Photographs taken at the time of a historic event can sometimes be slightly fuzzy. The photographer's hands may have been shaking with excitement or perhaps the crowd was jostling and pushing while the picture was being taken. A photograph of the same scene some weeks after the event often gives a clearer outline: the situation may have stabilised and temporary distortions been ironed out.
This is one possible interpretation of the latest Irish Times/ MRBI poll figures from Northern Ireland. The support figure for the Ulster Unionist Party at 33 per cent in the previous poll, excluding undecided, (published on June 5th) now seems somewhat inflated, especially given the party's electoral showings down through the years. Generally speaking, the party achieves that level of support only in Westminster elections where Democratic Unionist Party candidates are usually the ones who stand aside to prevent a split in the overall unionist vote.
The figure for Mr David Trimble's UUP of 27 per cent in the poll published today is very close to the 27.9 per cent the party achieved in last year's local government elections and 2.8 per cent more than its share of the vote for the forum in 1996.
The DUP, led by the Rev Ian Paisley, has risen by three percentage points since the last poll. Its showing of 16 per cent is comparable to the 15.8 per cent it achieved in the 1997 local government outing. It is also 2.4 per cent above the party's performance in last year's Westminster election but 2.8 per cent down on the forum showing.
The electorate may be responding to the DUP message and pulling back from the high-risk strategy of Mr Trimble in accepting the Belfast Agreement. But it is at least equally possible that what we see here is a normalisation, a steadier picture of the political scene than we got after the referendum.
While Mr Trimble may have reason for concern but not anxiety and the Dr Paisley grounds for encouragement rather than euphoria, the SDLP will feel a quiet satisfaction that its vote has dropped only one percentage point since the last Irish Times/ MRBI survey was taken on June 1st and 2nd.
If the party's 26 per cent figure were repeated at the ballot-box it would represent the SDLP's second-highest score since its foundation, exceeded only by the 28.9 per cent it attained in the 1994 European Parliament elections.
It is almost a cliche of opinion polling in Northern Ireland that respondents, presumably for reasons of personal security, are shy to reveal their adherence to Sinn Fein. For that reason Sinn Fein's 10 per cent must be treated with caution, especially since the party received 16.9 per cent in the last local elections and 16 per cent at the Westminster poll.
Nevertheless, Mr Gerry Adams may be encouraged by the 10 per cent of respondents who intend to vote Sinn Fein, compared with 8 per cent in the previous survey.
The Alliance Party's first preference showing here is down one percentage point since the last poll. But its 9 per cent is still a better figure than it has achieved in actual votes since 1987.
Since there is a 3 per cent margin of error in this telephone survey of 1,000 people (conducted on June 15th and 16th), it is difficult to read very much into the figures for the smaller parties. The UK Unionists remain at 3 per cent; the Progressive Unionist Party has risen from 1 to 3 per cent; the Women's Coalition has gone up from 1 to 2 per cent and Labour down from 2 to 1 per cent.
Observers fancy the PUP will do well and it seems it may do better than its fellow loyalists in the Ulster Democratic Party, although the UDP at least manages to appear "on the screen" this time, with 1 per cent. At a consistent 3 per cent, the UK Unionists can claim to be doing well for a small party in a tight market.
Since only about one-fifth of the seats in the 18 six-seater constituencies are expected to be filled on the first count, the question of second and later preferences is critical.
In the special circumstances of the North and given that voters have less experience of proportional representation than their counterparts in the Republic, it is not surprising there is a total of 41 per cent "plumpers", i.e. voters who intend supporting their own party and no other.
When the remainder are distributed, the Alliance Party remains on top but its 12 per cent is down on the 15 per cent it achieved last time. Allowing for the belief that opinion polls give Alliance slightly higher ratings than it tends to receive, the outlook remains promising for Lord Alderdice's party.
Among the larger parties, the highest percentage of transfers to Alliance comes from the SDLP at 22 per cent. It is slightly surprising that only 2 per cent of SDLP transfers go to Mr Trimble's party, given the de facto cross-party alliance in the referendum culminating in the "hands across the Waterfront" by the two party leaders at the U2 concert. Only 4 per cent of UUP transfers are going the SDLP's way.
There is a disparity between the transfers coming to the SDLP from Sinn Fein and vice-versa. A sizeable 53 per cent of Sinn Fein transfers go to the SDLP but only 20 per cent of SDLP voters return the favour. This may reflect the appeals by Sinn Fein leaders for a voting pact with the SDLP which the larger party has greeted with comparative coolness.
On the "most important issues facing the Assembly" there has been a potentially significant shift. Decommissioning was listed by 28 per cent of respondents in the last poll but has now slipped to 19 per cent.
Meanwhile peace, level with decommissioning last time at 28 per cent, has risen to 45 per cent. The religious breakdown is revealing. Last time, 33 per cent from the Protestant and mainly unionist community listed decommissioning as a priority and only 22 per cent mentioned peace. This time around, decommissioning has fallen to 25 per cent among Protestant respondents and peace has risen to 39 per cent. A similar shift is apparent among Catholic respondents: decommissioning is a priority for 11 per cent in this group, compared with 21 per cent last time. Peace is listed by 54 per cent in the current poll compared with 36 per cent last time. The overall figure for prisoner releases remains steady at 14 per cent.
In general, the low-key campaign seems to be benefiting the more hardline parties in both camps. As with the referendum campaign, a little more razzmatazz may be needed if the UUP in particular is to achieve its desired level of success at the polling booth next Thursday.