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Ciao,
After the first experiences with Newton 114/500, (the Moon and Saturn), I realized that with this telescope is not improved.
Since I can not buy it, I intezione me a Dobson 250 / F6
I considered buying a mirror,(a southern online shop promoted mirrors up to 300 mm
189 € yesterday they made + 90€), or let me.
At this point I need information: a common glass blank + tool + abrasive + aluminizing as it can cost you?
I await September to contact the industrial glassworks Tuscany Italy; to make a mirror diam: 250 mm what I have to cut the blank? 255?
I am reading the Texereau, I lettu all that there is on the blog (many things I did not understand in depth, I have to go back), I accept and links to other documentation tips
FrancoFranco
Ciao,
I have some books on the construction of telescopes in addition to Texeraux some are in German also the site http://www.otterstedt.de/wiki/index.php/Hauptseite although no date can be useful.
These are links to acquire materials:
http://www.stathis-firstlight.de/spiegelschleifen/material.htm
http://www.vds-astro.de/index.php?id=208
this is central to the materials
http://www.vds-astro.de/fuer-mitglieder/materialzentrale.html
the books are :
Paul Andrenelli “The amateur astronomer” Narrative practices sansoni 1979
in German:
Hans Rohr “The telescope for everyone” Rascher Verlag Zurich and Stuttgart 1959
Martin Trittelvitz “built reflecting telescopes -even” Oxford University Press Heidelberg BerlinDr.. Martin Trittelvitz also has a website, namely http://www.marty-atm.de/
I do not know if I was helpful
Enzo GreetingsFranco, the premise that I can tell you in all honesty, regarding the construction of the mirrors is that economic motivation is not one that can sustain the effort and study required to build a view.
sure, if done on a large mirror there is also a cost savings, but for small and medium diameters it is cheaper to buy, time money and energy spent for understanding and fulfillment are much higher than the commercial value of the final product.
Making a mirror is a challenge against yourself, a path of knowledge that leads to a lot of satisfaction, look in a telescope where the lens is built with his own hands, priceless.
hello Enzo, thanks for the links, it is always useful to have contacts with equipment suppliers !
Hello Franco. The possibilities are in these terms:
Calculate that a glass factory in Asti put me a pair of glasses 20mm thick and 310mm in diameter (one for the tool and one for the mirror) 100 euro.
But my question, The figure does not change if the thickness of a, and two or all of the glasses was 15mm instead of 20mm, and I believe that not even change if the diameter was 250.Calculates then you would buy abrasive grit 60-120-240-500-800 and the cerium oxide, + one kg of Gugolz summer gradation pitch #63, or winter #55, from French http://www.optiques-astro-moindrot.com or vice versa (unless i 30 EUR of pitch), dat our gems, a still figure close to 100 euro.
And finally realized that by sending to aluminizing the mirror, for example at ZAOT still you spare, perhaps little more than another hundred euro, that from here in total are 350 euro. Mal counted but certainly deferred by your lead times (and certainly with grandissmima satisfaction being a less difficult F6. See yourself also the movie the completion of the 200F6 in this blog) ).
So everything about the primary mirror that would cost less than that figure is ok.
Also because for a new telescope would still be to buy the poplar plywood for the realization of the structure; the trellis aluminum tubes, the remaining hardware, the focuser and the 50 EUR diagonal mirror of GSO (for example at teleskop.express.de).
On the other hand, the alternative would be to buy a new one already mirror, or a used telescope. Considering, however, that a good Chinese GSO 250F5 coast today in European prices just over 500,
http://www.teleskop-express.de/shop/product_info.php/info/p6707_TS-10—-250mm–10—f-5-parabolic-Newtonian-mirror-with-certificate.htmlWhile a good Hubble optics 400mm F5 coast “solo” 800 euro http://stores.ebay.it/hubbleoptics where you have to add VAT and a hundred euro for shipping and customs.
I few years ago I sold my good hubble 14″f5 a 500 euro, just to say how prices change.
But perhaps the last word says the price of a 250F5 539 euro +36 Shipping, works (satisfaction apart) It equalizes the cheapest of the construction costs:
Thanks for the info
Buy already built takes away the pleasure of doing; I consider that being Class 46 it's not that I remain a long time before.
But, with all my equipment, the construction of the telescope should be sent. Therefore I must evaluate the purchase of a kit mirrors.
For example, this kit; if it looks good I could buy it right away
http://www.nadir-astronomia.it/shop/autocostruzione/1188-kit-specchio-primario-e-secondario-geoptik.htmlFranco
Ah,ah,
do not worry Franco, to build the telescope mirror and it is true that it takes time, but not so much…Well, the price of that sounds great kit, and then the Geoptik I think that makes good products,
although there is talk of a 150 mm, I was given to understand that you wanted to make a 250.
Still better than I can tell you Giulio
I saw Geoptic kit from the link you posted, and the prices seem very good.
Obviously I will recommend that at least 8″, alias 200mm, because with 6″ not much more than you would see with your current 114. And nell'autopcostruzione the mirrors are the major cost.
Apart from this fact, the only piece to buy, the higher cost of the rest of the telescope, It is the focuser (provided that you do not throw a round piece of black nylon, or as in my 250F5 300F6, 130F7 or still visible here in the blog).M13, for example, passes from a simple speck milky to a spectacle type “Christmas tree seen from above”, comparable to a compact little cloud of single punctiform starlets.
Hi everyone
Giulio, last night I was undercooked and I took whistles for flasks
On Aliexpress I found this mirror; 200mm F4 with 150 € and 3 I should have months: so I would have time to build Dobson. Then if we go to a potreemmo pesnsare 300 crumbs from me
http://www.aliexpress.com/item/Newtonian-reflecting-telescope-D203-F800-D203F800-203800-reflection-Objective-lens-Secondary-mirror/32651882904.html?spmInteresting what you tell me of the focuser; I could have access to a lathe.
Have links?Franco
Hello Franco
Very interesting that purchase directed at absolutely impossible prices in Europe.I must say that I have already bought in China on a firm opinion on aliexpress. The service was absolutely positively although in my case over the decade 1590 refunds. It is a battery for a laptop that was compatible but was not. returned, and the amount was credited to me on Paypal without problems.
Given a choice would have opted for F5, because the finished telescope would be more comfortable because a little higher land, and why an F5 or F6 has much less restricted tolerances, and it is less difficult to achieve than an F4.
But I also bought a Chinese optical 360F5 hubble of direct import sandwich was a large mirror, then I sold because too heavy.
The image of the design of my focuser black nylon (the image scale is no longer 1:1 as my original CAD drawing :
Reckless version for eye 2″ (not tested):
His finished look:
Nylon is a turnable material with ease because it does not require special efforts, then, turning the tube is tensioned not so deformed. This fact , together with nylon That is a pretty self-lubricating materials, It makes it possible to fine tune the depth of the past to ensure that the threaded coupling is pasty and has not game over its entire length.
I'm not a turner, but some years ago I turned three a craftsman, and I struggled together 100 Euro material included.Eye to the Chinese Mirror, I do not think parabolic
I think it's a ball for use with a Barlow before the focal plane to bring it at least to F8, but even so would not fit…Price. I had not thought of. If so you'll end up with a telescope can not be improved and very poor quality.
Indeed there wrote, spherical mirror
Well, in September we try to call
Thanks for the link focuser, I just look at them for a moment
Franco
Ciao,
you just saying, but whether that happens to the Chinese spherical mirror there I build his tool pitch and began to polish it with cerium oxide?Franco
Very true, but it will start to come away from the outside because I started parabolizzazione.
Eventually I hypothesize, and I ask you to confirm, which will take the form of a parable; it is possible that the center of the mirror hang in the aluminizing, and in this case I wonder;
will bother to various tests?
Inpedirà redo the light?Franco
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