PhotoRobot SynchroBox - Functionality & Setup User Guide

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The following documentation describes the functionality and setup of the PhotoRobot SynchroBox, a multi-camera hub which synchronizes the camera shutter of two or more cameras. This information aims to support PhotoRobot customers who have recently purchased a device and are using more than one camera with PhotoRobot. It includes the theory, functionality, and setup of the SynchroBox to help facilitate its basic understanding and operation by the customer.

Note: The initial installation of a PhotoRobot system must always be carried out by an authorized PhotoRobot authority. Authorities with authorization to install PhotoRobot are an approved distributor, or a representative of the manufacturer itself.

Additionally, always refer to PhotoRobot Safety Information & Instructions along with any manual provided specifically with your device before first use of PhotoRobot.

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SynchroBox Technical User Guide

Thank you and congratulations on your PhotoRobot purchase. PhotoRobot represents decades of first-hand, professional experience and innovation in automated photography. Every device delivers an eco-system of ready-made solutions, with features tailorable around your business’ unique needs. 

Welcome to PhotoRobot. Use the following technical information to start your journey to understanding and maximizing production in the PhotoRobot-powered studio.

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1. PhotoRobot SynchroBox - The Theory

The PhotoRobot SynchroBox is required to synchronize camera shutter when using two or more cameras with PhotoRobot systems. SynchroBox functions as a multi-camera hub to synchronize the capture of individual frames by different cameras at precisely the right moment. It represents a solution to the issue that arises when working with cameras that have different shutter lags, and it supports up to 8 cameras in total.

To understand the theory of the SynchroBox, take for example the sequences of standard capture mode versus fast-spin capture mode with PhotoRobot. 

In the standard capture mode, there is the following sequence.

a) The plate moves to the desired angle.

b) The plate stops.

c) The camera photographs the object.

d) The plate begins moving to the next angle.

There is no adjustment necessary in this scenario.

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In fast-spin capture mode, the sequence requires several more stages.

a) The plate starts rotating at a predefined speed.

b) The Control Unit recognizes the angle to capture is approaching.

c) The Control Unit fires the camera shutter via shutter cable in advance.

d) The camera starts the capture process (sensor curtain movement, etc).

e) The capture process requires approximately 50 milliseconds (“shutter lag”).

f) The plate is continuously in motion during the shutter lag time frame.

g) The plate reaches the desired angle precisely when the camera’s shutter lag has concluded, taking the picture.

h) The Control Unit recognizes that the next capture angle is approaching, repeating the capture process in regards to shutter lag.

i) The plate rotation concludes after 360 degrees, stopping all movement. 

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Note: Due to the fact that each camera has a different shutter lag, it is necessary to adjust the Control Unit shutter advance for each particular camera. This is possible for the Control Unit (Generation 6) via its service GUI using the option “Trigger advance”. The “Trigger advance” value must be higher than the shutter lag of the camera. For example, if the shutter lag of the camera is 80 ms, then the “Trigger advance” should be approximately equal to or greater than 90 ms.

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2. Device Description - PhotoRobot SynchroBox

By design, the SynchroBox is a rack mount device designed for the synchronization of the camera shutters of two or more cameras. It is necessary when operating any PhotoRobot system using more than one camera at a time. One SynchroBox supports up to 8 cameras, providing a solution to working around different shutter lags of the cameras in use.

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Take for example a scenario using two cameras and a SynchroBox only as the splitter for both cameras, with no additional setup applied. At the same time, the Control Unit G6 “Trigger advance” value is zero. The shutter is then fired when the plate reaches the desired angle.

In this case, the steps of the sequence are:

a) The plate reaches the desired angle.

b) The Control Unit fires the camera shutter via shutter cable.

c) The shutter lag for both cameras counts down while the plate is in continuous movement.

d) The first camera takes the picture 50 ms after the desired capture point using “desired angle + X” degrees.

e) The second camera captures the picture 70 ms after the desired capture point using “desired angle + Y” degrees.

f) The “Y” value degrees are greater than “X” value degrees.

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As a result, there is no picture captured of the desired angle. Thus, adjustment is necessary so that both cameras photograph the desired capture point at the correct moment. 

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For this, the SynchroBox receives a “shutter fired” pulse from the Control Unit G6, and automatically identifies the length of the pulse.

Additionally, the SynchroBox has the shutter lag value for each connected camera, which was manually entered when set up.

Using these two parameters, the SynchroBox counts and fires the shutter of each camera with the appropriate advance.

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3. How to Measure Camera Shutter Lag

In order to measure camera shutter lag, it is necessary to have a PhotoRobot with any rotating plate, the Control Unit G6+, and a camera connected via shutter cable to the Control Unit.

Next, a local computer with PhotoRobot Controls App Software must be connected to the camera via USB cable.

Finally, a 360-degree protractor (downloadable online) is necessary to complete the following steps.

a) Place the protractor on the PhotoRobot device plate, using any pointer positioned outside of the plate and pointing to the edge.

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b) Turn the plate until the pointer is at zero. Note: This step is possible by hand even when the electrical engines are powered off.

c) Start PhotoRobot Controls App software, log into your account, and create an item using the workspace keeping in mind the given configuration. Then, open Capture mode, and open the folder “Other”.

d) Next, in a new tab on your browser, open the service GUI of the Control Unit (G6), which provides control over the plate using its IP address. 

e) In the service GUI, set up the robot with following parameters:

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• 1 = 4 pictures by 90 degrees;
• 2 = 40 ms pulse length for triggering the shutter;
• 3 = trigger advance 0 ms (no advance);
• 4 = no fastshots delay
• 5 = half-press of the shutter is activated

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f) Start the sequence by clicking the right arrow in the bottom-right corner of the control panel:

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Note: The sequence begins at 90 degrees and finishes at 0 degrees. At the same time, all photos are captured into the folder “Other” in the Controls App, as previously configured.

For example, refer to the following sample outputs (with a rotating direction to the left):

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• ‍Note: In these examples, image capture was approximately 6 degrees after the trigger was fired.

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g) Next, in order to transform 6 degrees into the number of milliseconds (ms) in this case, start the continuous rotation of PhotoRobot’s plate using the same speed from the previous step in the service GUI.

• Start a stopwatch and record the time for 10 rounds.
• In this test case, the resulting value is 61 seconds (61,000 ms).
• That means that 10 rounds is equal to 10 * 360 degrees (3,600 degrees).
• There is 1 degree time movement lasting 61,000 ms / 3,600 degrees, equaling 16.94 ms.
• There is 6 degrees time movement lasting 16.94 ms * 6, which equals 101.64 ms.
• Thus, the approximate shutter delay is roughly 102 ms.

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h) Finally, it is necessary to repeat all of the previous steps in order to identify the shutter delay for each different camera in use.

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4. SynchroBox Setup

For the setup of the SynchroBox, a prerequisite is that there is a Control Unit (G6) installed and fully operational. Further, ideally there will be 2 or more cameras from the same manufacturer and of the same model, each with a known shutter lag. 

In this case, use the following steps to set up the SynchroBox. 

4.1. Connect the SynchroBox to the Control Unit G6 via shutter cable. Note: This shutter cable is provided by PhotoRobot as a part of SynchroBox delivery, or under the part number KHCAR1R05. The shutter cable connects the Control Unit G6 “OUT” port to the SynchroBox “->IN” port (the smaller one, not the other one “=>IN”).

4.2. Connect the SynchroBox to the network via standard ethernet cable, using the same subnet connecting to the Control Unit.

4.3. Connect all cameras that will be in operation to the SynchroBox using shutter cables.

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Note: The shutter cables for the SynchroBox to the cameras are delivered by PhotoRobot under the part numbers KHCARCJ (Canon Jack 2.5 mm Connector) or KHCARN3 (Canon N3 connector) plus the extension KHCAR1R05, or as a so-called shutter cable set.

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4.4. Be aware that Camera 1 (port 1 of the SynchroBox) holds and operates the flash lights trigger device. This camera must have the largest shutter lag.

4.5. Set up the Control Unit (G6) “Trigger advance” value according to the shutter lag of the slowest camera (previously described in section 1 of this document). Note: When using PhotoRobot Controls App, be aware that this value is adjusted / replaced by the value set for the Capture mode - Fast Spin:

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4.6. Next, access the service GUI of the SynchroBox by entering its IP address in URL format into your web browser.

4.7. Set up the first slider “CU advance” to the same value as it is in the Control Unit, or to a corresponding value in PhotoRobot Controls. Note: Be aware that if these two values differ, the value in PhotoRobot Controls will take precedence. Then, there are 8 sliders corresponding to the 8 ports on the SynchroBox. The sliders each have two values: the advance (left button), and length of pulse (right button). The advanced value equals the shutter lag of the controlled camera (with the smallest real value approximately -50 ms). Length of pulse then relates to the time frame during which the shutter cable for the camera maintains contact. This value is provided by the camera manufacturer, or, if unknown, can be set to 40 - 60 ms.  

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4.8. Set up the input channel in the SynchroBox service GUI. Note: When using PhotoRobot’s shutter cables, the setup will always be as follows.

• IN port: A = focus, B = trigger
• Port 1 - 8: A = trigger, B = focus

• Note that there are only cameras 1, 2, and 3 set up in the above example.
• Because PhotoRobot is intended to use flash lights, set up camera 1 shutter speed to 1/100 or 1/125.

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4.9. Finally, configure the initial setup of all other cameras to a much longer shutter speed, e.g. 1/30 - 1/60. This will help to account for the possible difference in shutter lags between the cameras in use. The longer time frame will also ensure that all cameras catch up to the peak of the flash from all strobes. When working correctly, it is then possible to experiment by reducing the shutter speed of the other cameras if necessary.

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5. Multiple SynchroBox Setup

The SynchroBox supports up to a maximum number of 8 cameras. If more than 8 cameras are necessary, it is then possible to multiply the number of SynchroBoxes in use.

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• Connect the OUT port of the first SynchroBox to the IN port of the next SynchroBox, using the same shutter cable which connects the Control Unit to the SynchroBox. This shutter cable is provided by PhotoRobot as a part of SynchroBox delivery or under the part number KHCAR1R05.