C8 Collimating and Corrector Plate Question
My name is Chris. I live in Bellingham, WA. I'm fairly new to all this. I was given a 114mm/1000mm Meade reflector from an acquaintance a while back. About 3 months ago, I got that cleaned up and collimated as best I could. The issue was with the tripod. An abomination, I'm sure. Teeth of the RA stripped out around about a third of the round. I really enjoyed the small successes, but the issues with the tripod were to much to bear. I digress, and long story short, I discovered that a decent tripod was going to cost a bit of money, so...
I've recently purchased this C8 from a man in Enumclaw, WA. Everything seems to be in good working order, but I'm needing some help with collimating the scope, especially regarding the corrector plate and secondary mirror housing.
I've followed stringent procedures for cleaning the plate, primary and secondary. All that looks great compared to the state it was in when I purchased. I've attempted to collimate the secondary with good results, but I'm sure something's not 100%.
Besides the 3 adjustment screws on the secondary mirror housing, does anything else need to be done to the corrector plate? I marked the plate and replaced it in the same position as before the cleaning. The picture I'm showing is from the "before" cleaning pictures (there was debris on the inside of the corrector). The recess for the plate is in fairly tight tolerance - not much room for the plate to shift in any direction - perhaps 1/16" at most. I attempted to put the plate back in that position, although there was no shimming that did that originally... again, can barely move the plate around in the recess.
The secondary mirror housing is snugly screwed onto the corrector plate.
I've noticed that when I secure the plate in place with the corrector ring, the secondary housing can still spin counter-clockwise and clockwise (this is NOT turning the entire secondary mirror-already verified that). Using a collimating cap, I've noticed that this rotation of the secondary housing effects the centering of the primary looking through the collimation cap. Is that supposed to be the case on this scope? If I turn the secondary housing enough, either clockwise or counter, it eventually gets tight and feels really solid, but the centering of the primary is usually not at its best.
I was able to get things fairly well collimated at some point, but I may not have done it correctly. I realized later that I needed to go all the way through all my eyepieces (32/25/15mm + 2x Barlow). This may have affected my use of the 15 and Barlow since I may not have gone all the way up to that point. Is that true?
The other question I have is about the perpendicular aspect of the corrector plate. Is there any recommended adjustment to that aspect of things? I ask because I noticed that I could see some of the side of the secondary mirror housing when looking through the collimation cap. With the plate securing ring off, I carefully checked if that changed if I tilted the plate out of its recess. It affected and could correct some of that discrepancy. Is this type of adjustment necessary? Does it indicate a major issue with the scope (hope not)?
There is a small dent in the tube. Seems minor to me. Not a major dent at all. Also noticed that there are two empty screw holes in the gray main corrector plate housing which attaches to the orange tube. Are there supposed to be screws there? I notice that the housing is very secure to the tube and cannot be moved. The screw holes of the gray ring and the tube are perfectly lines up as well.
Ever since I was a kid, I wanted a telescope. I'm hoping I can get this working to the best degree possible. Any advice? Videos? Forum threads? I've done a lot of research, even before I bought this scope. I've watched countless YouTube videos. Sometimes Google just doesn't get you where you need to go. Any help is greatly appreciated.
All the best,
Edited by ChristopherLP, 14 April 2021 - 06:29 PM.