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Everything posted by Olsin

  1. I'm afraid i didn't really have any laid out plans for the rolling hatch and front plate. I kinda made it up as i went along. Nor did i get much documentation of the progress until it was basically done. This is where I'm up to at the moment. I'll probably end up darkening the interior as well as a few other minor bits and bobs although it's all fully useable now. I've had first light and had a great time with Mars and Saturn being prominent albeit low. It's definitely a game changer being able to just switch on and go without having to setup, align and eventually break down again. So yeh, that's it....the next project is automating the dome and digging an even deeper hole by the side of my observatory to build an underground warm room although......i think the wife probably needs a couple of years rest to get over this build before i start on the next..
  2. I've only got a couple of pictures from when i cladded the whole dome with an over and under bitumen sheet. This was the type that didn't need to need to be heated to be fixed, having it's own bitumen glue on the backside. It would have been good enough to fix this straight down on the bitumen primed plywood but instead, i coated the whole dome with another thick bitumen product which was allowed to dry. The bitumen sheeting was then stuck down on this. Once the whole dome had it's first layer on i then coated it all again with another layer of the same thick bitumen paste. This was also allowed to dry over the course of a few days before the top coat of bitumen sheeting was applied.
  3. A worry i had had right from the start now proved to be valid. The tiny plastic wheels i had originally fitted on the dome base where woefully inadequate. I hadn't even started to fix the 2 layers of heavy bitumen sheeting i planned as weather proofing and already the dome where hardly able to cope with the strain. I don't know what i was thinking. The running groove that the wheels ran in couldn't really be altered without stripping it all off and doing something different. I didn't fancy that so i shopped around and luckily enough found some much more suitable and robust wheels, that fitted perfectly into the existing groove. This operation also gave me the added benefit of increasing the height of the overlapping side skirts, giving me a much better rain protection. Once done, dome back on and bitumen primed. The dome rolls around very smoothly now.
  4. Once the hole had been finished i turned my attention to cladding the dome skeleton. I used 5mm plywood for this and it worked a treat. Then i sealed all the joining edges with a bitumen sealer and then painted the whole dome with another layer of the same sealant.
  5. It was now time to sort out the hole in the stone wall. I'm not a bricklayer and looking at the pictures, it's obvious. I should have knocked the hole larger to start with so that i had more room to find and fit stones so that i could have made the edges more contoured. Instead i used stiff boards and cemented the stones up to them. This gave me that straight edge to each side of the hole. I've since scraped away at it a bit but there's still to much straightness there. I'll probably revisit that eventually and change it.
  6. I was now waiting for a few good days so that i could get the dome out of the house and up on it's perch but weather and timing were often off. I ended up erecting the dome, getting a tarpaulin over it, insulating the finishing the walls and finishing the floor...all without getting any decent documentation.
  7. The floor beams are now in place and it's time to make a start on the dome construction. I received a set of plans for an 8 foot dome from a member here called Huw .. Thanks again Huw .. although the measurements were US and the dome was slightly larger than the one i intended. I puzzled over the drawing for a while before i realised that all the measurements could be derived from the base and the 2 main ribs regardless of base diameter. By this time the weather had turned foul so i brought the operation indoors. The base was cut out of 12mm plywood sheets. I planned on using 4 layers for the static lower base and 3 for rotating upper base. Each layer was glued and screwed together. For the upper layer i planned on a groove around the base which the rolling wheels that where to be fixed on the lower base, would roll in. This groove was finished off with 4 layers of epoxy fibreglass.
  8. My well over dimensioned mount bracket was made with a couple of brake discs and four lengths of 16mm threaded galvanised rods and painted down with black hammerite when finished. Its not the prettiest but it does exactly what it's supposed to do. I used a section of 25cm ribbed hard plastic piping that i had kicking around to use as the pier. This was levelled into place with a large plastic cut down pot around the bottom that would also be filled with cement to add a buttress to the pier. Because the ribbed pipe had a slight bend in it and was made of very stiff plastic, i needed some kind of bracing around the outside to force it straight. This would all end up being cemented into the foundations along with the pier. The long threaded rods which poked out of the bottom of the mounting bracket had thick wire wrapped around them to give the cement something to cling to. I had originally thought I'd just bend the bottoms but this was to hard to do with the tools i had. There was also more metal in the pier than i've shown. I'm afraid there's many other details i also haven't recorded on camera. When you're in the flow of things, the weather is good and moving from task to task without really thinking about it...stopping and taking pictures kinda gets left behind now and again.
  9. I didn't really know how large this foundation should be so i settled for a hole a meter in diameter and approx 45 cm's deep. In retrospect i could have gone deeper but the truth is, it was tough digging in the hard pack ground. The pier would also be in reinforced concrete and i estimated the finished weight of foundation and pier to be well over 200 kilo's. The hard pack would also add to stability. - The pier now carries a C8+avx and is rock solid, so my foundations were adequate. Once this was done, i covered the hole and waited for a break in the weather so that i could get some cement in. In the meantime i started on the walls of the observatory. The initial design allowed me to to align the dome slit with the door so that i could open both and walk straight in without having to duck down. This design was changed along the way as i saw that it would be overly complex plus bring weakness and instability into the finished observatory.
  10. By the middle of December i was down deep enough to where i needed to knock a hole through a stone wall I'd put up some years back. The hole would eventually be repaired and used as the entrance to the observatory. Once i was able to gain access straight into the hole, digging out became much easier. I just needed to dig down 25-30 cm's under the intended finished floor height, so that there was room to lift the floor up from hard pack ground. Once done i could dig out the hole for the pier foundation.
  11. On the 15th of November 2017, i took the first few wheelbarrows of soil out of the ground that I'd earmarked a few years back as the site for a small 2x2 meter domed observatory. Work commitments and other priorities meant that i knew i wouldn't be able to complete it before end of 2017 season. So as there was no hurry, i set about at a leisurely pace, digging out a few wheelbarrows of soil whenever i had the time and the weather was pleasant.
  12. I'd like to build this type of dome for my work in progress observatory. I've found plenty of geodesic and trapezoid calculators but haven't found any references to similar tools for this type of design. Is there something blatantly obvious i'm not catching?
  13. I couldn't help reacting to this simply because i couldn't be more in disagreement. That astrophotography should be "far more creative" than regular photography is blatantly incorrect. In astrophotography your target is fixed in space, it's view relative to our position is well known, there are no surprises......critique usually goes along the lines of, not bad, nice, awesome detail, stunning colours or whatever vernacular you've made your own or is common to your area. Terrestrial photography (yes there is also marine photography) can be used to elicit deep emotions which inspire people to do all manner of good and not so good things. A picture can release tears of sadness as well as joy. There is so much depth available within the hobby/occupation of standard photography. Astrophotography for all it's technique and creativity, doesn't come close to conjuring up the emotions and feelings a master photographer could inspire, with the world and it's myriad nuances as his palet.
  14. Of course you can. I don't stand outside to pack my 8"sct + avx down at end of session. I pick the whole thing up and carry it indoors. It has a bit of weight sure, but nothing any normally built adult should have any problems with.
  15. I've often wondered why telescope manufacturers don't install these as standard. It would be such a small expense for them.
  16. Simply put, you won't see colour in any DSO's if you're just looking in the eyepiece. They will for the most appear as a greyish smudge mark against a dark background, if you can see them at all. Faint nebula and suchlike only really become apparent through astrophotography. Images like your profile picture are achieved by long exposure photography. This is NOT how they appear to a naked eye looking through a telescope eyepiece. Astrophotography can be a rather demanding discipline. I suggest you read through AP posts here and elsewhere to get an overview of the kit, techniques and the myriad problems/challenges you're likely to encounter.
  17. No, i got that. I was mainly referring to the potential difference in coordinates between center in finder=enter, center in EP=align. Centering a star in a 1x telrad could still leave it out of FOV in a 20mm EP at FL 2350mm. My thought was a wondering if large inconsistent discrepancies in a stars position between pressing enter and align on the handset, could mess up goto accuracy..
  18. I'm not that experienced yet and have only recently ironed out the quirks in my own setup routine. What does strike though is you using a telrad with an Evo 9.25 scope. You give no reference to a reducer so that's a long focal length you're working with. I've never used a telrad but i understand they are just 1x. Maybe i'm wrong but i don't really see how that combination of FL and finder could be anywhere near precise. I spent a lot of time aligning my 6x30 finder with my C8 and i can usually put a star about halfway from the middle to the edge of FOV in a 20mm EP. Never get it spot on though despite the apparent sync between finder and OTA....there's to much focal length. You have more FL with a finder that's only 1x. A miniscule variance in head/eye/telrad position could give you wildly varying error margins when you align first with finder then EP..........or not. i don't know. Just my thoughts. I'm sure i've read a rule of thumb that said telrads and red dot finders are fine for shorter FL scopes, not so much so for the longer. Alternatively, and again not that i have a huge understanding of it, but have you ruled out cone error?
  19. Ah i see. So you plate solve to acquire a solid reference point in the sky that you can refer back to for imaging purposes. Point taken Geoff. Thanks guys..
  20. I keep seeing this expression written and talked about without really understanding what it is. So can anyone explain to me what plate solving is and how it increases imaging accuracy?
  21. Sorry Alan, i've only just noticed this. Yes you're absolutely correct. That badly thought through design bears all the hallmarks of a design team that didn't really give a toss. That amongst other things, is one of the reasons i'm reluctant to consider buying anything from Celestron again.. Why do you need to get new bolts made. Can't you simply swap them around as i mentioned to John? I can only say that even an "almost" aligned PA scope on my avx + c8 doesn't give me a satisfactory PA. ASPA always gets it tighter. I can now get 30 sec subs without star trails. With a f6.3 reducer attached i can push it a little higher. I was lucky if i could get 5 sec subs when i first started using ASPA. But that was before i understood the routine and didn't know to pick calibration stars as close to the area i wanted to image as possible. It's not really that bad once you've gotten used to it..
  22. I've used an asi120mm on my C8 and i wasn't overly impressed although that could very well have been because of bad to middle of the road seeing.The incredily small FOV makes good seeing conditions critical if you want to get a good focus. It's always seems to be jumping all over the place everytime i look at it. You can use this FOV Calculator to check out any combination of scope/ep/camera FOV. Click on "visual" if you want scope/ep FOV and "image" if you want scope/camera FOV. https://astronomy.tools/calculators/field_of_view/
  23. Thanks a lot Michael, that's what i was hoping to hear
  24. Thanks Pete .. I've seen those types of finder bases but without ever actually seeing one in the flesh, it's hard to decided how solid and substantial they are. A 60mm finder/guider weighing in at around a kilo would only be supported by 2 screws. To my mind that seems to little and even though i'm not initially guiding with this scope, i may want to try it in the near future. I'd want the finder/guider to be planted solid on the OTA.
  25. I couldn't really imagine it being any other way Here's the latest offering i've come across..This scope gets good reviews too. http://www.365astronomy.com/365Astronomy-60mm-Compact-Deluxe-Finder-and-Guidescope-Kit-with-1.25-Non-Rotating-Helical-Focuser.html But i still don't really know how i'd mount it on my C8. Am i right in thinking that i need another bar similar to the one already mounted onto my OTA, that is fastened both at the front and rear OTA housing ... and then a finder base screwed onto that for mounting the finder/guider? As in another of these bars..
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