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Working With Video (Part 1)

The Video Studio

With musical promotions employing the video medium increasingly, Andy Emmerson explains how to do-it-yourself


Your own video studio — an impossible dream or quite feasible for £200 or so? The choice is in fact yours but it can be done if you are prepared to — produce in monochrome — do some shopping around, and — wait for bargains. In fact, my system cost under £200. I'll also tell you how you can set up your own production system, too.

Block diagram of a video studio.


First of all you must have the cameras, and I have not included these in the £200 outlay. For hobbyist or amateur video productions these cameras need not be anything flashy, and you'll find that even viewfinders are not even necessary if the cameraman can see a monitor set at the same time. Old surveillance cameras will do and you can buy these for £50 upwards at secondhand shops and dealers who advertise in the Exchange and Mart. What is essential, however, is that they accept external synchronising signals ("syncs") from a central source (sync pulse generator, SPG). Otherwise, if the cameras are free running, you cannot mix or switch from one camera source to another without a visual disturbance. While not harmful, such a "glitch" looks distinctly unprofessional!

The heart of your production facility is the SPG and this will supply the signals to synchronise your cameras and the special effects generator (SEG). Many SEGs contain an SPG as well, and a second hand unit can be bought for £75 to £100. Likely sources are professional video dealers who have accepted them as trade-ins — they won't advertise them so you'll have to ring around and do some persuasive talking. Some of the better endowed technical colleges sometimes have old gear they will pass on to amateur groups, or sell at scrap value: if you know what you are buying you can get a real bargain.

Finally you will also need two monitors — monitors are simplified TV sets which take and display a direct video input. Normally they contain no audio or broadcast tuner sections. You need two — one for preview and one for line or output. Monitors come in all shapes and sizes; the little 9-inch and 12-inch screen models are ideal. Unfortunately they are also eagerly sought after by the home computing fraternity with the result that secondhand models are not as plentiful as they might be. Ancient valve monitors are much easier to find, but they tend to be hot and bulky, in fact you won't need any central heating in winter! Expect to pay from £20 to £60 for a small secondhand monitor or £10 to £30 for a large one.

Your video sources, say two cameras, are connected to the inputs of the SEG. The basic function of an SEG is to select one of two input signals and switch between them. Independent of which input has been selected for output to line, the preview switches enable you to monitor either of the input signals without affecting the output, which is connected to your video recorder. The output monitor displays the signal going out. So far I have assumed that the SEG has only two inputs: in fact it will probably have more, up to six, but there's no need to make things complicated! Most SEGs enable you to switch from one signal to another in a variety of ways, by cutting, wiping, fading or mixing.

Cuts are straightforward instantaneous changes; one moment you are looking at picture A, the next at picture B. The switching is done electronically to avoid disturbances on the screen. Wipes are more elaborate; one picture is pulled away like a curtain to reveal another picture. You can have horizontal wipes, vertical wipes, a mixture of both or diagonal wipes. More expensive machines also permit circle and diamond shape wipes or random square effects. You must have seen these visual effects on Top of the Pops, they look fine on this type of programme but like jingles on the radio they are best used sparingly.

Fades are where you fade a picture down to black or up again. If you mix or crossfade you fade up picture B as you fade down picture A and the two pictures appear on the screed simultaneously for an instant.

Let's be honest — visual effects are great fun and presumably you're into the video hobby for entertainment. If you've played with an audio mixer and enjoyed mixing sounds just wait till you get your hands on a video effects unit! Until the novelty wears off there's untold fun... most budget SEGs use slider pots for controlling wipes and fades, and the better ones incorporate microswitches to switch out the resistance at the end of travel. On the professional machines you have levers which are geared to rotary potentiometers and these have a superb "feel" to them.

When you go shopping for an effects unit you'll probably be offered a Japanese made machine about ten years old. Reliable makes include Sony, Panasonic, Shibaden and Ikegami. Most models are desk-top devices with built-in power supply and SPG. If you buy your cameras together with the effects unit all well and good — otherwise describe what cameras you have (or take one along). This way you should avoid buying something incompatible; there are traps for the unwary. The one volt video signal is universal but some of the older Japanese cameras had non-standard sinewave drive signals. Avoid buying gear with unfamiliar sockets — if you don't possess matching plugs checkthat you can still get hold of these. And make sure you get an operating manual with any device, ideally you should have a service manual as well since nobody will repair it without one.

You may need to make up new cables to connect your cameras to the SEG, normally this will be no problem. Coaxial TV feeder cable, the thinner and more flexible VHF type, is ideal for this purpose, and most video equipment uses either BNC or UHF (PL-259) connectors. You can buy these at professional video shops but they come cheaper at CB or amateur radio shops.

Be sure to make a good job of soldering plugs. A small iron is useless on the PL-259 type since there isa lot of metal to heat up and you don't want to melt the plastic parts by slow cooking. If in doubt ask in the shop. Many mysterious losses of signal can be put down to loose strands of the braiding shorting the signal to ground or dry joints giving poor connections.

This article will be completed in the next edition of 'Working With Video'.


Series

Read the next part in this series:
Working with Video (Part 2)



Previous Article in this issue

Guide To Electro-Music Techniques

Next article in this issue

Depeche Mode


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - May 1982

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Topic:

Video / Film / Picture


Series:

The Video Studio

Part 1 | Part 2


Feature by Andy Emmerson

Previous article in this issue:

> Guide To Electro-Music Techn...

Next article in this issue:

> Depeche Mode


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