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Everything posted by Dyptorden

  1. Guys, no offence ... but I write again... there is NO T-Ring picture in this whole topic. Thank you for the pictures John and houston, it's clear now.... since I never used 2" accesories until now, I forgot about that accessory.... Everything is fine now !!! Thank you very much !
  2. What do you mean by "the focuser should be much deeper" ? I just pulled the tube out so that you can see it in the picture... i can roll it inside until there's nothing out.
  3. The ring came with the telescope. If I take the ring away, I remain with the focuser's tube only which is larger than the barrels... I can't fit the 2" accessories directly in the focuser's tube without the ring.
  4. It has no threads and looks similar to the one you've shown me. (sorry... but I can't edit my posts, don't know why I don't have the Edit button)
  5. Here you have the focuser with and without the ring
  6. What I just tryed was obtaining focus while holding the powermate in my hand, and I have observed that i must scroll the focus out at maximum and still hold the Powermate almost 1cm at distance to the focuser.I guess I need some kind of extender... but if I buy it... will it fit if no other 2" accessory fits the focusers ring?
  7. It has nothing to do with no T-Ring I have two 2" accessories, and none of them can be inserted into the focuser's ring, since the focuser's ring is 0.8mm narrower in diameter (it only has 50mm and the 2" accessories are 50.8mm).
  8. Hi, My first two 2" accessories arrived, just to take me from smile to anger in a second. I just bought a 2" Powermate and a 2" T-Adapter but they won't fit my focuser ring. I took some measures, and they both are 50.8mm but the ring has the inner diameter of exact 50mm. Is there any alternative to grinding the ring's interior diameter for 0.8mm? Or are there on the market similar but better constructed rings? (I didn't find rings only, and I can't afford at the moment buying another and maybe better focuser) I attach some photos, Thank you for your time,
  9. I have an 8" Dob, and she is not my girl, but a friend's.Her father is not into astronomy so it might be a challenge for him to keep her interest. His lack of knowledge/experience is the reason that makes me avoid a collimating telescope. Regarding that Infinity, I don't find specs such as : does it have more eyepieces? can you use other eyepieces? what is the maximum magnification (i think i saw somewhere it has a fixed 30x magnification...so no interchangeable eyepieces)? On the other side, I saw similar spec telescopes that do have 1.25" focuser.There is one from Omegon, almost identical (i believe it's really identical) : http://www.astroshop.eu/omegon-telescope-n-76-300/p,33242 --- is there any difference between them? And also there are the Skywatcher N76/300 Herritage Celestron N 76/300 Firstscope (this one doesn't have a finder, and some say it's worse than the Herritage). National Geographic Dobson telescope N 76/350 Kompakt DOB (neither this one has a finder) Should I still go for the Infinity recommendation? Thank you very much for the opinions
  10. Still I am taking into consideration those mini-dobs.... the 76mm ones. Are there any possible collimation problems? You can't collimate the primary and you only have the 3 orientation screws for the secondary (not the depth one). What are the chances her father might need to collimate it?
  11. Since I am not her father, and her father is not too much into astronomy... she will have nobody to collimate the dob... i have some doubts regarding the dob...
  12. Hi, What do you recommend for a ~5 years old child? a 76mm dob or a 60...maybe 70mm refractor (AZ mount)? The apperture is similar... what about the quality of the image? I would have to choose between scopes such as: Sky-Watcher 705AZ2 Celestron Powerseeker 60AZ or National Geographic Telescop Dobson N 76/350 Kompakt DOB Omegon Telescop Dobson N 76/300 DOB A disadvantage of the mini-dobs is that they take more space I guess...
  13. How did you make an 180 second unguided exposure and get clear image ... no trails?
  14. usually a bit late but I am so glad receiving them I use this practice since long, due to the fact that there are ppl who only write in one of them.
  15. I just made an experiment 2 minutes ago. Took the 2"-1.25" adapter off and I kept this 3x barlow (1.25") with my bare hand, a bit deeper into the focuser.I obtained clear image. What can I do so that I put the barlow deeper into the focuser? Any astro specific item to use? (I won't move the primary ) In few days my 4x Powermate 2" should arrive. Could I have the same problem with it?
  16. Hi, I have an 8" Dob and I tried to watch Jupiter with my three eyepieces : 4mm, 17mm and 25mm. They work perfect. Later I borrowed a friend's Barlow (the default plastic Celestron Barlow 3x he received with his Celestron Powerseeker 60EQ) but I can't focus at all no matter how low or high I moved the focuser when I used the 17 and the 25. Any ideas why is this happening, and what can be done (what extra equipment I might need to obtain focus)?
  17. Your formula sharkmelley : star_trail_length_in_pixels = focal_length_in_millimetres * exposure_time_in_seconds / pixel_size_in_microns / 15 Is the same with : exposure_time_in_seconds = star_trail_length_in_pixels * pixel_size_in_microns * 15 / focal_length_in_millimetres My Nikon D40 has a23.7mm x 15.6 mm sensor size and 6MPixel According to the formula : Pixel_size = 1000 * sqrt (sensor length * sensor width / number of pixels) , it results that my camera has a 7850 pixel size. The telescope has a 1200mm FL So the exposure_time_in_seconds in order to get a 1 pixel star_trail_length_in_pixels : exposure_time_in_seconds = 1 * 7850 * 15 / 1200 = 98.125 seconds? I can't really believe it.... where's the mistake?
  18. Anyone can share their experience of using Bandmate Planetary Filter on Saturn?
  19. One more thing.Since my Nikon has a 1.5 crop factor, i guess the 0.41 seconds become 0.27 seconds of maximum exposure before getting star trails?
  20. Thank you very much for the answers...yet regarding my second question... if I use ... a 4x Powermate to make pictures to Jupiter, or Saturn, will they fit the image? or will I have any other sort of problems?
  21. Hello, I need and advice, especially somebody who used powermates "known to be exponentially" better than barlows. Due to lack of money I intend to buy those 2x and 4x powermates from TV so that I won't need to buy smaller eyepieces... this way the 12mm would become 6mm and 3mm, the 16 would become 8mm and 4mm and so on. How much quality\light would I sacrifice by using those barlows? Should I better wait more and buy smaller eyepieces (in mm) and use no barlows? And second question, if I want to go for planet photo, would the 2x or 4x powermate be too much magnification (some say that the best planet photos need no barlows).At the moment I have no t2 adapter so that I can test, so I need your experience I own an 8" DOB / 1200 FL / Nikon D40. Thank you,
  22. yet... could anyone tell me how is the formula modified when I use eyepiece?
  23. One more thing is that I don't speak about "evident". I don't want star trails at all !! So probably I will have to stick with the 0.41 seconds... If I shoot through eyepieces, what would the 500/fl formula become?
  24. I own a Nikon D40 and a 8" Dob with a 1200 Focal Length... so the maximum exposure length would be 500/1200 = 0.41 seconds ?
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