>for a slightly more realistic effect.

Interesting. I do a lot of photography with flash and you got me thinking about what the "realistic picture" looks like. To get a definitive answer, I'd setup my video camera, then pop a flash, then analyze the result. In lieu of that, I'm forced to thought experiment:

First, the flash exposure of most cameras will be 1/60 second, however, the flash will be "pre-exposing" for perhaps 1/4 second (maybe less?) with a steady light, then it will pop (probably still steady?), then the light will decay for perhaps 1/4 second. So I think Chienworks half a second value is about right. IOW, you're going to have the effect for 1/2 second. Still, I'd guess a quicker (1/10th second) increase, followed by a longer decay (4/10th second) would be more pleasing.

Second, the screen shouldn't go completely white. (After all, its only the people looking *into* the flash that are snow blinded :-). More realistically, the subject goes very bright and with a great deal of contrast.

But I might be on the wrong track, spewing irrelevant information. The big issue is: Do you want the screen to imitate (1) what its like to be in the room where the flash is taking place, or do you want the screen to imitate (2) the results of the flash, i.e., the flashed-still picture? These are completely different.

If (1), then its a 1/2 second effect keyframing the brightness/contrast (b/c) at the very least. You might also need to keyframe the saturation. I'd use the color curve instead of the b/c, since you'll need to "cheat" a bit to make a nice picture, i.e., the b/c is a sledgehammer, while the color curve is a chisel. For greatest accuracy, try to brighten everything close to the camera lens to near-white, with a more subtle increase for the background. This might require masking, a not-so-easy technique in general.

If its (2), then forget most of the above. Insert a b/c that goes near-white, then fade into a still and hold the still for a second or two, before cutting back to the scene. Generate the still by taking a snapshot of the event. Edit the still as follows: Add brightness and contrast to everything in the *foreground* (you will probably have to mask the foreground, no easy task), and darken everything in the background. Basically, brightnes is determined by proximity to the camera lens.

...This might have been more than you wanted to hear :-) I'm actually just about to start the video portion of a wedding slide show project, and this was an opportunity to think out loud. IOW, I might try some "flash" transitions between stills. I'm hoping to see anyone with some prior experience chime in.

Chienworks, after all that I think your solid white overlay + opacity blend will work better than messing with the b/c. Or perhaps a combination of the two. Its probably really hard to get that "white flash" solely with the b/c in a way that doesn't turn the picture into something completely unrealistic. Perhaps a composite with a multiply rather than an add? Something that crushes the whites and contrast at the same time.

What about just using the flash transition?

Using the flash transition would require splitting the event and then extending one side of the split over the other. True, it wouldn't involve generated media on another track, but i tend to prefer more explicit methods (add a white event) to implicit methods (crossfade two clips and add an effect) as they are often easier to grasp and follow, even if they may require more keystrokes or mouse clicks. The other problem with the flash transition is that the ramp up and fade times are equal which doesn't seem like a realistic flash. Flashes usually start almost instantaneously and then seem to fade more slowly.

Of course, Vegas usually allows many different methods to achieve a goal. Adding a Fade to Color envelope with a top color of white, bumping it up to 90% top color over a frame or two, then back to normal over half a second or so is probably the absolute simplest method. It's probably not very obvious for a beginner though.

Here's another technique originally posted by Briggs last year. I've used it and it produces a great effect... (I haven't tried the Flash FX, but I will next time)

<snip>
Camera Snapshot Effect

Here's a relatively easy to do effect I've seen used to simulate someone taking still shots with a camera.

1. Insert a velocity envelope. Zoom way in on the frame that will represent the snapshot and, just after it, add two envelope points. Set the first one to normal speed and the second one to 0%. Drag the right end of the event out for however long you want to hold the still shot. (Right click the event, select properties, and turn on the resample and reduce flicker options.) Setting a stop motion like this communicates to the viewer the exact shot that was captured by the camera.

2. Add the Brightness and Contrast video event FX to the event. Add a keyframe at the frame where you went to 0% velocity (let's call it "X"). Add a second keyframe at X minus 1 frames, and a third keyframe at X plus 6 frames. Set the middle keyframe (X) to Brightness=0.40. This step simulates a camera flash and subsequent fade.

3. Add the Black & White video event FX to the event. Add a keyframe at X and X minus 1. Set the X keyframe to Blend=1.000. The black and white effect combines with the stop motion to help distinguish the shot that was captured.

4. Add a camera shutter sound effect (I got one by searching findsounds.com). Drop out your existing audio during the stop motion if you want to further enhance the effect.

<snip>

He's uploaded a sample video (Camera Snapshot Effect) to Chien's site
http://www.vegasusers.com/vidshare/

Frenchy