Why light beams front? A photographic question.

If it's an LED light I have notice that they pulse and if you turn your head real fast or have a slow shutter speed it will look like a string of lights. I am guessing that the locomotive in question is traveling left to right in the pic.

 

Jerry

I also figure the loco was traveling left to right.  Guessing the ghost images are a result of the difference from the time the shutter opened until the flash went off.

 

In my opinion on camera flash is an abomination.  Invariably the foreground is washed out, the background dark.  Far better to turn off the camera flash, use a tripod and whatever light is available along with the camera's self timer to trigger the shutter release, and the in-camera white balance to adjust the color, or adjust it in the photo software that came with the camera.

 

Pete

 

 

Gentlemen. What you have there is a short exposure from the flash, like 1/1000 of a second, exposing a much longer camera shutter picture. The camera is trying to shoot an available light exposure which is probably 1/4 or 1/2 second, while the flash jumps in and does an instant exposure with the proper intensity for the aperture, size of the lens openning. Because the electronic part, the flash, is properly exposed, the lens part, shutter/aperture is obviously not set properly.  Most likely you have set it for available light and then forced flash.  Being an electronic/mechanical combination, there could be severalactual explanations for this phenomenon/mistake.  But be advised that there are times that you would want this to happen.  If the loco is STANDING STILL the photo would show a nicely exposed loco with softer balls of light for the headlights etc. This is also how you would do a shot of the loco with long streaks of light.  A good tripod is required and a fair amount of testing is required to produce the result. Hope this guides you in the direction you seek.

The shutter was open longer than the flash lit the scene.  So the headlights were still on so they show in the photo the whole time the shutter was open.

The locomotive was traveling forward, long hood forward, or right to left in the photo. I could have understood it if the locomotive was traveling left to right, as some of you surmised. But it was not.

shutter goes off and flash triggers. Depending on power flash duration is somewhere between 1/500 th to 1/2000th of a second. the shutter is open after the flash anywhere for 1/60 to 1/250 th of a second. During that time the train is dark except for the headlight. The headlight has just enough exposure to be recorded (its about 1 stop under exposed) pulsed could be oscillating of it

 

this is the same idea I shoot roller derby with. My camera synchs about 250th. I underexpose the background 1-2 stops and set the flashes to go off around 1/4 power .the flashes give me. An effective speed of about 1/800 th and the ambient is low enough that I do not get much secondary exposure. But if the skater had a light I would get the same effect you get. 

If your camera has the option you can use a trailing curtian fls sync.  This mean that the flash goes off as the shutter begins to close.  Are you shotting in auto or manuel.  You really need to set the camera yourself, use the flash sync which is probably1/250, I am guessing as I am not familiar with that model.  I hope this helps.
Ron

I have to be nasty and say, they are 'Foo' 'Fighters!"

Ralph

My conjecture is pretty much as Chris states.  But I believe the lower headlight and class lights (notice there is two balls there too) must actually be very quickly pulsing.  The top headlight beam of light represents the length the engine moved after flash but before shutter closed and the lower headlight & class light balls are two pulses during same length of travel.

 

Just my two-cents.

My question is this:  what exactly are you trying to achieve shooting a moving target with a flash?  

Ron S has the solution if you insist on shooting a moving target.  You should use a trailing shutter.  The effect you are seeing has to do with WHEN the flash fires during the time that the shutter is open. 

 

If you do as Ron S suggests, with the exact same settings on the camera (exc use trailing shutter), you will still have light streaks but they will trail from the start of the loco towards the back, not in front of the loco.  

I agree with other comments, though, if the blur ("speed blur") isn't your specific intention, shoot a standing loco.

Ron

If you're trying to get a "speed blur" you need to lose the flash and bring in external lighting.  

Thank you, everyone, for the comments. it seems the consensus is that it has to do with light/shutter relationships, but I confess I am still unclear as to the actual physics.

 

Why a visible "beam" of light is seen in front of the locomotive, moving in that direction, remains a mystery to me.

 

In response to questions like this: "what exactly are you trying to achieve shooting a moving target with a flash?"

 

I really wasn't specifically trying to achieve anything. I was just playing around taking photos of the trains while operating them.  With the limitations of the relative darkness of the museum at that time of morning, and the limitations of the camera, I was just trying to get a photo without a blur. Seems to work on the locomotive, the light observation was a surprise.

 

 

Bill, the beam of light is because the train is moving across the open shutter after the flash has gone off.  The flash illuminated the train in one spot, but the headlight is bright enough to keep showing up on the cameras sensor.  The spots, I would presume, are because the bulb (an LED?) is actually flickering on and off at a rate that the human eye can't see, but the camera captures. 

I was wrong about the direction of travel.  Chris has it right.  Shutter opens, extremely short duration electronic flash fires, shutter remains open long enough to allow the engine to travel forward and for the lights to register the amount of travel, which would be dependent on the speed of the loco.

 

Apparently sophisticated cameras have a "trailing curtain" flash sync, which means the flash triggers as the shutter is closing.  Didn't know about this and I'll certainly look into it if I decide to move up to a DSLR.

 

Pete

Being a professional photographer, I can unequivocally say....that the orbs of light means your train is "haunted"     time to call Ghost Busters!..

Here is an explanation that even uses a model train and discusses the leading and trailing (2nd curtain) flash synch

 

http://photo.stackexchange.com...second-curtain-flash

Very interesting - I had no clue about any of this.

Here is another explanation with good illustrations of normal and second curtain.

 

Thanks for posting, Bill!

 

Alex

Thanks to all who responded and for the great links. I've learned a lot today, thanks to OGR and its members.

Phasers and photon torpedoes?

 

Jerry