Posted by Kent Staubus on September 19, 2007 at 9:12 AM
After a year of thinking about it, I finally called up B&H and ordered three Elinchrom Skyport receivers and one transmitter for my three high powered Nikon flash units. These will allow me to set the flash units up to 400 ft. away so I can light up the dark. I plan on using them to light up moving trains at night, out in the rural areas. One thing I'm having to think about is how to meter the flash since they are not TTL. I have a handheld flash meter, but it won't always be possible for me to climb up on top of a railroad trestle and take a meter reading. I'm thinking what I might do to start is set the flash units in a line down the tracks and put each exactly the same distance from the tracks. That should make it simpler to come up with just one meter reading that works for all of them rather than having to adjust three. Maybe I could just take a guess based on the GN/distance formula and then adjust my camera exposure using the histogram? Where is a good online source to learn how to meter the flash manually?
Think of a train rolling 40 mph through the dark countryside on a cold Minnesota night, the crew all snug inside their Dash 9. As they cross a big wooden trestle bridge, --ZAP--!!!!! For an instant night turns into day, and just as quickly it's dark again. "What the heck was that?"
You're on the same thinking track I would use, Kent. Distance will be the key to flash intensity on the subject, irrespective of shutter speed (provided you don't go higher than max sync). An archery range finder might be useful for "measuring" distances you can't span on foot. If the flash is to be your sole light source on the train itself, that creates the possibility of going for much longer exposures to fill in landscape and/or sky details, too.
I'd sure let someone know that your are going to be "flashing" the trains, though. I'd hate to be in your shoes in the dark if the train reports that someone took a potshot at them!
Posted by Bob Miller on September 19, 2007 at 10:43 PM
Be sure to use your 5th battery in the flashes- it will speed up the recharge. Sounds like fun!
I would set things up in advance at any similar location sans train/ same time of day to do your tests to give you your base settings.
You might also look at setting the angle of view for the flashes, I dont have my manual with me to help with that. You might want to set it up so the forward flash is more a spot, and the 2 side are wides. Dont forget stands and some way to anchor them, the light might look better coming from above.
Elevation will be very, very good to keep from hitting the ground between the light and the train, and worse yet, closer to the light. You'll end up with really unsightly overexposed ground that will really detract from the light on the train.
If you can't get lots of elevation, try using a scrim (light blocker) to control the bottom edge of the beam. You can experiment with this at home, but basically the further the scrim from the light, the sharper the shadow edge and the easier it is to control. On the negative side, the further from your light the scrim is, the bigger it will need to be from side to side in order to keep the light from "reaching" around it. I'm betting that if you can get a scrim about 2' in front of the light it will give about the right effect at the distances I'm guessing you're working, but it will also have to be pretty close to 2' wide at the same time. You can get away with less, but experiment first and count on lots of light pops on site when you're positioning the scrims for your train shot. In that light, battery #5 will be very welcome on an SB-800. Be aware however, if it's windy those scrims make terrific sails and you'll need both solid supports for them and extra weight on your stands.
Scrims and elevation sound like too much hassle? Just be really conscious of the bottom edge of your light spill and position your strobes accordingly. Any kind of a scrim even 6" away from the light will help "flatten" the bottom so you can still concentrate the hottest part of the light beam right on the subject while not hitting the ground in front of it, but the shadow edge will be softer. And even that may be a good effect in your shot.
You cna divide the flash to subject distance by the guide number of the flash to get the f-stop. With multiple flashes you multiple the guide number by the square root of the number of flashes to get the guide number of the flashes combined. Example of 3 flashes with a guide number of 100 would be: the square root of 3 is 1.73 time 100 is 173 then divide that be the flash to subject distance. I hope this helps.
Discussion
4 repliesThink of a train rolling 40 mph through the dark countryside on a cold Minnesota night, the crew all snug inside their Dash 9. As they cross a big wooden trestle bridge, --ZAP--!!!!! For an instant night turns into day, and just as quickly it's dark again. "What the heck was that?"
Kent in SD
I'd sure let someone know that your are going to be "flashing" the trains, though. I'd hate to be in your shoes in the dark if the train reports that someone took a potshot at them!
I would set things up in advance at any similar location sans train/ same time of day to do your tests to give you your base settings.
You might also look at setting the angle of view for the flashes, I dont have my manual with me to help with that. You might want to set it up so the forward flash is more a spot, and the 2 side are wides. Dont forget stands and some way to anchor them, the light might look better coming from above.
Elevation will be very, very good to keep from hitting the ground between the light and the train, and worse yet, closer to the light. You'll end up with really unsightly overexposed ground that will really detract from the light on the train.
If you can't get lots of elevation, try using a scrim (light blocker) to control the bottom edge of the beam. You can experiment with this at home, but basically the further the scrim from the light, the sharper the shadow edge and the easier it is to control. On the negative side, the further from your light the scrim is, the bigger it will need to be from side to side in order to keep the light from "reaching" around it. I'm betting that if you can get a scrim about 2' in front of the light it will give about the right effect at the distances I'm guessing you're working, but it will also have to be pretty close to 2' wide at the same time. You can get away with less, but experiment first and count on lots of light pops on site when you're positioning the scrims for your train shot. In that light, battery #5 will be very welcome on an SB-800. Be aware however, if it's windy those scrims make terrific sails and you'll need both solid supports for them and extra weight on your stands.
Scrims and elevation sound like too much hassle? Just be really conscious of the bottom edge of your light spill and position your strobes accordingly. Any kind of a scrim even 6" away from the light will help "flatten" the bottom so you can still concentrate the hottest part of the light beam right on the subject while not hitting the ground in front of it, but the shadow edge will be softer. And even that may be a good effect in your shot.