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Ben the Ignorant

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About Ben the Ignorant

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  1. Waves are waves

    I didn't know loudspeakers could be made that big, but they hit barriers like very large scopes do. That 80" vibrates only between 28Hz, not such deep bass for such a large membrane, and 2500Hz, very low under the 20.000Hz we can hear. Oversize (amateur) telescopes are underexploited in resolution because of turbulence, and oversize speakers are underexploited in frequency range. Makes me like my moderate telescopes and amplifiers even more. I currently have two 10" amps, the most powerful is only a 40w; I used to play a Peavey Studio Pro 50, but it was really a 57w amp, and its 12" speaker moved so much air, never could play at a decent volume and distortion level without disturbing people. So I sold it to a friend's son after I saw he understood and respected the quality. Speakers have to produce the waves when scopes can collect them passively, but in both cases great size causes more problems than I would deal with. I will obviously look into all oversize telescopes that I might find in a star party, but I don't think I'll ever buy one bigger than 16".
  2. Waves are waves

    Obviously, but we're talking about personal equipment.
  3. olympus 10x50 dps1 vs omegon nightstar 15x70

    Hi, Damian. Look for the wider field; some 10x50's sport a 5° field, others offer a 6.5° field. 70mm binos take in twice the light, and display many more stars in clusters.
  4. Waves are waves

    No, the unifying theory of everything is a formula I read somewhere: "95% of everything is junk!".
  5. Imaging target suggestions ED80?

    How about NGC 4236 in Draco? It's not too faint at mag 10.7 but it's huge, 22' by 5', yes that's not a typo, twenty-two by five arcminutes! Surface brightness is low but its sheer size should make the pic rewarding.
  6. Waves are waves

    Yes again, and it goes the same for sound.
  7. Waves are waves

    Yes, and that is the diameter of the standard astro binocular; even some 40mm latest-tech speakers pump out some very decent sounds when there is no room for larger ones, and this is also the format of some fine performers in binocular lenses. The trend seems to be confirmed if it is not a chance resemblance.
  8. F10 apo's?

    Sky-Watcher made the Acuter 90mm f/10 excellent doublet apo: http://www.davidesigillo.eu/test_acuter.html Maybe you can find a used one.
  9. Waves are waves

    Funny, the physical laws of reflection, refraction, scattering, diffraction, etc, are similar for sound waves and light waves, but the resemblance does not stop there. Listening to various car loudspeakers, I found the minimal diameter for an acceptable sound is 70mm, and that's also the smallest diameter for a satisfactory telescope in my view. 80mm grant a little more resolution in both, and 80mm is a very popular diameter in compact scopes or compact radios, at least the older ones. They make 90mm scopes to get some extra oomph, and the 90mm loudspeaker begins to issue more discernible bass, so much so I keep one from an old radio my father bought in the 70's, not knowing what I'll do with it but the bass, checked that when plugged to a guitar amp, is noticeable enough despite the size. Then the standard louspeaker size in non-toy stereos is 100mm, and the standard refractor size to get good resolution and power is also 100mm. There must be a reason if so many observers buy that many expensive 4-inch apos, but not nearly as many buy tighter apertures for comparable sums. Following the same progression, monitors in studios have 125mm to 130mm loudspeakers (that need to be complemented by a tweeter because the similarity cannot be total between light and sound), and these diameters are also the ones that provide deeper resolution on planets. 150mm approaches real power in telescopes, and 150mm is also the entry-level size for a guitar amp, like my 15 watt Fender Frontman, which does not lack bass despite its handbag format (WonderWoman's kinda big and heavy handbag). 200mm is quite enough for most observers, resolution-wise and power-wise, which happens to match the size of more serious amps. I have a modded Stagg 20w 200mm guitar amp and an Ampeg 20w 200mm bass amp, both are plenty large enough to deliver a full sound in their range. There is a reason if so many 8-inch Schmidt-Cassegrains and newtonians are in use everywhere! Then the 10-inch scopes are heavier, but not unbearably so, and the 10-inch loudspeakers also deliver the near-maximal power and resolution for an amp that remains not hard to carry around. 12-inch scopes deliver enough light and detail to satisfy most everyone; again, the equivalent 12-inch size amps give out enough frequency range and raw power to please the vast majority of players. Size and weight become an issue in both cases, but not enormously so. And lastly, the ultra-large 15" amps or 15" to 16" scopes start another league in power and resolution but they both become equally difficult to transport. Not quite apples and oranges in my opinion, does it seem like a coincidence to you?
  10. Guidance

    Hi, Bazmo. Use what you have for a few weeks before buying anything new; conditions change, turbulence and air humidity can make it look like the gear is not okay. Wait till you know your equipment better, and let your eyes learn how to deal with nighttime vision at the eyepiece. In the meantime ask as many questions as you like, answers are free and they give no buyer's remorse.
  11. What I'd like from a scope

    Check the Bresser Messier and the Kson tabletop dobs on this page: https://www.teleskop-spezialisten.de/shop/Teleskope/Dobson/bis-200mm:::219_4_58.html
  12. Favourite Class Of Object, And Reasons

    All of them, for a complete image of what the sky holds.
  13. So much traffic about this new little 72 scope! I hope someone will show its star test and a Ronchi pattern. Would be even more interesting if several imagers do it, to see how consistent the production is.
  14. Eskimo Neb - Can't Find it !

    True, as our friend coatesg says, 37x can make it look like an anonymous star, especially if turbulence is strong. Try a little more magnification. I often spotted it from the city with 80mm scopes, not difficult at all unless you assume it will be much larger than a star and its small halo of scattered light. Tune your eyes to a small bluish round soft cloud, and you'll spot it with ease when you scan the right section of sky.
  15. Nice. Only 303€ and less than 2 kilos! After many comparisons between scopes and binoculars I concluded 70mm is the minimum aperture to make deep sky and planetary detail blossom; don't know that I'll buy a scope smaller than my 80mm scopes but if I did it would be no less than 70. Don't worry about the glass type, my FPL-51 80mm f/7 semi-apo has such clean images, any modern semi-apo must be great, too. Aberration-wise, this 72mm as an advantage due to its smaller diameter which is offset by the shorter f/ratio, overall it should be as good. Last night I had the first clear night in ages, with incredibly dry air. Going from 14x to 140x no chromatic spill to speak of, not even on brightish doubles, or very bright singles! Inside and outside focus disks almost identical, very little green/violet differenciation. I made a 70mm mask for my semi-apo, and I can say the loss of resolution is very slight. No more 70mm achromats that had to be one meter long!
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