In terms of my own ideal moral boundaries? Well, it depends on the circumstances. I will refer to this hypothetical person as X.
1. If X made/caused to be made the images: Guilty beyond doubt. Lock X up and throw away the key. Sexual assault of a 7yo? Are you kidding? Absolutely wrong and absolutely should be removed from society before more harm is caused.
2. If X did not make the images but contributed to their creation via payment: Guilty. By payment, he has directly helped fund this and future crimes.
3. If X did not make the images but contributed to their creation by other means: Grey area. Could be considered part of a conspiracy to commit a crime. Would depend on the circumstances.
4. If X did not make the images and had no link to the person(s) who did: Not guilty, of course. There is no link between him and the crime. He merely has a visual record. Obviously a promising candidate for counselling, however. To be treated the same was as, say, someone found with 10GB of execution photos/videos.
I wonder what answer you were expecting? I am sorry but I just cannot accept that making a copy of a file can be considered a criminal offence or even wrong.
I consider anyone who rapes 7yo kids to be utterly reprehensible, by the way. That is fucking sick. Lock up anyone who does that, forever, and I will applaud you. But possessing an image of the crime in progress? That should not be a crime, that should never be a crime, that should not even be able to be a crime.