An electronic device, comprising: an image sensor (300, 400); and one or more processors (120, 510), wherein the one or more processors are configured to: start a photography session at an intial read-out speed of the image sensor; receive a signal for high-speed photography; set the read-out speed of the image sensor to high speed; store a first plurality of image frames as per a first frame rate among selected images read out from the image sensor in response to a signal for starting recording of images; detect a variation associated with an external object included in at least two image frames read out from the image sensor; when the variation associated with the external object meets a designated condition, store a second plurality of image frames read out from the image sensor as per a second frame rate higher than the first frame rate; when the variation associated with the external object does not meet the designated condition after storing the second plurality of image frames, store a third plurality of image frames as per the first frame rate among selected images read out from the image sensor; generate a video including the first plurality of image frames stored as per the first frame rate, the second plurality of image frames stored as per the second frame rate, and the third plurality of image frames stored as per the first frame rate. an image sensor (300, 400); and one or more processors (120, 510), wherein the one or more processors are configured to: start a photography session at an intial read-out speed of the image sensor; receive a signal for high-speed photography; set the read-out speed of the image sensor to high speed; store a first plurality of image frames as per a first frame rate among selected images read out from the image sensor in response to a signal for starting recording of images; detect a variation associated with an external object included in at least two image frames read out from the image sensor; when the variation associated with the external object meets a designated condition, store a second plurality of image frames read out from the image sensor as per a second frame rate higher than the first frame rate; start a photography session at an intial read-out speed of the image sensor; receive a signal for high-speed photography; set the read-out speed of the image sensor to high speed; store a first plurality of image frames as per a first frame rate among selected images read out from the image sensor in response to a signal for starting recording of images; detect a variation associated with an external object included in at least two image frames read out from the image sensor; when the variation associated with the external object meets a designated condition, store a second plurality of image frames read out from the image sensor as per a second frame rate higher than the first frame rate; when the variation associated with the external object does not meet the designated condition after storing the second plurality of image frames, store a third plurality of image frames as per the first frame rate among selected images read out from the image sensor; generate a video including the first plurality of image frames stored as per the first frame rate, the second plurality of image frames stored as per the second frame rate, and the third plurality of image frames stored as per the first frame rate.