The rules for the Nikon Photo Contest 2012-2013 – which is open to photographers worldwide – state: ‘Scans of photographs taken with film cameras are not eligible.'
When the competition was last run two years ago it allowed photographers to submit scans of pictures originally captured using a 35mm, or an APS film camera.
Nikon still lists the F6 and FM10 film-based SLRs on its website.
Nikon UK has confirmed that the F6 is still a current product.
The overall winner is set to scoop one million yen (nearly £8,000).
The latest contest, the 34th, will continue to accept images that have been retouched using image-editing software.
This year's competition, launched in Japan on 25 October, adds a movie category.
A spokesperson for Nikon Europe, who is dealing with press enquiries about the competition, was not available for comment at the time of writing.
The rules do not immediately make clear the copyright status of images once entered into the contest.
Asked to clarify this, Nikon UK told us: ‘To confirm, entrants retain full copyright over their images - winners are credited whenever their image is used and Nikon has limited rights to use winning images in connection with the competition.'
The winners are due to be announced in April 2013.