Jim -i Pad and i Phone video capability makes them fantastic for communicating condition questions in real time using Google Hangout, Skype, etc with a conservator and the size of the image is great for READING photo images and diagrams. But like all mobile devices, they remain a tool best suited for emergencies – gathering fast documentation of time sensitive events – roof leaks, earthquakes, vandalism, sculptures falling from pedestals and the like. For detailed, hi-resolution, color-accurate, digitally archival museum photos, they are, as yet, not appropriate and a Digital Single Lens Reflex camera with prime lenses that capture RAW format files remain essential.
The i-pad has a fixed aperture f 2.4, 5 megapixel digital camera with a CMOS sensor and a Bayer filter for color mosaic assembly. The iPhone has an 8 mega pixel camera with the same lens and sensor setup. Digital Single Lens Reflex cameras have the same CMOS sensor and color filter but very different color processing and detail-gathering capabilities.
From a museum record standpoint, the problems here are:
Lens diameter is a problem because, truly, resolvable details per pixel are dependent upon the gathering power of the lens on each pixel on the sensor. Tiny lens, lousy resolution, regardless of the sensor size (Mp).
Lens apertures need to be user controlled and for museum documentation, adustable between F5.6 and F 11. Any higher or lower and there are inherent distortions in the digital information.
The iPhone and i Pad color space are proprietary. Like all mobile-phone cameras, the phone super-saturates greens, blues, and reds to really make them “Pop” for the consumer. The resulting JPEG is compressed and inaccurately rendered for condition, publication.
The mobile devices as yet do not capture non-compressed, RAW file formats- although this is on the way. JPEGs start their lives compressed with no meta-data about illumination, F-stop, speed, ISO or lens focal length. To make the time it takes to compose truly meaningful, worthwhile photos for condition records, cataloging or publication, you want that digital info in order to make the photo to useful for generations. Get a good, prime 50 mm Macro lens and a good DSLR camera capable of capturing RAW files.
Also, START by getting a copy of the AIC Guide to Digital Photography, 2nd edition, ( http://bit.ly/1djGBTW ).