Magazine article American Cinematographer

Cinema Workshop

Magazine article American Cinematographer

Cinema Workshop

Article excerpt

VTR CABLES

The automobiles of the late 50's were characterized by large fins and multiple tail lights. The rear of modern ENG/EFP cameras are no less characterized by the Snap-On* battery bracket and the normal proliferation of electrical connectors. Some of these connectors usually facilitate external accessories such as a remote CCU or a test/set-up device. Two connectors that are always present are the VTR connector and the video out BNC. While this BNC connector is the primary and simple method to get video out of the camera, there are many circumstances where the VTR connector offers advantages.

The VTR connector, unfortunately, is not standardized and varies depending on camera manufacturer. It always involves multiple pins, and it is thus quite obvious that this connector facilitates several functions. While the type of functions available through the VTR connection also varies from model to model, certain ones have become somewhat standard.

All VTR/camera cables include "video out" and some form of trigger signal to start and stop the VTR. Most also include a "video return" feature enabling the camera viewfinder to be used as a monitor to playback previously recorded material. Those VTR's providing actual off-the-tape monitoring while recording (Hitachi HR-100 type C, JVC 4700 U-matic, etc.) can feed this offthe-tape image to the camera via the camera/VTR cable. By pressing the "video return" button while shooting, the cameraman can switch the viewfinder over to monitoring this off-the-tape image in lieu of the normal camera videc-out.

While no one can argue the practicality of these functions, there is one additional feature common to most VTR connectors that is enigmatic, at best. This is the ability to power the camera via the VTR/camera cable. Many consumer or home video users employ one battery internally within the VTR and power the camera from this same battery via the camera/VTR cable. While this practice may make sense for the amateur, it has several serious drawbacks for the professional. Before a professional makes a final decision on this matter, he should consider the following points:

1. Voltage -Unlike most consumer cameras which are designed for 12 volt supplies, virtually all professional video ENG/EFP cameras are designed to operate with a 13 to 14 volt nominal battery source. While some of these professional cameras may operate marginally with a 12 volt battery, they clearly provide optimum performance with the proper 13-14 volt battery. This is due to the fact that all professional cameras employ advanced switching type (constant power) regulators. These regulators convert excess voltage into power, thus the 14 volt battery will provide more than 20% more power and more than three times the reserve voltage of a 12 volt battery. Moreover, under adverse conditions, or as batteries age, the benefits of the 14 volt battery becomes increasingly important. Under certain circumstances, the 12 volt battery may cease to operate altogether where the 14 volt can still deliver full capacity. This is because most professional cameras cease to function much below 11 volts. Unfortunately, a 12 volt battery can go much lower than this. On the other hand, the normal operating range of the 13 or 14 volt battery is well above this 11 volt cut-off.

The problem is that all portable VTR's require 12 volts, not 14. Thus if the camera is being powered by the VTR, it is only getting 12 volts. …

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