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Collimating a Newtonian – The Correct, Easier and Definitive Approach: Incorporating the Cave and Laser Telescope Collimators when useful

Handbook / Manual

By: Peter R Clark, FRAS(Author)

65 pages, colour & b/w photos, colour & b/w illustrations

Peter R Clark (privately published)

3 customer reviews
Paperback | regular edition (15 pages) | Mar 2017 | Edition: 4 | #221923 | ISBN-13: 9780957645400
Availability: In stock
NHBS Price: £7.50 $10/€9 approx
Paperback | extended edition (65 pages) | Mar 2017 | Edition: 4 | #236277 | ISBN-13: 9780957645431
Availability: Usually dispatched within 5 days Details
NHBS Price: £12.50 $16/€14 approx

About this book

This booklet contains correct instructions at last for achieving symmetry and great reliability easily for Newtonians, including their secondary mirrors when used with the fastest primary mirrors. Fifty pages have been added to its 4th edition to give the background story to the 5 years development.

For the Newtonian reflector, owing to the 90° change in the light path, adjusting the two lateral adjuster bolts of the secondary mirror achieves less as f ratio reduces. So the author has developed over 5 years the scientific approach needed as opposed to all those universal intuitive let downs particularly on fast optics where reviewers talk about endless tweaking. Their latest efforts do not scale up to the task. These instructions have been proven for accuracy and reliability since 2014 and really ruffle feathers.

You will  have found impressively little or no adjustment to make by star test to f 5 at the highest magnification, indeed scientific support sought later in Norton's Star Atlas 11th to 15th edition page 50 has no mention of it. Proven over 4 years to f 3.0, stages 5 to 7 in the book will achieve very reliable collimation for the fastest telescopes if a rigorously collimated laser collimator's beam is used for making easy the increasing need of accuracy of the vertical tilt of the secondary mirror first time. Additionally, the 65pp booklet also contains useful information on preparation of the telescope, optician endorsed mirror, lens and plate cleaning, dew covers, an eyepiece matching and upgrading chart, care in transport, EQ mounting, faint object finding, a set up for collimating the laser collimator with images and drawings and making the founding discovery, the Cave Collimator.

"'The Cave Collimator was excellent for my Maksutov–Newtonian telescope and very good for my Rumak–Cassegrain."
– Professor Ian Morison, Jodrell Bank

Reviews (3)

The instructions work well with good results
By Peter 2 Mar 2018 Written for Paperback

"Peter Clark's more scientific technique for Newtonian 'scopes works well and requires just a peephole eyepiece as the only gadget needed. I have used the method on my 6" and 10" telescopes with good results. I do not have either a Cheshire eyepiece or a laser collimator and having seen the latter used can appreciate the risk of an eyeful of laser beam! There is no electronic aid that can substitute for a sound understanding of how a Newtonian is constructed and set up."
– Christopher Eagleton, Beverley

Author's notes:
Christopher's comment about the laser collimator is pretty fair for his two f 5 Newtonians, but by f 3.9 is proving essential for the increasing accuracy in vertical tilt needed by the secondary mirror. Laser collimators do not feature in my instructions until stage[6]. Its beam will then be well within the secondary mirror diameter. Neither big bolt heads nor establishment writer could help the review of a 3.8 on p.94 of Sky at Night Jan 2018.

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His Cave Collimator works and the book takes over
By Peter 2 Mar 2018 Written for Paperback

"I am currently converting old spherical f3 Newise mirrors to paraboloids for putting them into telescopes for wide angle work, using coma correctors. Naturally, collimation will be an issue so we will be making use of your work."
– Peter Wise

Author's notes:
Peter is a recipient of the BAA's Horace Dall Medal for showing marked ability in the making of astronomical instruments.

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Taming the dastardly thing.* It's all over now!
By Peter 3 Mar 2018 Written for Paperback

It has been very reassuring to have journeyed from adjusting both mirrors at every session for 4 years to just the f/3 primary mirror slightly twice a year since 2013; mainly by eventually regarding the secondary mirror's two lateral adjuster bolts as like the handlebars of a bike. Correction by turning them can cause the rider to fall off by gyroscopic inertia. Similarly, adjusting a Newtonian telescope's two lateral bolts just because they are there causes a fall off from collimation achieved. Then sourced from ideas and trusted writers, lower grade compensation then produces a twisted light path fit for one temperature. The instructions chapter steers you clear of such disasters, rocking the boat and ruffling feathers on the way. Adjustments have become easy and reliable for any f ratio.
Slipping back into wrong methods again is actually prevented by the re-engineering support suggested in Norton's Star Atlas 11th and 16th editions from 1950 p.50. Then on the internet additionally there's Conrad Hoffman's secondary mirror holder* and in S & T October 2010, Ed Jones's Tracking Travelscope. They either don't fit the two lateral bolts or they lock them into being strict followers of the central bolt. Thus are instructions constrained into exactly the same method that scales up to the fastest optics as the author developed with words arising from his work alone before trawling for like mind support. Commercially, the principle of one adjuster (with slaves) falls foul of the establishment. There's nothing they'd claim three bolts are needed for that rotation about the central bolt doesn't perform more easily within the arc of concern at stage [2] and better for both medium and high magnification interests. Adjustments feel micrometer like with no hit or miss from 4 years into the task, even with the f 3.0 primary mirror of the main development 'scope.

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