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Old 03-17-2015, 10:07 PM   #53
Noct Foamer
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Location: South Dakota
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Quote:
Originally Posted by KevinM View Post
Hi Kent,

1. The biggest concern that I would have about using flashes is temporary degradation of the crew's night vision. It takes about 30 or more minutes for the human eyes to adapt to the dark and develop their maximum sensitivity. ... The concern is, of course, that if the crew's vision is degraded, even for just a short time, and something were to appear on the tracks ahead, their recognition of the situation, and therefore their response, could be delayed.


2. I've been tempted to try night flash photography, but the stories that I hear from pilot colleagues about being flashed with laser pointers and other devices during the critical minute or two before landing just leave me concerned about putting train crews in a similar position.

1. I'm now going on my tenth year with flash, and have photo'd hundreds of trains, mostly in the Midwest. I have some experiences and observations. Living where I do, I know quite a few of the train crews fairly well to quite well. We talk. What they've told me over the past decade is that my flash are so fast they really don't have any impact on them at all. There are maybe three reasons for this. First, the duration is about 1/1000s and they are relatively far away. The eyes don't have time to react. Second, crews are looking down the tracks and I place flash off to the side at angle. Third, their eyes are NOT accustomed to dark--they are staring down the extremely well lit path made by those three bright headlights. I've measured the light from those headlights and it's about half the strength of my biggest flash at full power. The headlights are actually stronger than the little 4AA flash I often use. So, this is a total non-issue as their eyes are NOT accustomed to darkness in the first place. At any rate, hundreds of trains going on 10 years and not a single complaint or issue. I have sat in cabs with my biggest flash pointed directly at me (on conductor's side) and popped it from about 40 ft. away with an 8 in. high output reflector. It was surprisingly low intensity! Train crews repeatedly tell me that coming to a grade where a big truck has its brights on is far more of a problem than my flash. This is believeable because the truck lights are constant where mine are a fraction of a second. As for my little 4AA flash (Nikon SB-25,) the type 90% of the guys use because they are cheap and fast, crews sometimes don't even see them go off at all! It's just not an issue. As long as I'm not fouling the tracks, they don't care. When I started out I used the little 4AA flash at 1/4 power because I was a little nervous, but after talking to these guys for years, I now will put out my big monolights, equiv. to 15-20 of the little 4AA flash, and use them at full power. Naturally with that much power it means that I can place them much further back than I can the little flash. In this shot I had two monolights at full power placed 60 yards from the track and a third placed 100 yards away. Light loses strength very fast--geometrically:

https://www.flickr.com/photos/96826069@N00/16658345346/

I will add that I do avoid setting up right before a switch or a W-board, more because I don't want to be a distraction. I do this during the day as well--the distraction is me, not the flash.


2. Laser pointers are a different matter entirely. They are a highly polarized beam, very concentrated. The beam holds together over great distances and the more powerful ones (used for astonomy) will actually permanently destroy your retina. It's not the same thing at all. (I took a lot of science/physics for my medical science degree.) Think of throwing a single 4oz. rock vs. throwing 4 ounces of loose sand.



Kent in SD
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