Abstract: A base film for a photographic film, which (A) consists essentially of polyethylene-2,6-naphthalenedicarboxylate containing naphthoic acid unit in an amount, in terms of methyl naphthoate, of 2 to 1,000 ppm, (B) has a light transmittance, T.sub.400, of at least 95%/cm at a wavelength of 400 nm when a solution of 10 mg/ml of the polyethylene-2,6-naphthalenedicarboxylate in a hexafluoroisopropanol/chloroform mixed solvent having a hexafluoroisopropanol/chloroform weight ratio of 2/3 is measured, (C) has a yellow index Y.sub.ID of at most S, and (D) has a haze value of 2.0% or less.

Abstract: A base film for a photographic film, wherein (A) the base film is formed of a polyethylene-2,6-naphthalenedicarboxylate copolymer formed from 2,6-naphthalenedicarboxylic acid as a main acid component and ethylene glycol as a main glycol component; (B) a solution of 10 mg/ml of said copolymer in a hexafluoroisopropanol/chloroform mixed solvent having a hexafluoroisopropanol/chloroform weight ratio of 2/3 shows a light transmittance, T.sub.400, of at least 97%/cm at a wavelength of 400 nm; (C) the film has a yellow index, Y.sub.ID, of 5 or less; and (D) the film has a haze value of 2.0% or less.

Abstract: A biaxially oriented polyester film formed from an aromatic polyester composition containing:(A) 100 parts by weight of an aromatic polyester, and(B) 0.005 to 5 parts by weight of calcium carbonate particles defined by:(a) a length/width ratio (2a/2b) in the range of from 1.25 to 3,(b) an average particle diameter (D), as a diameter of a circle converted from an area, in the range of from 0.05 to 5 .mu.m, and(c) an ellipse coefficient, represented by the following equation (1), in the range of from 0.7 to 1.2, ##EQU1## wherein R is an ellipse coefficient, S.sub.1 is an observed area of a projected plane of a particle, and S.sub.2 is an elliptical area determined on the basis of observed values of the length (2a) and width (2b);and a magnetic recording medium formed of the above biaxially oriented polyester film and a magnetic layer formed thereon.