Help required shooting high-speed action with flash

[carregwen]

I know it's bad form to link to rival sites, but this tutorial is very interesting. I've tried shooting water drops, but reading this it looks like I have been doing it all wrong. I tried in a kitchen where there was ambient light coming through a window, combined with my flash. But Ash seems to use a very low level of flash power close to the subject in a completely darkened room. Has anyone tried this method? It certainly produces some stunning results. Does what he says about the power levels and a darkened room make sense?

http://www.talkphotography.co.uk/for...d.php?t=208624

[rick55]

Hi, Rob;

This is very much the setup that I used for my water drop shots posted here. The thread includes a link by Jereon to a video about the techniques. I turned off all the lights in the room. There was a little light from a door, but if the flash didn't fire, the exposure was dead black. If you look at Jim B.'s album, he has a photo of his setup, which looks very much like that described in the setup in the thread you reference. That was the "light going on" for me (no pun intended). I had been putting my flash too far back, on a stand, and trying to keep it below the level of the basin. I moved it forward, just out of frame, and nuked the reflector. I didn't use the snoots (might be worth trying).

I used half power for my shots. According to this page, half power on a 580EX is 1/1667 s burst. You can see in the "coronet" shot that the tiny droplets are blurred a bit.

In the shot I did of my table saw, I used 1/16 power to freeze the blade. Same kind of thing: I had some light in the room, but I made sure it was low enough that with no flash, it was a black screen.

Cheers,
Rick

[JK6065]

I think I'll try this technique next week since I think it does make sense. It helps freezing the droplet completely and for me this is a way to shoot with the flash not mounted on the camera (I don't have any equipment to use the flash remote).
Though timing still is the critical part and capturing a collision will be a really hard one to get.
Though I'll let you know if this technique worked for me.

[rick55]

Though timing still is the critical part and capturing a collision will be a really hard one to get.

I cheat on the timing. I made a pump with a servo motor, 1/8 inch tubing, and some check valves from Amazon. The servo motor squeezes two loops of the tubing, with a check valve before and after the loops.

An Arduino microcontroller board controls the servo motor, and also fires the camera, so about half the shots are captured at the expected point of the cycle. I figure I'm better at hardware and programming than I am at photography, so I might as well take advantage of it.

I'll be happy to pass along the Arduino code and the circuit for firing the camera, if anyone's interested.

Cheers,
Rick

[carregwen]

Rick

Thanks for all the info. That video is pretty amazing - more like a science lab than a photography studio! I'm going to have to give this a go over the next few days. I can see that the timing may be the difficulty, but there are several options (one of which you mention) for getting that sorted.

[rick55]

Here's a blog with a video of a set-up that's much more "do it in the basement": gavtrain blog. See "week 52." The setup looks like mine (and Jim's, which I shamelessly copied). I use a microphone stand for the tubing from which the drop emerges, rather than a lab-style support stand, since I don't have to support the weight of the water.

Cheers,
Rick

[Jim B.]

Hi Rick,
Sounds like you have a nice setup put together.I'm not comfortable working with electrical stuff to build a trigger system.
If I had money to burn I'd get one of these:
http://www.bobrigby.com/brp_products...utterbeam.html
For now,I rely on my sense of timing.

I set up with lights on to get the camera focused.Start a drip with a frequency that I think will produce.I turn lights out and use a flashlight to get my timing down for the drops.

I start firing at the interval I have in my head.I get good results this way,but would like to get a bit more precise on timing.

I haven't figured out the timing and drip interval to get drop collisions yet.

[rick55]

Hi, Jim;

The shutterbeam looks like a very cool set of gadgets!! But boy, they aren't cheap.

Cheers,
Rick

[Andy]

Does what he says about the power levels and a darkened room make sense?

Yes - less to reflect in the water in a dark room and the lower the flash power the faster the flash duration.

You could just use the max flash sync speed and lowest ISO to kill the reflections. As long as the flash is reasonably powerful you should be OK for freezing the action.


The wings aren't quite frozen but I doubt water drops will be moving as quickly. I took that outside on a nice sunny day.

[carregwen]

Yes - less to reflect in the water in a dark room and the lower the flash power the faster the flash duration.



The wings aren't quite frozen but I doubt water drops will be moving as quickly. I took that outside on a nice sunny day.

I'm sure there are a lot of people confused by flash power/timings (I certainly was until I found out) I always thought that if you turned down the power on a flash it did just that - turned down the power level and fired for the same period of time. I never knew that it simply fired for less time. I knew that flash wasn't really affected by camera shutter speed because it normally fires faster, but this business with power levels was new to me. Thanks to everyone here so far for their comments.

In your bee shot you have nearly frozen the action, and it looks as if you have made the background darker than it probably was (which is what I would normally want to do) - is that right?

[rick55]

Hi, Rob;

This is a simpler example than Andy's. I had enough ambient light from a couple of windows on a slightly overcast day to see what I was doing. But an exposure without flash just showed on the display and a line on the left of the histogram. I had a 580EX with umbrella on the left, set on manual at 1/16 power. I also had a slaved 430EX forward just out of frame to the left, bounced off the ceiling, so as to illuminate the background a bit. I could have used another flash, or even a fixed light: I would have liked to at least try it with the background a bit brighter.

A 3500 rpm table saw with a 10 in. blade has teeth moving at about 1800 in./sec. So the 1/15,000s flash strobe allowed about 1/10 in. of movement.

Cheers,
Rick

[carregwen]

Hi, Rob;

This is a simpler example than Andy's. I had enough ambient light from a couple of windows on a slightly overcast day to see what I was doing. But an exposure without flash just showed on the display and a line on the left of the histogram. I had a 580EX with umbrella on the left, set on manual at 1/16 power. I also had a slaved 430EX forward just out of frame to the left, bounced off the ceiling, so as to illuminate the background a bit. I could have used another flash, or even a fixed light: I would have liked to at least try it with the background a bit brighter.

A 3500 rpm table saw with a 10 in. blade has teeth moving at about 1800 in./sec. So the 1/15,000s flash strobe allowed about 1/10 in. of movement.
Cheers,
Rick

Quite safe to reach across and put your hand on in fact?

Yes, that shows it really well - good example. I can't understand why you can't have a camera function that allows you to record flash exposure as well as shutter exposure. Surely the flash unit (which is usually coordinated with the camera) can measure it and record in EXIF.

Your mixed lighting seems to work well. I suppose the ideal setup is to get some ambient or even flash light to illuminate the background but not influence the foreground subject too much, but leave that to the foreground flash?

[rick55]

Quite safe to reach across and put your hand on in fact?

If I got my hand in and out in 1/15,000s.

I can't understand why you can't have a camera function that allows you to record flash exposure as well as shutter exposure. Surely the flash unit (which is usually coordinated with the camera) can measure it and record in EXIF.

That's a really good point. It wouldn't work in this case, since I used an RF trigger, but with a setup like Canon with the 580 on the hot shoe, there's no reason it should only put in "flash fired." If you can set the custom functions through the camera, surely it can tell you how much flash power was used, which would be very valuable information: if you knew how much was fired in an ETTL blast, you could use it to adjust manually.

Your mixed lighting seems to work well. I suppose the ideal setup is to get some ambient or even flash light to illuminate the background but not influence the foreground subject too much, but leave that to the foreground flash?

Exactly: in this case it was the slaved 430, which was a little dim, bouncing off a high ceiling. I might have tried turning on the overhead lights, but they're fluorescent, and at 1/125, I worry about catching the flicker at different points. With more ambient light, there's also some concern about getting some illumination of the saw blade, but that might be okay. It would be worth turning on 2nd-curtain sync in that case, which I didn't do here, since I had effectively zero exposure of the main subject area without flash.

Cheers,
Rick

[JK6065]

This morning I tried the technique as in the tutorial rob posted.
It allows me to freeze the water about literally and allows me to flash from behind.


1.6s . f/11.0 . ISO 400 . 125 mm . flash manually at 1/32

I'm still working on some kind of technique to time the shot exactly right to capture collisions.
But anyway, using only the flash for exposure works very well and gives you stunning 'freezes'.

[carregwen]

This morning I tried the technique as in the tutorial rob posted.
It allows me to freeze the water about literally and allows me to flash from behind.


1.6s . f/11.0 . ISO 400 . 125 mm . flash manually at 1/32

I'm still working on some kind of technique to time the shot exactly right to capture collisions.
But anyway, using only the flash for exposure works very well and gives you stunning 'freezes'.

Think I should point out I only posted someone else's tutorial - it wasn't mine. I wouldn't know where to start

Excellent, Jeroen. Really good for first go. Did you use a darkened room? Needs a little food colour in the water or some colour gel on the flash? I have to try this. (Note to self: Don't get addicted to something else)

[JK6065]

I'm aware that it isn't your tutorial, though I might have not been clear enough in my comment.

It was only a first try to see how it would work. I did not pay that much attention to colours. I'll do that next time, just like trying to get the collision captured.

I used a nearly dark room to get the exposure completely black when shooting without a flash but with al little bit of light so I can see what I'm doing anyway. Though the dark environment makes it's very difficult to time the shots, since I have to do it all by hand. Especially capturing the collision is very difficult because of the dark room.

[rick55]

Beautiful shot, Jeroen!

I should have noted before: I have overhead lights where I do the water drops, and I turn them off because I've discovered that with the ripples, water will find anything possible to reflect. But I leave on some lamps that are "out of the view" of the pan. As long as I don't have any specular highlights on anything visible from the pan, and the room light is low enough that an exposure without flash is black, I find that I can have light in the room.

Cheers,
Rick