Worth every cent that they cost. I could not do wide field from my light polluted sky over my backyard in suburban Melbourne without it. In fact I possess three a 48mm, 52mm and 58mm. All of my images are done with the Hutech LPR filter unless specified ie Hutech Nebula or Astronomik narrowband. They are also very robust so cleaning is not an issue. The main advantage they have over other brands is two extra peaks between light pollution wavelengths.
The optical quality is very good and if you swap a Hutech LPR filter for the Hutech NF focus does not change.
Here are a few examples
All done with a Canon 5DH and Canon 300mm F2.8L, Hutech LPR filter.
Lagoon & Trifid 2.5MB
http://members.optusnet.com.au/~trlee8/LAGTR_L.jpg
Corona Australis 2.1 MB
http://members.optusnet.com.au/~trlee8/corA_ehdr07.jpg
Omega Cent and Centaurus A 2.8 MB
http://members.optusnet.com.au/~chee.../OC&CA_HDR.jpg
Here is a mosaic done with a Hutech Nebula Filter 2.5MB
http://avandonkbl.bigblog.com.au/dat...0113220304.jpg
Bert