High speed sync

Although I am able to shoot the D40 with my remote triggers at 1/640s, I can only shoot at 1/250s with my D200 and D700 with these CTR-301 RF triggers. I'm not going to get into the technical details why the entry level D40 can and the semi-pro D700 can't. That's another story for another day. But, wait! The D700 CAN shoot at a much higher flash sync speed, just not with the CTR-301 and the manual flash that I have.

This is where the SB-900 comes in. The SB-600 and SB-800 as well. With these SB-xxx strobes, you can shoot at 1/8000s with the D700. Why do you need this? If you shoot in low light or controlled lighting conditions, like a studio, you don't. But if you shoot in a location that has a very bright background light source, then you need to bump up the shutter speed or stop down the aperture to not over expose the back ground. Of course, when you do this, you will under expose the subject.

Here's an example of a natural light where I needed to expose the face, but because the background light is so bright, to proper expose the face, it over exposes the background.


D200 70-200mm f/2.8 @ f4 1/125s ISO 100

For this shot, I wanted to shoot a bit open to thin out the DOF, so I shot at f/4. Then to expose the face, I had to shoot down to 1/125s. Now, if wanted to expose the background, like the sky line, correctly, I probably would need to go up to 1/640s or maybe even 1/1000s. Of course, Chloe's face would be too dark.

This is where flash comes in to help put light on her face to balance the exposure. Well, in this case, if I had to shoot at 1/1000s, I can't use the manual flash I have which only syncs at 1/250s.

With the SB-900, not only can I shoot at 1/1000s and as I noted above, up to 1/8000s, it will also shoot iTTL. TTL, meaning Through The Lens. iTTL is just Nikons new acronym for intelligent TTL. We'll talk more about TTL at a later time...back to high speed sync. Below is a shot I took with the SB-900.


D700 70-200 f/2.8 @ f/3.5 1/1600s ISO 200

The camera was set to matrix metering and aperture priority mode. This means the D700 will balance the exposure based on the overall picture, which includes the background light. This is why the camera picked the shutter speed of 1/1600s. So, without the flash, Ashley's face would be way under exposed. With the SB-900, using iTTL, which will talk to the D700 and try to even out the light as well (flash power). Because of this, I had to tell the SB-900 to increase the power by +1EV. This will help put more light on Ashley's face since I need to over compensate for the bright background over weighting the average exposure value.

This is why it's nice to have a flash that will work with the camera at any shutter speed.