摄影星等是以传统的干版或底片拍摄得到的星等。

在光度计出现之前，要精确的测量天体的亮度，是用照相机来制定它的视星等。这些影像，使用正色的摄影胶片或干版，在蓝色端的视频谱比人眼或现代的光度计敏锐。结果是，蓝色星的摄影星等会有比现在视星等低的星等（也就是较亮），因为它们在相片上的亮度比现代的光度计明亮。相反的，红色的星有着比视星等较高的摄影星等（也就是较暗淡），因为它们显得比较暗淡。例如，红色的超新星人马座KW的摄影星等介于11.0〜13.2，但是视星等在8.5〜11.0。也常见在星图上列出蓝色星等（B），像是剑鱼座S和天箭座WZ。

Before the advent of photometers which accurately measure the brightness of astronomical objects, the apparent magnitude of an object was obtained by taking a picture of it with a camera. These images, made on orthochromatic photoemulsive film or plates, were more sensitive to the blue end of the visual spectrum than the human eye or modern photometers. As a result, bluer stars have a lower (i.e. brighter) photographic magnitude than their modern visual magnitude, because they appear brighter on the photograph than they do to modern photometers. Conversely, redder stars have a higher (i.e. fainter) photographic magnitude than visual magnitude, because they appear dimmer. For example, the red supergiant star KW Sagittarii has a photographic magnitude of 11.0 to 13.2 but a visual magnitude of about 8.5 to 11. It is also common for star charts to list a blue magnitude (B) such as with S Doradus and WZ Sagittae.