I need lighting help please. :) - DPChallenge Forums

Canon EF 100mm f/2.8 Macro

12/30/2006 01:41:13 PM · #51

Originally posted by liquids:

Here is a short description of my general approach:

I have used a variety of Canon digital SLRs: D60, 10D, 20D, and now the 5D. In some ways the 20D has been the best for this work.

I like a 180mm macro lens: it gives me good working distance, a narrow angle of view, and excellent optics. The camera is about 2-3 feet from the splash zone to get a reasonable field of view.

I use fairly typical high-speed photography techniques:

I leave the shutter open for a relatively long time (in a darkened room) and use a flash to illuminate the splash. The flash needs to be of a fairly short duration to stop the motion well. I use something like a 50 microsecond flash. I get this by modifying the photo sensor circuit on Vivitar 285HV flash. Timing the flash is done with a photogate and electronic timer. I have built my own timing and triggering devices (a few different ones, as I learned how to do it better.) www.hiviz.com has techniques, equipment diagrams, and kits.

The photography is actually the easier part of what I do.

Handling the fluids is what takes the creativity and patience. They are so willfully non-linear! I have developed a fairly complex system to create drops and do the timing. Still, I take a lot pictures and make a lot of mistakes.

One setup is described in //www.dpchallenge.com/how.php?HOW_ID=38.

You might have a look at: //www.photosig.com/articles/1489/article and //www.popphoto.com/howto/2508/you-can-do-it-how-to-photograph-water-drops.html

//www.makezine.com/flashkit/ looks like a reasonable starter kit.

North Carolina School of Science and Mathematics (courses.ncssm.edu/hsi/) has some good info.

Andrew Davidhazy, at the Rochester Institute of Technology, www.rit.edu/~andpph, has good information on high-speed techniques, as well as other fascinating types of photography.

Harold â��Docâ�� Edgerton, of course, is the father of the xenon flash tube and high-speed photography. Search for his books on Amazon.com.

users.skynet.be/fotoopa/ has some creative techniques.

Equipment for can be purchased from www.bmumford.com and www.woodselec.com.

Martin Waugh
www.liquidsculpture.com

Thank you so much. That was a very thorough post. I appreciate it. I'll go have a look at those sites. Thanks again! :)

Crystal

Message edited by author 2006-12-30 13:44:24.

yann

12/30/2006 03:44:49 PM · #52

Originally posted by Spazmo99:

Originally posted by yann:
Very interesting thread as I'm trying to understand how to better shoot water drops.

The question that's hunting my mind is: What's the speed of my SB-600 ?

I know my D80 has a max flash sync of 1/200 only which isn't fast enough for a really HQ freeze but if my SB-600 is faster, I should be able to shoot in a dark room and use the flash speed as the "shutter speed". So what is the speed of the SB-600 flash?

I've been trying to find information on that matter all over the net but found nothing concerning the SB-600.

Here there is someone saying the SB-800 is as fast as 1/56,000 but I'd like more information: //photo.net/bboard/q-and-a-fetch-msg?msg_id=00Ivcv

There has to be a chart somewhere with specs on flash speeds for the SB-600 like this...

power ---> speed
1/1 ---> 1/10,000
1/2 ---> 1/20,000
1/4 ---> 1/25,000
1/8 ---> etc...

I think you're confusing two things; flash duration and camera sync speed.

Flash duration is a function of your flash unit and the power setting. Lower power means a shorter duration. That's how the manufacturer varies power. The pulse of light isn't any brighter or darker for higher or lower power, the pulse of light is longer or shorter. That pulse will be much faster than the sync speed.

Sync speed is a function of your camera, specifically, it's the fastest shutter speed which the first curtain of the shutter is completely open before the second curtain starts to close. With shutter speeds faster than the sync speed, the shutter basically is a moving slit.

Ok but what are the numbers? That's what I'd like to know.

If I set my flash to full power (1/1), what's the pulse duration?
If I set it to 1/2, what's the pulse duration?

and so on, for all the possibilities.

I know it's gonna be shorter than 1/200, but what are the actual numbers?

liquids

Canon EOS-20D

12/30/2006 05:05:21 PM · #53

Yann,

//www.bythom.com/flashcompare.htm has specs for some Nikon flashes (for full-power duration), but not the SB-600. It would be a reasonable guess that the SB-600 is about 1 millisecond at full power, and at lower powers it will be roughly proportional.

In the end, you need to use a power setting that is low enough to stop the motion. But, unless you know how fast the subject is moving and the magnification, and do the math, knowing the flash duration is not going to be all that helpful anyway. Furthermore, the flash does not turn on and off instantly - it ramps up and down in a bell-shaped curve. The "duration" that is given is usually the 1/2 brightness value, but that doesn't necessarily tell you how much blur you will see (because the tail-ends of the time/brightness curve is still going to illuminate the subject).

All of which means that you're going to be experimenting just the same. Take a picture at each of various power settings, and see what you get.

Or, you can measure it in a couple of different ways (I use a fast spinning disk of a known speed with a stripe on it - a fast clock).

Martin

Spork99

OM System OM-1

Canon EF 100mm f/2.8 USM Macro

12/30/2006 06:57:30 PM · #54

Originally posted by yann:

A quick search found this:

Originally posted by Photo.net forums:

...To get a shorter effective flash duration you can use manual, variable power. For example the effective flash duration of the SB-600 at 1/8 power is approximately 1/6,600 second. The effective flash duration for 1/16 power is approximately 1/11,100 second. Please see page 88 in your SB-600 manual...

Link

Originally posted by mir.com's SB-600 page:

Flash duration (approx.):- 1/900 sec. at M1/1 (full) output; 1/1600 sec. at M1/2 output; 1/3400 sec. at M1/4 output; 1/6600 sec. at M1/8 output; 1/11100 sec. at M1/16 output; 1/20000 sec. at M1/32 output; 1/25000 sec. at M1/64 output

Link

Message edited by author 2006-12-30 19:01:13.

12/30/2006 10:45:51 PM · #55

Just got around to trying some more today. I havent looked at them all but this one is odd.

looks like a knife or a leaf or something. but anyhow. I think I have the lighting down. Thanks a bunch guys. My problem now seems to be focus. Since I'm dropping the water by hand it rarely falls in the same spot so in manual focus it's just not as sharp as it could be. I hope that makes sense. I need to set up a rig of some sort and get something good to make drops with rather than just squeezing a wet paper towel. lol. It's kind of messy and hard to control.

:)

Crystal

asimchoudhri

Canon EOS-5D Mark III

12/30/2006 10:53:25 PM · #56

Originally posted by jaded_youth:

[...]Since I'm dropping the water by hand it rarely falls in the same spot so in manual focus it's just not as sharp as it could be. I hope that makes sense. I need to set up a rig of some sort and get something good to make drops with rather than just squeezing a wet paper towel. ...]l

i like the picture... looks like the splash is from the first drop in a small stream. have you tried a dropper? they have them cheap at drug stores... if you clamp that in place (clothes pin or something) you can have a fairly good idea where it will land and thus be able to pre-focus. a dropper may also allow you to have more control over the size of the drop. your posts over the last two days have me excited about trying this...

Canon RF 24-70mm f/2.8 L IS

12/30/2006 10:59:51 PM · #57

Originally posted by asimchoudhri:

Originally posted by jaded_youth:
[...]Since I'm dropping the water by hand it rarely falls in the same spot so in manual focus it's just not as sharp as it could be. I hope that makes sense. I need to set up a rig of some sort and get something good to make drops with rather than just squeezing a wet paper towel. ...]l

i like the picture... looks like the splash is from the first drop in a small stream. have you tried a dropper? they have them cheap at drug stores... if you clamp that in place (clothes pin or something) you can have a fairly good idea where it will land and thus be able to pre-focus. a dropper may also allow you to have more control over the size of the drop. your posts over the last two days have me excited about trying this...

yeah I wasnt actually doing the drops yet when I took that shot I was just pouring the water into the plate to start but I kind of like how it came out. I'll definately get an eye dropper or something like that. I just havent gotten around to it yet. I'm lazy :P

kirbic

Canon EOS R5

12/30/2006 11:01:15 PM · #58

Just a note: I didn't see this posted earlier in the thread, so if I missed it I apologize.

IreneM's shot was done in a rather unorthodox way. She used *conntinuous* lights, 1000 watts worth, and set her shutter speed to 1/4000s. This is quite different from the approach where you use a short-duration flash in a dark (or semi-dark) room. In Irene's approach, the shutter controls the exposure time. In the traditional approach, the flash duration does, and the shutter speed is really of little importance.

Message edited by author 2006-12-30 23:02:26.