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Axunator

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Everything posted by Axunator

  1. Jeremy - quite a coincidence, my main rig is C9.25 and Tak FC100DF on AZ-EQ6 and Berlebach Planet, and I sit on Berlebach Nix II. I’m quite happy with Nix, and tend to use quite a wide range of seating heights. To avoid the eyepiece on the apo to get too low when looking near zenith, I keep the mount rather high on the tripod, which means that looking closer to horizon raises the eyepiece quite high, especially on the shorter SCT. FWIW, I’m pretty tall myself, 194 cm. It is true that Nix II is not very compact, less so with the optional foot rest installed (which I do have and like, but it’s in no way necessary of course). But it still fits sideways in the trunk of my old RAV4 with the rest of the gear (and even some bags). Fozzie, If you need me to get some measures from the Nix, just let me know!
  2. Still looking... For clarification, when I wrote ’excellent condition’, I meant mainly optics, normal minor cosmetic signs of use in the barrel etc are ok of course.
  3. Looking for Nagler 16T5 in excellent condition, including box and end caps, shipped to Finland. PayPal payment preferred (I will cover PP fees, of course). Thanks!
  4. Focuser in FC-100D’s is easy to screw off and on without tools for ultra-compact transport if needed - that will shave appr. 10 cm off the length (don’t have my DF now at hand to measure exactly but that’s the ballpark figure), and I presume this will apply also to the DZ. However, with the dew shield screwed off the DF is even shorter than DZ due to its 6 cm shorter f.l. But then you have to protect the lens somehow and pack the dew shield safely to protect it from getting bent out of shape. So I’d feel safer to travel with the new DZ...
  5. Yes, it’s an insulation wrap: two layers of reflecting aluminized bubble wrap with a thin foam layer sandwiched in between. I added it last spring after lot of talk about SCT/MCT insulation on CN, and I have to admit it seems to decrease required cool-down time to effectively zero. Haven’t tried it during really cold winter weather yet, though. I still also use a corrector dew heater band under the insulation (at low power), if I don’t put a dew shield on, since I need battery power for the mount anyway. With an insulated dew shield, insulation is supposed to prevent the cooling of the corrector below dew point, making active dew heating unnecessary.
  6. Tak FC100-DF + C9.25 on AZ-EQ6 and Berlebach Planet:
  7. The max true field of FC-100DF with a 2” EP is 3.6 degrees, quite a bit more than half of NP101...
  8. I see several advantages in these, as compared to standard SCTs: - easier thermal management compared to closed tube SCTs - way easier dew management (no corrector plate) - flatter field due to slower primary - much wider diffraction-limited coma-free field (standard f/10 SCT has coma-free field of ca. f/5 Newt, whereas f/12 Cassegrain equals ca. f/12 Newt, i.e. very wide diffraction-limited field. EdgeHD and ACF SCTs are of course a completely different story in this regard, but come with a price tag to match... yet still have that dew-magnet corrector plate). - no mirror flop during focusing (can be avoided with after market focusers in SCTs as well, albeit with a price) Of course, there are downsides as well: - a bit narrower FOV due to longer focal length (although diffraction-limited field is wider compared to standard SCT, see above) - diffraction spikes from the secondary spider - fixed focal length (back focus in 8" is reported to be 150 mm behind the 2" focuser), which may affect the use of some accessories, like binoviewers - more difficult to collimate because of hyperboloid secondary I guess you can tell that I'm excited ? And yet I'm still quite happy SCT owner as well ?
  9. Remains to be seen. I believe there are several visually oriented amateurs out there (count me in!) who fill find an open tube classical Cassegrain design - even at f/12 - very tempting and interesting... Especially at these prices. Whether it will be sufficiently profitable for GSO/TS/Astronomics, only time will tell. At least their RCs have been going on for years, and they are targeted to quite narrow audience as well.
  10. Piero, I know what you mean when you talk about bending of the MEF3 aluminum plate. In fact, after my mishap that eventually led me to fine tune the focuser tension helped me to get rid of that spongy feeling of aluminum plate bending! Another thing that I noticed affected the bending was the tightness of the screw (the one with two tiny spanner wrench holes) holding the aluminum plate and the green box - if it's loose, you experience more bending and sponginess. Another spot to adjust Tak focuser are the two tiny hex screws at the top of the focuser (the other one of these is hiding under the large focuser locking knob that you can remove simply by unscrewing it). From the factory, these screws are under a protecting drop of clear lacquer. To adjust, one needs to soften the lacquer e.g. with a tiny amount of acetone and puncture through the lacquer. I have not gotten around to adjust these, because I don't have exactly the right size Allen wrench (the one that came with MEF3 is not the right size for these). There are several threads on CN that discuss adjusting Tak focusers to perfection, that's where I learned about these upper screws. However, I was also able to adjust the focuser well enough for my liking with just the brass box screws underneath. Punching through the lacquer may also affect your warranty (not sure about that), so proceed at your own risk...
  11. Yes, under the green box there is a smaller brass box with two screws that adjust the tension of the pinion against the teeth on the focuser tube. Very tiny adjustments of these screws have quite a significant effect on the feel of the focuser. It’s an incredibly simple (you might even call it primitive...) mechanism, actually. The adjustment on mine became loose by itself during an observation night (a scary experience!), that’s how I learned it - had no choice but open it up and figure out what’s going on. Be very careful to not overtighten it - you may even bend the pinion! (Guess how I know that ? Luckily, you can get a new Tak pinion e.g. from Ian King for about 40 GBP).
  12. My Paragon 40 clone (SW Aero ED 40) was astigmatic enough at the edges in my FC-100DF that I eventually made the switch to Pan 41 - despite twice the weight and thrice the price. To me it was worth it, as the Tak + Pan 41 combo makes a truly splendid wide-field scope. But I can understand why someone would prefer the much lighter and more compact Paragon, especially since 90% of the field is really, really nice.
  13. Have you ever tried TMB Paragon 40 or its clones? How would you compare its off-axis performance to 5K Meade? I'm asking because Paragon seems to have a lot of fans out there, but its edge of field astigmatism was quite distracting to my taste.
  14. Second that. I recently bought a second (third? fourth?) hand C9.25 from a rather well known UK vendor specializing in used astro & photo gear. Before making the purchase, I emailed and asked if there are any known issues with the scope, none declared (I got a reply immediately). Once the scope arrived, I noticed immediately that the secondary holder was loose, letting the secondary rotate and wiggle in the corrector plate, making permanent collimation impossible. I let them know that I'm not happy (first politely, later more strictly but still in a civilized way) and asked how we should proceed correcting this. Now it's 2.5 weeks, no reply whatsoever. Needless to say, I'm not gonna buy anything from them, ever again. Thanks to good folks at Cloudy Nights, I got really great and friendly advice of how I can try to fix the problem myself. I considered returning the scope, however, they never even replied to my return request form, so I considered it too big risk to courier the scope back to UK at my own expense, with no guarantee of getting a dime back... Come to think of it, a fellow amateur astronomer with reasonable track record of posts on the forums like SGL and CN is probably 1000% more reliable source of used equipment than a second-hand dealer like that. Apologies for the rant, just a reminder that just because the seller is a dealer doesn't mean you are backed up in case of problems, when there's no official manufacturer warranty. Dealers selling new astro stuff have always given first-rate service.
  15. PM sent. I'm interested if you're willing to ship to mainland EU...
  16. I recently got SW Aero ED 40 after reading good reviews about it and other TMB Paragon clones (AT Titan II ED and TS Paragon 40, of which at least the latter seems to be the exactly same rebranded EP as Aero, although recently discontinued). In my Tak FC100-DF (f/7.4), the outer edge of Aero shows severe astigmatism. The field curvature in a small APO may of course worsen it, but e.g. my Nagler 26T5 remains tack sharp all the way to the edge in the same scope. Would love to try Pan 41 with the Tak, as the 3.5 deg field is quite spectacular even in Aero. The price you pay in exchange for perfect edge performance is 3-4 times the cash and 2 times the weight, though...
  17. If that's the case, and you want to use such a heavy setup on a long-term basis, it will be a good idea to get an extra CW. In itself, it's not unheard of that an EQ mount is supplied with less counterweights than what is required to balance maximum or near maximum advertised payload. In fact, it's quite usual, even with premium mounts costing xyz times more than SA... I would be happy to try to balance SA with a supplied CW and 3-4 kg payload to confirm your observation (just to make sure there's no other potential issues with your gear that might explain this), but I recently sold mine after getting HEQ5 (forget about grab and go with that one!!). Actually, one potential thing comes to mind: how tall is that Manfrotto ball head that you're using? It may shift the center of gravity of your camera gear too much away from the pivot point, thus aggravating the balance problem by increasing the leverage on the camera side (remember, to achieve a balance, the product of the mass and the distance of c-o-g of that mass from the pivot point should be equal on both sides). Since you have the 1/4-20" screw in the dec shaft, try attaching your lens/camera combo directly to that, omitting the ball head altogether, and see if it helps. You can still aim your lens anywhere you want by adjusting the RA and dec axes. Even if balance could be achieved, I would use a ball head only with shorter and lighter lenses. Good luck and clear skies!
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