An electric field (EF) is the effective means for effect on a flame because there is ionized medium in a reaction zone. In this paper we investigate the effect of variable spatial configuration of the weak EF (U1 = 1300 V) on diffusion combustion of propane in a nozzle-attached and lift-off flame mode (in a burner nozzle Re = 400 ÷ 7000). For the experiment the scheme set a rotation of an intensity vector of the EF was designed and constructed. Spectrozonal photography of own flame radiation at the wavelengths of excited radicals (OH* , CH* , C2 * ) provides information about the EF effect on processes took place. After processing of the data obtained as a result of the shooting, a radical radiation intensity distribution along a diffusion torch was plotted and compared with and without the EF effect. It is found that the rotation of the intensity vector of the EF leads to a growth of a maximum emission intensity of radicals CH* and C2 * and its shift down the torch height to the burner mouth, at the same time the length of the radiating area decreases considering all radicals selected for the investigation. All this testifies to the intensification of the burning process exposed to the preset EF configuration. The research of the flame using spectrozonal photography at the wavelengths of excited radicals OH* and CH* in a flame stabilization area allow to determine a local air-fuel equivalence ratio α.