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Showing results for tags 'secondary mirror'.
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Good afternoon all and hello from cloudy maidenhead! Recently getting back into astronomy from a few years break and have just bought a Celestron cpc 800 which i love! (i used to have a 8" Dob but it was too cumbersome to take to darker skies) Anyway as my title suggests i started\cleaning the front correction glass when i noticed the center with the collimating screws was able to rotate!? As i tried to tighten it, it kept on rotating (oh no!) This left me no choice but to remove the front glass to get inside to tighten it. I marked very carefully the exact orientation of the glass as ive heard this is matched to the main mirror and screws etc... When i removed the front end as feared the the secondary mirror was rotating also and i have no idea what position it started in! Will this just be a simple issue of re-collimating the scope or does the main and secondary mirrors need to be aligned some how? On a second note as i had the correction glass out i decided to clean both sides of it... I cleaned it very carefully and happy with the results but the glass didn't look coated in any way, just perfect clear glass. does this sound normal? Thanks for your help in advance guys Stu
Have you ever thought about why your Newton telescope has the dimension it has, primary and secondary mirror, focuser, f/number and so on? I stumbled in to this tool Newt-Web that Kenneth H. Slater has developed further from Dale Keller's code. It's an online design tool page for Newton telescope. It's a very intuitive page where you can put in some figures about a Newton telescope that you want to built and get back information about it's performance. It give a ray trace and important data back. From that you get understanding when a Newton telescope design is good or not. I have done some test and written it down on my homepage so you can see the different steps and my comments: http://astrofriend.eu/astronomy/projects/project-design-newton-telescope/project-design-newton-telescope.html I already know some of the physics and math, but never got to know so much in short time what happens when you change a parameter and what happens inside the telescope. Beware, I'm still in the learning process and not all what I have written is fully correct. I recommend you to take a look at Newt-Web page even if you never will built a telescope, you get knowledge and understanding that could be very valuable when you shall buy a Newton telescope. /Lars
Hi, newbie at using a telescope. I have recently got a Celestron astromaster 130eq. I finally got chance to use it last week viewing the moon, I got some brilliant views and images. Using the 20mm erecting eyepiece and 10mm eyepiece that came with the telescope. (Pictures below to show that all was fine) I also have a 6mm plossl eyepiece, 15m Kellner eyepiece, 2x Barlow, and red, blue and moon filters. This morning with it been clear and Jupiter and Venus is clear view I Set up my telescope as normal, got the planets into view on my telescope used the 20mm eyepiece to clarify it was In view and it was just the a small white dot which I expected. So I started to reduce down the eyepieces to get a closer view and as I was slowly trying to focus all I could see was the secondary mirror in the lense. I tried a range of my different lenses to try and get it into focus even starting at the 20mm and working my way down and I just couldn’t see anything without the secondary mirror housing in view. at one point I could see something behind the secondary mirror image however I couldn’t make out what it was despite trying to focus slowly in and out. Looking at forums and advice could it be that I’ve actually locked on to a star which is further away hence why I can’t focus. Please help.