Quote:
Originally Posted by Kokatha man
......the Orion sight tube/collimator........
ps - did that Andrews tool(?!?) provide any use Eric?
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Thought it best to take this discussion out of the laser collimator thread. The story behind this is that I had three collimation tools - a 35mm film cannister with a hole drilled in the bottom, a GSO laser collimator, an Orion combined sight tube/Cheshire. I've been using my film cannister sight tube and my laser and have never felt comfortable that I know how to use the Orion properly, regardless of reading the instructions. Eg. I could not get the crosshairs in focus. One night, I had the chance to compare looking through an Andrews -sourced Cheshire and the Orion and what I saw through the Andrews made sense. So when Darryl (Kokatha man) said he was happy to discard his Andrews Cheshire, I convinced him to send it to me so I could experiment further.
I've had one brief session comparing the Orion and Andrews. When I have a few hours to spare, I'll sit down during the day and carefully work with them until I fully understand. I have printed out all Geoff's (Starkler) guidance on the correct use of a Cheshire and will persist until I have it right.
From the other night's brief session, all I can say is that the view through the Andrews continues to be much less confusing. Both showed the primary mirror centre ring well centred under the peephole, after my usual visual inspection of the secondary mirror position and use of the laser. They have a different size machined countersunk hole that places an image of a dark circle where the peephole is (ie. in the centre of the shiny reflected circle generated from the 45 deg surface. That seems to be affecting how I see it. The Andrews has no cross hairs so I don't have the confusing out of focus crosshairs I see in the Orion (It must be my aging eyes - I've moved my head back from the peephole, but they don't come into focus.)
Both Cheshires will wobble around a bit in the 2"->1.25" adapter I am using, if I push sideways on them. This, of course, moves the images out of alignment. I may do what I have done with the laser I use - adding a layer of contact (yes, school book type "contact") made for a very snug fit in the adapter.
So, more to do yet before I know what is what and achieve confidently, a basic level of reasonable collimation. (Scott (Tannehill) showed me the operation of an autocollimator in the 12" - I have a ways to go before I add that additional level of perfection to my collimation.)
Eric
