I have been volunteered to shoot portraits of couples in front of a Christmas tree at an office party tonight. In order to keep it simple I am going to bounce a 580 into an umbrella slightly off camera. I am wondering what aperture will give me a pleasing exposure of the tree. I am thinking about 4.0 - 5.6. Does that sound about right?
Almost forgot, you may also want to reduce your flash output by 1/3 of a stop or more so you will not blow out the Christmas tree lights. The Christmas tree lights will be warm so you may want to use a CTO filter on your flash for color ballance.
Won't a reduction in flash output result in an underexposed photo?
The way I will do it is to set my Sekonic on the shutter speed I want then adjust the flash power to give me the aperture I am looking for. I did a mock setup last night and that was at about 1/4 power with the "model" (my mannequin) about 3 feet from the umbrella. Are you saying I should do this and then drop the flash power slightly? (I shoot in M mode and trigger with a PW)
Almost forgot, you may also want to reduce your flash output by 1/3 of a stop or more so you will not blow out the Christmas tree lights. The Christmas tree lights will be warm so you may want to use a CTO filter on your flash for color ballance.
No, you don't have to do this. A proper flash exposure plus, as mentioned earlier, dragging the shutter to gather the tree lights will do the trick. Don't try to compensate for the color of the tree lights. The shutter shouldn't be dragged so long that it lets the tree lights actually illuminate anything, and if white lights look warm, that's fine.
John Power wrote:
Won't a reduction in flash output result in an underexposed photo?
The way I will do it is to set my Sekonic on the shutter speed I want then adjust the flash power to give me the aperture I am looking for. I did a mock setup last night and that was at about 1/4 power with the "model" (my mannequin) about 3 feet from the umbrella. Are you saying I should do this and then drop the flash power slightly? (I shoot in M mode and trigger with a PW)
The shutterspeed controls the ambient exposure and not your flash exposure. The lower your shutterspeed go, the more ambient light will be mixed with the flash exposure. 1/30th sec. usually gives a nice balance between flash and indoor ambient light. If you have a Sekonic L-358 you can meter the % of ambient and flash light for desired ratios.
Daan B wrote:
The flash duration will freeze motion... not the shutterspeed of your cam. At least, when shooting in manual
I have struggled with this concept. I can shoot at a low shutter speed and freeze the blades on a turning ceiling fan but about 2 years ago I shot a program where girls were modeling wedding dresses as they walked down an aisle. I set the SS to 1/30 to let some ambient light in and many of the photos were a bit blurry. I am now wondering if that was because maybe they were out of the range of the flash power hence the problem.
I know flash concepts are simple to many here but unfortunately I am not one of those
But I am getting there
Part of the equation of stopping action when dragging the shutter is to keep the ambient lights in the space, except those you want to be featured, off or down low. No light = no blur will be seen. So in the case of shooting the family in front of the tree you'd want to turn the tree on the and room lights off. The flash will illuminate the tree at the same time it illuminates the people and the lack of any ambient light will prevent blur.
In the case of the girls walking down the aisle the ambient light was too bright relative to the flash. If you wanted to freeze the action and get ambience in the background you'd want use a faster shutter speed to block out the ambient and then bounce a second flash off the ceiling to raise the "ambience" of the background with flash.
On a related note:
If trying to create blur trails behind a moving person with 2nd curtain sync you'd want to have enough ambient light on the moving person to create a "ghost" image that is about 1-stop under exposed while at the same time keeping the space behind them open so there is nothing flash will reflect off of. It requires a bit of planning. First you need to figure out how long it will take the person to travel about 2/3 the width of the frame to the point where you want to freeze them with flash. Say that takes 3 sec. Then that would be your shutter speed. You'd press the shutter just as they enter the frame, the ambient will create the blur trail as they move, then just before the shutter closes the flash will fire and freeze them 2/3 of the way across the frame. To get the ghost trail effect you'd need to find the aperture which makes the blur trail 1-stop underexposed, then adjust flash power for correct exposure at that aperture.
OK. Even 1/30s didn't give me the exact look I was hoping for but it was good enough. I used a silver umbrella. I think the next time I will stick with white. As it turned out there was a plug right by my light stand so I could have taken one of my 300ws Profoto monolights but the 580 did OK. I guess I should always throw one in the trunk when doing something like this...
