about taking the photo above, so that the city lights will be nice and pretty in the picture along with your main subject?

Lets take that as an example in our discussion. Since it was very low light, the camera gave me around 3 secs of exposure with a aperture of f/16. I fired a flash on my subject at 1/4th of its power from side 45 degree. The subject was fairly close to the camera.

During daytime, its not much of an issue as mostly the shutterspeed is fast enough. In the above case, I need to make sure subject does not move even after the flash is fired. Once while shooting the subject moved & I got a ghost effect.

[homank76]

Do you want the background in focus or not?

If the answer is no, then set the camera in manual and set the ISO at 200, Aperture around F/8 and shutter speed around 1/200 to 1/50.

If the answer is yes, then you are doing it right, you just have to decide if you want the flash to fire when the shutter first opens or when its about to close. Either slow sync or rear slow sync.

Hope this helps.

[Gaurav Prabhu]

I want the background in focus. I tried first with a shutterspeed of 1/250(highest X sync) but as expected got a black background with a few light bokehs.

Will rear sync(I think this is the 2nd curtain if I'm not mistaken) work with a manual flash?

[scootermcq]

Originally Posted by Gaurav Prabhu

Lets take that as an example in our discussion. Since it was very low light, the camera gave me around 3 secs of exposure with a aperture of f/16. I fired a flash on my subject at 1/4th of its power from side 45 degree. The subject was fairly close to the camera.

During daytime, its not much of an issue as mostly the shutterspeed is fast enough. In the above case, I need to make sure subject does not move even after the flash is fired. Once while shooting the subject moved & I got a ghost effect.

If you have ghosting, you are really getting too much ambient light, and not enough flash. I have done portraits with 10 second exposure and freezing the subject by flash, without any motion blur. I did use rear curtain sync. I am not sure if your camera & flash combination will do it, but if you balance flash & ambient correctly, it will not make a difference.

[Gaurav Prabhu]

Originally Posted by scootermcq

If you have ghosting, you are really getting too much ambient light, and not enough flash. I have done portraits with 10 second exposure and freezing the subject by flash, without any motion blur. I did use rear curtain sync. I am not sure if your camera & flash combination will do it, but if you balance flash & ambient correctly, it will not make a difference.

Will try if my camera supports rear sync with this flash. Else you say, I bump up the flash power?

[ccting]

I believe you need to calculate GN, f-number and distance, and also the bounce back surface behaviour, angle of reflection.