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Council to all those looking for materials to go directly to the manufacturer, they have their clients' lists, and will turn to you nearest-
Newport glass per il pyrex, Schott Italy for suprax, ITALY SAINT-GOBAIN for the excellent quality calciosodico.
Phone calls directly to the sales office because the big companies do not take into account email.The three rubberized bearings of the rotating table have arrived 700 mm and I modified a plumbing die for motorization a 58 revolutions per minute for traction. I am well on track with changes to the workbench, early photos.
The windows have arrived!
https://goo.gl/photos/AZCGFTJ1LGKYGcsVAVery comprehensive as always Massimo and Giulio.
In fact, while relying on proven and safe theories, the same is not true of the tests where the turbulence of the air also affects the few meters that divide the mirror from the tester. I also have doubts about the efficiency of the use of dedicated cameras and software because they need a practically perfect system both mechanically and processing, and the possibility of subjective interpretations is increased with short focal lengths and large diameters. It may be useful to repeat the test and look for the statistical average to get closer to reality.
So far the very little experience accumulated has supported me in dubious readings, no objective quantification to remove glass, but the hand and in the end only the errors or the successes directed the processing. You have probably always been satisfied with being under the canons 1/4 lambda to evaluate the quality and correctness of our work, some seeing that their tests were well defined and clear thought that they had reached who knows what perfection, but probably it was simply due to the use of the ronchi with copper wire in the air and a super-shiny optical surface.A question, Ronchi and Foucault tests for normal mirrors but for short focal lengths?
Astrotechnician recommends the Bath interferometer, on youtube I found this: https://www.youtube.com/watch?v=wINnmX15qrw
But it is enough to test a 20′ F 3,5?P.S.
I have not yet finished studying the texts that I have found here, thanks Giulio.Wait to launch yourself on this project, I still have many doubts.
With the evolution of focal courts in recent years, coma correctors and wide field eyepieces has become difficult to make a choice.
For me, I have a technical background left in the 70s′ it is even more difficult.
Definitely the 20-inch mirror′ it will be under F4, a nice ultrashort and light dob for visual observation and wide field as far as possible obviously, I hope to reach 1 field degree I would be satisfied.
The 380 at the beginning I took it to take my hand on a still human diameter, and I would not like to make a small replica but a different instrument and as Gregorian teases me because it is abandoned and relatively simple to make, I am equally attracted to Mel Bartels' projects.
If I have to make a choice based on my experience, there is no history, newton point.
Instead, what matters most to me is the possibility of using the glass for large diameters combined with the foam glass to give the mirrors stability and non-deformability.
There are several studies and attempts both hot and cold and this is the option I want to try. Glass-foam sandwich with cold glue, then tests will validate the results or not.
@ Giulio, yes model aircraft is the other toy.Because the Gregorian?
Why has no major defects compared to the Cassegrain, the primary is identical, the advantages there would be in the processing of secondary, concave and ellipsoid, almost a sphere.
The cons would be attributable to a greater length of the optical tube, but ease of collimation and especially straight image as in a normal terrestrial binocular, a great advantage!Ok grattavetri, the material I received, I reconstruct the Ronchi test, and I'm ready for new adventure.
This time childbirth with two mirrors at the same time, one for me from 510 mm and one for a friend of mine from 380 mm.
It creates a new thread?
Place all the photos in sequence in a single on-line container like that of the preceding telescope?
Someone math expert and programs who want to work together for the realization of the smallest optical mirror with a different shape from newton?
I thought to gragoriano, perhaps restore a telescope obsolete with the possibilities today would be interesting?I guess that your last speech, Maximum, It is not reported to Luca, seems to me the classic white fly!
commits, risks, he studied and worked as a musso, forgive the expression dialect, and it is on its way to becoming a great grattavetro.
But maybe you have not correctly interpreted my post that, far from criticizing the younger generation was an admission of responsibility and guilt that instead we NOI old.
We, we were not able to pass on our knowledge, we do not have involved young people, we have allowed the manufacturers fuorviassero the meaning of’ amateur astronomy, and we have not done anything to get things back on track, which is not only sell.
This forum sheltering in part the things, at least tries! But we are too few in fact very few, so much so that some of our people “ri” all started from scratch because they have not found any that send information directly.
I think so because extremist? I do not think so.OK Luca did not understand your approach. then good luck to your project even if they do not agree, this serves a school to confront different opinions.
I see the projects of any type only if feasible and above all economic and in terms of costs of intellectual and physical efforts.
But do not take my criticism as negative, it is not I raised doubts I have externalized you a little violently I admit.
Also I respond to Massimo Marconi, My location “Taliban” It is because I've seen too many young people who allow themselves to be fascinated by the beautiful results that can be obtained and then affacendati stallholders bustle around expensive recovery systems, but once you obtained those beautiful photographs and displayed like trophies to relatives, friends and lose interest in the message boards, some after a few months, and telescopes take the dust or are sold.
They spent a lot of money but they have not developed an interest in astronomy. For this reason I am and remain Dobsonian with a map in hand and I'm more interested to convey this sense of wonder rather than technical and scientific information, what comes next when it is supported by a real passion, it is love that drives people to face any challenge.
The most famous astronomers and known are prepared but also love their work, and this is not taught in school, but in the field and people like me go for dark meadows know what I mean.
Gemini Excuse me if I was a bit brutal, but I just had a discussion with my partner and you do not have any guilt, but I have heard criticisms and proposals similar to yours, plans for the future mirror with absolutely legitimate reasons but I am a visualist and I do not care the scientific aspect but enjoy nature, the moment, the moment, how to observe the sky is a personal matter. For me it is rapidity of assembly, be up and running quickly and not waste time in set up the telescope complex to fully observe the sky in the few perfect moments, dob forever.
No photo, to those who have to show photos when you just bring your eye? Those looking for asteroids, comets or extrasolar planets are a very small group of people who make a second absolutely boring work, hours of pictures and monitoring the work done with painstaking precision. To me there, Instead there to see something nice to my children and grandchildren, convey the wonder of enjoying nature in general and specifically of the sky. The wonder that for thousands of years has led generations of astronomers to observe the sky.I would not be unwelcome, but with the grain 40 enough 8 Hand hours without rotating plate to dig 6 mm, and then subsequently 1 Now for grain in the best hypothesis and a pair in the worst. Working in manual must be smart, or you'll kill fatigue.
One trick is to make a plywood diameter mirror disk if you work on it full diameter with a border to contain it, practically a lid to which are added two handles to be able to challenge. On top of this “tool” leans a nice weight to the gym at least 5 kg…… or a car battery, back and forth without pressing, and with a good grip. Too bad I do not have the tool would otherwise put the photos that are more explanatory.I see now what you want to do, a system 5 mirrors? 88% reflectivity mirror every thing you eat in terms of reducing brightness? I do not know calculate it but 10% lost for every mirror ago 50% thrown away, why throw it? Obstruction around 40% the Cassegrain and your efforts to build it are useless, bought a pair of binoculars and you are set
There are the newton photo looks the Alluna Optics site, Northek etc. cost a kidney!!! and those projects make sense!First mirror? First time you compare yourself with a shorter focal length? Have a listen to those who did some normal newton mirror and normal mean F6 or higher, do a great newton F3.5 / 3.8 already difficult to achieve if not difficult for the vast majority of grattavetro. Of course if you settle the minimum wage with respect to lambda, coma, and especially always astigmatism that there is no edge retorted or other processing disadvantages that weaken virtually all cravings to excel in almost all on the short focal lengths can then go but not expedient, you will not have a great mirror.
I do not want the teacher, I am only realistic. You want a mirror excelled in a configuration in which very few compete? Without at least one question, because there are so few who do,?
Why is not convenient, or because it is a quite difficult challenge even for the most experienced?
To give you an example on my way to see, childbirth in fourth on large diameter mirrors, F4 or so but already I think twice under the f4. I would like to do for years in the house the plane mirrors, I'm not even approached us after reading some articles. I wonder if maybe I will need a 100 or I try to do well, but already I know I will be a challenge given that the sacred cows of grattavetro have had several failures.
Returning to the optical configuration, but you want to make the brightness of a newton little obstructed than any other type? Would introduce an additional advantage, the contrast on a craft mirror devoid of surface roughness gives you spectacular images. Also for me as a visualist the Cassegrain are dark, dark , unexciting Gray, of ciofeghe only useful for planetary and photographers, with a ridiculous useful field.
Make a newton F3.5 muster a coma corrector and enjoy like a hedgehog for life!!!!!!Too good, I modified slightly Giulio project to get you a telescope but more robust case. Breached the size imposed by the hand luggage of the airlines of the original project, I was free to increase the size of the plywood panels that are to be 15 mm and unfortunately even the weight of nearly 14 kg, but the practicality remains and also the speed of implementation. Tried on the moon with 8 mm e barlow 2,5X, until 525 enlargements still moves without jerks or jamming, if it just normal binocular eyepieces without turrets and various ammenicoli is balanced in all positions.
Photo of the “Wizard” the lab is my partner adventures, aeronautical engineer, mathematical, physical, astronomer, “weighs Pever”, as one who weighs pepper in Milan.
and perpetually in contrast with me, proponent of light wells, and he astrophotographer.
