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Crossway

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About Crossway

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    Star Forming

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    Northumberland
  1. I think it might have been 10 or more years ago when I was invited to attend a lecture at the University of Newcastle 's observatory which was then located at Close House , Wylam Northumberland. They had a large reflecting telescope . perhaps of the order of 14 imches or more which they were proud to show to us visitors. The mirror, I thought, was very grubby indeed and I mentioned this to our host who told me that the performance of the mirror was not un duly affected by this and that they would only clean it as a last resort..........he didn't explain where this last resort lay. I think that I have heard elsewhere that primaries can look a lot worse than they would appear to be. Pete
  2. Just curious really, but is there any real significant difference between observations using a Skywatcher reflector and a Celestron of the same size. A dealers catalogue of Skywatcher scopes invariably states that the primary mirrors are parabolic. The technical descriptions of the Celestron scopes does not mention this..........although it may well be a fact. I have to say that my own use and regard for my Celestron is without any criticism at all. Pete
  3. Very pleased to have got my new home made ex bino optics ) finder scope up and running with great success. I fitted crosshairs in the eye piece using fibre optic filament which, when magnified gives a somewhat "vigorous" image but absolutely ideal for its purpose.. I had also done some experimenting with putting cross hairs in a 20mm eyepiece to assist in aligning the main and finder scopes but as I proved to myself this is not at all necessary and a waste of time. The alignment is carried out in daylight anyway ....in my case via a very distant tree on the horizon and centring the image in the scope field is very satisfactory. Pete
  4. My post this a.m about this calamity was curtailed prematurely by a domestic arrangement to do with shopping!!! Having made sure that my scope had suffered no exterior damage I set it all up again and checked the optics and was astonished to find that the collimation was absolutely intact. My finder scope was pointing somewhere else but soon got it back on line. So the system is OK again. I am sorry to hear that other stargazers have had some hairy moments as well ......its a nasty jolt. I have now had time to examine the dovetail assembly and although the Celestron anchorage bolt seems perfectly adequate I wondered whether to drill through the dovetail on the opposite site and insert another bolt. In the meantime though the "preventer " belt I fitted is a bit incongruous but I'll see how I get on with it. Pete
  5. I had my scope out last night setting up a new finder which I had just made and relishing the seemingly once in a while really decent clear skies. I had just targeted into the Hyades which were at a moderately high altitude when my scope ( a reflector ) slid out of the dove tail and crashed down onto a hard paved surface. The noise of the crash was awful and it was a while before I dared pick it up and didn't know what to expect in the way of damage ........at the least some misalignment of optics or worse, a cracked primary.. But how very very fortunate to find that the only evidence of the calamity was the eyepiece of the finder which had been pushed into the barrel. And absolutely minor. A very carless and avoidable accident......... the azimuth knob is the same pattern as the dove tail knob and I just happened to turn the wrong one. Had I been working with my refractor I reckon the damage could have been much worse. I never want an experience like that again so have now devised a simple " Preventer! arrangement between the OTA and the tripod head. I have also fitted a cover over the dove tail knob. Should have done this before, Pete
  6. Helpful replies and thanks everyone. Will enjoy getting started on my next project and have taken serious note of warnings about treatment and care of these filters. There was a thread in SGL just a few days ago about the on going absence of clear night skies .........here in the North East it seems to be permanent . Murky days are in high figures as well so hopefully a new sun filter will attract some good luck!! Pete
  7. Thank you everyone for very useful replies and 0bviously the Baader solar film is a thoroughly well tried and safe answer . The examples mentioned seemed to refer to refractor scopes , perhaps a bit dense of me but I assume the same treatment applies to reflectors. Pete
  8. There was reference to sun filters in a reply to my previous thread of yesterday. Having always been very aware of the hazards of sun damage to ones eyes , through my time as deck / navigation officer in the merchant navy ( Sextant usage) I have never had any interest in direct solar observation with telescopes or binos. HOWEVER could I ask if there is any Perfectly Safe filter which can be home made. I think I know what the answer might be ! Pete
  9. Thank you for your help Peter, I'll look forward to trying the arrangement next full moon, or thereabouts but take point re. reduction in resolution.
  10. The Astromaster Reflectors have a protective cover / blank which fits into the front end of the OTA. The cover itself also has a small concentric demountable plug. Can somebody please tell me what this is intended for. There is no mention of it in the Celestron info. sheets. Pete
  11. Ouch ! I walked right into that one didn't I and have come out of it with some useful knowledge . Thanks for replying guys. I have no longer got my £15 moon filter but would have been looking at it in a new light ......and not even going to mention puns!. Pete
  12. I don't know what special optical attributes a budget moon filter is supposed to have but a £15 one I used to use seemed to be nothing more than a piece of coloured glass . I had heard that "proper" ones made from polarised glass. I made my own moon filter from a piece of Perspex acrylic sheet.....moderately tinted with a neutral effect, It was protected on both sides by the original paper overlay and perfect for what I wanted. The result is very satisfactory . Glare from the full or near full moon is greatly reduced and consequently the contrast is also improved. So in performance it is certainly no worse than the fifteen pounder. ......and because I made it myself , it is probably better!!.
  13. Some good ideas folks have. And I now know what/ where the field stop is !! I am persevering with human hair but had a trial run using fibre optic filament from an old Christmas tree illumination. Worked OK but the filament is much "fatter" than you would think when magnified in the FS zone. Also, I think that the cross hair image would be more functional if slightly out of focus and therefore placed outside the FS point. More experimenting.
  14. Looking forward, Paul73, to see how you get on with this. A good idea to use the filter holder but just wondered if the "hair" is a bit on the thick side. Perhaps my plan to use genuine hair won't work either but nothing ventured,,,,,,,,,,,,,,, !
  15. Thanks for replies and pleased to have confirmation that this procedure is perfectly doable. I haven't heard the expression field stop before but obviously this sounds as if it would be located at the extremity of the focussing eyepiece. Have I got this right?
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