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Notes from the field ...

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#1 choward94002


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Posted 20 April 2019 - 12:58 PM

Now that galaxy season is winding down (and the weather is starting to cooperate) a few quick notes that I've found from this season, might be helpful for some people (or not) ...


- A suggestion that KokathaMan made about putting a neoprene gasket between the corrector plate and the retaining collar has really paid off ... due to that stopping water infiltration via capillary action from the corrector plate the internal humidity of the OTA's that used that has dropped by about 10-15% compared to prior years which for dewpoint is 'kinda huge.  I couldn't find a good source for the super-thin neoprene, I went with the 1/64" rubber sheet from Grainger


- A suggestion that Ed at DSP made about tightening the clutch locks on the mount from "superman" to "just enough to hold" as also really paid off ... a bit of background, due to Celestron mounts using servo motors and not stepper, if there is a resistance to movement the motor will simply draw more current in response, resulting in a burned out motor/ control board/ both.  Ed's observation was that since the mount (should) be balanced anyway, if the clutch locks are just barely enough to engage the clutch then any resistance must be from an external "bad thing" (like a cable snag, or a pier collision, which you don't want to fight against anyway ... I lost a camera due to a cable snag ripping out the USB connector due to this kind of fight once) and so you want the clutch to "slip" rather than "fight".  It took a bit of doing to get things dialed in (the clutch isn't perfectly round, imagine that, so what "locks" at one position will freewheel in another) but once I found the clutch "high spots" to engage the locks on and got my mounts adjusted so that the clutch would just barely engage at those high points (I put a 6oz weight on the end of the OTA, that was the "breakaway" limit) the mounts worked fine and over the season there were four "oopsie" moments that would have been a problem if the motors had been allowed to "fight", the last one a surprise snowstorm that dropped 6" of snow onto the OTA and camera assembly, unbalancing the rig by at least 10lb on the camera side.  Woke up to find all of the mounts nose up and the mounts spinning away, but no burnouts 


- A suggestion that another member made a few months ago about enclosing the entire rear section of the OTA where the "good bits" are (camera, focuser, etc.) with a light garbage bag attached to the OTA with a cable wrap strap also paid off ... much less dust/ spider/ debris ingress on those components, and during the aforementioned surprise snowstorm it saved 13 OTA's from having all the sensitive bits covered in 6" of snow ... it doesn't contribute noticeably to wind shear, the camera cooling fans don't show any change versus "open" (likely since the bag volume is so large) and as a side note with the camera cooling fans adding heat to the system (keeping the bag interior warmer than outside) I have much less condensation issues with the "good bits" than in years past


- Related to the "garbage bag" change was putting the controller laptop, UBS hubs and thermal management RaspPi computer into a ZipLoc "mattress size" bag attached to the pier side with the laptop fully extended.  Everything stays dry and warm enough to work properly, the bag conducts enough heat away so the laptop doesn't overheat, I can see through the bag to the screen if I'm there locally (I usually use VNC remotely) and I can press on keys though the bag as well.  Cables run out a hole I cut in the top corner (sealed with tape), whole thing hangs from a side of the pier


- Voyager gets yet another strong thumbs up from me, as does SkyTools4 Imaging for it's planning.  Compared to last season when I was using AstroPlanner and SGP Voyager has let me increase my "usable time on target" by about 26% and SkyTools4 has let me increase my "targets imaged per night count" by about 19%, resulting in significant net increases not only in the number of high resolution pix of targets being completed but with fewer exposures being dropped onto the floor, and that's even with the additional complexity of my taking "L" channel exposures with the 183 on some of the objects.  I really push both of those hard to local photographers, really worth every penny (plus!) paid for them


Clear skies to everyone, time to start gearing up for planetary nebulae and seeing just what my "L" channel can do with those!

Edited by choward94002, 20 April 2019 - 01:01 PM.

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