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Riemann

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About Riemann

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    Dorset UK

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  1. You can minimise image shift with the standard focuser by always finishing focusing with an anti-clockwise turn. Anti-clockwise pushes the mirror upwards. It is a slight pain but works and becomes sort of second nature after a while.
  2. EQ mounts are a little confusing at first but become second nature after a few goes. Getting it working properly on your first night out is a really good result. You may find it useful to practice during the daylight (even indoors) the setup, pointing and tracking procedures, or you may already be beyond that point Very impressive what you managed to see first time out. M31 is indeed a fine sight.
  3. Whilst my points in reply to the bonus question were correct, this point is really more important.
  4. Hi - these are not stupid questions Some thoughts that may help.... Question 1: I am not sure where you get 85% from. 17672/10207 = roughly 1.73 i.e. 73% extra. But leaving the arithmetic aside, the principle is basically correct. The only other thing you have to worry about in a reflector is subtracting off the impact of the central obstructions before you compare the areas. If the central obstruction is roughly the same size then you might actually end up with somewhere around 85% extra after all, but that would depend upon how big it was. Question 2: If thing A i
  5. I started in 2012 with a SW 130/900 on EQ2 just like you. Will never forget my first views of Jupiter, Saturn, M31 and M42 through it. I bought a second hand C11 SCT with GOTO last year. I am glad I went through the manual stage but have not regretted the switch to GOTO at all.... yes it takes a little while to line up each time but takes the frustration out of the hobby for me. I take my hats off to the patient and knowledgeable astronomers who find things manually. I go through stages of regretting not getting a C9.25 for easier portability and being delighted with my C11 fo
  6. I can't help you with a Meade but I did some carefully measuring on my C11 a few weeks back. There is a 3 inch adapter that fits onto the OTA. The visual back screws onto the 3 inch adapter (with the option of a focal reducer in between). Where the visual back screws onto the 3 inch adapter the thread diameter is approx 50mm which tallies with the 47/48mm posted by Chris above. However, the 3 inch adapter is narrower internally, approx 38mm at its narrowest. This is substantially narrower than the visual back and the 54mm baffle of the C11. Because light goes at a diagon
  7. Definitely not stainless steel.
  8. Some stainless steel is slightly magnetic, some isn't. I have some 40+ year old stainless steel spanners that are slightly magnetic. But I thought the definition of stainless steel was that it was a chrome steel that does not rust under normal conditions. The aforementioned spanners still do not have a spot of rust on them, despite being kept in slightly damp garages for most of their life.
  9. I am loving this thread. In fact I like many of your project threads Gina - you are an inspiration. Can't wait to see how your grandfather clock turns out. I don't really need an oscilloscope, but as a teenager back in the analogue days I used to have a couple of them and they are definitely nostalgic for me. If I do ever need one [or tell myself I need one ] then I will be using this for a template, maybe plus a resistor ladder at the front end so I could cover a wider voltage range. Good luck with finishing this one off!
  10. One thing to bear in mind, if something is so faint it won't stand out against the background light pollution it doesn't matter how much aperture you use, it still won't stand out. If you have light pollution around your house there is a limit to how useful extra aperture will be to you at that location. If you have light pollution, you are forced into using a dark site to see very faint objects and whilst you may be physically able to move a large telescope you might end up wishing you had bought something a bit smaller and easier to manage. I am speaking from personal experienc
  11. That should keep things going nicely
  12. Maplins do a good range of plastic boxes for electronics. As well as Julian's advice re how clean the inverter is, have you checked the power and current implications for your batteries? If you are going to be drawing anywhere near 300W then that is going to put a hell of strain on 12v batteries - even assuming 100% inverter efficiency, 300W would draw 25 amps from a 12v battery, and drain a 20Ah battery in under an hour. If you are just powering a laptop then you may be OK though you should factor in a realistic power loss for the inverter, eg if you have a 40W laptop, and 85% i
  13. Hi Spill If you not using a recticule eyepiece with a cross-hair, then 20mm is not going to be particularly accurate - it is surprisingly hard to get stars exactly centred and a long focal length eyepiece makes any error from centre worse. You would be better off using a higher powered eyepiece. I think your scope comes with a 9mm but if you have a 6mm that would be even better. If it is hard to get stars in view with the 9mm during align, then roughly centre with the 20mm then swop to the 9mm before finalising the centering of that star. Peter
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