I want to find a 4.5 inch primary mirror. Not just any run of the mill with 1/4 wave ratings. I want sharp images and the ability to use high powers. Even 1/10 wave will not fit my needs. You guys who know mirrors know what I want. Where do I find this mirror ? Sick of the mass produced junk and what most people think is good. I'm sick of blobs of light instead of airy disks. Don't suggest refractors I already have that but its not what I want. Can't make my own. No where to do it.
Where to find it...................
Started by imgary, 10/21/2002 09:47PM
Posted 10/21/2002 09:47PM
Opening Post
Posted 10/22/2002 08:08PM
#1
This may also be another reason for a better than good 4.5 inch mirror. If I start with good then I know what to expect. Of all my scopes I had to take someone else's word that they were good. Well I can tell you that's not a good way to get a good one. If the 4.5 excellent mirror does its job I will then have something to base my future purchase on using my own eyes. A 10 inch comparison to a 4.5 inch is not fair but to a degree it is. ANY scope worth its wieght can and will resolve a star to an airy disk "thats the function of the mirror besides gathering light". NOT an airy spot or put another way a blob. Understand, that I understand conditions exist and most of the time those conditions effect optics. I think here that a reflector cannot achieve the same performance as a refractor but could be close !! Thats what I want at least close. My XT8 is close as I can get so far and my homebrew 6 inch f/8. All my fast scopes have blobs for stars and teeny tiny hard to see airy disks even on bright stars. Thats all for now.
Posted 10/23/2002 05:01PM
#2
I have to say I have really enjoyed reading and understanding this message thread. Thanks to all that have replied. Its gotten a little off topic now and again but its been fun. Now, let me pose a slightly new question. I undestand that a 4.5 inch scope is not much more than a toy and does'nt seem very important in the scheme of things. But what occurs in one scope can be related directly to in another. Heres the question: Would I have just as good a mirror if it were f/8 and spherical as compared to parabolic ? It seems to me that the parabola in itself introduces problems such as critical aiming, collimation, distortion etc. Whereas the spherical mirror would less likely to introduce those problems. I don't wish to start a whole technical discussion. Bad idea or workable is all I need and perhaps a short conclusion with your reasoning. Of course if you want to write a book thats ok too. Oh and don't worry about the XT10. I'm just gonna kick it to Mars. Along with the Mini Max that won't work either.
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