My newts have been orientated with guide scope on top , focuser / camera off at 2 o’clock and finder off at 10 o’clock since I started the hobby.Balancing this orientation was fairly straightforward.
I’m considering changing this set up after 4 years to focuser / camera underneath at 6 o’clock and removing the finder ( only slip in the shoe if I need it )
I’m thinking it will improve the centre of gravity with the additional mass on opposite sides of the axis and minimise inertia to a small degree
Whether it improves PHD2 guiding at the end of the day only testing over time with prove that.
Also I’ve tried balancing slight east heavy , west heavy and neutral, with no discernible improvement in guiding stability ( probably due to using belt driven mounts which have had backlash tuned out as best as possible )
I welcome any comments in regards to scope orientation and balancing in particular with imaging newts
I guess the first question to ask is, are there any issues with the current performance that are of concern and maybe need fixing? I can see lots of pros and cons with the new configuration but if things are working ok now …..?
I’ve been promoting this setup for a long time but had very little response or inquiry. It improves the ability to balance no end and moves the center of mass closer to the RA axis. Consequently it moves the weights further up the counter balance shaft reducing moment of inertia.
I guess the first question to ask is, are there any issues with the current performance that are of concern and maybe need fixing? I can see lots of pros and cons with the new configuration but if things are working ok now …..?
Nothing needs fixing however we are always looking for improvements in performance ( be it only minor improvements )
So I guess I won’t know until I try it
I’ve been promoting this setup for a long time but had very little response or inquiry. It improves the ability to balance no end and moves the center of mass closer to the RA axis. Consequently it moves the weights further up the counter balance shaft reducing moment of inertia.
Thanks Ryan
I’m definitely going to rebalance with this configuration
So many Astro channels showing imaging newts with this set up
Cheers
Martin
In my later years of Newt imaging, I oriented the tube/focuser pointing down, so that the weight of the camera, filter wheel, hung down the axis of the counterweight bar. Guide scope on top of the tube, centred. Weight the set up slightly east heavy, as I pretty much always imaged to the eastern sky to zenith. This served me well on open newts.
In my later years of Newt imaging, I oriented the tube/focuser pointing down, so that the weight of the camera, filter wheel, hung down the axis of the counterweight bar. Guide scope on top of the tube, centred. Weight the set up slightly east heavy, as I pretty much always imaged to the eastern sky to zenith. This served me well on open newts.
For what it's worth Martin, I also run my Imaging train pointing almost at 6 o'clock.i was using the standard 200pds, so guides open and Imaging train were fixed in relation to eachother. I didn't do any maths, but found that i needed to rotate the tube so Imaging gear was at mayb 6.45 and guidescope and cam were at about 4.30... their relative weight and distance from the axis dictated that this gave me perfect balance.
With the Imaging gear up top I need both counterweights at the end of the extension, plus a 2.5kg plate... with them rotated I got rid of the 2.5 and moved the inner counterweight up about an inch, and in my mind this was making it much easier for thr mount to do its thing.
I might just add that the strength of your focuser is very important if your running inverted, as the camera and filter wheel (if used), puts some pull effect on the focuser draw tube. The 10" carbon strut newt i built used a GSO R&P in the inverted configuration, and it was fine. The manual Moonlights are ok but they are way beyond stock quality. Finally, if you are using auto focus equipment, and applications, obviously you cannot lock the draw tube; so pay attention to the weight handling specs for the auto focus equipment (it's not just lifting capacity, but pull resistance when inverted).
Re orientated and re balanced my Newt yesterday with focuser down
This allowed removal of an extension shaft and counterweights pushed much closer to OTA
Another positive spin off was balancing. Balancing was so much more precise compared to before
Setting up tonight
See how it tracks and guides
Thanks for all the input
Cheers
Imaged the Rosette last night on the western side of the meridian for a couple of hours using the new configuration and balancing , tracking and guiding were excellent, PHD2 had the mount down to 0.58 to 0.61 ( Dec 0.30 RA 0.48 ) for a solid hour pointing to the northwest. Never guided this tight ever with this mount in 4 years. Conditions were average , humidity was 95% and it felt like it too.
So far great results with the new configuration but it’s only one night. Even though Rosette was quite low descending from 48 degrees down to 29 degrees when I eventually finished , I’m keen to test the set up on higher targets in the east.
The rig was set slightly east heavy ( should have been slightly west heavy ) which probably accounted for Ra being a tad higher ?
There were no larger excursions in Ra , it was well behaved and Dec was rock solid
All in all a successful test
Cloudy nights again for the next week or so, can’t wait to image again
I can't imagine why you would want balance to be west heavy?
I’ve never balanced slightly west heavy, mostly even balance or just leave east heavy through the whole session, but some resistance against the Ra on the descending target on the western side at lower altitudes may help ?
Your thoughts ?
Martin, I look forward to seeing how you go over time as I have set up my camera at 10am and guide scope at 2pm. I’m wondering wether a camera set at 6 would improve guiding. The reduction of inertia makes good sense. Although my guiding appears good in numbers, I am still getting too many subs with elongated stars that I have to throw out.
Martin, I look forward to seeing how you go over time as I have set up my camera at 10am and guide scope at 2pm. I’m wondering wether a camera set at 6 would improve guiding. The reduction of inertia makes good sense. Although my guiding appears good in numbers, I am still getting too many subs with elongated stars that I have to throw out.
Regards,
Stéphane
Based on last nights guiding the re orientation is a winner but more nights are needed to quantify
Your obviously using a 50mm guide scope in the offset shoe bracket. I started with that option but changed to a centrally mounted 60mm guide scope on a solid mounting bar on the tube rings , much more rigid system especially with imaging focal lengths at 1000mm +
In regard to your elongated stars what are your Ra and Dec numbers ? Are they close in value or significantly different ?
Is your polar alignment tight ( less than 1 or 2 arc minutes )
Maybe you have some high Dec backlash ?
Try the guiding assistant in PHD2 it will give you plenty of data to evaluate any issues
Cheers
Martin
I’ve never balanced slightly west heavy, mostly even balance or just leave east heavy through the whole session, but some resistance against the Ra on the descending target on the western side at lower altitudes may help ?
Your thoughts ?
I think it is better for the worm to remain engaged on the same face of the ring gear and be exerting pressure to rotate the ring gear so the mount moves from east to west. You achieve this by balancing east heavy regardless of which side of the meridian you are pointing.
If you balance west heavy the worm needs to release pressure from the ring gear to permit the scope to move west. It will likely result in stick/slip movement and poorer tracking.
It is also better to be east heavy than neutral balance as you don't want the worm swapping between the two faces of the ring gear as the scope moves. There will always be some backlash in the Skywatcher EQ mount worm drives and this will be influencing tracking in RA if the worm is not working against one face of the ring gear.
Happy to be corrected if anyone sees it differently.
I think it is better for the worm to remain engaged on the same face of the ring gear and be exerting pressure to rotate the ring gear so the mount moves from east to west. You achieve this by balancing east heavy regardless of which side of the meridian you are pointing.
If you balance west heavy the worm needs to release pressure from the ring gear to permit the scope to move west. It will likely result in stick/slip movement and poorer tracking.
It is also better to be east heavy than neutral balance as you don't want the worm swapping between the two faces of the ring gear as the scope moves. There will always be some backlash in the Skywatcher EQ mount worm drives and this will be influencing tracking in RA if the worm is not working against one face of the ring gear.
Happy to be corrected if anyone sees it differently.
Correct !!
I’m not a mechanical engineer but I just looked at a mounts worm gear in operation on a video clip and since it drives in the same direction the leading edge remains the same and therefore any additional pressure applied by the ring gear ( caused by east heavy balance ) to keep the gears meshed at a constant pressure improves efficiency of motion.
So slightly east heavy will work east to west across Ra
Happy to be corrected as well
Thanks
Based on last nights guiding the re orientation is a winner but more nights are needed to quantify
Your obviously using a 50mm guide scope in the offset shoe bracket. I started with that option but changed to a centrally mounted 60mm guide scope on a solid mounting bar on the tube rings , much more rigid system especially with imaging focal lengths at 1000mm +
In regard to your elongated stars what are your Ra and Dec numbers ? Are they close in value or significantly different ?
Is your polar alignment tight ( less than 1 or 2 arc minutes )
Maybe you have some high Dec backlash ?
Try the guiding assistant in PHD2 it will give you plenty of data to evaluate any issues
Cheers
Martin
I am also using a 60mm guide scope. Polar alignment is always within an arc minute, so no issues there. I’ll check the numbers and run the guiding assistant. My opinion is that it might be nothing to do with guiding, but might be to do with tilt, as I get elongated stars several subs in a row, but the issue then fixes itself as the OTA rotates. Either way, these little issues are slowly getting ironed out one at a time. Just need to fix this one soon!
I am also using a 60mm guide scope. Polar alignment is always within an arc minute, so no issues there. I’ll check the numbers and run the guiding assistant. My opinion is that it might be nothing to do with guiding, but might be to do with tilt, as I get elongated stars several subs in a row, but the issue then fixes itself as the OTA rotates. Either way, these little issues are slowly getting ironed out one at a time. Just need to fix this one soon!
Hmm.... camera at 10am , guide scope at 2pm
Are you a bar attached to the tubes rings to mount your guide scope ?
If not, a 60mm guide scope is a big sucker just to mount off a single bracket or shoe bracket !!
