I have decided to get my secondary re coated with Dielectric coatings at L&L this winter. 71 layers to produce virtually 100% reflectivity for only $55 is pretty reasonable. Richard and I talked about the controversy concerning changes in figure and he assured me that he produces 1/20 wave optics for a major company and each one is checked after coating by that company. He starts off with 1/30 wave optics to make sure that the 1/20 wave will be met and says he has no problems with the Dielectric coatings making the grade.
Another interesting detail was that the Dielectric coatings provide a better, more even, reflectance in the red and blue spectrum in the visual range. So they might even be better for Astrophotography?
It was also mentioned that cleaning is no problem with them, that you could use your t-shirt if you had too. 8O I would never do that, but it would be nice to be able to clean the secondary without it becoming scratched. My secondary had something on it when it arrived that would just not clean off the coatings with normal methods and the only thing that got it off was repetitious cleaning with pure alcohol, MEK and Acetone. Even then it did not all come off. I would really love to know what the heck it was! The fellow I bought the Starmaster from stated that it had never been cleaned and the scope was only 7 months old. So I have no idea of how it could have been so covered with this substance. It looked as if you had placed something on it and then smeared it around! :S
I did get it pretty clean in the end, but not without some sleeks and small scratches in the coating. They do not seem to effect the views, but I just don't like to see them there, so the coating will be done.
I will try to let all know how this all turns out.
Another interesting detail was that the Dielectric coatings provide a better, more even, reflectance in the red and blue spectrum in the visual range. So they might even be better for Astrophotography?
It was also mentioned that cleaning is no problem with them, that you could use your t-shirt if you had too. 8O I would never do that, but it would be nice to be able to clean the secondary without it becoming scratched. My secondary had something on it when it arrived that would just not clean off the coatings with normal methods and the only thing that got it off was repetitious cleaning with pure alcohol, MEK and Acetone. Even then it did not all come off. I would really love to know what the heck it was! The fellow I bought the Starmaster from stated that it had never been cleaned and the scope was only 7 months old. So I have no idea of how it could have been so covered with this substance. It looked as if you had placed something on it and then smeared it around! :S
I did get it pretty clean in the end, but not without some sleeks and small scratches in the coating. They do not seem to effect the views, but I just don't like to see them there, so the coating will be done.
I will try to let all know how this all turns out.
[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue
Amateur Imager
