Lert
if you are using Registax you are probably capturing as jpegs which is very "lossy" format. You are much better off capturing as a RAW file..but then you will need some software to process . IRIS is free-comes with an intimidating front end but works wonderfully and you can get an excellent step by step guide here :
http://www.saratogaskies.com/
(grab the cookbook print it off and you'll never look back
)