The department owns an Edgertronic High Speed Video Camera available for student and faculty use in both teaching laboratory and research settings. The camera model is the SC1, the first generation made by Edgertronic, which can record up to 882 frames per second at 720p resolution. (See additional model specifications.)
Getting the camera
The Edgertronic Camera is kept under the supervision of Bruce Duffy, the “IT person” for the Physics and Astronomy department. If you’d like to check out the Edgertronic, simply confirm with Bruce that the camera is available to be checked out and assume responsibility for the camera by signing it out (along with any accompanying materials). Bruce is also available to answer questions and provide helpful tips on using the camera, as well as point you to additional documentation if needed.
Camera parts and auxiliary equipment
- Camera body: This is the blue box with lens mount that houses the CMOS image sensor, as well as the internal computer hardware and software. The lens mount should have a cap, which can be removed by rotating clockwise.
- Nikon camera lens: The lens should have a front cap, which can be removed by squeezing the tabs, as well as a semitransparent cap at the back where it mounts. The lens controls both focus and aperture size.
- AC power adapter: A wall outlet power cable is provided in the case and plugs into the camera in the lower left corner of the camera back. Additionally, a 12v automotive power socket plug-in is provided.
- Ethernet cable: This is used as the connection between the camera and the computer you are using for configuring settings and recording.
- Remote trigger: The camera can be optionally triggered using this wired switch rather than the web UI.
- SD card: An SD card provides the data storage for recordings from the camera. The top left of the camera back has a slot which holds the SD card during recording and storage.
Auxiliary equipment: Ask Bruce about checking out equipment from the department.
- Computer: Lab computers around the department can be used to record footage with the Edgertronic. For additional portability, there are also Mac and Windows laptops available for check out.
- Tripod: Tripods are available from the department and PEPS (Presentation, Events, and Production Support) has additional options available.
- Lighting: High speed video requires much more lighting than standard photography. The department has a few lights available for this purpose, and PEPS has a much wider selection of lighting that can be helpful.
Setting up the camera
- Mounting the lens: Begin by removing the mount cover on the camera, as well as the front and back covers on the lens. Next, align the white dot on the lens with the red dot on the mount, press down slightly, and rotate counterclockwise until you hear the lens click into place. To remove the lens, press down on the blue tab while reversing the turn above.
- Powering up: The camera turns on immediately once you plug in the power cable into the round slot at the bottom left corner of the camera back. A indicator light next to “CAMERA” should show solid green when the camera is fully powered on.
- Connecting to your computer: A computer is used as the user interface with the camera. To begin, make a physical connection from the camera to your computer using the provided ethernet cable. The indicator light next to “SYSTEM” should show solid yellow. In order to connect with the camera, your network settings will need to be configured. Instructions for this process for both Mac and Windows operating systems can be found below in the “Configuring network settings” section.
- Navigate to the Web UI: Access the Edgertronic’s Web Browser User Interface (Web UI) by opening Google Chrome and navigating to http://10.11.12.13/ (the UI is only compatible with Chrome at the moment).
A note on cable management: When in use, the Edgertronic camera will be connected to at least two cables, with one of those going to a laptop or computer. Be mindful of how to set up this cabling so that it is out of the way when you are recording, and not at risk of pulling the computer or camera off the table.
Configuring network settings
Mac: Navigate via System Preferences -> Network and select ‘Ethernet’ or ‘Thunderbolt Ethernet’ from the lefthand side pane (if neither of these appear you may have to use the ‘+’ in the bottom left-hand corner in order to select the Ethernet interface). Select ‘Manually’ for the ‘Configure IPv4’ option, set the IP address to 10.11.12.1, subnet mask to 255.255.255.0, and press ‘Apply’. Your window should something like this:
To return to your original settings, revert the ‘Configure IPv4’ option to ‘Using DHCP’.
Windows: Navigate via Control Panel -> Network and Internet -> Network and Sharing Center -> Change adapter settings -> Ethernet and click on ‘Properties’ in the ‘Ethernet Status’ window. At this point you will be asked for an admin username and password to continue. If using a personal computer you may proceed, but if using a lab computer you will have to ask Bruce to help you configure these settings. After entering admin info you should see a window that looks like this:
From the ‘Properties’ window double click on ‘Internet Protocol Version 4 (TCP/IPv4)’ which will open a new window. In this window set the IP address to 10.11.12.1, subnet mask to 255.255.255.0, and press ‘OK’. Your window should look like this:
Adjusting camera settings
The Edgertronic does not auto-focus. This means that you will have manually rotate the front piece of the lens in order to view the object of interest clearly. There is a fairly tight range for what distance from the camera will look focused for a given setting (also depending on aperture size). You can focus on an object up to a minimum of about 37 cm from the camera, given the limitations of the default Nikon lens.
The aperture size is also manually controlled on the lens. You can adjust the aperture size by rotating the inner ring on the lens. The larger the aperture, the more light is let in, which is helpful in high speed photography, where as much light as possible is often needed. The trade-off is that a larger aperture can only focus objects at a tighter range of distances (called depth of field). If you need a broader range of objects to be in focus you will need to use a smaller aperture, at the cost of brightness.
The Edgertronic also has a number of settings related to the digital data acquisition side of the camera, which are controlled from the browser interface. To access the Edgertronic’s Web Browser User Interface (Web UI), open Google Chrome and navigate to http://10.11.12.13/ (the UI is only compatible with Chrome at the moment). The page should open to a ‘Settings’ tab. The other tabs (‘Options’, ‘Overlay’, ‘Favorites’, and ‘About’) are not essential for basic camera operation (see documentation at wiki.edgertronic.com). Note that you can close the window by pressing the faint ‘x’ in the top right-hand corner (circled in red).
Within the ‘Settings’ tab you should see 8 quantities you can control:
Sensitivity: Called the ISO, this determines the degree of amplification of signals of light from each digital component. A higher ISO means that a scene will appear brighter, since a given amount of light falling on the image sensor will produce a larger signal. However, this also means that there will be more noise in your image, leading to less clarity. Therefore, you should use the lowest ISO at which you can still see your objects brightly enough.
Shutter speed: This determines how long each exposure of the sensor will last. A longer shutter speed will allow more light to be detected, creating a brighter image. This comes at the cost of capturing motion. In order to get crisp images of quickly moving objects, a low shutter speed is needed. The shutter speed also bounds the frame rate, since the shutter can’t be open longer than the time interval between frames.
Frame rate: This determines how slowed-down your video will be. The higher the rate, the slower the video. For example, standard video frame rate is 30 per second, so if you filmed a high speed video at 60 frames per second, it will play at half-speed (1 second of filmed time will play over 2 seconds). The frame rate must always be smaller than one over the shutter speed.
Vertical/Horizontal (resolution): The vertical and horizontal resolutions determine what region of the camera’s field of view you would like to record. To capture the maximum dimensions are 1280×1024, which will use the camera’s entire image sensor. You can, however, choose smaller dimensions (part of the image sensor) in order to gain a higher frame rate. This tradeoff exists because the camera has a fixed data read rate of 756 Mpix/sec, so if you want to capture more frames per second, you will need to use a smaller portion of the sensor, as determined by the resolution.
Duration: How long do you want your recording to be? Depending on the event you’re trying to record, choose a duration that will allow you to see the entire event, without recording too much excess footage. The camera’s SD card has a finite storage at 8 GB, so be aware that long duration recordings (>15 seconds) at high frame rates may run up against this bound.
Pre-trigger: This is a useful feature in the case that the event you are trying to record is unpredictable, such as a bolt of lightning. Using pre-trigger means that the camera is constantly recording and overwriting footage, so that when you trigger the camera, it stores some of the recording before triggering. The percentage determines how much of the recording will be before the trigger. So if you want to record the second before the trigger only, you would set the duration to one second, and the pre-trigger to 100.
Shot Count: Sometimes you may want to record multiple events in quick succession but not have the footage in between. To record multiple videos in a row, set the shot count to a whole number > 1.
Note: You may have noticed that there are trade-offs between several of the settings, especially shutter speed, frame rate, and resolution. The Web UI will automatically constrain these settings, so if you request a series of settings which are outside these trade-off limits, the actual settings will be different (see ‘Requested’ vs ‘Actual’ columns. The easiest way to get a better understanding of how these settings behave in relation to each other is to try a variety of settings, and see how they affect the qualities of the video you are making. A more detailed description of how the camera settings on the Edgertronic work can be found at: wiki.edgertronic.com/index.php/Beginners_Guide_to_edgertronic_high_speed_camera
Once you are done making adjustments to the settings, hit the faintly gray-colored ‘x’ in the top right hand corner of the settings window. You should see a live image of what the camera is looking at. This is a good time to adjust the aperture and focus until the image looks clear and bright, and go back the settings if you need to make further adjustments. You should also see a button box in the top left corner of the window, with the following five buttons:
These buttons do the following, respectively:
Playback: Play the last recorded video stored on the SD card.
Download: Download the last recorded video stored on the SD card to your computer’s ‘Downloads’ directory.
Settings: Go back to the Settings/Options/Overlay/Favorites/About window.
Eject: Before removing the SD card (for transfer to a computer), unmount the drive using this button.
Help: Opens a new tab to a local copy of the Edgertronic documentation at wiki.edgertronic.com
Trigger: This triggers the video to record footage. Depending on the pre-trigger settings, this could store footage from before the trigger, after, or some combination of both. See additional documentation for how to use the remote trigger.
To begin recording simply hit the ‘Trigger’ button. After the video is done recording and processing, you can save to your computer by hitting the ‘Download’ button or continue recording additional shots.
Using the SD card
The Edgertronic records the videos to the large format SD card that inserts into the slot in the upper-left corner on the back of the camera. To copy data from the card to a computer for analysis, or to free up space on the card, you will need to eject it and insert it into a computer with an SD card reader slot (such as one of the iMacs in our lab).
If the camera is turned off you can just remove the SD card by pushing it into the camera to activate the spring-loaded ejection mechanism. If the camera is on, you must first select the Eject button (described above) to “logically” eject the card, and then physically eject the card.
Once the card has been inserted into a computer’s SD card slot you can inspect it’s file system. The recordings are stored in the ‘DCIM’ subfolder in the form of “.mov” files. For each .mov file there’s a corresponding “.txt” file that records all the camera parameter settings at the time the recording was made. At this point you can copy the files from the DCIM subfolder to the computer’s file system.
Once you’ve copied your files you should delete them from SD card to recover space on the SD card. On a Windows system you simply delete the files. On on a Mac you must explicitly empty the Trash on the Desktop after putting the files in the Trash while the SD card is still mounted on the Mac. That’s because (on a Mac) putting the SD card files in the trash just moves them to a hidden “.Trash” folder on the SD card, and emptying the Trash from the Mac Desktop actually removes the files from the “.Trash” folder, freeing up the space.
Returning the camera
Make sure to return the camera components to the case, as well as any other borrowed equipment, exactly as you found it. It is important that the appropriate lens and camera caps go back onto these components. If you run into any issues using the equipment, contact Bruce with your questions and concerns.
NOTE: Please remove your files from the SD card before returning the camera as a courtesy to others.
Thorough documentation is provided at wiki.edgertronic.com.