Having read on the Fujifilm website that the NP50A battery supplied with the F770EXR camera isn't commercially available I ordered the next best thing as a backup battery, i.e. the plain NP50 (without the A). Having had poor quality generic equivalent batteries for other cameras I played safe and ordered the genuine battery. As it turns out this battery equals or exceeds the specification of the NP50A. The minimum current ratings are: NP50A 940mAh, NP50 960mAh. This cost about half the price shown on Jessop's website.