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Everything posted by rfdesigner

  1. rfdesigner

    m106 New

    M106, 17x 5m L, 17x 1m40s each RG&B Processed in IRIS
  2. rfdesigner


    From the album: Just some Astro Pics

  3. rfdesigner


    From the album: Just some Astro Pics

  4. I've been slightly less than perfectly happy with the guiding, finding it hard to beat 4 arc seconds FWHM in my raw subs. So... I've made a new bracket for the RA motor out of 6mm thick 60mmx60mm aluminium angle.. and finally I've got it guiding tonight with the newly secured setup. On a 5 minute sub working at 1500mm focal length on 5.4u pixels I'm getting a FWHM of 4.01 pixels, that's 3 arc seconds FWHM. The focussing image (1 second long) was giving 3.3 pixels FWHM, so that suggests the guiding should have been about 1.7arc seconds FWHM or 0.77arc seconds RMS (PHD agrees). I'll have to check the log and see if PEC might be able to make a difference now. Not perfect, but certainly a good big step in the right direction, and leaves me with bigger fish to fry, like getting a coma corrector and filter wheel installed. Time for a little happy dance!
  5. Try a machine wide search for anything less than 24 hours old. If you're using Windoze 7 turn off the indexing.. it doesn't work properly, missing loads of stuff... a well documented MS foul up. If you think you know where the file is, try refreshing, in W7 has an apauling habit of showing out of date file listings so missing off your latest additions. Hope you find it Derek
  6. I had a recent message about this blog, good to know I haven't been writing into thin air!.. and of course I've added nothing for too long. So.. where are we? 1. Mount functions: Slew works Guiding Works PEC kind of works.. I have a new PEC algorithum which should improve things. Park, needs adding GOTO needs adding, software written with this in mind. 2. Drive needs propper PCBs and dsPIC in the base to allow GOTO (spherical maths, needs sin/cos/tan) 3. Base unit needs boxing up. 4. Hand Controller needs the backlight working, not currently wired in. 5. Hand Controller needs boxing. Performance: Primary concern is the performance of the mount itself, so I plan to strip down the RA worm and rebuild with new bearings and new bracket, with a bit of luck things will be much improved, currently its 15 arc second peak to peak over a single cycle plus an additional 15 arc second peak to peak cycle to cycle, and it's rough. It's the roughness that's the biggest concern, followed by the cycle to cycle variation. Derek
  7. Thanks Stolenfether. We're really enjoying the house, a place that's ours!.. plus a dark sky, and something a bit historic and a decent sized plot. just need to get the obsy built, and get new roof on the house, and lots of insulation, and a new bathroom, and a new kitchen, and a new... ok.. it needs a bit of work!, but at least it's unique. might get time to notice the moon!
  8. Well it's been a LOONG time since last posting. A house move and other family crises intervening. Finally things are settling down and I managed to get out under the stars for the first time proper at our new house. Scope is now in a semi-permnent position (scope permanent, camera, PC etc. not) So got the gear guiding again and got out my new and shiny ATIK 383L+ :D Thin cloud + full moon so I was never going to get a good shot :mad:, but at least I could get the scope aligned etc. New for this session: 1. Atik 383L+ 2. decently dark sky (in theory, when it isn't cloudy) 3. semi-permanent position. Result: About half a dozen stars recorded on 12 x 1 minute frames. FWHM ~= 3.5 arc seconds. stil a way to go on that, target is 2 arc second FWHM. Guiding log below (this is at 1.5m and 8.3u pixels, so about 1 arc second per pixel) notable issues: 1. mount needs the self programming PEC re-write adding. 2. worms need some new ball beaings (in the post) and new motor mounts (also in the post) 3. CCD iced up a touch, so I mustn't run it so cold for now. (one of the problems on a newt, the CCD can face down, spilling cold air)
  9. rfdesigner


    And here's the image: 100% crop
  10. rfdesigner


    Well.. I've now got an OAG (SX-OAG) and after many months of delay caused by other demands and uncooperative weather, I got my first autoguided shot with the mount. I knew the DSLR and the guider were not parfocal, so I accepted the inevitably poor shot and had a crack anyway. Stacking 30 x 30 second shots with no software registration showed the movement was not discernable. Out of focus yes, but 'sharply' out of focus, not just blobs so the autoguiding is really working. Next up: C mount extension tube and DSLR remote control for multiple long images. nearly there! Derek
  11. rfdesigner

    Light pollution

    Generally yes, but there is news. The CfDS has been officially recognised and is being listed to by governement (Bob Mizon who kicked off CfDS now has an OBE for his efforts). Light disign is very likely to become part of building regualtions soon, which will have a very wide ranging effect. Hampshire is installing down lighting units across the county, other counties are doing the same, these are buying a magnitude of sky darkening (this has been achieved near Bob Mizons place.. although the wider area isn't yet fitted out with these better lights, so performance may be better than 1 mag.). We also have a nationally recogised dark sky park up in Scotland, which means again that those in power are waking up to the problem. Also it depends very much on where you live, London and you will be lucky to see the moon.. Where I live in slightly rural Hampshire and the milky way is visible overhead, and go out to darker spots and things can get very good indeed. Finally many councils are now turning out some street lights after midnight or 1am... so stay up late and find out what happens. Derek
  12. Next in line is was the second axis. I added the code, debugged it, and got the slew working for it. All relatively simple as it was a cut a paste from the RA axis but without needing to make it track, same error feedback but it keep calculating the same position, sounds a waste but once GOTO and corrections for misalignment and atomspheric effects on position get added it will be changing continuously. anyway.. added the circuitry, tested, added the motor drive chip and motor and bingo.. worked first time!.. really!, all the way from the hand controller through the PICs and out to the motor. Next: lets stick it on the scope.... now where is that bolt... bother!! It's imperial.. whitworth? BSA?.. no idea.. bit like M8 but coarser thread.. any imperial thread gauges anywhere to measure the other one?.. of course not. so I'm googling for a solution but it hasn't presented itself yet. if anyone has any ideas.. I'm all ears (eye's not being that useful until this is working :-)
  13. Take a look at the 2.4GHz systems and micro servos. I have one (DX6i), and it is very small and very light.. designed for the model aircraft market (not that I use it for that) Derek
  14. Thanks, hmm.. servos from a USB socket, nice idea. thought: does anyone do a radio control system with a USB socket at the transmitter end? Derek
  15. Well after much hair pulling head bashing and general frustration I've finally got my hand controller communicating with the motor driver. So you choose 'slew mode' and press the east button, and the motor starts slewing east, let go and it immedaitely resumes its normal tracking, press west and it turns to the west. Might seem simple but it's been anything but. Two completly seperate chunks of code in two seperate PICs. The first PIC scanning a keypad for finger presses, interpreting modes double key presses etc., communicating down a 2meter I2C comms link, interpreted by another PIC and then the correct motor instructions sent over the same I2C wires to the motor drivers. Not straight forward.. but adding the GOTO commands will be no more than a couple of evenings work, essentially that's how the slewing is working now, it's slewing the target point and the motor is playing catchup. Autoguide port?.. childs-play. And I've just confirmed, it's hot plugable. Am I happy... of course.:D Do I expect anyone else to follow what I'm on about.. :o, maybe not. never mind Derek
  16. rfdesigner

    Which scope?

    Alt Az will track more or less as accurately as an equitorial, but you get very fast image rotation. If you want to image with an Alt Az you will either have to use an image de-rotator (another motor at the focusser, which then needs controlling accurately) or you would need a wedge so that the fork mount is 'pointing' at the north pole. A second issue with an Alt Az and an image de-rotator is that it still can't image across the zenith... it has to rotate extremely fast as you go past the zenith. The real amateur solution is the wedge, but they're not free. If you go for a german mount then it will expect to be polar aligned, again if it isn't perfect, then as you track you get image rotation, but only slight compared to an Alt Az, and if you image with lots of shorter images, say 10 minutes each, then slight rotation isn't usually an issue. Can you tell I only have German mounts? yours utterly biased :D Derek
  17. Sorry to see someone else suffering what I suffered I went the crayford route about 10 years ago. ... oh the pain and anguish. In the end I popped round the model shop we had a work and for the price of a beer I had a 2" to 1.25" adapter/extension with slip ring made up. Now I have my 25mm 1.25" plossel parfocal with my camera Not having such a brilliant facility available at work any more I'd probably buy some 2" extension tubes and a 1.25 to 2" adapter if the craford didn't come with one. Point is it would never produce a system parfocal with your camera... hmm maybe I should get my adapter I have made up in a larger batch. Derek
  18. On the face of it easy, but in practice less so. In my case my drive system has been slightly lagging the stars and I'm trying to work out exactly where the error lies. It looks like the error is around 2% so worm wheels on their own don't account for it, but it could be part of the problem I thought it might be that the worm wheels got swapped when the mount was refurbished, in which case the mount would be running a tad slow. So how do you count 360 teeth?.. and trust your answer when you're done.. Solution: reprogram the drive to slew the mount through 360 degrees.... then I know it's done 360 worm revolutions, if the mount has come back to the exact same spot it started at then it's a 360 tooth worm wheel. Result: 359 teeth. So it's not that. I did however establish that it slews at 2.5 degrees per second... I can live with that :D So why is it slow?.. well analysing the various processor signals it looks like it might have been missing an interrupt every so often, and these are used to get the timing spot on. At 40 interrupts per microstep and one missed interrupt per microstep that makes a 2.5% slippage. So a bit of assembler to speed up processing and now there's no lost interrupts.. I won't know if it's right until I can star test it again. It's bound to be cloudy for the next fortnight. Sorry... Derek
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