The ST5 extension is attached to RAW images shot with the ST-X model of SBIG CCD cameras. The format is also known as Santa Barbara Instruments Astronomical Image and SBIG represents a brand of specialized imaging cameras, mostly used in astronomy, color photometry, medical imaging and a few other scientific and industrial sectors. As part of these niche uses, ST5 images are considered rare and are probably difficult to open using regular image viewers.
The quick and simple way to handle your files is to get a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch conversions. As you will soon realize, reaConverter will help you avoid spending countless hours trying to figure out how to convert multiple ST5 files as once.
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