If you take a photo of a photo that's already copyrighted, you may still need to get permission from the original creator before using it. Simply taking a photo of a copyrighted image does not automatically make it fair use. The copyright law gives the creator of an original work the exclusive right to reproduce, distribute, and display the work publicly. When you take a photo of a copyrighted image, you are creating a new work that is derived from the original, and you may need permission from the original creator to use it.
However, there are some exceptions to this rule. If the photo you are taking is for personal use, such as for a personal project or for social media, you may be able to use it under the fair use doctrine. Fair use allows for limited use of copyrighted material without obtaining permission from the copyright holder. However, it's important to note that fair use is determined on a case-by-case basis, and it's always best to consult with a legal professional to determine if your use of a copyrighted image would be considered fair use. Ultimately, it's always best to err on the side of caution and obtain permission from the original creator before using a copyrighted image.