During my umpiring days at the international level, there was no third umpire to help out in close line decisions, nor there was a Match Referee, except in my last two seasons. There also wasn't any light-meter to ascertain the light. All we could depend on was our experience! The idea was to offer the light to the batsmen if the bowling was fast or fast-medium. This used to be an intriguing and irritating decision to make. But that's how we managed it.
he sightscreen at the Far (Tata) End of Mumbai's Wankhede stadium
Today of course, the umpires have the benefit of light-meters. If the minimum reading on it is lesser than the prescribed standards, then it means that the light is not good and the batsmen may opt to continue or go off. Similarly, the light can be checked from time to time after play is temporarily abandoned. Whenever the light reading improves, the players are called back. There is a light indicator near the scoreboard on most grounds in England. It consists of five electrical bulbs. The bulbs light up one by one as the light starts fading. Play can proceed till the third bulb lights up. After that, out comes the light-meter!
The light-meters obviously cannot be disputed, but 'poor light' conditions were often debated in our times.
In the famous Lord's Test of 1963, the England batsmen found it very difficult to pick out Wesley Hall and Charlie Griffith when either of them was bowling from the pavilion end. The reason was that there was no sight-screen provided at that end as it would have blocked about 200 seats in the Member's Stand, strange as it may sound.
The sightscreens on Australian grounds used to be very small in size. Whenever it was moved at the batsman's (striker's) request, the spectators sitting behind would move to the other side and vice-versa. Further, these screens were somewhat transparent.
It is now mandatory to have sightscreens of a specified width at both ends. The height has to be 15 feet and the width 40 feet. Screens that are mobile have to measure 15 feet X 20 feet.
Advertisements are permitted on the sightscreen behind the striker in these commerce-driven days. These are blanked out when an over is bowled from that end. Once during a Test in Mumbai, the roller pin in the sightscreen developed a snag and the advertisement could not be obscured. Play was held up until a huge tablecloth was borrowed from the home team's dressing-room to cover the advertisements.
I remember the compound wall being used as a sightscreen at one end at some non-Test centers in India. At Rajkot for instance, the pavilion-building was white-coloured till the first floor, specifically for this purpose.
The height of the sightscreen continues to pose problems even though the length of the boundaries has been cut down. Naturally, the longer the boundaries, the larger sightscreen (in height) was required.
At the Wankhede stadium, the staircase leading in to the Garware Stand from the E & F Blocks, which is right behind the sight-screen at the pavilion end, is invariably blocked by police/volunteers / personnel whenever an over is in progress. Such movement above the sightscreen can distract the batsman. The same is the case at the Eden Gardens in Kolkata. In our time, we had to summon an official on the ground and explain the problem. Nowadays the umpires have walkie-talkies to convey the message.
A spectator wearing a red or yellow-coloured dress is often told to move away, even though he / she might be seated a little away from the screen. A funny incident occurred during a Test against England at the CCI in Mumbai. Tom Graveney, who scored 175, was batting at the pavilion end, complained, and a policeman posted near the sightscreen was asked to move away. The umpire and some players were frantically waving at him, although he was standing a good 10 to 12 feet away from the sightscreen. Poor thing could not understand why was being singled out! Finally, Hemu Adhikari, who was fielding in the covers, rushed to him and told him to cover the buckle of his belt that was reflecting the sunlight!