Tethered Camera Operation

As technology has improved digital cameras have become more and more portable. Smaller and more ergonomic cameras have made digital photography more practical - however, there are times when it is preferable to use a more static system with camera and computer connected. This is known as tethered camera operation. This document is aimed at anyone who might need to operate their camera from a distance, in an awkward position or wants to preview the image on a high quality computer screen.

Introduction

While it is possible to connect the majority of cameras to a computer in order to download the captured images, this should not be confused with tethered operation. In its most basic form tethered operation downloads images as they are taken; more advanced systems offer full control over the camera.

Tethered operation is commonly used when the camera is positioned high up on a copy-stand or in situations where the presence of the photographer may be distracting (for example natural history photography) or unnecessary (such as computer controlled time lapse photography).

The early professional digital camera backs lacked an LCD display, internal storage or physical controls and had to be operated from a tethered computer. From the computer the photographer could control the capture settings, preview the shot and store the captured images. These cameras where normally designed for the busy studio where portability was not one of the major design considerations.

Medium format digital camera back operated from a tethered computer

Over time the LCD screens, complex menu systems, on-board storage and power supplies have been integrated into the professional digital camera back and the cameras are now equally at home in the studio or on location. So why are more and more software manufacturers producing applications which will allow tethered camera operation?

• A camera tethered to a computer will normally have access to more storage space than one using on-board memory cards
• Captured images are named and drawn directly into the workflow
• The computer can control exposure intervals for specialist applications such as time lapse photography
• Images can be viewed or previewed on a higher quality computer screen
• The camera can be used in dangerous situations or places that the photographer cannot access easily
• The camera can be used in situations where the presence of the photographer might disturb the subject such as wildlife photography

Tethered operation is mainly offered by digital SLRs or larger format digital systems. To use a camera tethered to a computer you simply need a two way communication (cable or WiFi) between the camera and computer and a tether application.

Tethered systems

The most common form of tethered camera operation is where the captured images are transferred directly to a watched folder on a computer. The pictures are displayed almost immediately after the shutter is released, and a large computer screen makes it easier for a number of people to inspect and discuss the composition. If the image is good enough it is drawn into the workflow, if not it is retaken.

With the watched folder system the photographer concentrates on operating the camera while an operator on the PC checks, tags, edits and saves the images.

While it can take longer to transfer a captured image through a cable than save it on a memory card, this system can still speed up a workflow and eliminate the quality control issues introduced when images are signed off on the camera's display.

More advanced tethered systems offer full control over most of the camera's settings from the attached computer. This is of particular use when the camera is placed in an awkward position. This type of remote control is commonly used with copystands or with low level aerial photography using cameras on extending masts.

Unlike the watched folder approach the remote camera control system is not significantly faster than standard camera operation however, it does offer more precise control over the process of photography. More and more SLR camera manufacturers are offering a 'real time' preview of the scene on the camera's LCD display, often referred to as Live View. This feature is of particular interest to the tethered camera operator as it allows the user to alter the camera controls or adjust the subject and see the results in 'real time' on a remote PC.

Tethered camera photographing architectural detail on stand 4 metres above the ground

Connection

The connection used to tether the camera to a computer is normally via a standard cable such as USB or Firewire, or wirelessly via a WiFi network.

The maximum length of a USB or Firewire cable is limited (5 metres for USB), though it may be possible to use powered hubs to extend the range, within limits. Tethered cables connect two very expensive pieces of equipment so it is essential that care is taken when linking them to avoid risk to the operator or equipment.

While WiFi networks are more complex and can be prone to broken connections, they reduce the trip hazard from cables in the darkened studio and allow the photographer to work freely within the range of the wireless network. Currently, additional hardware is required to exploit WiFi tethering; this is normally in the form of an external device which is connected to the camera's USB port, though WiFi transmitters are also now being incorporated into memory cards.

There is also a hybrid application from OnOne software that allows the operator to have wireless control of the camera from an Apple iPad/iPhone/iPod Touch but download the images to a (cable) tethered PC. This type of hybrid solution is a cheap alternative to the manufacturers' own WiFi hardware.

Tethered applications

At first, tethered applications were mainly produced by the camera manufacturers. In recent years a large number of third party software developers have entered the market and there is now a wide range of tethered applications.

These applications vary widely in price, feature set and the cameras they support. Before selecting a tethered application it is worth identifying the features required and then evaluating a trial version of the software.

Some camera manufacturers (such as Canon) produce their own tethered applications which they supply free with their cameras, while others (such as Nikon) currently charge for the software. For this reason third party software manufacturers tend to concentrate on supporting those cameras that are not bundled with free tethering applications.

Basic tethered applications do little more than trigger the shutter using the current camera settings and then transfer the captured images to the computer. Apple's Image Capture utility allows the operator to trigger the shutter remotely or start a time lapse sequence.

Apple's Image Capture application which offers basic tethered camera control

Free applications like DCamCapture (PC) and Sofortbild (Mac) present the user with more capture data and greater control over the camera's capture settings, supported cameras can also be used with Live View.

The DCamCapture application offers basic remote camera operation (Nikon only) along with Live View

Widely used workflow applications such as Adobe Lightroom and Apple Aperture offer tethered image transfer along with limited remote control features. These applications transfer the captured images directly into the workflow.

Tethered camera control in Adobe Lightroom 3, the grey circular button on the right releases the shutter.

More sophisticated applications such as Nikon's Camera Control Pro and Canon's EOS Capture allow the photographer to adjust all of the important capture controls as well as many less important ones. Some will also support Live View and provide a live display of the camera's viewpoint to the attached PC.

Nikon's Camera Control Pro is an example of an application which offers total remote camera control.

Some applications transfer the captured image to the tethered computer and store a duplicate on the camera's memory card, while others ignore the memory card and only transfer to the PC. If the images are not going to be checked on the PC immediately after capture a system that backs up to on-board memory will reduce the risk of data loss.

Camera on copystand controlled from tethered computer using the Live View option in Sofortbild

Conclusion

While the majority of photographers prefer to be liberated from their computers, there are occasions when images need to be brought directly into an image workflow or when the photographer wants to control the camera from a distance - in such cases a tethered solution may be preferable. Software manufacturers are aware of this need and have produced applications that support most recent digital SLR cameras.

If the decision is taken to use a tethered system, careful consideration should be given to both the needs of the project and photographer:

• Does the camera you intend to use offer tethered operation (check the manual)?
• Is tethered software supplied with the camera?
• Is full remote control required?
• Is Live View required?
• What camera and computer combination is being used?
• What is the budget?
• If the photographer will not be holding the camera during tethered operation a stable and secure support should be used.

Published in: Creating

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