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AlentejoSkies

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Posts posted by AlentejoSkies

  1. I still have and use my 6" f/8, although the 8" f/6 I used to have was noticeably better on the fainter stuff in a side to side comparison. In my case it came down to what I was happy to carry. The 8" was just a touch too bulky and heavy. Only a small difference, but in practice the 6" was and still is my first choice. The 8" primary is under my bed in a box.

    Good luck. Take a good look at the details. In my opinion you can't go too far wrong either way. Choose one and use it. A good dob around that size is enough to last anyone some years.

    • Like 1
  2. Hi,

    Is there someone with the experience to let me know how feasible it is to think of hanging a WO binoviwer off a Heritage 130P Flextube?

    Please note, I'm a confirmed binoviewing enthusiast. The question is

    1) whether the H130 focuser can handle the weight. I'm willing to work on this if it's the only issue.

    2) If the two tubes of the UTA were extended 100mm less than fully, and the collimation checked, allowing the BV to reach focus without a barlow, is spherochromatism at f/5 anyway going to spoil the view even at low magnifications?

    3) Stretch goal - put the whole thing on an AZ-GTi on a Manfrotto 055?

    That would be great, if it works. Or is it only thinkable to someone who has never had this OTA in their hands?

    Douglas

     

  3. Clear skies here.  Just witnessed a magnificent immersion. Just watching the fine crescent of Venus with the occasional cloud scudding across was already wonderful, and then suddenly the lower surface brightness moon seemed to materialise, almost menacing. Venus looks so spherical at this point. A few friends are passing by on the way to work. Don't lose concentration! I've been manually tracking for the last hour since I lost goto and I don't want to lose Venus now. Immersion takes a while, Venus setting, settling into the moon. And it's over. Time to get the girls to school!

    • Like 2
  4. So, in answer to my own question:

    Coming in from the battery case, removing the slotted retaining ring opens the switch module (take care, springs included). Coming in from the other end, circlip pliers takes off the aperture/protection cover over the laser, which itself can be removed by loosening the 9 grub screws hiding under the rubber sleeve. 6 of these grub screws hold and align the laser module, and 3 hold the battery -ve contact in place. The laser diode module appears to be a standard 3V module, which I will now try to replace as it seems to be the part that has failed.

    Nicely designed and made.

  5. Good afternoon.

    I have a nice Baader laser Colli MkIII that has unexpectedly stopped working and I'd like to open it up and clean the switch/check the contacts and so on. But of course I'd like to keep the alignment. Before I jump in - did anyone else already take one apart, and if so, do you have any tips?

    PS. batteries are good, polarity correct, visible battery contacts clean. Current draw is too low, at about 1mA, and not stable.

  6. 8 hours ago, Chriske said:

    ... and our very first part was 'born'....

    That catches the feeling of excitement and amazement of my first part pretty well too!

    So, just to be sure on the question of cold, I put a discarded print piece (the same PET-G) in the icebox for a few hours and took a hammer to it this evening. I had to give it quite some blows to chip a first piece off and I didn't get its structure to break before I felt I had to stop to not disturb my neighbours.

    Was hoping to test tonight whether the new rings would shed light on whether the old rings (hose clamps) had been causing my collimation issue on the lovely little ETX-105, but looks like the cloud is here to stay. And that's a good thing down here in southern Portugal.

  7. Thanks Chriske. Looking forward to seeing the files.

    The aluminium barrel should be no problem. Even a good reason to use the workshop lathe. Dual speed knob will have to wait though until the next time a friend is going to the States. That BD601 planetary reduction drive with a unit price 12 dollars for five or more is fine, but the postage to Europe is prohibitive. I'll buy a few though when I do get a chance, so if anyone wants one posted within Europe and is willing to wait with me an indeterminate time, let me know!

  8. So, I spent my weekend with a Prusa i3 mk3, Onshape and Fusion 360. First time I've tried this, and I'm just amazed! Many thanks to @John78 for sharing his parametric model from a couple of years ago. I am so impressed by the result that I just have to show it here (my family and friends only somewhat share my enthusiasm).

    Next stop has to be a focuser. @Chriske, you've got a PM incoming.

    And then, well I've got so many ideas now!

    3D printed tube rings.jpg

    • Like 2
  9. Great thread. Thanks.

    As I will soon have a nice 8" f/6 mirror set in the post thanks to @Stu, I've been giving a bit of thought to putting together a dob optimised for binoviewing, and was out again last night trying a few eyepiece combinations with the kit I have to see if this is the way to go. Here's a few rambling notes from last night's testing...

    Targets: Jupiter and Saturn. Site: Alentejo, Southern Portugal.

    Scope 6" f/8 homebuilt dob, WO binoviwers, a couple of glass path correctors (GPCs)

    In the last four years I've put some effort into learning about and using astronomical optics - and I already had a good professional background in optics. I've learned a lot, but what most amazes me is what I see through the eyepiece now using actually the first equipment I bought and made. When I first built this scope I was impressed to see faint lines on Jupiter. Now I see swirls and patterns, a wealth of colour. The question is not whether I can detect the GRS, but how does it look tonight. The globe is full of features. What once looked like an aspirin now looks like a photo with character and characteristic. I have acquired quite some equipment since those first days, but I'm talking about using exactly the same setup as I started with. The only thing that changed there was me. And a lot of that had to do with getting comfortable and using binviewers.

    Anyway, I was actually checking  a few eyepiece combinations, bino versus single.

    First test: Televue 15mm Plössl on one eye, Vixen 15mm NPL on the other. 2 X GPC correctors for a total magnification of about 220. I can only reach focus with stacked GPCs at the moment. Next scope should be different. Hence the experiments.

    These two 15mm Plössls are not parfocal, but with a bit of fiddling around, I was surprised to find it works. The difference between the two eyepieces was minimal center and edge. I could convince myself either way which was better, and will keep that question open for now. What was obvious is that the Plössls were way better off-axis than the WO 20mm pair that came with the BVs, that I usually love.

    On these planets, I just love the immersive view of two eyes. I can watch the planet move across the field of view again and again. One-eyed viewing for me seems technical in comparison.

    But then just as I was convinced again that nothing beats binoviewing, I did try a nice little 9mm volcano top ortho with one GPC srewed directly into the bottom to more or less match magnification to the above pairs. And then I had to admit that there was clarity and detail there that was not with the combinations I have available for binoviewing. Tried to see if that still held true if I just used half the binoviewer and my one ortho, but the need to stack GPCs gave too high magnification - horrible.

    Not a super-fair test as the unmatched magnifications makes a big difference in itself. But this morning I couldn't resist buying that second 9mm Ortho that's been on ABS for a while! Let's see what happens with two! And the next scope will definitely be built with some way of setting up for binoviewing with and without GPCs.

    Will try tonight with the ETX-105. Totally different beast, but it has a much larger range of focus and can handle binoviewing without GPC.

    • Like 1
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