Wednesday, March 25, 2009

Wednesday: A Cool Flash Trick From My PreCon & Photoshop World Opens Today

Good Afternoon Everybody,
Yep, I'm in late blog mode again today. We wrapped the PreCon yesterday had a great group of photographers attending, and got some terrific images. I have to say, shooting in the Old South Church was quite a kick. The place is gorgeous. We even pulled of a cool shot off outside. I'll post it tomorrow.

Anyway, I got to get scooting pretty quick as I'm in the middle of the The Tech Expo/ trade show trying to get the post on the air today. Let's get to it.....

Cool Flash Trick Wednesday
We came out of the church yesterday which was right down the street about two blocks from the Hynes Convention Center - can you believe it - we took a bus. Anyway, we came out of the church about 4:15 p.m. Across the street was one of those slick steel and glass buildings flanked by a beautiful blue sky with white puffy clouds - what a great background for a portrait. In this case, think executive portrait.

I had my executive who really looks like a groom step into the shot. Only one problem - he was standing in direct sunlight. I decided to shade him with a 36 inch panel I had with me. Now his face was in the shadows so I had to get light on his face. The problem was the bright surrounding light - I needed a low ISO and fast shutter speed to to get the sky a dramatic shade of blue.

I tested the shot at 1/400 second at F16 - now the scene looked great. I just had to get the light on my executive. I brought my Quantum in close - remember my small aperture and low ISO. I needed a lot of umph coming out of my flash. My assistant, a class member got the light just right on the subject.
Next problem - my Canon 5D Mark II only syncs at 1/200 second. That means only 1/2 of the sensor sees the flash during the exposure. Look at the first image - only the right side of the image area received the light. But, the groom was on the left side. Here is the easy fix - flip the camera 180 degrees so that his part of the image area catches the flash during the exposure. Check out the next image above- it worked. Pretty cool, eh? I love the shot.

Anyway gang, on that note, I'm out of here. See everybody sometime tomorrow. -David


  1. Couldn't you have just used high speed flash sync, moved your flash in closer to adjust for the lower flash power, and gotten the same results? I know my Nikon D700 and SB900 has that option, and I'd assume the Canon 5DMk11 does as well. I like the flipping the camera trick, but it just seems like an awkward way to shoot. Particularly if you had to do this shot under the pressure of a wedding day. Just curious...

  2. We keep learning from you Mr. Ziser.

    I personally would have preferred the sky to be perhaps half a stop brighter.

    Rob, I think David's flash was already very close to the subject as he points out. I don't know if the Quantum he used support high speed sync like the 580Ex o the Canon and your SB900 on the Nikon.

    PS: Are those visible speckles sensor dust - visible secondary to using f/16?

  3. If I'm understanding this,
    would it also have been possible to use rear curtain flash sync, and have the flash come in at the end of the exposure, and eliminate the need for the rotation?
    Thanks for all your teaching andtime put into this. We know how busy you are,and appreciate the effort in passing on your experience! -Ed

  4. David, the clouds must have been moving fast that day, I definitely like that big white puffy cloud there in your final version. I have to agree with Hanna that I would have the sky a bit brighter if it were mine. Nice work as usual and thanks for all your tutorials.

  5. David,

    The high speed sync for the 580ex II works really well. Yes you need to bring the flash in closer, but you can put it on manual zoom to concentrate the flash. If you still need more power, add a second 580 to it. And to make it all work great you can use the PocketWizard MiniTT1.

  6. Dear Ed,

    You kept me scratching my head long!

    I am thinking out loud here. At speeds lower than or equal to your max sync, we know that the whole sensor will be exposed by the time. In this case, I can see rear/second curtain sync making a difference on the photo.

    In front sync, the flash fires as soon as the first curtain exits. In rear sync, the flash fires a bit later. So if your exposure is 1/2 a second, your flash will fire 1/2 a second after you press the shutter button. This means, it fires just right before the second curtain creeps in. Ok?

    At higher speeds, I am guessing it wouldn't make a difference, since the flash will be fired before the first curtain exits the frame anyway. lol, I hope I got this right.

  7. Glad to hear I got the light just right on the subject! Thanks for the great Photoshop World class, David, it was an excellent day!

  8. Rather than doing the 180 flip, would using an ND2 filter to drop the shutter speed also have the effect of getting full frame sync?

    Would the ND have affected the background?

  9. Couldn't you have simply lowered the ISO 50 and shot at 1/200?

  10. Steve and Anonymous - this would only work if you also increased the power of your flash at the same time. If you're already shooting 1/1 power, you couldn't do this. Even if you had the ability to increase your flash power, you might want to keep it lower anyway to increase battery life and reduce cycle times.

  11. lowering iso will work because the duration of the quantum flash and the way focal plane shutters work means you are throwing away power at 1/400

  12. or just drop to F11 instead of F16