2

I would like to capture the flight path of my darts in long exposure, however I don't have much experience of the technique.

The flight time of the dart will be approximately 120ms, possibly slower with a modified throwing action. With a luminous flight, is this likely to be long enough to capture a light trail in complete darkness?

Before I invest in this whimsical project, it would be good to get an idea of how likely it is to succeed, and if there is anything I can do to improve the results.

Edit: I will be using a Canon 60D DSLR.

Johnoldinho
  • 21
  • 3
  • Related: https://photo.stackexchange.com/q/21776/9161 – Saaru Lindestøkke May 12 '20 at 14:17
  • @szulat I thought of that, too, but getting one that will pulse multiple times within the space of 1/10 of a second might be not-quite-cheap... – twalberg May 12 '20 at 14:39
  • Very interesting suggestions that did not occur to me, I will explore this further. – Johnoldinho May 12 '20 at 15:23
  • @twalberg you would be surprised. There’s a stroboscope app that I downloaded on my phone to see how fast my fan was spinning. Somewhat dim because you’re limited by the brightness of a phone light, but it was surprisingly useful – Ryan May 12 '20 at 20:40
  • @Johnoldinho Do you want to "freeze" the darts or show a continuous blurred trajectory? – Michael C May 14 '20 at 04:39

2 Answers2

2

If you use continuous light, even against a well-darkened backdrop, the dart will show only as a faint streak. If the dart takes 120 ms to fly from hand to board, any given position's image will last only a fraction of a millisecond, and continuous lights bright enough to record the dart well will be huge, hot, and expensive.

A repeating electronic flash in addition to the continuous light is probably the way to go -- a series of frozen images, with the streak of light connecting them, will both give the impression of motion and tell the viewer what they're seeing.

Older camera flashes can't be set up to do this, though apparently many more current ones can. Otherwise, you need a true stroboscope, and these aren't as common as they used to be. You might be able to borrow one from a high school or college physics department, but be sure you get an understanding, up front, who pays for repairs if a 40-50 year old piece of electronics fails while you have it.

An alternative that might take several tries to get just right (and will be much harder to check success on film than digital, unless you're shooting an instant type) would be a drag shutter flash shot. If you have a shutter that can do M sync, you can fire the shutter when the dart leaves the hand, and the 20-22 ms M delay will let the dart fly partway before the flash fires, giving a single nearly-frozen (or fully frozen, depending how much flash power you need) image, but the continuous lights will still give the streak and, with a shutter speed of around 1/4 or slower, a reasonably solid image of the dart in the board.

Zeiss Ikon
  • 7,141
  • 13
  • 37
  • Plenty of low cost strobes have the ability to do 'Multi' mode strobe which is stroboscopic flash for x number of pulses at y pulses per second. – Michael C May 14 '20 at 04:42
  • 1
    @MichaelC I often get caught by the term "low cost" in photography. Does that mean under $100, or under $1000? – Zeiss Ikon May 14 '20 at 11:08
  • Pretty much every shoe mounted flash I paid more than $100 for has had the feature. Most were in the $100-200 range. Studio lights don't always have it, but higher end ones do. – Michael C May 15 '20 at 02:02
  • @MichaelC that explains why I'm not familiar with that feature, then -- the most advanced flash I've owned was a SunPak made in the early 1990s. Auto exposure and, as I recall, a zoom light pattern. I'm not a big flash user or a studio shooter. – Zeiss Ikon May 15 '20 at 11:00
1

I don't have an answer on whether or not this will succeed (my feeling is it won't because the flight is too dim), but if you have access to the camera the most practical thing would be to just try.

The largest unknown is the brightness of the luminous flight, that makes it hard to predict.

A first step would be to see if the camera registers the luminous dart at all:

  • Charge up the luminous dart in the sun (not sure how long, but longer is better I think)
  • Set your lens to the widest aperture. That's the lowest F-number, depending on your lens that's somewhere between 1.4 and 3.5.
    • A wider aperture gathers more light. If you can choose lenses, choose the one with the largest maximum aperture (lowest number)
  • Set your shutter time to 1/10 as that matches the flight time of 120 ms the closest.
  • Set the ISO to the highest setting available (that's 12800 on a Canon 60D)
  • Focus on the dart
  • Darken the room as best as you can
  • Take the picture

If the flight is clearly visible you can now continue and try if the flight remains visible on the photo when you throw it.

If the flight is very dim, or not visible this won't work with your current gear. A camera with a higher maximum ISO is needed (often expensive), or a brighter flight/dart is needed. Maybe you can put something together with an LED?

Saaru Lindestøkke
  • 8,648
  • 3
  • 39
  • 94