Sylvester111

Aha! Now I see! It’s brand new so must have been a bit stiff when I first loosened it as it didn’t seem to do anything (loosened clutch and it still only turned by the black knob at the back, but with a little encouragement, the top now turns freely with the clutch loose) Thanks!

This is probably a stupid question, but what does the clutch knob do on the Star Adventurer DEC bracket (not the SA itself)? I thought it would be to change resistance on the movement of the top rotational plate, but it seems to make no difference. I only know it’s called the clutch knob from the manual. It’s the one I am pointing to, here:

Couple more shots from last night (mayyybe I over saturated the end results a bit). But happy to get 3 minute exposures with very little star elongation (to my eyes). SA with ASI 120MM-S and mini-guide scope for guiding. Unmodified EOS RP with 100-500mm lens at 500mm, f6.7, 1600 ISO but I think I need to drop to 800 next time and maybe push the lights to 4 mins. 3 min exposures for these . I used SharpCap for initial polar alignment but found it quite off when I tried a drift align in PHD2. Might go straight to PHD2 next time. Slowly learning! Rosette Nebula 26 shots stacked, Carina Nebula only 8 shots as I may have been pointing in the wrong bit of the sky for the initial 8 shots...

I need to experiment more, but bad collimation may be the answer. and you are right, now it’s dialled in, hopefully I don’t need to touch it again Thanks!

The Orion and Horsehead with my SA and EOS RP plus 100-500mm RF lens. Unguided shots and was very happy with its tracking.

Hi all, Just a quick question that I can’t quite get my head around. When I rotate the scope end to focus on stars for guiding, the image on SharpCap rotates as well. I don’t really understand how this can happen? The camera sensor doesn’t rotate and surely the lens is just being a lens, so it can’t twist the light through it? It doesn’t matter too much, but if I use PHD2 for focussing help, I have to click on the same star each time I try to focus, as it’s moved and PHD2 doesn’t know where it is any more. Kit is ASI120MM-S and ASI mini guide scope. Cheers

Cool. That makes sense. And more success from my end. I think there may be a driver or hardware issue between PHD2, my ASI120MM-S and the Star adventurer as far as ST4 goes. I seem to have to unplug it and reconnect it between each stage in PHD2 (from calibration to guiding) or the mount doesn’t receive commands. Not a great price to pay now that I know it’s an issue. One other strange thing was I did a very accurate polar alignment in SharpCap, moved to my target star and failed on the calibration. So I did a drift alight and found the PA was quite far off. I was meticulous in my movements and the mount didn’t shift, as I found my target. Anyway, after a bit of fun getting the drift alignment in, I was able to calibrate and guide on a target as a test for 4 minutes at 500mm with very little streaking. Excellent result! I’ll keep playing, but thanks for all the advice!

Thanks Ken, very informative. I'll try the 'Ask for Coordinates' driver next time. What I had been doing was going into the settings (brain) and adding in just the DEC value for my target, but coordinates might be better (and I wont forget if it asks each time). I suspect I was calibrating too close to the pole when I was doing my initial tests, I'll try calibration on-target next time to see how I go. I've been trying to get this working in sporadic tests and learning all the time, so I might have fixed a few other things along the way that could account for it! As to moving the guide scope and DSLR, currently I have them connected together on the same bracket so both point in the same direction. I was wondering whether having the guide scope fixed to the mount and guiding in one place in the sky, but the DSLR pointing at another, might work (then I wouldn't need to re-calibrate each time I changed targets for the DSLR as the guide scope wouldn't move so would be following the same star)?

Success! Although I am not 100% sure why... I completed the Polar Alignment with SharpCap as per usual and made sure I have an 'excellent' polar alignment. I then swapped to PHD2 and made sure the focus was better than before. I initially tried a calibration in the same way as I have done it before. I left the guide camera alone (so still pointing in the rough direction of the SCP from the PA) and tried to calibrate. The guide star barely moved and I cancelled out of the cal early as it looked like it wasn't going to be any better than before. Your suggestion that the guide rate was too low, made me try moving the guide scope a bit (I basically twisted it to the left of the SCP) and tried again. Boom, calibrated in a dozen or so steps and then seemed to guide really well. PA error was just over 5 arcmins I think and the HFD was bouncing around a bit but seemed to be nearer 3.5 / 4. The only thing that confuses me is quite what I have done to make it work? I think I have tried all this before, with the only difference being I point my DSLR at a target before calibration (my guide scope is normally attached to an L bracket on the camera body) rather than just turning the guide scope to slightly off the SCP. I didn't get a chance to try pointing the guide scope elsewhere with my camera. Do you think my improved focus / possibly improved PA would have made the difference? Are there any 'rules' about where a guide scope needs to point to get a good cal? I'm just wondering if I need to get a dual dovetail and have the guide cam separate from the DSLR? Thanks again, I'm excited to see if I can thread the needle twice and may even take a photo. PHD2_GuideLog_2021-01-12_231628.txt

Thanks for that, I’ll give all those suggestions a go. Unfortunately I’ve had to come back home from holiday and I get a lot more cloud here. But very luckily I can see the SCP from my apartment balcony just over the block opposite. Nothing to photograph (and I might make the neighbours nervous with a telephoto lens out there!) but it should be good enough for guide testing. I used SharpCap for PA and can’t remember the final score but it was an ‘excellent’ alignment The other good news is that I stuck a tape measure to a wall and the SA is acting upon east and west signals sent to it. Normal rate to cover 5cm at about 7m was 1m45s, with me pressing west all the time (a series of 3 second pulses) it was 1m20s and then east was 2m30s. I’ll keep cracking on!

Was able to do a number of tests last night. First lesson was that the guide commands don’t get to the SA unless the ST4 cable is plugged in after hitting ‘connect all’ in PHD2 for some reason. But still no guiding at all. Movement stays at normal sidereal rate no matter what is sent. I was worried my rig might be too heavy, but even with just the guide camera and miniscope there was no difference. I’ll have to wait till I get home to have a look at the wiring / pin outs to see if there’s an issue there.

I doubt any printer would be able to do small screw threads at the moment, they are just not precise enough. Large threads (M20 or so I guess?) I think you could get away with, but they may not be of as much use to you. Do not despair, however! There are solutions. You could get inserts to go in the 3D items you print, or do what I have done in the past and print holders large enough to go over the mounts and friction fit (for example, I printed an adapter to go from a webcam to a microscope top, it fitted over the camera shroud and microscope shaft). More info on threads here: https://shop3dchimera.com/blogs/connecting-the-dots/to-print-or-not-to-print-threads-and-3d-printing As for printers, I have a UPPlus at home and have used an UPPlus2 (https://www.3dprinting.co.nz/products/3d-printers/up-plus-2-3d-printer/). Both great small scale printers but older models now. One thing to think about is the size of the parts you want to print. They need to be able to fit on the print bed so a 20cm x 20cm x 20cm part won't print on a 10cm print bed unless you print it in sections. Nicer to print it in one piece though! I would also suggest that parts will reliably print on only about 80% of the print bed size without warping. So, an 8cm part will print on a 10cm bed quite happily, a 9.5cm part is getting close to the edges and may warp. I have also used a Lulzbot (https://www.lulzbot.com/) which has been great and has a much bigger bed. Something else to consider is software. The usual process is: Get or make a 3d model on your computer (usually called an STL file) > put it into the 3D printer software (sometimes called 'slicing') > send it to printer. With the UPPlus I do my design, send it to the printer software and press print (the printer is attached to the PC). With the Lulzbot I do my design, send it to the slicer software, this produces a file that I then have to walk over to the workshop and stick in the printer. The slicer / printer software is usually not too hard to understand, but generating the 3D model can be a task. 4 ways: 1) Learn a 3d modelling package like Blender (free) or Solidworks ($$$). Design your model and it'll be perfect. 2) Get someone else to do the design for you. I think there are sites out there where you can send someone dimensions and get a model back. 3) Find the perfect model on a site like Thingiverse (https://www.thingiverse.com/). Great for common shapes and objects that others may have printed before. Generally no good for anything bespoke. 4) 3D scanner. Unless these have much improved, my experience has always been that I need to do a lot of work on the results and generally am better off doing it all myself instead. Feel free to ask any more questions.

Thanks Ken, Usful to know it slow down rather than reverses. I can try a bit more of a test now. Still cloudy here but hopefully tonight. for Dec I had been using the dec of the target, but I will try it at 0° for testing. Cable should be good as it’s brand new and came with camera. Lights flash on SA so it looks like it’s receiving commands. thanks again!

I see there are a few topics on this so sorry in advance it annoys anyone. I have a Star Adventurer that I works well for unguided astro shots, but I am keen to now get it actively guiding via PHD2. The only problem is that it doesn't seem to be working. I am getting the dreaded "The star doesn't move enough during RA calibration" message when I try to calibrate. Things seem to move in one direction (which I think is West), but I don't see any evidence that it is moving in the opposite direction. So my question is, when asking the mount to move against it's standard rotation, does it actually go backwards, or just slow its rotation to allow the starts to 'catch up'? Info on what I have done / set up if it informs things: I am in New Zealand so Southern Hemisphere (as set on the SA). Set up is ZWO ASI 120MM-S with mini-guide scope, using the on-camera ST-4 port to the SA. Laptop is running PHD2 (also tried the ASI app). Polar alignment completed successfully in SharpCap, then PHD2 for guiding. I've set the 'dec guide mode' to off in PHD2 and entered the declination of my target. I have tried manual guiding and the LED's on the SA flash when I tell it to move East or West (which I believe is a good thing) and they do nothing when I try North or South (which makes sense as the SA is a RA only mount), I have let PHD2 choose the guide star. Binning is 1, focal length 120mm, 8 bit mode in SharpCap but don't think you set that in PHD2? I have used the brain calculated 'calibration step' and increased it manually (to 3000ms). Log attached but it will include a bunch of tried and failed tests in there. If the clouds clear, I will try again tonight... I think I had the calibration work once, but not sure what I did differently then (and I may have done something stupid and fooled the calibration) PHD2_GuideLog_2020-12-10_165427.txt