LANC Shepherd
User Manual

The Details: The point of this device is to enable digital stereo photography with exposures synchronized in time and space. A big part of this goal is to have the camera electronic command cycles synchronized, and the LANC Shepherd displays the degree of sync while the cameras are powered up. The LANC shepherd also helps synchronize the two cameras' electronic cycles by powering the cameras up at exactly the same moment. By providing a camera "on" command at the same time, the cameras usually power up very closely in sync. Perhaps the cameras need to clear the cobwebs, but it seems that the first power-up often is way out of sync, and subsequent power-ups are closely in sync. If the sync is adequate for the shot, one can take an exposure immediately. If not, one can wait for the sync to drift to a more optimal interval, or cycle the power again. The controls on each camera continue to work as usual when this device is being used, and this device can be used as a wired remote for a single camera as well.

When at least one of the cameras is on, the ACC or LANC cable provides power for the LANC Shepherd. Previous versions of the LANC Shepherd used an onboard battery, but this new version with an enclosure does not require a battery.

It is best to have the camera mode selectors on "playback" on the Sony DSC-V1 while powering up initially, then changing the mode to one of the photo modes once I have good sync. This way, you can rapidly power up and down the cameras without the longer time required for the lenses to motor out and back in. The LANC Shepherd shows the degree of sync in fractional seconds and in milliseconds (one millisecond is 0.001 sec). Once the  cameras are in sync, change to one of the exposure modes, and you will be ready to shoot. NOTE: When the cameras are attached to a battery charger or external power, the cameras are in some sort of stand by mode for charging, and cannot be synchronized by the usual LANC Shepherd power button. The cameras have to be on battery power for the power-up sync to function.

The zoom buttons can be used to adjust the zoom of both cameras at the same time. For stereo photography, the zoom has another function beyond decreasing the field of view of the photograph--it can have the effect of decreasing the stereo base (distance between the cameras). For a greater discussion on camera placement see Lens Separation in Stereo Photography An advanced discussion for two camera photography by David Lee or purchase the book The World of 3D. By stepping back and zooming in, there will be less depth effect for a given field of view. The cameras will receive a zoom command at the same time from the LANC Shepherd, and will adjust the zoom while the buttons are held down. There is no feedback from the cameras about the current focal length, so synchronization of zoom between the cameras will degrade with more zoom adjustments--after a few adjustments, it probably is best to reset the zoom by taking the zoom to a stop, then back to the desired focal length. Typical accuracy for many cameras is less than 1% image size difference between the two cameras for zoom adjustments, which can be easily correct if needed with most computer graphics programs, but accuracy of the zoom will depend on how well the cameras are matched. Ideally, the cameras would have close serial numbers for the best chance of power-up sync and matched zoom.

Once the cameras are in sync, and both cameras are set up the same way to take a picture, press the lock/shutter button half way down, wait for the cameras to achieve focus and exposure lock, then press the button all the way down to take a stereo picture. To have synchronized shutters, it is important to first press focus lock for a moment, wait until the cameras are fully locked (focus, shutter, aperture), and keep the focus lock down until the shutter is pressed.

Video Camera Support: The LANC Shepherd senses the type of device attached, and uses the appropriate commands.

Power-up sync works the same way as with still cameras--again, the cameras must be on battery power to sync properly with the LANC Shepherd power button. Turn on the cameras with the mode switch set to "camera" (not playback mode), and use the LANC Shepherd to turn the cameras off. Then power up the cameras in sync using the ON button on the LANC Shepherd. The LANC Shepherd functions work the same whether recording to tape or to memory stick.

The red "Record" button on the LANC Shepherd toggles on or off video recording.

The LANC Shepherd can be used for still photo capture on those video cameras so equipped. Press the shutter/focus lock button down half way to capture an image, and press the button all the way down to save the image to tape or memory stick (depending on the cameras capability and mode setting).

The zoom rate with video cameras can be adjusted with the LANC Shepherd. The zoom rate adjust requires holding down the shutter button half way during the period of time needed to make the adjustment. With the shutter button held down half way, bring up the adjust screen by pressing "zoom in". Press "zoom in" or "zoom out" to make the adjustment. Then release the shutter button to save the new zoom rate to memory in the LANC Shepherd. Zoom rate can be adjusted from 1 (glacial) to 8 (mach).

Self-Timer: Digital cameras all have this feature on their own--set the timer, and then the photographer has ten seconds to scramble back to the group before the exposure--but this feature with stereo cameras will typically take an exposure seconds apart. With the LANC Shepherd, press the red "Timer" button to start the countdown, and again if needed to abort. The count down is displayed on the LCD, and seconds ticked off with a piezo sounder. At five seconds, the LANC Shepherd initiates focus lock, and at zero on the counter, the LANC Shepherd triggers both cameras at exactly the same time for a synchronized exposure.

Flash Photography With Internal Flash: Synchronizing flash is probably the most difficult aspect of stereo photography, and discussion of flash can get complicated in hurry. 

Nonetheless, flash photography works well with the help of the LANC Shepherd. Since both cameras must be configured the same for exposure sync, both flashes must fire, but one flash must be blocked for best flash synchronization and best stereo quality. The LANC Shepherd indicates which flash to leave open to the subject, "M" for the right master camera cable or "S" for the left slave camera cable. Rather than switch back and forth blocking flashes, I usually just block the slave flash, and insist on "M" being displayed for a flash exposure.

Flash sync generally works well as long as the sync is less than about half the shutter speed (for example, if 1/500 sec shutter, sync less than 1/1000 sec). In reasonable light, regular flash mode can be used to fill in shadows, and this works quite well and reliably to at least 1/500 sec exposure with the Sony DSC-V1. Using flash as the sole light source in darkness does not work as reliably, and "slow synchro" flash works about half the time. So just use the regular flash mode in reasonable light with excellent results.

Flash Photography With Third Party External Flash: A regular third-party external flash will of course work with the LANC Shepherd if the camera model has an active hot shoe (yes Sony DSC-F828 DSC-F717 and DSC-V1, no Sony DSC-S75 or DSC-S85) in the same fashion as internal flash as discussed above. Configure both cameras to use the external flash on the hot shoe, and attach the flash to one of the hot shoes, then insist on a "M" displayed for flash on the master camera or "S" for flash on the slave cable.

Flash Photography With a Sony External Flash: Follow this link for detailed information about using the Sony external flash units with the LANC Shepherd. The Sony HVL-F1000 "External Strong" accessory flash, and the Sony HVL-F32X "High Grade" accessory flash can work well with the LANC Shepherd with attention to a few details. Both of these flash units share the "ACC" or "LANC" port. Both come with a small steel camera bar with a false flash shoe.

How Synchronized Is Enough?  

As a general guideline, I suspect that a displayed sync greater than 1/10th of the shutter speed will be potentially noticeable for average photography. For example, for a shutter speed of 1/250, a sync greater than 1/2500 (0.40 msec) will produce just noticeable disparity for an average city street corner with wind, people walking, and slow moving cars. Action photography, with considerably faster motion and shorter shutter speeds, needs to have a sync proportionally better, and I generally try to take these photographs with as good a sync as I can achieve (on the order of a 0.01 msec or 10 millionths of a second).

In the end, the LANC Shepherd allows really a remarkable degree of synchronization if it is required, and allows sync time to be a stylistic choice for stereo photography as well.

Mounting the Cameras: Here are a few tips:

The digital camera lenses are not necessarily aligned with the camera body. The lens on a digital point-and-shoot camera is mounted on an internal chassis, and the external camera body is just a shell. So count on shimming the cameras once they are mounted for proper stereo alignment, particularly if the cameras are not both mounted in the same orientation (such as over/under, bottom to bottom, etc).

The Pictures: Here are a few sample images taken with a pair of Sony DSC-V1 cameras.

Crossed View Parallel View 129k.
Marriott, Waikoloa Beach, Hawaii.
The ubiquitous gas torches. 

Crossed View Parallel View 250k.
Mammoth Bar Off Highway Vehicle Area, near Auburn, California.
1/500 sec exposure shutter priority, with the three shot burst mode (second exposure shown).

Crossed View Parallel View 198k.
Forest Hill, California.
1/500 sec exposure, shutter priority.

Crossed View Parallel View 377k.
Crossed View Parallel View 312k.
Yuba River, near Nevada City, California.
DSC-V1 with LANC Shepherd, shutter 1/1000, aperture 4.6, sync around 0.02ms (1/50000 sec). The second set is with about 20% zoom.

Rob Crockett Copyright 2004, All Rights Reserved.

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