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About celkins

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  • Interests
    Photographing "faint fuzzies",
    Scuba diving - photographing wrecks & swimmy things that get between me & the wreck.
  • Location
    Nantwich & Cambridge, UK

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  1. An absolute position focused can never go negative - what does it mean to be further in than "all the way in" (i.e. at zero) ? You really should start fully wound in, and then track out to focus under software control, so that it knows your real position, not just some arbitrary starting point, as would be the case with a "relative position only" focuser... Clear skies, Carl
  2. Personally, I like the AR152s - my first big scope, and I still have it, though it gets little use at the moment. The Bresser scope has pretty good chromatics - the objective doublet is F10, with a secondary lens group at the top of the focuser tube, giving F5 overall, and a generally pleasing view, IMHO. I don't think the ES scope uses the same Petzval optical design. At the end of the day, I don't think you'll be disappointed. clear skies, Carl
  3. I don't have exactly this kit, but was using a C11 Hyperstar on CGEM-DX until a few days ago (now on a CGE Pro): I think you'll find it too tight, particularly with a dew shield in place - my roughly 6'x6' area has a couple of "slew carefully" points to avoid hitting the south wall.
  4. Sounds like a normal approach to me - if it is, you'll notice a difference when parking from the east, in that it'll still wind out the backlash in the same way, but after moving in the opposite direction (assuming you've not changed those settings). You will see the same behaviour when seeking to a target...
  5. You'd be better off posting this to the phd support list, where the developers hang out.
  6. You really shouldn't run network cables in the same trunking/conduit as mains - there's a possibility of interference, but it is definitely a risk from an electrical safety viewpoint; each cable is probably only rated around 300v to a common, so it only takes a single fault in the insulation to leave you close to danger
  7. I don't have the same setup, but I opted to use a NEMA 17 12v/200 step stepper from the off - over engineering, maybe, but it's been a fun project, and gives very precise control via the fine focus knob, which is good for my Hyperstar setup due to the very narrow CFZ. This certainly doesn't lack torque.
  8. In essence, yes, correct - as long as you accept the same commands from the driver, and return the expected return codes, then it won't see any difference: my implementation uses an Adafruit motor shield to provide micro stepping control. It should *run* okay on an uno (I'm using an uno clone), but a "universal" sketch would be difficult due to the number of possible hardware variations - your motor board is different to mine, are both different to Dave's (IIRC). You should need minimal changes as you outlined above to implement your own clockwise & anti-clockwise routines, using step(1)
  9. I think the most significant thing, here, is whether the focuser declares itself to ASCOM as "absolute " - implying that it keeps a notion of an absolute position, or whether it's "relative" - in which case all motion is relative to where you are at the start, wherever that may be... My variant on this uses non-volatile memory to store the stepper position regularly, and declares that it's absolute; it sounds like you support relative motion, at the moment, Dave, which is perfectly valid, and in some ways a more logical thing to do, since then any changes outside of the driver (manual movement
  10. I2c bus - with a repeater from NXP ...I'm also using i2c for a couple of temp sensors, to control a 40mm fan on the stepper heat sink - without cooling, it gets rather hot when position holding, but it's prone to jump if I de-energise the coils.
  11. I just read the sensor directly, calculate the dew point, and report it on an LCD that I've attached; that will be located in my warn room.
  12. Yet to test how effective automatic temp compensation is, but theory suggests that for my setup (C11/HyperStar), with its tight focus requirement, it's probably worth while. I also chose to use a sensor which reads humidity, so that I can keep an eye on how close I am to the dew point... Good thread, everyone, and thanks, Dave, for inspiring me to build an auto focuser.
  13. I'm sure you won't be disappointed - I've been using this combination for a while, and, IMHO, it's great
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