I have a trial lawyer for a nephew. He says photos are generally admitted as evidence on the basis that someone testifies that they are authentic. I don't think negatives are generally part of the evidence.
Now, if the prosecution wants to argue that the photos have ben tampered with, I think he's in for a bit of trouble. My understanding is the original images have been sent to a certified lab. It would depend a bit on how quickly the image files got to an independent custodian.
Whether the judge understands the technology is irrelevant. What matters is whether experts agree that tampering with the images is not possible in the time frame available. If there is a series of images, that will tell a story, and it will be very difficult to argue that a particular image has had its timestamp altered. I'm not even aware of any software that can alter the metadata without leaving its own signature.
I can just imagine the trail that would be left by a bunch of kids trying to locate a hacker capable of tampering with the images. How do you quickly locate a CIA level hacker without being observed?
Nifong's whole photo position is absurd. The authenticity of digital photos when you have the equipment is verifiable, absent some cia level of ability. If you have multiple camera sources, phones or cameras, the ability level required to quickly force the date and time or alter the photos is astronimical. So, if he wants to argue that the photos time stamp is wrong (that is if his case depends on showing beyond a reasonable doubt that the time stamp is wrong) all he needs to do is set up an indepenent examination, it is not really a judgmetn call. If the photos were tampered with, he has strong evidence of guilt. The fact that he does not do that examination, and is going to depend on a pathetic non-expert is all i need to know about the guy. If he were an honest guy, he would set up a meeting with the defense, select an expert, and have the his expert and the defense expert to a joint analysis.
The photos will come in for sure. The bigger question is whether a pathetic whore of an expert hired by Nigong will be allowed to speculate about whether the photos are authentic.
I think it has already been demonstrated that the metadata is rather easily altered.
The key will be the watch in the photos, and Nifong is almost guaranteed to say the watch was set wrong on purpose, going by the other odd things he has said.
http://www.slate.com/id/2140303/