Question on zoom flash; Nikon SB-700.

jwbryson1 · Oct 25, 2011

I'm a bit confused with respect to zoom flash on my new SB-700. Does this flash actually permit the photographer to zoom the flash closer to the subject? How does that work? How is light "zoomed" closer?

Also, should the zoom setting on the flash match the zoom setting on the camera (e.g., both set at 28mm)?

Finally, how does zooming the flash work in conjunction with the lighting "window" distance. In other words, if I'm using i-TTL flash and the settings say I should be between 8-10 feet from my subject, does changing the zoom on the flash change the distance I need to be from my subject?

Sorry for all the questions--I'm a total newbie at off-camera flash and I'm trying to absorb as much information as I can get my brain around.

Thanks!

Robin Usagani · Oct 25, 2011

Zoom means you make the flashed area smaller. If you make it smaller then your flash power is focused on a smaller area and stronger. Let's just say your flash is mounted on camera an you are using 18 mm lens. Then you manually set your flash to let's say 100mm. If you point the flash forward, your photo will look like you have a flash light in the middle of the frame.

jwbryson1 · Oct 26, 2011

Thanks, I think I understand what you are saying. Again, I just got my SB-700 and I'm still experimenting with it and learning how to use it.

Appreciate the feedback.

480sparky · Oct 26, 2011

The flash tube is physically moved within the unit itself. When you're shooting with wide-angle lenses, the tube is moved towards the subject to the light is allowed to spread out more. When you shoot with a telephoto, the tube is moved back, creating more of a 'snoot' effect.

When you have the flash mounted on the camera, you can hear a little motor move the tube as you zoom in and out.

Big Mike · Oct 26, 2011

I think the previous posters answered your question...but just to add to that...

The reason the flash head zooms, is to make it more efficient. It zooms to match the focal length of your lens, so that the angle of light coverage from the flash, matches the field of view of the lens. In other words, if you're shooting at 70mm, but your flash is putting out enough light to cover the view of a 35mm lens...you would be wasting a lot of light...which means the flash would be working harder than it needs to, which means that the recycle times would be longer and the batteries would die faster.

So by zooming the flash head, it's trying to be as efficient as possible.

Now, if you take your flash off-camera, it's a whole different story. Now you still use the zoom to control the spread of light, but you can get really creative with it, putting light just where you want it (or not).

480sparky · Oct 26, 2011

jwbryson1 · Oct 26, 2011

So, Mike, if the SB-700 is attached to the camera's hot shoe, and I have a zoom lens, are you saying the flash will automatically adjust to match the focal length of the lens, or is that a manual adjustment that I have to make myself?

jwbryson1 · Oct 26, 2011

480sparky said:

Spark, the video is unavailable.

jb

Robin Usagani · Oct 26, 2011

If you set it to auto, it will adjust it self. But I im not a nikon user so I dont know what that flash can do.

Big Mike · Oct 26, 2011

So, Mike, if the SB-700 is attached to the camera's hot shoe, and I have a zoom lens, are you saying the flash will automatically adjust to match the focal length of the lens, or is that a manual adjustment that I have to make myself?

As mentioned, if you have it set to auto, it will zoom itself as you zoom the lens....or you could manually choose the setting.

Like Schwetty, I shoot Canon, so I'm not all that familiar with that flash...but with my flash, it adjust the flash head zoom when you zoom the lens and activate the metering or AF (half press the shutter release button etc.).

Also, I don't think it's an issue any more...but 4 or 5 years ago, the flashes were still zooming to match the FOV for film cameras (wider than most DSLR). So there would still be some wasted light if you had a DSLR that wasn't full frame. But the modern flash units/cameras are smart enough to know that the FOV is narrower with a smaller sensor, so they zoom the flash out to match the actual FOV.

Another point I forgot to mention is power/light output. A flash units power is rated by it's GN (guide number). The guide number is directly related to the 'working' distance (how far away your subject is). As you zoom the flash head to give you a tighter beam, the same amount of light can go farther...so it's like you have more power. Techincally, it's not more power, it's the same amount of light...but when concentrated into a tighter beam, it can give you a farther 'reach' with your flash.