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Vic, your messages are great! I learn a lot from them, but to fully understand them... I have to read them at least 3 times...Well worth the effort!

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So... in your first paragraph, you seem to be saying that if you wanted to, you could correctly collimate a scope and have all the circles concentric?

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The key being that, in the first step, you'd have to start out with the secondary mirror slightly offset in the focuser tube. (I'm not interested in trying it, but I am curious to know if it could, physically, be done.)

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I'm not worried about minor errors in my DSC performance. I'm a beginner. Maybe someday minor errors will become significant to me, but right now minor errors with my DSCs are the least of my problems. I'm just trying to collimate me scope!

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Thank you very much for all your help! Your expertise, and willingness to share good information, is greatly appreciated by those of us that know less than you do!

Round Four, comin' up...

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By the way, the misunderstanding of making all visible images concentric is one of the reasons I wish people would quit recommending that Andy's Shot Glass website tutorial. It has goofed up more people than it's helped.

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I think I'm done!

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By the way, the misunderstanding of making all visible images concentric is one of the reasons I wish people would quit recommending that Andy's Shot Glass website tutorial. It has goofed up more people than it's helped.

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The thing that is nice about the Andy's Shot Glass video is that it is very visual. Sure, it doesn' show the offset--which is unfortunate--but for folks that are starting from zero, it does lay down the basic steps in a straightforward way.

I happen to be a very visual learner. I probably collimated wrongly several times using the video before I could even begin to appreciate the much more nuanced explanations that the experts offer.

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It encouraged you to do it wrong so it has value?
How about something that's correct, with illustrations?

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You know, there could be a career here, just traveling the country collimating telescopes.....cell phone, internet based, work out of your van, just you, a van, and a 25" Teeter with Zambuto Mirror Reflector....Have Scope, Will Collimate????

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You actually think I could make money doing this?

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By the way, the misunderstanding of making all visible images concentric is one of the reasons I wish people would quit recommending that Andy's Shot Glass website tutorial. It has goofed up more people than it's helped.

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The thing that is nice about the Andy's Shot Glass video is that it is very visual. Sure, it doesn' show the offset--which is unfortunate--but for folks that are starting from zero, it does lay down the basic steps in a straightforward way.

I happen to be a very visual learner. I probably collimated wrongly several times using the video before I could even begin to appreciate the much more nuanced explanations that the experts offer.

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It encouraged you to do it wrong so it has value?
How about something that's correct, with illustrations?

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My car has an awfully lot wrong with it, but it has value. It gets me to where I am going.

I could spend weeks studying a 300 page thesis on collimation that might be the unquestionable authoritative source, but if watching a flawed video in five minutes, then reading Jason's above post in 20 seconds gets me to exactly where I need to be, which is more effective?

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By the way, the misunderstanding of making all visible images concentric is one of the reasons I wish people would quit recommending that Andy's Shot Glass website tutorial. It has goofed up more people than it's helped.

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The thing that is nice about the Andy's Shot Glass video is that it is very visual. Sure, it doesn' show the offset--which is unfortunate--but for folks that are starting from zero, it does lay down the basic steps in a straightforward way.

I happen to be a very visual learner. I probably collimated wrongly several times using the video before I could even begin to appreciate the much more nuanced explanations that the experts offer.

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It encouraged you to do it wrong so it has value?
How about something that's correct, with illustrations?

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My car has an awfully lot wrong with it, but it has value. It gets me to where I am going.

I could spend weeks studying a 300 page thesis on collimation that might be the unquestionable authoritative source, but if watching a flawed video in five minutes, then reading Jason's above post in 20 seconds gets me to exactly where I need to be, which is more effective?

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But if your car's manual suggested you add oil to the gas tank it wouldn't be very useful, would it, whether or not it had useful information on other facets of car maintenance?
My point is that short (far from 300 pages) tutorials with illustrations exist that do NOT mislead the telescope owner to expect a result he cannot achieve. Jason's threads here on CN are some good examples. He illustrates the steps, and he doesn't mislead.
I don't doubt that a good video tutorial would be a valuable thing. But SO many CNers have been misled by the ASG video, it's just time to stop recommending it to anyone.
That's IMO, of course, but I'm not alone in that.

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By the way, the misunderstanding of making all visible images concentric is one of the reasons I wish people would quit recommending that Andy's Shot Glass website tutorial. It has goofed up more people than it's helped.

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The thing that is nice about the Andy's Shot Glass video is that it is very visual. Sure, it doesn' show the offset--which is unfortunate--but for folks that are starting from zero, it does lay down the basic steps in a straightforward way.

I happen to be a very visual learner. I probably collimated wrongly several times using the video before I could even begin to appreciate the much more nuanced explanations that the experts offer.

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It encouraged you to do it wrong so it has value?
How about something that's correct, with illustrations?

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My car has an awfully lot wrong with it, but it has value. It gets me to where I am going.

I could spend weeks studying a 300 page thesis on collimation that might be the unquestionable authoritative source, but if watching a flawed video in five minutes, then reading Jason's above post in 20 seconds gets me to exactly where I need to be, which is more effective?

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But if your car's manual suggested you add oil to the gas tank it wouldn't be very useful, would it, whether or not it had useful information on other facets of car maintenance?
My point is that short (far from 300 pages) tutorials with illustrations exist that do NOT mislead the telescope owner to expect a result he cannot achieve. Jason's threads here on CN are some good examples. He illustrates the steps, and he doesn't mislead.
I don't doubt that a good video tutorial would be a valuable thing. But SO many CNers have been misled by the ASG video, it's just time to stop recommending it to anyone.
That's IMO, of course, but I'm not alone in that.

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Ok, but your example is the equivalent of ASG's video saying "drop primary mirror on cement floor for best performance". In reality it is more like using 89 octane instead of the recommended 93 octane. I don't disagree that a video that explains offset would be better. I just happen to think that most descriptions that exist are more technical than they are pragmatic. Technical descriptions have their place, but a pragmatic and visually oriented approach appeals to a lot of people--beginners especially.

Perhaps we need a new video that gets it right.

I'm not trying to be argumentative... in fact you're one of my favorite posters on CN.

Edited by uniondrone (12/07/12 06:36 PM)

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Yes, the first drawing is incorrectly drawn...The reflection of the secondary, and everything inside of it, should be shifted to the right... so that the reflection of the secondary is centered on the spider. That would leave the reflection of the eyepiece shifted slightly to the left. (I think I said that right.)

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There's something weird going on between the two eyepieces. I think they're misaligned, or something.

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You told me to pull the sight tube out of the 2" to 1.25 adapter once before. I couldn't believe I was reading what you said correctly, at the time, so I never tried it. (It still seems crazy to me.) You just kind of hold the eyepiece there, above everything? I'll give it a try, since I now believe you mean what you're saying.

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