Well, the oldest version of the 3DS Camera app (from the japanese 1.0 3DS firmware) still has the data for this feature, so someone made a mod to re-implement it, but it seems like in later 3DS system updates, all leftovers of this feature got completely removed, meaning the mod is not compatible with newer versions. And even then the feature will always give an error on any firmware.
Nintendo 3DS Camera Community
