The 37-page class-action complaint was filed on behalf of customers against New York-based Nikon Inc, by US law firms including Zimmerman Reed which says the spots appear in the ‘upper left corner’ of their pictures.

Lawyers state that the move followed ‘lengthy investigation and speaking to numerous affected consumers’.

The complaint alleges that ‘the oil and dust spotting in the D600 is the result of a defective shutter mechanism which consistently splatters oil and dust onto the camera’s image sensor’.

The legal action, dated 19 February, appears to have been lodged just a few days before Nikon promised to replace the shutter for customers who continue to suffer from dust spots, after carrying out sensor cleaning.

The complaint, filed in the United States District Court for the Northern District of California, claims that the internet is ‘saturated’ with consumer complaints that accuse Nikon of falsely promoting the D600’s picture-taking qualities.

It adds: ‘These complaints detail the frustration of consumers who paid $2,100 or more for what they believed to be a “pro-level” camera that would deliver professional picture quality.

‘Instead, images documenting life, experiences, and family milestones have been ruined.’

Asked to comment on the lawsuit – first reported by website Nikon Rumours – a Nikon spokesperson told Amateur Photographer today: ‘As this is an ongoing legal matter, we’re unable to comment at this time.’

The lawsuit points to an initial ‘service advisory’, issued by Nikon on 20 February 2013, that suggested the problem was a result of “natural accumulation of dust” affecting “some cameras” in “rare instances”.

Nikon recently issued an updated advisory notice.

The D600 was announced in September 2012.

On it website, Zimmerman Reed claims that spot and blemish issues ‘may not appear until after a consumer has taken at least several hundred photographs’.

Law firms Pearson, Simon & Warshaw and Hausfeld joined Zimmerman Reed in the class-action.