Showing posts with label High Speed Photography. Show all posts
Showing posts with label High Speed Photography. Show all posts

Thursday, 29 September 2011

High Speed Photography

High Speed Photography is used in physics, health research, sports and more. This article describes how to capture super fast movements using ordinary camera gear and a little home made electronics.
How to take photos like the one you are seeing here. It's a glass of Champaign, being shot with a BB gun. It is the same idea as posted in this gallery. You can use this technique to take picture of exploding things like tomatoes, watter balloons, watermelons, or even you Canon camera as you smash it against a wall for not understanding the menus (Sorry, could not resist...) 

Freezing fast motion (AKA High Speed Photography), can give some pretty special photographic effects. High Speed Photography is used in physics, health research, sports and more. This guide describes how to capture super fast movements using ordinary camera gear and a little home made electronics. I will describes the setup I used the problems I encountered and what I did to solve or work around them.

Here is a nice example of High Speed Photography:

Capturing a balloon just as it punctures

Nuking an apple 


Capturing such images introduces a lot of challenges. How does one handle timing with exposures times

faster than 1/6000 second!?
We have to handle shutter lag, synchronize the flash and time the exposure to just the right moment.

But the shutter lag of any normal camera is so long that it will be all most impossible to time the exposures. And how do you synchronize the flash with an exposure time of less than 1/6000 second?
To work around the problems with shutter lag and flash synchronization, the exposure is done in a completely dark room. This way the shutter can opened without actually getting an exposure. The exposure time set on the camera just has to be long enough for the action to happen while the shutter is still open. Because the room is dark, the long exposure time will not have any effect on the final output (this is because no light enters the lens to hit the sensor / film)

To actually get an "exposure", a flash is fired. The flash light duration will now become the actual

exposure time.
SO now we need to see how long does it takes the flash to fire. It turns out that the output power of the flash, actually affects the duration of the light, so to get exposure times. If you need exposure faster than 1/6000 seconds, the output needs to be reduced. For more information on the light duration please see the test I ran on my Sigma EF-500 flash.
Now we only need to synchronize the flash with the action we want to capture.
This can be done in several ways. For example synchronizing with a balloon puncture, can be done via sound. Impact-actions, like a BB Soft air gun pellets, can be triggered with a mechanical switch, like in the picture below. When the pellet hits the cd-cover it's pushed on to the switch, which then triggers the flash.

The Gear:
  • Balloon (OK - we are going to nuke this one, so don't use your favorite)
  • Digicam
  • Tripod
  • Sigma Flash
  • Home made sound trigger (more info). If you do not have an optical slave you can use the Universal Sound Slave Circuit
  • Needle (or BB-gun, see below)
  • Backdrop (I use a black Bristol sheet)
The Setup
First step is to set-up the scene. The black Bristol sheet is used as backdrop. The balloon, flash, microphone
and camera are placed like in to image below 
 
 
Gear settings:
  • Flash: optical slave and 1/16 output power.
  • Camera: Exposure time: 1-2 sec. ISO 100-200 Aperture F 11-16 manual focus.
  • Microphone: The distance between the balloon and microphone, is used for synchronization. 50-70cm is good for balloon punctures :-)
Next step is framing and focusing:
While trying to stay within the best performance on the lens, I either zoom or move the tripod, until I have the desired framing. Focus can be obtained either automatic or manual, but do remember to switch to manual to lock focus, otherwise the camera will try to focus when the lights are switched off.
Now it's time to test the setup and lightning. All lights are switched off and the shutter is set to bulb.

To fire the flash I just clap my hands. Then I review the image on the camera, checking for exposure, framing, focus and DOF.
To get the correct amount of light / exposure, one can Increase or decrease:

- the strobe distance to the balloon

- the output power of the flash

- the aperture on the camera

- ISO sensitivity on the camera

Taking the shot (pan intended :))
The test is repeated until satisfactory result have been reached, and the real photo can be taken. This is done the same way as when testing, but instead of clapping, the balloon is punctured with a needle.

One could also just fill the balloon with water and shoot it with a BB Soft air gun :-)


This article was contributed by Karsten Stroemvig (aka Lullaby), see his other great high speed photograph projects
 

Monday, 15 August 2011

Home-Made High Speed Photography

Pictures of high-speed events such as popping balloons, breaking glass, and splashing liquids reveal interesting structures not visible to the naked eye.

This is a quick tutorial to get you started with high speed photography

 Configuration: The flash settings can be confusing. Set the flash to ETTL and the camera work on P, but it is limited, so I will talk about a more flexible way to do it. I suggest you set the flash in manual mode and power setting to its lowest level or more (1 / 64). This makes the flash fire the very brief flash of light, which freezes the action better. Set the camera to AV mode and select a support of F-stop value (5.0 or higher). The higher F-stop will be the largest depth of field, and help keep the discussion topics.

Installation:
The installation program does not need to be a fascinating (see photo). Use tripd align the camera near the object, preferably in parallel to the lens to the subject so that everyone has to concentrate. You need to be close, because the flash power is reduced. You can grip the camera, but the focus can be difficult. Then, focus on the subject. If you are doing the droplets of water, the easiest way to do this is to transform a small stream of water (about the diameter of the drops as you want) and concentrate on it. If you can not do that, then focus manually until the drops appear to twinkle a bit '. Take some test shots and make sure that the fire and the lighting is in good condition. You can adjust the brightness of the image, only to reduce the growth of the F-stop or increase the ISO value (keep it below 800 to maintain low noise).

DIY - High Speed Photography at Home

Freezing fast motion (AKA High Speed Photography), can give some pretty special photographic effects. High Speed Photography is used in physics, health research, sports and more. This guide describes how to capture super fast movements using ordinary camera gear and a little home made electronics. I will describes the setup I used the problems I encountered and what I did to solve or work around them. Here is a nice example of High Speed Photography




The inclusion of such images introduces many challenges. How do you manage the timing of exposure time

seconds greater than 1 / 6000?

We have to deal with a shutter lag, to synchronize the flash and the exposure time just in time.

However, shutter lag of a normal camera is so long that it will be even more impossible in the time of exposure. How to synchronize the flash with an exposure time of less than 1 / 6000 seconds?

To overcome problems with shutter lag and flash, exposure takes place entirely in a dark room. This image can be opened without actually getting the exposure. Exposure time just set the camera to work long enough to happen when the shutter is still open. Since the room is dark, a long exposure does not affect the final result (This is because the light does not penetrate the objective of hitting the sensor / film)

To actually get an "exhibition" is a flash was used. Flash Light will now be the real time

exposure time.

So now we have to see how long it takes the flash. It turns out that the power of the flash output, which in fact affects the duration of the light, in order to get shutter speeds. If you need exposure faster than 1 / 6000 seconds, the output is reduced.

:

Celebration of High Speed Photography


A digital camera, a fast-moving subject, and a little knowledge on how to take better photos of moving subjects will get you started on the road to some of the most interesting pictures I've taken. Despite a lack of definition can be effective in communicating a sense of speed of movement, some photographers want the issue to be frozen in time for special effects photography.