Here is a good article to read about the GLP and is use.
Here is a good article to read about the GLP and is use.
It had its own little history section in a collection of ATM Journal articles some years back.
Being only “invented” by at least three people independently during WW 2, most elected to keep them secret, Bowers being in German-Occupied Netherlands and Maksutov in Russia. However, Maksutov got his published in a journal, and first come is first recognized. The premise is simple: a curved optical component with no real magnification called a “meniscus” is placed in front of a regular spherical mirror, cancelling out spherical aberrations.
Little happened to the design after the war. In 1956, John Gregory published a design in Sky and Telescope and Allen Macintosh created the Maksutov Circulars meant to make designs and help available to amateur telescope makers.
Later, this pair organized a group of people to get some glass blanks “slumped” to the correct shape is order to make it faster and cheaper to make these telescopes.
Before I get into the guts of the matter, one has to understand CLEARLY the effort required for this type of scope:
You need to be able to control the curves you generate, both on the mirror and the corrector to a fairly fine degree, and the final thickness of the corrector affects the performance of the finished telescope. Generally people do the mirror and corrector in parallel
A number of these blanks were made in the late 1950’s, in the sizes 4 1/2″,5 1/2″, 8″ 10 3/4″ and the huge 11 1/4″. The reason for the odd sizes was they require a mirror blank SLIGHTLY larger than the optical. Many of these were made and purchased (about $30 for the 4 1/2″ size and $130 for the huge 11 1/4″ version. Even now, more than 50 years on, many of these raw blanks are still extant , never having been made into telescopes. I think they ran into the same problem I did with my first, an 11 1/4″ bought in 2008: they are simple in theory but execution is another matter.
A lot of these have been passed on in estates and are being sold off by people who don’t know what they are or think they are more trouble than just getting a commercial scope. Same with me. I built a number of smaller mirrors to get a handle on grinding, I found some small correctors to start on that won’t break me if I fail the first one or two times. The cheap Schmidt Cassegrains along sunk them. A flat corrector is cheaper to make in larger sizes, so the Maksutov is now an niche design relegated to only a handful of makers. One maker still remain: Questar with their 3 1/2″ and 7″ models. A 12″ model was limited to only 16 examples (one in Greater Vancouver). Intes-Micro and Aires of Russia still make them to order but not a regular production of them and AstroPhysics does.
Other makers came and went: Tinsley, Vega, Max Bray, Quantum et al.
Two types can be made: Newtonian or Cassegrain versions. The Newtonian is easy as you simply make a spherical mirror, easy to do accurately and with a smooth figure. There is a subset, where you can use a sub-diameter corrector closer to focus, in some cases as a Mangin type mirror or even double pass.
The photo at top shows the results of my interest in getting the raw and finished pieces for building Maksutov scopes.
On the case are slumped and molded blanks as they arrive from optical glass manufacturers or suppliers. To two at the outside left and right are the HUGE Hayward Glass of California’s 11 1/4″ X 1 3/8″ thick and the other really large one is a 10 3/4″ by Hayward as well. This size allows the making of a variety of designs that use a 12″ or 12 1/2″ mirror blank for a complete telescope.
The two at the right middle are a 7 1/2 and a 5 1/2″ and the 4 smallest are the 4 1/2″ ones. 2 of the latter have had a start with rough grinding.
On the carpet are the semi-finished 6″ and 4 1/4″ Maksutov correctors and their mirrors.
Various publications exist for making these scopes, notably “Construction of a Maksutov” by Fillmore and “Bulletin C”, published by Sky and Telescope, as well as articles in Sky and Telescope.
MY first exposure to this niche of ATM was an old issue which had a 10.8″ version built by AAVSO member Howard Louth. He doesn’t give many details but it became apparent that he simply used “well established techniques” to arrive at the proper curves for his corrector.
Here is a great article on the BC Hydro web site that shows we are not along in the challenge of dealing with LPA.
The CBC is carrying a news story about the Thirty Meter Telescope, designed (in part by RASC member Craig Breckenridge) at Dynamic Structures in Coquitlam:
Home Depot is carrying a International Dark-Sky Association approved out door wall mounted light fixture. The price is 39.98. Can use up to a 100w bulb and has a motion sensor built in.
I installed the light, replacing my globe style one and it took about 10 minutes. I also installed a Philips 40 W Amber light bulb.
I still have light on my steps when needed and it has made a huge difference on the light trespass in the back yard. Check it out and lets support the Home Depot on this product.
It is made by Hampton Bay, made in China and the upc is 4633589006.
Not all Home Depots had them in stock and not all were promoting the International Dark Sky Association with the marketing material up at some stores.
By posting on the web site and having people talking to Home Depot we will get more awareness, step one of the big picture
Light Pollution Abatement
Attention All Members
I have recently accepted the role of Chair, LPA RASC Vancouver. I have been a member of RASC for about four years and have been actively involved in the AOMO here in Maple Ridge. As an amateur astronomer, the night sky is very important to me and I am looking forward to helping preserve and improve the dark skies we have.
As you all are aware, light glare, light trespass and light pollution here in the lower mainland and in the City of Vancouver, in particular, is a large problem. These problems have a direct impact to us as amateur and professional astronomers. From the basic enjoyment of the night sky to having a debilitating impact on imaging or severely hindering any kind of scientific research being done, light pollution needs to be managed and ultimately reduced for all to enjoy.
Not only does light pollution impact the astronomy community but it has negative impact on other areas within the community including health and wellness of the public, wildlife, crime, safety and energy consumption to name a few.
In the past, there have been many successes in communities all across the country and around the world that have been able to directly impact the issue of light pollution in a positive way. Through City Ordinances and By-Laws that deal directly with sources of the problem, light pollution can be and has been noticeably reduced. It is my belief that the willingness to do something about light pollution is never far away but we must harness that willingness to effect positive change around us.
Efforts here in Vancouver by Vic Baker, Past Chair, have made a solid impact in awareness to the public. Congratulations to Vic and all of the supporting members that have been working directly and indirectly on this ongoing project.
To keep the momentum moving forward, I would like to take this opportunity to introduce my plan that would assist in the management and reduction of light pollution in the City of Vancouver and surrounding areas. Clearly, any change will come from efforts of many individuals working together collectively towards one goal.
To achieve this goal, I will assemble a committee of not only astronomers but of other members of the public who are impacted and who would benefit from light pollution abatement. Amongst those on this committee, I would like to see representation from the City of Vancouver representing the change processes as well as industry representation for lighting products and services. I also hope to see individuals that have had success in other communities in dealing with light pollution abatement.
From this committee will come a Strategic Plan that establishes goals, objectives and action plans that everyone can be part of and get involved in with.
The plan will be focused around:
· public awareness and education;
· the measurement of current status and future results ;
· a process to work closely with the City of Vancouver to support current and future avenues in dealing with light pollution abatement; and
· create a model for others to use
I feel safe in saying that we all have a passion to manage and reduce light pollution and I feel very strongly that it can be done. Using a collective efforts approach will be impactful and efficient to meet the challenges ahead.
As I start to assemble the committee, I would like to hear your thoughts on what you feel would be helpful in achieving our goals of managing and reducing light pollution.
If you would like to participate on the committee, please let me know as soon as possible. Also if you know of anyone who you feel would be a great committee member, please pass on this invitation to contact me.
I can be reached on my cell phone at 604 649 8356 and email at [email protected]
Chair, Light Pollution Abatement
Moon and Venus through a double-paned window
This set of posts is about the TV Lens we were generously given by CTV to make into scopes.
Myself excluded, most people with these will need to make a tripod, and some kind of mount, probably a fork mount for sake of simplicity.
I recently acquired a planer as well as a second table saw that I can keep in Vancouver, so I have enough tools to build parts for people without such tools for the cost of material.
The tripods can be made of 2 X 6 lumber cut at an angle for legs, two pieces of plywood glued together for the mating plate. Door hinges can be used for the tops of the legs and a chain connected to eye bolts to prevent the tripod from collapsing.
The fork is a special problem. Mine is made out of a piece of aluminum tubing rectangular in cross-section. To make the U shape, I cut 22.5 degree wedges of material out, bent it to shape and had it welded by Pro-Tec Marine Welding in North Vancouver for $140. I didn’t cut through completely, but left the cut so that one side of material was still there and with enough room between the cuts so that when they were brought together, a proper weld with filler rod could be done. Mine ended up being not quite parallel but close enough I can probably cold-set them.
One problem with this lens is where the focus comes to. I think it may be too close to the last lens element to make for a convenient position, so I think some kind of negative lens element is needed to add some back focus distance.
I was able to get a couple of photos of the moon through my Skywatcher 80mmED refractor a few nights ago. These are worlds better than the pics I took with my camera lenses, but they still lack a lot of the detail I was able to see visually. There were some rilles (long, winding canyons) in particular that were striking through the eyepiece, but which didn’t show up in the photos.
And, for fun, here’s the same photo with the colour saturation artificially enhanced. I don’t know how representative of reality the hues are, but this is what came out of my camera: