An electronic device for combining images, comprising: a first camera including a first view angle, having a first f-number; a second camera including a second view angle that is smaller than the first view angle and having a second f-number greater than the first f-number, wherein the first camera and the second camera are synchronized; a memory; and a processor, wherein the processor is configured to: obtain a first image having a first brightness and corresponding to an external object, using the first camera, based on a first exposure time set for the first camera; the electronic device being characterized in that the processor is further configured to: obtain a plurality of second images (620, 661) having a second brightness and corresponding to the external object, using the second camera, based on a second exposure time set for the second camera which is substantially the same as the first exposure time, wherein a number of the plurality of second images is determined based at least on a difference between the first f-number and the second f-number; generate an image that is corrected to have a brightness corresponding to the first brightness by using the determined number of second images having the second brightness; and generate a composite image corresponding to the external object based at least on the first image having the first brightness and on the corrected image. a first camera including a first view angle, having a first f-number; a second camera including a second view angle that is smaller than the first view angle and having a second f-number greater than the first f-number, wherein the first camera and the second camera are synchronized; a memory; and a processor, wherein the processor is configured to: obtain a first image having a first brightness and corresponding to an external object, using the first camera, based on a first exposure time set for the first camera; the electronic device being characterized in that the processor is further configured to: obtain a plurality of second images (620, 661) having a second brightness and corresponding to the external object, using the second camera, based on a second exposure time set for the second camera which is substantially the same as the first exposure time, wherein a number of the plurality of second images is determined based at least on a difference between the first f-number and the second f-number; generate an image that is corrected to have a brightness corresponding to the first brightness by using the determined number of second images having the second brightness; and generate a composite image corresponding to the external object based at least on the first image having the first brightness and on the corrected image. obtain a first image having a first brightness and corresponding to an external object, using the first camera, based on a first exposure time set for the first camera; the electronic device being characterized in that the processor is further configured to: obtain a plurality of second images (620, 661) having a second brightness and corresponding to the external object, using the second camera, based on a second exposure time set for the second camera which is substantially the same as the first exposure time, wherein a number of the plurality of second images is determined based at least on a difference between the first f-number and the second f-number; generate an image that is corrected to have a brightness corresponding to the first brightness by using the determined number of second images having the second brightness; and generate a composite image corresponding to the external object based at least on the first image having the first brightness and on the corrected image. obtain a plurality of second images (620, 661) having a second brightness and corresponding to the external object, using the second camera, based on a second exposure time set for the second camera which is substantially the same as the first exposure time, wherein a number of the plurality of second images is determined based at least on a difference between the first f-number and the second f-number; generate an image that is corrected to have a brightness corresponding to the first brightness by using the determined number of second images having the second brightness; and generate a composite image corresponding to the external object based at least on the first image having the first brightness and on the corrected image.