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Last night I could do my first test with a Raspberry controlled HEQ5 mount. Worked much better now compare with all problem I had one year ago. I succeeded to: Plate solve, auto focus, take images. What's left to fix, auto guiding, GPS module to communicate.
Tonight it looks to be a clear night too. I will do a new test run, concentrate me on the auto guider, now in the beginning I use the internal guider, later maybe I change over to PHD2. Very exiting.
My setup of HEQ5 and a 300 mm Pentax 645 lens:
Hi to all.
The most popular mounts - even those that are included in the small-medium range group, do drive the axes rotation via worm wheel coupling .
This one are plagued by the drawback that I have always considered very unpleasant: the mechanical play is not properly controlled and it can’t be always limited within acceptable tolerance limits.
The adjustment of Back Lash (BL) is entrusted to two screws (more often they are grains) usually positioned at 180 ° from each other. However - as we all know, even a wheel very slight eccentric creates
an inconstancy of contact with the worm: when the play is adjusted for an initial position of the axis, it is not in other positions.
In other words, there are positions where the worm rotates with adequate friction, others in which the same friction can increase significantly, and still others where it is so reduced to the point
that it causes excessive play.
So, the tuning screws are sometimes too tight and sometimes too loose … mission impossible to find the right compromise!
This behavior is already annoying in manual movement because the task of pointing at an object in a steady way is not feasible because it ever 'jumps'.
In photography it's even worse.
Not only does an unavoidable backlash often appears in Dec – and it is very badly correctable also by the autoguider software, but- and it is dirty worse, the tracking in RA does not perform evenly
and smoothly. The typical ‘micro’ irregularities in star images is what we see in our shots.
Many high range mounts adopt different methods to contain lashes, and the best ones adopt mechanical systems with which that error is reduced to zero.
With this long introduction, I will tell you what very simple modification I thought of making on my HEQ5.
Please, stay tuned 🙂
For sale is my beloved but now superfluous to requirements HEQ5 Pro for £650
It's in a used condition as you would imagine. I've had it for about 4 years and found great success with this mount. Ideal for those beginning astrophotography and also good for visual users.
I'm calling it "deluxe" due to the upgrades I've had done.
- It's belt modified
- It's had brand new bearings and grease
- The backlash has been expertly setup
- It has the latest polar scope
- The power port has been replaced with an aviation style port which is a lot more secure
It'll come with the hand controller and at least 1 counterweight (if I can find the second it'll come with both). The polar scope cover has been lost. The counterweight is rusty as always. There is some marring on the counterweight bar housing as shown in the photos.
It also will come with the modified power cable required also.
Note: the power LED sometimes doesn't illuminate but the mount is still powered (please see the photo with the hand controller).
Collection or local delivery within Northampton
Last week I discovered a reasonably wobble on the RA axis on my HEQ5 which ended up causing lots of double stars on my subs (i am guessing because the mount kept wobbling between the two positions.) So I did the worm gear adjustment and the wobble seems to have disappeared. I did a full slew rotation check and couldn't tell any binding/grinding (I had binding at 1st attempt but was resolved after further adjustments).
Thanks to the clear skies last few nights, I had it running throughout the night 3 times now. My overall guiding is much better than before, averaging between 0.6 and 0.8 Total error. However, when the mount gets closer to the home position (usually after 2-3am), I seem to start having tracking issues. I have attached screenshots to show examples; sometimes it's trailing, sometimes it's double stars, and sometimes it makes a u-turn to track back to the original position.
PHD log files from another night are here: https://openphdguiding.org/logs/dl/PHD2_logs_tych.zip
Is this a balance issue that becomes apparent when the mount is more vertical? I'm relatively new to using this mount, so most of my previous sessions have been closer to the meridian. Or is my worm gear tightened just a bit too much and causing issues? I can't really hear anything wrong when slewing at high speed.
Only other thing i can think of is, I sometimes get error messages on PHD but pulse command being ineffective, but these happen at other times as well without causing any issues.
It's losing me 7-8 frames over the span of 2.5 hours, so it would be nice to get it resolved if anyone has any ideas?