Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.


  • Content Count

  • Joined

  • Last visited

Community Reputation

5 Neutral

About DragosN

  • Rank

Profile Information

  • Gender
  • Interests
    Art, Drawing, Photography, Music, SF
  • Location
  1. Indeed, very tempting. I just wait for the first reviews. Only that the 12,5 mm it's a little odd, between 9 and 14. Maybe 11, or 11.5 could be better.
  2. That are good news, especially for Eastern Europe. Not that we don't have enough store here, but most of them don't have many accessories.
  3. This is not about light gathering. Is about making a better telescope, in terms of contrast. Yes, is it possible that this is not the right solution, but this have to be tested to say clearly, is working or not. I have already figured some solution for testing in real life, step by step, every objection that has been raised, and hopefully, in 2 or 3 weeks I will show first results of those tests. And, if those test will show good results, I will try to make an improved version of this design, which I've already made.
  4. I think I understood what is the source of confusion. Probably, you think that I'm interested of how much light is lost. I'm not. I'm interested of where this light is lost. In the center. Exactly where unobstructed system performs at their best, where abberations are minimal, Newtonians has no signal. Maybe my idea will not work. But I know how APO telescopes, and even long achromatic telescopes are working, and that is what I intend to achieve, if it's possible.
  5. I work with some programs for designing Newtonian telescopes. They are counting the linear obstruction, mainly. And they show the area percent if you want. I usually look at telescope stores, to see what's new. Everywhere, the obstruction is given in linear percent, nowhere in area percent. Yes, the area obstruction is 11% in this case, but I didn't use it, and as far as I know, nobody does it. Almost. At last, is the same thing, the obstruction is the same, whatever is calculated in linear percent or area. Only the numbers are different. And I know enough math to do the transformation if I want and need. I still remember the square of the numbers from 2 to 20, and the square root for 2, 3, 5, and 7, with two decimal digits, even if I'm not young anymore.
  6. Nytecam, I have used one small mirror, a small refractor lens, and 4 diagonals to test the position of the image. Initially the design was with only two tertiary mirror, but the test show me that the correct solution was with three. I never count the area obstruction, only the linear obstruction, which in this case, 300 mm primary, 100 mm secondary, is 33%. As far as I know, Dall transfer lens was never used for Newtonians, only for Mak and DK. Of course, never say never. I will think about. But if you talk about the faze of the light, this can be corrected by adjusting the positions of elements. Of course, extremely fine adjustments. VLT is working like this, and despite the light pass length is different, the images are combined. Anyway, I will look to that ''Overcast Evenings'', if I will find it. More about this design, I'll be able to say more after I will do some tests. If the result will confirm my expectation, all will be mechanical problems (yes, a lot of it). I just hope to find time sooner, cause there are not simple.
  7. Or, it could not be. I have done some research, and it seems that the problems are not so big, or have a fix. But I will come back with specifics when I will finish.
  8. Yes, diffraction is still present, and can be more weird than at any other model of spider and obstruction. But what I was interested was an increase in contrast, but it seems there are no many chances to get this.
  9. Light to the refractor come from the back, the pink arrowed lines.
  10. Ags, Mak is one of my favorite scopes. But two years ago I've sold my SW 150/1800 Mak to buy a Celestron C8. I still don't know if it is better or not. Astronymonkey, yes all that problems are real. JamesF. I don't even dare to say that it wouldn't be less expensive, simpler, and so on, with a bigger mirror. But that not the point. The point is to look for new solution. Could be better, or not, the quest is the real thing. And, by the way, despite of that problems, I hope that some day I will be able to built such a scope, even in a small format, to put it to the test of reality, whatever the result will be. Soupy, the pozition of the image is designated by that circle with a tail. I've made some test before, with a small 112 mm mirror, a 40 mm refractor lens, and 4 star diagonals of 1,25'', separate for each optical pass, refractor and reflector, to test if is correct.
  11. Sporadic Dobstronomer, and Gooseholla, thanks for feedback. At first, that's what I am looking for, as long I can't test the idea, and not even make some simulation of it on a program like Zemax. I'm not good at this kind of programs. I will think about your opinion. and I'm waiting for others.
  12. Usually I don't publish projects which I don't made and tested myself, but now I have to make an exception. This projects came in my mind in a very bad financial period, and there is no sign of a change in the foreseeable future. So, I decided to make it public. From the first time I've made an Newtonian telescope, almost 10 years ago I was looking for a solution. In time, i have seen some, but all have a problem. It works only for slow to very slow instruments. I think that Ed Jones ''Chiefspiegler'' telescope is the fastest. An today, fast and very fast Newtonians are more and more in use, especially for photo, and especially in Europe, where the weather is good for short periods of time. So, my idea, because until now is just an idea, is to combine a fast Newtonian, F/D=3 to 5, with a slow refractor F/D>10, both having the same focal length. This is a drawing of my project: It is essentially a Newton mirror 1. with a hole inside, where a refractor group 3. is placed upside-down. The light come to the refractor group by the upper small tube, through three mirrors, 4,5 and 6, pass through the refractor group, and goes to the secondary mirror 2, of the Newtonian. In this way, the part of the primary mirror which is normally not used, is now almost complete covered by refractor group. In my drawing I used the following data. 1. Primary mirror, 300 mm diameter, 1200 mm focal length, F/D=4. I've choose this data because I have a 300/1200 mm mirror, and such an instrument could be a good photo tool. 2 Secondary mirror, 100 mm small axis. So, a linear obstruction of 33% 3. An 80 mm diameter, 1200 mm focal length refractor, F/D=15. 4.5.6. Tertiary mirrors, bigger than 90 mm small axis. 4. and 5. at 22,5*, and 112,5* degrees, 6. at 45* degrees. This will give a theoretical linear obstruction smaller than 7%. Maybe 1 or 2% bigger than this, because of the secondary offset. Anyway, a very small number, for a fast instrument. And now, the questions I can't fully answer. - Could such a scope be functional? I think it is. Of course, best results will be made with apochromatic lens, but regarding the very long F/D ratio needed, maybe even some achromatic lens could be used for visual. - Can such a scope be made, and at what price? By the industry it can be. And I think that even experienced ATM can do it. Of course is not simple. and is not cheap. An APO lens, three tertiary mirrors with good reflections properties, and a somehow complicated light pass, means some significant expenses. More, there are some technical difficulties, like aligning the refractor group (lens plus tertiary mirrors) with the primary mirror, but I consider that can be done. - What about aberations? My main concern is about coma, because the refractors aberations are expected to be very low at such a long F/D ratio. How will a coma corrector will affect the light passing through the refractor, What will be the influence of the circular obstruction? Also, I don't have an answer. - Would such a scope be practical? In my opinion, such a telescope would be the closest approximation of a general instrument. Good for visual and photo, with a smaller price and size than a APO refractor of the same diameter, and maybe with optical quality closer to that of a big APO than any other. But to all those questions, the real answers will come in time, if enough people and enterprises will dare to build it. I would like to try myself, but as i said before, my business, portrait and caricature, is flat broke (I hate selfie ). More than this, I had some more projects which waits for better times. As a different approach to Newtonian body, with some improvements, an equatorial fork mount, and some useful photo accessories. So, if you like my ideas (already posted some on this forum), and you can spare some money, any donation is very welcomed, at this paypal address: dragos.n.802@gmail.com Thank you for you attention, and I'm waiting for your feedback.
  13. Can't say much. Awesome, marvelous, ... small words, for a gigantic accomplishment. Maybe a good place for it is at the ESA home building. Or maybe you can print it in small sections, 12''x16'', and sell it as a serial photo. And i'm not joking. I think that a lot of people would love to buy, the whole picture, or a part of it. in steps, and put it together like a cosmic puzzle.
  14. Yes, I will, but I don't know when it will be. I hope will be next week, even in an unfinnished shape, cause I want to have it at the eclipse. One side for camera with a lens, another for C8, on a smaller mount. A photo-video one. And the bridge is smaller, and lighter, to carry it very easily.
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.