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About JamesF

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  • Birthday 15/02/67

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    Wiveliscombe-ish, Somerset
  1. SCB-2000 with C8 at F6.3

    Far more than I'd like, believe me And that's even after spending three or four evenings a week coaching swimmers. James
  2. Altair Astro and Linux

    Depending on which release of which distribution you're running, I believe you may also need to restart udev using something like: $ sudo service udev restart (or a reboot should work). James
  3. SCB-2000 with C8 at F6.3

    You can still do maths on cloudy nights James
  4. SCB-2000 with C8 at F6.3

    Even plossl eyepieces have varying fields of view and different field stop sizes though. My point is that the whole "same field of view as a 6mm eyepiece" thing can be a misleading description because "your eyepiece may vary", be it a plossl or otherwise. Also of course the FOV of the camera is rectangular and that of the eyepiece is circular. If you do the maths for a 52 degree eyepiece (which is one of the common fields of view for a plossl, I believe), then the field of view across the width of a 1/3rd sensor is about the same as you'd get with an eyepiece focal length of a smidge over 5mm. The field of view across the height of the sensor is about what you'd get with a 3.5mm eyepiece. The field of view across the diagonal is closer to the 6mm eyepiece, so perhaps there's a sense in which the comparison might be valid there. However, the actual area of the sky that you'll be able to see in a 6mm 52 degree eyepiece is about 70% greater (assuming I've done the calculation correctly than with the 1/3rd sensor in the same telescope. So my assertion is that it's a messy and confusing comparison. And not only that; it can tempt people into believing that cameras behave in other ways that are similar to eyepieces, such as having magnification. And then you have a whole catering size can of worms spilt on the floor James
  5. Altair Astro and Linux

    Actually, to save you having to go through the hassle of joining the support group just to download it, the beta for 64-bit Linux is available here: http://cameras.altairastro.com/drivers/linux/AltairCapture.x64.run James
  6. Altair Astro and Linux

    There is a beta release of AltairCapture (or whatever it is called) for Linux and OSX that may well support it, though I don't have one to test. If it does work with AltairCapture then there's a strong possibility that it will also work with the next release of oacapture on Linux and OSX, along with many, if not all, of the other Altair cameras as long as the beta release is already installed so the drivers are available. James
  7. SCB-2000 with C8 at F6.3

    Is that the field of view of a 40 degree 6mm BGO, or an 82 degree ES 6.7mm, or a 100 degree 6mm Ethos? James
  8. FRBs

    And in a galaxy far, far away, a little green man is still trying to get reliable wifi reception at the end of his garden (Actually, I think this stuff is quite fascinating. There was a Horizon programme about FRBs a while back which included the story about the microwave oven interfering with the detectors.) James
  9. Help required

    Yup, it seems like the most sensible suggestion. No need to bend any more than is necessary to fit the camera and adjust the alt/az bolts. James
  10. Can someone confirm this mount please

    I'm in agreement with Ian. The EQ5 doesn't have that graduated collar at the top of the DEC axis and has flat plates on the ends of the alt/az bolts rather than "dumbells". The CG-4/EQ3-2 also has those flat sides cast on the RA housing, but the EQ5 doesn't. And the CG-4/EQ3-2 DEC clutch lever is on the side of the DEC housing, whereas the EQ5 has it above the polar scope cap. I would have to wonder though if it wouldn't be a better move to buy a new or second-hand mount with the GOTO already fitted and sell this one on. I seem to recall looking at the same thing a few years back and deciding that it was financially more sensible to do it that way (that is, the cost of the EQ3-2 with GOTO less the second hand value of the existing mount was less than the cost of the GOTO kit). James
  11. Thinking About Making A Mount.

    Were I going to built my own mount I think the first questions I'd need to answer would be what OTA I wanted to put on it and whether I might care about field rotation. Possibly whether I wanted it to be electronically-controlled, too. Those three things might have a significant impact on the final design. As regards bearings, I can't help thinking that I own two motorbikes, one of which is quite capable of breaking the motorway speed limit in first gear and the other will do somewhere upwards of one hundred and sixty-mumble mph. There's potentially a huge amount of stress on the steering head and swing arm bearings, yet they're really nothing astonishing. Oh, and the second has an aluminium box section frame. I've stood the Ducati on the front wheel under braking (on a racetrack) which must put a massive load through the headstock. So perhaps in the telescope world accuracy is more important than "massiveness"? James
  12. Refractor for WL Solar??

    I'm perhaps less surprised by that given that both OTAs should have fairly good correction. I'm really not sure how the 80ED and ST120 would compare, as obviously the 120 has 50% better resolution, but you're still seeing the full spectrum and the colour correction would not be as good, potentially losing some of the benefit of that improvement in resolution. Perhaps that's where using a continuum filter would help. James
  13. Refractor for WL Solar??

    Replacing the focuser, you mean? I'm not sure there's much else that fits without a fair bit of work. I thought the 100RS focuser was supposed to be fairly good (though single speed?), to be honest. James
  14. Refractor for WL Solar??

    To be honest I've never tried using the ED80 for white light observing. Perhaps I should have a go sometime. Could be weeks looking at the weather forecast though James