Recent experiments in long-range photography show up limitations.
In 1998 Richard Carter and others investigated the field capabilities of 16 mm cine photography with a view to informing the debate on the subject. The hypothesis they tested was that under some normal conditions a common type of anglers boat might not always be recognisable as such when at long range, typically one mile. They selected a 16 mm Bolex camera as being among the best of its type, and fitted a commonly used 135 mm lens. The film stock chosen was Eastman 7222 Double-X Negative film.

Throughout the photography the target boat was directed by radio, and its range was measured with accuracy using a Barr & Stroud FT37 80cm base Optical Rangefinder.

                        The 16 mm Bolex H16 Reflex Cine Camera                                The Barr & Stroud Rangefinder
 
 

            Original camera negative scanned at 10,000 dpi by Raynor Technical Services
 

The above image is a single frame from an experimental film taken by Richard Carter with a 16 mm Bolex cine camera fitted with a 135 mm lens. It shows a typical anglers boat crossing the loch towards the far shore, which is about one mile, or 1600 metres, from the camera. In most frames the object is not recognisable as a boat.

              Photograph of 35 mm film print  scanned at 10,000 dpi by Raynor Technical Services

For comparison purposes, this is one frame from the film taken by Loch Ness Investigation Bureau member Dick Raynor in 1967 using a 35 mm cine camera fitted with a 17 inch  (430 mm) lens. The range is again about one mile, but the combination of larger film format and longer focal length lens gives a different field of view. The "quality" of the 35 mm picture is visibly higher than that of the 16 mm picture, but neither is good enough to resolve the objects causing the disturbance, as the enlarged insets demonstrate. This would naturally suggest that even longer lenses should be employed, but experience indicates that with lenses beyond 1000 mm the combined extra requirements of increased camera stability and (usually) worse maximum aperture defeat the objectives. Poorer light transmission must be countered by  faster film or longer exposures, both of which will reduce the detail in the image of a moving subject.

It now seems rather unlikely that long-range photographs will ever enable us to recognise any unidentified animals, it is the inescapable conclusion after 67 years of failure. Only close range pictures will be of any value to science, and in such a vast environment the most important factor governing success or failure might simply be Chance.