Hi List: A simple point but I still must ask. Some collimation instructions, and comments on list, state that a collimation screw must NEVER be loosened. ...
Tom Slater
tslater@...
Feb 1, 2004 9:05 am
63942
From: "gstrumol" <gstrumol@...> Subject: [sct-user] Re: Collimating a celestron 8" ... Hi Gary: I took a chance and tried the URL. It downloaded in ~2...
The secondary swivels on a center pivot, but it's not a "captive" swivel. The three screws are "pull" screws, so generally, when you loosen one screw, the...
Take a look in the Files section for a jpg I placed there a long time ago called "secondary mirror.jpg" (near the bottom of the list). It shows a sketch of the...
In a message dated 2/1/04 3:06:24 AM Central Standard Time, tslater@... writes: Can we loosen a collimation screw to correct the star image skew? I'm not ...
In a message dated 2/1/04 12:49:05 AM Central Standard Time, jmmahony@... writes: You can get to it from Rod's instructions, sort of. Go to the URL in...
... From: "gnowellsct" <tim71pos@...> To: <sct-user@yahoogroups.com> Sent: Saturday, January 31, 2004 6:33 PM Subject: [sct-user] Re: the much maligned...
I bought a used 8" Meade 2080 on astromart. The onwer told me the image was very good for a SCT. To make a long story short, the image was pretty bad. He had...
Greetings I have a meade 8" LX5 with a 2" diagonal that I use for backyard visual astronomy. I am interested in the Orion 2" to 1.25" helical fine-focusing...
A friend of mine makes his living developing adaptive optics for the Keck telescope. The mirror-rippling trick really only works if you have a bright guide...
To All, I don't know if it's the proper thing to do, however, for many years now, I have had the focal reducer lens attached to the output side of the 2"...
Yeah, it is a constant discussion topic I know but there is so much to learn. WHY, in the name of time, don't the manufacturers use 4 screws @ 90° to move the...
Tom Slater
tslater@...
Feb 1, 2004 3:29 pm
63954
I'd offer the following possibility: 3 points define a plane uniquely but 4 do not. So pulling on one of 4 screws with the other 3 defining a plane for...
Hi Tom Dont know where you read that but it is just not true. It is true that there needs to be tension on all of the screws since they have to "pull" the...
... much to ... 90° to move ... @ 90° do ... in the ... tweaking! No ... Tom, Not a good analogy, think of a piece of stock protruding 80" to 140" from the...
Because it isn't kinematically stable. This is one reason that three-jawed lathe chucks are almost always used on rotationally symmetric parts. Trying to...
From: "morganml12000" <morganml12000@...> Subject: [sct-user] Re: Overworked collimation topic ... Hi Mike: Thanks. I never realized that the secondary...
Tom Slater
tslater@...
Feb 1, 2004 7:05 pm
63959
Tom, Because it is easier mechanically to do the adjustment if there are 3 screws. With 3 screws you can adjust just one of the screws without moving any of...
Hi Well, physically it is not that long but one has to remember the scope is, in effect, over 8 ft long for a 10 inch f10. So that is the "leverage" the beam...
The direction to move the secondary is not guaranteed to lie along either the X or Y axes, so I don't see that 4 screws simplifies that aspect of collimation....
WHY, in the name of time, don't the manufacturers use 4 screws @ 90° to move the secondary. I use a 4-jaw lathe chuck all the time and 4 jaws @ 90° do not...
From: "Don D'Egidio" <djd521@...> Subject: Re: [sct-user] Overworked collimation topic ... say, the movements are 90º to each other. It has now become...
Tom Slater
tslater@...
Feb 1, 2004 8:42 pm
63966
Since the standard issue human eyeball can adjust its focus over a reasonable range, focusing for visual use is generally not critical. If you're having...
That's an intersesting approach. It sounds like your reducer is inserted backwards in the light path, but I'm not sure how important that is. The distance...
Does the forward "input" tube of the diagonal also screw into the mirror body with the same threads? If so, you could put the reducer there, and it wouldn't...
I think Don has hit the nail on the head. For the scope manufacturer to go to a 4 screw collimination system would require drilling and tapping another hole...
Most newbies live in fear of those three little screws, and you want to add a fourth, and add that extra terror to their lives? Tsk tsk! Mark ... avast!...
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