This photo above is considered one of the top ghost pics of all time. It was taken in 1925 from an oil tanker and the faces of two dead sailors are supposedly seen. A fantastic article about this can be found here. Ultimately, it was discovered to be a fake. There were a lot of fake spirit photos back then and the concept that sailor's faces were seen in the sea and photographed with a 1925-era camera is just about as impossible as it sounds. Ironically, it had been tucked away into lots of archives of the best ghost photos ever taken.
I will be honest about ghost photography--I do not think it's possible. I think there are a lot of things that can go wrong taking a photo and also those who will play with photos. I do not see cameras as capable of capturing phenomena because the fact that it is extremely a rare occurrence that a photo cannot be explained. Between pareidolia (thinking you see shapes in photographed items, like faces in orbs) and the issues with pixelation, lighting, shadows, dust, bugs, et cetera, we just don't get genuine ghost photos. We get some photos we haven't figured out the explanation for, but I don't think there is anything about a camera that suddenly makes it able to pick up what it does not pick any other time. If spirit activity is all around us, regular photos should be showing it if cameras were capable of picking it up.I don't give up the hope that some day a camera can act more like a human eye and capturing things were are seeing on the hunt, but for now I do not find them of any use in the field other than to documentary the environment for archives.