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malc-c last won the day on June 30 2021
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You have to understand that these are mass produced commercial telescopes and as such lack precision. The scales and indicators are to get you close within the limits of the design (thickness of the lines on the dial, or indicator). If you want absolute precise PA then plate solving is the only way to eliminate any errors and get the mount aligned to the best of its abilities. Again, it's horses for courses, you will get more accuracy with more expensive mounts as they are produced to a higher degree of precision and tighter tolerances. Looking at your nebula image, its a bit difficult to see given the 1200 x 800 resolution, but it seems the slight "unroundness" seems to be in one direction, which could quite simply be the fact that Alignment is good, but the tracking is struggling. This could be a multitude of reasons, from the scope not being balanced correctly, or balanced to well without any bias to remove backlash in the gearing. We've certainly seen far worse first attempts so don't be too downhearted. One thing to remember is you don't need to expose for long periods to get data. Sometimes it's easier to take 100 x 10, 15 or 20 second exposures and then stack them and let the post processing do the work to bring out the details, than to try and take 50 x 1 or 2 minute exposures that end up spoilt by tracking or alignment issues.
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I did say it was a simplified set up, and I've never seen an Gti scope to find out that skywatcher changed the traditional design of having a pin on the mount onto which the azimuth adjustment screws press against. Given that this thread is now some three pages long and we seem to have covered basic polar alignment which has only led to confusion, I agree with the poster above that it would be worth making further enquiries at your local club or society. We have members in our society who are often willing to assist on a private one to one basis where its easier to teach people how to set a scope up by being there than over the phone or posts on a forum. As a society we also run telescope workshops where members / or prospective members can bring their scopes along and get answers to questions they may have. With regards to the requirement of rotating the mount to place polaris in the correct position, hopefully the drawing below might help. For argument and to make it simple, lets say that Polaris is at the 9 O'clock position in its 24 hour rotation around the NCP. Placing Polaris on the ring at the 9 O'clock would correctly place the NCP to the right. If you didn't know the position of Polaris and simply placed it anywhere on that ring, such as at the 3 O'clock position the this would place the NCP (and the RA axis of the mount) way off to the left. I also read through the online manual and the mount set up, particularly the PA is very poorly defined. Goes off at a tangent to describe a utility to show the Polaris Hour, but then no real detail on what to do with it. One other thing, I think the OP needs to take on board that PA is critical if you are doing unguided exposures. The earth is spinning really fast and any error will result in anything form egg shaped stars to trails. I can remember a thread where people were competing for the longest un-guided exposure before misshapen stars or trails were seen when using an HEQ5 mount. From memory it was around 5 minutes but the mount had been hypertuned and PA was done via plate solving, but that was the extreme required. Given the large tolerances and variables such as the way Polaris appears to move within the polar scope 20 - 30 seconds exposures will probably show trailing etc when un-guided.
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Basic Polar Alignment of an EQ mount Place the tripod on the ground with one leg (often indicated with an N) facing North. Ideally the tripod should be level. A normal magnetic compass can help if you are not sure which direction North is Place the mount on the tripod and secure it by finger tightening the bolt. The two Azimuth adjustment bolts should be open enough to fit the spike on the tripod between them Set the angle of the mount to match the latitude where you are observing from Read the manual that came with the scope and set up the alignment of the polar scope as suggested - this can be done in the daylight and use a landmark that is some distance away. It can be tweaked further at night but centring Polaris in both the finder scope, main scope and then the polar scope. Once the polar scope has been set up place the mount in the default home position (google that if not sure) Use the AZ and latitude bolts on the mount to centre Polaris on the cross hairs of the polar scope Look up the position of Polaris to get its orbital position Use the latitude adjustment bolt to move Polaris to either the 12 or 6 O'clock position Slacken of the RA lock and rotate the mount until the bubble or markings on the polar scope is in the same "hour" of Polaris is in its rotation around the NCP and then lock off the RA axix Use the Az bolts and Latitude bolts to place Polaris on the ring and in the bubble / markings (as shown in that video I linked to) Once in position tighten the securing bolt and check that Polaris is still on its mark Release the RA lock and place the mount back into the default home position. Power on the mount and run through a 2 or 3 start alignment. If any of the target stars are slightly off the centre of the eyepiece then make the small adjustments USING THE DIRECTIONAL BUTTONS ON THE HANDSET - Do NOT use the AZ/Lattitude bolts Once the alignment routine is complete place the mount back into the home position and then select your target. This is a very simplified routine... but the main area where you are going wrong is that you are performing multiple polar alignments when they are not needed - It's a one off procedure done before any observing session
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Why oh why don't you read what people have already told you... Once you have polar aligned using the polar scope DONT DO ANY OTHER POLAR ALIGNMENT THROUGH THE HANDSET !! The fact you stated that the two stars used in the normal set up alignment were pixel perfect in the centre of the field of view without making any adjustments suggest you had done a very good job of polar aligning using the polar scope. You should have left it at that Apologies for the rant... but you should really read what people are posting and follow their
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Skywatcher's synscan app fails to connect with ser2net
malc-c replied to olwaldi's topic in Discussions - Software
In "PC-Direct" mode the handset acts as an EQDir cable and passes through the commands, hence it now returns the firmware version of the motor board in the mount. Sorry I can't help further as I never used a wireless set up. -
Skywatcher's synscan app fails to connect with ser2net
malc-c replied to olwaldi's topic in Discussions - Software
Can't really help, but the HC05 is basically a BT virtual com port, so you'll get the basic TX / RX transitions, but an advanced operation may well be above the firmware's ability, or as you say, not up to other BT standards. What puzzles me is the command :e1 is a request for the mounts firmware version, which normally returns a string '=vvvvmm' as response where vvvv is the version and mm is the mount type. But reading the protocol manual, when sent to a handset it returns the position data protocol document -
Time out / drop outs can happen for one or many reasons. I powered my HEQ5 from a 13.8v regulated supply (its in an observatory), used an home built EQDIR cable based on an FTDI cable purchased direct from the FTDI website, which was connected to the PC via a 5m active USB cable and never experienced a loss of communication between EQMOD and the mount. Others, like you seem to experience poor coms even though they have tried swapping most of the kit out. Occasionally it seems connection is via hubs, either external or internal to the computer that is being used. One turned out to be due to the high bandwidth requirement of a camera which caused the hub to drop "packets". For older boards that are PIC microcontroller based the firmware hasn't changed form 2.0.4 for some years. Newer boards that use ARM processors run the 3.39 version. When connected the handset / EQMOD sends :e1 and :e2 command to the mount which instructs it to return the firmware version. My guess is that the PC application is transposing the digits incorrectly as it pars the string it receives back form the mount. There are a lot of steps between the application used to instruct the mount to do something even before it's left the PC. The commands are sent through EQMOD through the virtual serial port which converts the data into the USB standard, which then gets converted to TTL Serial which the mount can understand. Factor that in with the physical connections and the fact the mount moves it's very easy for something to cause a slight loss of comms at some point.
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It was as an example of why the mount would end up with the RA axis rotated away form the home position. Nothing else. The fact EQMOD rotates the mount precisely to the hour position helps if you use that software, but it can still be done manually If Polaris was bang on the NCP then it would be simple to place it under the cross-hairs of the polar scope. But as it orbits the NCP placing it inside the "bubble" or the ring (depending on the age of the mount) at the correct hour the mount needs to reflect that so you get the RA axis inline with the Earths axis. BUT this is only really important if you are intending to image with the set up. Visually you could just place Polaris under the central cross-hairs and it would be good enough. The only other suggestion if you are stull hung up on PA is to use the search function and read the 100's of previous posts on the subject, or search YouTube and watch any of the 1000's of videos on the subject. If you are still looking for a precise alignment then look at shelling out for a Polemaster camera and use plate solving such as the plugin featured in Sharpcap (Other plate solving applications are available)
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Because you need to rotate the mount around the RA axis to match the "hour" that Polaris is at for the time of using the mount. This old video is using EQMOD to control the telescope, but basically you would do the same using the handset to rotate the mount to the polar hour, which means the mount will move off the default home position.
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Forget the alignment process for now. Polaris orbits the NCP, so you first need to know where Polaris is in its rotation for what ever time you are observing. In the above example of the polarscope Polaris is about 10:40 (hence the 0, 3, 6, and 9 markings). So placing Polaris on that centre line of the ring at that position will put the NCP in the correct place. Simply putting Polaris anywhere on that ring won't work, as for example, if you put polaris over the ring at the 3 O'clock position it would place the NCP way off to the left rather than to the right. Once you have correctly polar aligned DO NOT move the mount other than releasing the clutch on the RA to place the mount back to the default home position with the weights down. If you knock it or manually move the mount you'll undo all your hard work. Once in the home position run the star alignment routine. This normally involves picking a target, letting the mount slew to target, and then using the directional buttons on a handset, or on an app, centre the target star, then confirming it centred before selecting the second target. Again, any adjustment to centre the star needs to be done by the mount control and NOT by releasing the clutches and manually centring the star. This is so that the controlling method, be that a synscan handset or app works out all the offsets as a result of the polar alignment (you will never get it 100% spot on, but 99.9% is close) so that it can apply it to further gotos so the targets end up centred with little or no further adjustments.
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It's normally the other way around. You set the mount up so it's in the home position with the N leg pointing North. Undertake Polar alignment using the long and latitude bolts, release the clutches and place the mount back into the default home position, lock them off and then run through the 2 or 3 start alignment routine
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DIY controller for ZWO AEF. Question about the resistor value.
malc-c replied to ofranzen's topic in DIY Astronomer
I guess it depends on how it uses the reduced voltage to govern the speed. If it's simply a direct connection to a motor. If it gets fed to an analogue to digital pin of a micro controller then the results might be a very variable speed. The problem is unless the EAF is dismantled and the PCB examined we are all second guessing. -
Skywatcher HEQ5 Pro pillar mount built for under 30 quid
malc-c replied to Varavall's topic in Discussions - Mounts
The edges on the "birds nest" look like they would be sharp enough to cut every time you need to tighten the central bolt holding the mount.