Fill-in flash in bright daylight

I am confused. The other day I was at Centre Island taking pictures of friends participating in a dragonboat festival. It was a bright day with a fair amount of sun. I thought I could just connect my SB-800 speedlight to my new D300 and the camera will just know what to do with the flash. Well, all the background of all the shots I took with flash was over-exposed. The highest speed the camera could be cranked up to was 1/320 sec. I could not figure out it could not go higher. I had set the D300 in Aperture Priority mode.

I just re-read an article I wrote in 2008 about using the SB-800 with my D80:

http://photonfarmers.blogspot.com/2008/09/d80-and-sb-800-high-speed-flash-sync.html

In the last paragraph of the article, I said the D80 would not be able to shoot faster than 1/60 sec in Aperture Priority mode with the hotshoe flash on. It would sound like what happened on the island ... except that today, I thought I'd retest the SB-800 with both the D300 and D80 in Aperture Priority mode.

In both cases, with the SB-800 mounted, I pointed the camera at a bright scene that required a high shutter speed of exposure, like 1/2500 sec. I expected the camera shutter speed to be set automatically to 1/60 sec. To my surprise, the shutter speed adjusted appropriately to 1/2500 sec.

I thought, from my earlier 2008 experiment, that the maximum shutter sync speed in Aperture Priority mode is 1/60 sec (if a faster speed is desired, the D80 needed to be in Shutter Priority or Manual mode.) It does not appear to be the case. It worked fine in Aperture Priority. Could a newer firmware I might have upgraded the camera with, allowed for faster shutter sync speeds with the SB-800??

It does not explain what happened at the island though. Maybe I did not set the D300 to sync with the hotshoe flash in FP mode, as I do not recall seeing the "FP" mode on the SB-800 LCD panel. The "FP" mode needs to be turned on for the camera to sync with the SB-800 up to the camera's own maximum shutter speed. It could also be that I did *not* use the SB-800. I might have just used the built-in flash, which I think was limited to 1/320 sec.

In any case, I am now more ready for a wedding in a couple of weeks. I am sure my relatives will want their pictures taken everywhere, so I had better be ready for it.

D80 and SB-800 high speed flash sync

This modern piece of electronics is sure packed with a ton of features. Add a hot shoe flash and the feature set just got expanded by another 50 different options, or maybe more.

When the SB-800 was shoed on the D80 in the Aperture Priority shooting mode, I noticed that the shutter speed was always at a constant 1/60 seconds regardless of what aperture setting I dialed. Could there not be a way to increase the shutter speed? There is.

Last night, my mind got really curious. I could not understand why I could not shoot faster than 1/60 seconds with flash. 1/60 seconds is fast and the flash would freeze your subject but 1/60 seconds is still slow if your subject is a fluttering hummingbird. Well, I did some testing and so far this is what I found out.

First, the maximum flash sync speed, which is the fastest shutter speed possible where the whole sensor is exposed to light, of the D80 is 1/200 seconds. That speed is how fast a Focal Plane shutter curtain can move across the sensor surface. Faster than this shutter speed, the two shutter curtains will move in tandem with a small gap equal to the shutter speed between them. Without the SB-800 speedlight, the fastest shutter speed when flash is used is 1/200 seconds.

With the built-in flash, in Aperture Priority mode, for some reason I cannot understand yet, the fastest shutter speed is 1/60 seconds. In Manual and Shutter Speed Priority modes, the fastest speed can be set to 1/200 seconds. So, if you want to shoot at speeds faster than 1/60 seconds with the built-in flash, you need to switch over to Manual or Shutter Speed Priority.

With the SB-800, it is possible to go beyond the 1/200 seconds limit. On the Nikon D80, Custom Menu item #25 is called 'Auto FP'. FP stands for Focal Plane, referring to the Focal Plane shutter curtains. Auto FP should be turned on to enable automatic High Speed Sync between the D80 shutter and the SB-800. This will allow the camera to shoot at speeds up to 1/4000. For an explanation of how the Focal Plane shutter works, I highly recommend this article by Derek K. Miller (the best explanation, albeit a little long, of how the shutter curtains work I have read so far) and this video of the Nikon D3 shutter.

Once you have turned on 'Auto FP', it is still not possible to use speeds faster than 1/60 seconds in Aperture Priority mode. You need to switch over to Manual or Shutter Speed Priority to crank the shutter speed all the way to 1/4000 seconds. This is very cool but I wonder if it is any useful. The fact is, at speeds past the maximum sync speed, say 1/500 seconds, the second Focal Plane shutter curtain trails the first curtain by 1/500 seconds, i.e. exposing the sensor to light by a slit that lasts only that much time. When the flash pops (not a single flash but multiple flashes, i.e. strobes) the sensor is exposed to the reflected light through a moving slit. The slit moves down the sensor surface in 1/200 seconds. I wonder if shooting a fluttering hummingbird at a shutter speed of 1/500 this way is better (strobing light) than simply keeping the shutter speed within the maximum flash sync range (one flash pop).