Re: next up: polar alignment tutorial
Hey Brian,
It would be great if you could touch on an older format. I have the G11-G1. I¡¯m not 100% sure if I¡¯ve been performing the alignment correctly.?
This is a picture of my scope. The hang up is how to accurately align the ref constellations. Not really sure how to apply the ref marks - second star points etc ?
I¡¯m not interested in purchasing alignment aides such as pole master just yet.?
Thanks!
Nick
|
Mostly astrophotography. ?Study is exactly what I¡¯ve been doing. ?I did a lot of study and learning as part of my research into which mount I wanted so I feel I have a good handle on things for starting out. ?I¡¯ve run the tutorial beginning to end several times again since I placed my order. ?I¡¯m going to run through computer. ?Been using a dslr and apt for a while with old setup and everything is already on a nuc. ?Ive disassembled my old rig and reconfigured for the G11 intending on using the Ethernet port and it¡¯s already connected to micro router and home network. ?I¡¯ve tested it about as much as I can without an actual mount. ?Just waiting on the mount for that last connection. ?I¡¯ve had a guide scope and camera for about a year now to polar align with sharpcap. ?Wow, that¡¯s amazing, drift align is history! ?I have to learn to use it as a guider still but I think I¡¯ve researched that well too. ?The camera and scope are already sized to my OTA based on best practices I¡¯ve read. ?We¡¯ll see how that goes. ?I¡¯m not going to bother with guiding at first, relying on the mount while I learn Gemini inside and out. ?Then I¡¯ll learn guiding.
No doubt I¡¯m not as prepared as I think I am and there will be moments when I think WTF? ?I¡¯m looking forward to it.
|
Hi Bill! ?Welcome to the family:-). ? How do you intend to use your mount? ? Visual or Astro photography or a little of both? ? Do you plan to run from a hand controller or through a computer? ?One thing I did when I was waiting for my new mount was spend a great deal of time working through the hand controller tutorial/simulation on the Gemini 2 website. ? That helped a lot in learning where everything is. ? Gemini can do a LOT of things, so the results is a layered tab system, that can be a little intimidating at the start. ?However, a little bit of time and things become second nature. ?I have really grown to like the Gemini 2 system. ?There is a lot of knowledge here so ask questions often:-). ?
Cheers!
JMD
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Re: next up: polar alignment tutorial
I use phd2 drift align, and am able to get really good PA. I take my time, and get it really well dialed in. I can keep the alignment for months even though I take the mount in every night. I use this simple method described here:?
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Re: next up: polar alignment tutorial
Brian - One further clarification. The "Movement" or flexure I'm talking about is only during Visual Inspection of the mount. When I'm manually moving the mount around, or just pushing and pulling the OTA around manually. I'm often only using the RA tracking motor, and loosening the Dec and RA lock knobs to slew manually to my target. Then letting the mount track in RA. I just want to make sure I'm tightening up all the bolts in all the right places. For Polar alignment, after Altitude adjustment, the instructions are not clear on if the Bolts should be tightened down (for visual or for astrophotography).?
Andrew
Thanks,
Andrew?
--
Main Telescope:?Explore Scientific 152ED APO Refractor in Carbon Fiber
Mount:?Explore Scientific Losmandy G11 Mount w/PMC-Eight
Other Scopes:?Meade 8"LX90 SCT, William Optics ZenithStar 66mm APO Refractor
Binoculars:?Oberwerk 20x80 & 25x100 Giant Binoculars, Alpen 8x42
|
Re: next up: polar alignment tutorial
Brian - I think the movement I saw was due to the EQ Head to Tripod Bolts being loose. Now that they are tight, I do not get any movement there.?
The other place I see some "movement" or maybe just "flexure" is right at the Altitude Lock Bolt area. I still need to go through Polar Alignment again, so I may need to use the Altitude Adjustment Knob to get the elevation correct. After I have that "nailed", should I tighten down the Altitude Lock Bolts?
The Azimuth Locking Knob is another spot I would double-check to make sure it is tight after adjusting Azimuth in Polar alignment.
Andrew
--
Main Telescope:?Explore Scientific 152ED APO Refractor in Carbon Fiber
Mount:?Explore Scientific Losmandy G11 Mount w/PMC-Eight
Other Scopes:?Meade 8"LX90 SCT, William Optics ZenithStar 66mm APO Refractor
Binoculars:?Oberwerk 20x80 & 25x100 Giant Binoculars, Alpen 8x42
|
Re: next up: polar alignment tutorial
Hi Andrew
thanks for your input, much appreciated
>> it is the first time I can see some extra movement in the mount.
can you clarify what you mean by "extra movement"? is this during visual inspection, slewing, tracking, guiding, etc.?
On Sun, May 23, 2021 at 8:30 AM ACorkill < viram@...> wrote: Brian,
I recently switched from a 35 pound payload to a 60 pound payload. I have the G11, so that is maxing out the weight capacity and it is the first time I can see some extra movement in the mount. I became aware that I had not fully tightened the EQ Head to Tripod Bolts, so the extra weight was moving the EQ Head. I fixed that issue, but started to wonder which other bolts might not be fully tight. I polar aligned the previous scope, and will soon polar align with new payload.?
Anything to watch out for when you double the payload? That would be of interest.?
I'm using my set-up for Visual observing, and only doing iPhone or DSLR astrophotos. So after I polar align the scope again, I believe I'll remove the polar scope, as I don't really need it again, unless I get unforeseen movement. My Tripod and Mount are in a permanent position, so I'm not tearing down after a session. The reason I'd remove the polar scope is because I have the CKS and the Polar scope illuminator gets in the way when turning the RA Clutch knob. I suppose I could just remove the illuminator as well. Any input about keeping the polar scope in or out?
Thanks,
Andrew?
--
Main Telescope:?Explore Scientific 152ED APO Refractor in Carbon Fiber
Mount:?Explore Scientific Losmandy G11 Mount w/PMC-Eight
Other Scopes:?Meade 8"LX90 SCT, William Optics ZenithStar 66mm APO Refractor
Binoculars:?Oberwerk 20x80 & 25x100 Giant Binoculars, Alpen 8x42
-- Brian?
Brian Valente portfolio
|
Re: next up: polar alignment tutorial
Brian,
I recently switched from a 35 pound payload to a 60 pound payload. I have the G11, so that is maxing out the weight capacity and it is the first time I can see some extra movement in the mount. I became aware that I had not fully tightened the EQ Head to Tripod Bolts, so the extra weight was moving the EQ Head. I fixed that issue, but started to wonder which other bolts might not be fully tight. I polar aligned the previous scope, and will soon polar align with new payload.?
Anything to watch out for when you double the payload? That would be of interest.?
I'm using my set-up for Visual observing, and only doing iPhone or DSLR astrophotos. So after I polar align the scope again, I believe I'll remove the polar scope, as I don't really need it again, unless I get unforeseen movement. My Tripod and Mount are in a permanent position, so I'm not tearing down after a session. The reason I'd remove the polar scope is because I have the CKS and the Polar scope illuminator gets in the way when turning the RA Clutch knob. I suppose I could just remove the illuminator as well. Any input about keeping the polar scope in or out?
Thanks,
Andrew?
--
Main Telescope:?Explore Scientific 152ED APO Refractor in Carbon Fiber
Mount:?Explore Scientific Losmandy G11 Mount w/PMC-Eight
Other Scopes:?Meade 8"LX90 SCT, William Optics ZenithStar 66mm APO Refractor
Binoculars:?Oberwerk 20x80 & 25x100 Giant Binoculars, Alpen 8x42
|
Re: DIY Spring Loaded Worms for the G11
Thanks Michael -
Those were peak to peak numbers, though the RMA number was still
above 5 if I recall.? I agree that something is not quite right
and requires some fiddling.
While the unguided error seemed a bit larger than I expected, the
guiding performance was very good in my opinion.? Ultimately
that's what I care about, since I do not shoot unguided subs.?
Unguided error is purely a tool for troubleshooting any mechanical
issues.? I'm very happy that the native PE appears to be
relatively smooth and regular.? And no signs of the dreaded 76
second PE, or any other obvious harmonics.? Predictive PEC was
able to tune out the worm error and any other PE with ease.
The geartrain is not stock Losmandy.? I am using stepper motors,
belt drive reduction, additional bearings, shafts, and helical
couplings.? As you can see, there are a lot of unaccounted
variables here.? But starting with what I do have control over,
the worm bearings are indeed preloaded while snugging them into
the makeshift OPWB.? I do not have any noticeable side to side
movement of the worm between bearings, and there is no perceptible
notchiness or catching of the bearings as the worm spins. ? With a
1140mm focal length refractor, any side to side backlash from the
worm moving between bearings is quite easy to feel.? However the
method I'm using to locate the pivot bolt seems to be an obvious
weak link.? I could still have other issues that may be taken out
with a belville washer like you suggest, but I think I need to be
certain the pivot location is sound first.
I have spent some time doing my best to center the shafts and to
get the least amount of runout from the flexible helical
coupling.? Like the oldham coupler, the set screws do pull it off
center a touch.? I will readdress this once again after I improve
the pivot bolt issue.? As a temporary troubleshooting method, I
may simply shim the gap between the makeshift OPWB and the motor
bracket to keep the worm assembly pressed towards the outside.?
Ultimately I'd like something a bit more elegant, but that should
be enough to tell me if I'm on the right track.
Thanks again for your thoughts,
-Tony
On 5/23/2021 10:41 AM, Michael Herman
wrote:
toggle quoted message
Show quoted text
Nice report Tony.
If you were interested in trying further
improvements (vs just autoguide and shoot the stars!)...some
thoughts.??
I was not sure if your value of 12-15 arcsec
RA PE was RMS or Peak to Peak.
If the 12-15 arc sec PE was an RMS value,
that sounds very high for a Losmandy precision brass worm
on a G11 RA drive.? At least for an RMS value it is way
too high.? ?I think the G11 brass worms run under 3 arcsec
RMS in general.? I have found some that are about 1 arcsec
RMS. (Would appear double for a GM8 RA drive, as the worm
drives a smaller ring gear.)
So your thought to swap the RA and DEC worms
is a good idea.??
To convert RMS to Peak to Peak a rule of
thumb (if the oscillation were a pure sine wave this is
exact) multiply the RMS value by 2.8.??
However other factors can mask the worm
itself because they wobble at the same rotation rate as
the worm.? They are:
1. An offset or an angle between the input
and output of the Oldham coupler.? This is probably the
biggest contributor, as it is a challenge to line up those
shafts and to get the center plastic coupler part to only
rotate, not shift.
2. On a Tucked Motor system:?
... the transfer gears must be centered on
their axles.? One is on the gearbox.? One is on a the
short shaft driving the Oldham coupler.? They must exhibit
no wobble. { The older direct drive systems did not have
these 3 parts (2 gears and the short shaft). } You can
reposition the transfer gear of the gearbox by moving the
gearbox using it's two mounting bolts.?
Note that: The inner transfer gear on the
short shaft cannot be moved...it is made at one location
in the vertical mounting plate.? There is hardly any room
to move that short shaft to optimize the Oldham coupler
alignment due to the precise countersink indentations in
the vertical plate made for the plate mount bolts.??
You observed that there is a large time lag
(hysteresis of about 0.8 sec) in the DEC tracking
diagram.? Something is loose...and is moving when you
switch direction.? Most likely it is the DEC worm capable
of sliding left to right along its axis.? I prefer to
prevent that,...add an R4 Belleville spring under the
rightmost R4ZZ bearing, and that bearing must be polished
down in OD and lubed to allow it to slide under the spring
force.? Once you add that the worm will stay pushed toward
the Oldham coupler bearing end, and both bearings will
stay tight in axial compression.??
The small grub screws that hold the Oldham
coupler to it's shafts tend to loosen up too.? Inspect the
coupler ends for any looseness and snug those grub screws
down.?
Anyway, your autoguiding was nice and fits
your needs.? Keep shooting and having fun!
Best,
Michael
?
On Sun, May 23, 2021, 6:06 AM
GuitsBoy < guitsboy@...> wrote:
Got some initial guide results with the spring loaded
worms last night.? My initial reaction is that it may have
helped, but certainly didn't hurt anything.
Conditions last night were mediocre at best, so my
results should be taken with a grain of salt.?? We had
LOTS of passing clouds, and a bit of variable breeze.? I
was guiding on M13, near zenith, historically a difficult
spot for me because the intentional weight imbalance on
the DEC (camera heavy) doesn't work well here.? I was
shooting 30 and 60 second subs, dithering every other
frame. ?? Seeing was good but not great, but transparency
and clouds were below average.? This is using a 60mm guide
scope with a 240mm focal length.? I seemed to have the
best results from a 1 second exposure with multi star
enabled.? I have an OAG that I will eventually move to,
but since I'm used to using the guide scope, I wanted to
keep things apples to apples.
First, my guiding assistant results (guiding disabled)
were lackluster at best.? My peak-to-peak RA numbers seem
to be artificially inflated due to some RA tracking
drift.? My drift rate is somewhere around 2.4 arc-sec/min,
so the RA error peak to peak climbs the longer it runs.?
Smoothing it visually, the worm appears to have roughly
12-15 arc-sec native PE.? This is right in line with the
results I had with the static mounted worms, so no big
surprise here.? I think I should swap the RA and DEC worms
to see if it improves at all.? I might also apply some
tracking rate adjustment.? I suspect the RA drift is due
to a sub optimal RTC in the cheap Arduino board that runs
the whole show.? Tracking rate adjustment may help if the
drift is consistent from night to night.
Next is the declination backlash.? I really expected this
to tighten up, but it did not seem to.? Measured backlash
seemed to be between 650? to 900 ms (ran twice), which was
higher than the static worms.? I suspect this is from some
wiggle room in the pivot bolt.? Perhaps if I can tighten
this up, things will improve here.?
Now for the actual meat and potatoes guiding.? Here, it
seemed to shine.? I saw .61 and .58 arc-sec RMS overall
average.?? While sitting there watching, there were a few
times where my number (current screen average) dropped to
.48!? And most promising, the breeze did not seem to move
the mount nearly as much as usual.? Typically I would set
up a wind break to calm it down, but didn't feel like
setting it up at 11pm.? These numbers are the best I've
seen on any mount without using a wind break.
I think my next order of business is figuring out how to
remove any play in the pivot bolt side.? Then maybe swap
worms between the DEC and RA to see which has less native
PE.? But overall, I think the spring loaded worm mod shows
some promise.? I can't wait to test it on a night with
better conditions.
Thanks,
-Tony
|
Re: DIY Spring Loaded Worms for the G11
Nice report Tony.
If you were interested in trying further improvements (vs just autoguide and shoot the stars!)...some thoughts.??
I was not sure if your value of 12-15 arcsec RA PE was RMS or Peak to Peak.
If the 12-15 arc sec PE was an RMS value, that sounds very high for a Losmandy precision brass worm on a G11 RA drive.? At least for an RMS value it is way too high.? ?I think the G11 brass worms run under 3 arcsec RMS in general.? I have found some that are about 1 arcsec RMS. (Would appear double for a GM8 RA drive, as the worm drives a smaller ring gear.)
So your thought to swap the RA and DEC worms is a good idea.??
To convert RMS to Peak to Peak a rule of thumb (if the oscillation were a pure sine wave this is exact) multiply the RMS value by 2.8.??
However other factors can mask the worm itself because they wobble at the same rotation rate as the worm.? They are:
1. An offset or an angle between the input and output of the Oldham coupler.? This is probably the biggest contributor, as it is a challenge to line up those shafts and to get the center plastic coupler part to only rotate, not shift.
2. On a Tucked Motor system:? ... the transfer gears must be centered on their axles.? One is on the gearbox.? One is on a the short shaft driving the Oldham coupler.? They must exhibit no wobble. { The older direct drive systems did not have these 3 parts (2 gears and the short shaft). } You can reposition the transfer gear of the gearbox by moving the gearbox using it's two mounting bolts.?
Note that: The inner transfer gear on the short shaft cannot be moved...it is made at one location in the vertical mounting plate.? There is hardly any room to move that short shaft to optimize the Oldham coupler alignment due to the precise countersink indentations in the vertical plate made for the plate mount bolts.??
You observed that there is a large time lag (hysteresis of about 0.8 sec) in the DEC tracking diagram.? Something is loose...and is moving when you switch direction.? Most likely it is the DEC worm capable of sliding left to right along its axis.? I prefer to prevent that,...add an R4 Belleville spring under the rightmost R4ZZ bearing, and that bearing must be polished down in OD and lubed to allow it to slide under the spring force.? Once you add that the worm will stay pushed toward the Oldham coupler bearing end, and both bearings will stay tight in axial compression.??
The small grub screws that hold the Oldham coupler to it's shafts tend to loosen up too.? Inspect the coupler ends for any looseness and snug those grub screws down.?
Anyway, your autoguiding was nice and fits your needs.? Keep shooting and having fun!
Best, Michael
?
On Sun, May 23, 2021, 6:06 AM GuitsBoy < guitsboy@...> wrote:
Got some initial guide results with the spring loaded worms last
night.? My initial reaction is that it may have helped, but
certainly didn't hurt anything.
Conditions last night were mediocre at best, so my results should
be taken with a grain of salt.?? We had LOTS of passing clouds,
and a bit of variable breeze.? I was guiding on M13, near zenith,
historically a difficult spot for me because the intentional
weight imbalance on the DEC (camera heavy) doesn't work well
here.? I was shooting 30 and 60 second subs, dithering every other
frame. ?? Seeing was good but not great, but transparency and
clouds were below average.? This is using a 60mm guide scope with
a 240mm focal length.? I seemed to have the best results from a 1
second exposure with multi star enabled.? I have an OAG that I
will eventually move to, but since I'm used to using the guide
scope, I wanted to keep things apples to apples.
First, my guiding assistant results (guiding disabled) were
lackluster at best.? My peak-to-peak RA numbers seem to be
artificially inflated due to some RA tracking drift.? My drift
rate is somewhere around 2.4 arc-sec/min, so the RA error peak to
peak climbs the longer it runs.? Smoothing it visually, the worm
appears to have roughly 12-15 arc-sec native PE.? This is right in
line with the results I had with the static mounted worms, so no
big surprise here.? I think I should swap the RA and DEC worms to
see if it improves at all.? I might also apply some tracking rate
adjustment.? I suspect the RA drift is due to a sub optimal RTC in
the cheap Arduino board that runs the whole show.? Tracking rate
adjustment may help if the drift is consistent from night to
night.
Next is the declination backlash.? I really expected this to
tighten up, but it did not seem to.? Measured backlash seemed to
be between 650? to 900 ms (ran twice), which was higher than the
static worms.? I suspect this is from some wiggle room in the
pivot bolt.? Perhaps if I can tighten this up, things will improve
here.?
Now for the actual meat and potatoes guiding.? Here, it seemed to
shine.? I saw .61 and .58 arc-sec RMS overall average.?? While
sitting there watching, there were a few times where my number
(current screen average) dropped to .48!? And most promising, the
breeze did not seem to move the mount nearly as much as usual.?
Typically I would set up a wind break to calm it down, but didn't
feel like setting it up at 11pm.? These numbers are the best I've
seen on any mount without using a wind break.
I think my next order of business is figuring out how to remove
any play in the pivot bolt side.? Then maybe swap worms between
the DEC and RA to see which has less native PE.? But overall, I
think the spring loaded worm mod shows some promise.? I can't wait
to test it on a night with better conditions.
Thanks,
-Tony
|
Re: DIY Spring Loaded Worms for the G11
Got some initial guide results with the spring loaded worms last
night.? My initial reaction is that it may have helped, but
certainly didn't hurt anything.
Conditions last night were mediocre at best, so my results should
be taken with a grain of salt.?? We had LOTS of passing clouds,
and a bit of variable breeze.? I was guiding on M13, near zenith,
historically a difficult spot for me because the intentional
weight imbalance on the DEC (camera heavy) doesn't work well
here.? I was shooting 30 and 60 second subs, dithering every other
frame. ?? Seeing was good but not great, but transparency and
clouds were below average.? This is using a 60mm guide scope with
a 240mm focal length.? I seemed to have the best results from a 1
second exposure with multi star enabled.? I have an OAG that I
will eventually move to, but since I'm used to using the guide
scope, I wanted to keep things apples to apples.
First, my guiding assistant results (guiding disabled) were
lackluster at best.? My peak-to-peak RA numbers seem to be
artificially inflated due to some RA tracking drift.? My drift
rate is somewhere around 2.4 arc-sec/min, so the RA error peak to
peak climbs the longer it runs.? Smoothing it visually, the worm
appears to have roughly 12-15 arc-sec native PE.? This is right in
line with the results I had with the static mounted worms, so no
big surprise here.? I think I should swap the RA and DEC worms to
see if it improves at all.? I might also apply some tracking rate
adjustment.? I suspect the RA drift is due to a sub optimal RTC in
the cheap Arduino board that runs the whole show.? Tracking rate
adjustment may help if the drift is consistent from night to
night.
Next is the declination backlash.? I really expected this to
tighten up, but it did not seem to.? Measured backlash seemed to
be between 650? to 900 ms (ran twice), which was higher than the
static worms.? I suspect this is from some wiggle room in the
pivot bolt.? Perhaps if I can tighten this up, things will improve
here.?
Now for the actual meat and potatoes guiding.? Here, it seemed to
shine.? I saw .61 and .58 arc-sec RMS overall average.?? While
sitting there watching, there were a few times where my number
(current screen average) dropped to .48!? And most promising, the
breeze did not seem to move the mount nearly as much as usual.?
Typically I would set up a wind break to calm it down, but didn't
feel like setting it up at 11pm.? These numbers are the best I've
seen on any mount without using a wind break.
I think my next order of business is figuring out how to remove
any play in the pivot bolt side.? Then maybe swap worms between
the DEC and RA to see which has less native PE.? But overall, I
think the spring loaded worm mod shows some promise.? I can't wait
to test it on a night with better conditions.
Thanks,
-Tony
|
Hello Bill!
You will probably find operating the mount fairly intuitive if you have used a telescope before. You'll probably want to do an indoor assembly first to go over the basic features. My first time out I had it up and going where I wanted in just a few hours. Just remember to add the weights before the telescope, and use the safety stop at the end of the bar to save your toes. Properly securing the OTA in the dovetail and locking down is next. After that you can do balancing and polar alignment. If you are just starting out in imaging you have made a nice selection from which to proceed.?
Best Regards,
John
|
Congrats and Welcome Bill!
>>>I¡¯ll solicit some advice.? If anyone has any wisdom on what I should make sure I do before I race to assemble and use the new mount when it arrives, I¡¯m all ears
All the advice i have is pretty much in those videos :) :)?
Take your time, don't panic if something doesn't quite work correctly. If you aren't sure, ask (here or send an email to techsupport at losmandy dot com)?
Hi, just wanted to make my first post.? New around here, so new that I don¡¯t even own a Losmandy mount - yet.? I have a G11 on order and I¡¯m told it¡¯s about 3-4 weeks out. ?
Thank you all for the many threads I¡¯ve read, I¡¯ve learned a lot and think it will help me get acclimated to my new mount quickly, I¡¯ve only ever owned a mount with a simple clock drive so far so this is a big leap for me.? I¡¯m starting to feel like it¡¯s 3 weeks before Christmas and I¡¯m 8 again. ?
Also, thanks Brian V for all the tutorial videos, those have been amazing.? I¡¯ve watched them all so many times my wife walks into the room and says ¡°are you watching that again?¡±
I¡¯ll solicit some advice.? If anyone has any wisdom on what I should make sure I do before I race to assemble and use the new mount when it arrives, I¡¯m all ears. ?
Thanks again for what seems like a great resource and community.
Bill
-- Brian?
Brian Valente portfolio
|
Re: next up: polar alignment tutorial
I can vouch for Michael¡¯s Belleville washer solution. ?Since I installed it on my GM8 I now have almost no shift as I tighten down the bolts after alignment. ??
|
Re: next up: polar alignment tutorial
On Sat, May 22, 2021 at 09:13 AM, alan137 wrote:
I can get extremely precise PA with sharpcap, but the accuracy seems to be a bit off since I still get a very slow RA drift.? I dunno it's either due to refracted vs real pole, king rate, equipment flex, etc.? I think I'd need to do some kind of a drift alignment to trim to the final value, or just cheat and adjust the RA divisor rate
Alan, Even though I start with PoleMaster, I try to finish off PA with PHD2 drift align, unless I am pressed for time. They seem to be close but are never the same. I do drift at the south meridian/equator zone first to adjust AZ, then do a star in the East to adjust ALT. Otherwise I will see some drift over the course of an evening and start losing data in the margins which I'll have to crop off during processing. If you are off in AZ, you should see Dec drift; if off in ALT you should see frame rotation. But a continued RA drift I'm not too sure about. If you are using PHD2, you could try to recalibrate on the target of choice after PA, and see if that helps. You might get a warning that you were too far from the equator or were not orthogonal, but try to ignore that. The recalibration might compensate for pulses needed at that different Dec value.?
|
Hi, just wanted to make my first post. ?New around here, so new that I don¡¯t even own a Losmandy mount - yet. ?I have a G11 on order and I¡¯m told it¡¯s about 3-4 weeks out. ?
Thank you all for the many threads I¡¯ve read, I¡¯ve learned a lot and think it will help me get acclimated to my new mount quickly, I¡¯ve only ever owned a mount with a simple clock drive so far so this is a big leap for me. ?I¡¯m starting to feel like it¡¯s 3 weeks before Christmas and I¡¯m 8 again. ?
Also, thanks Brian V for all the tutorial videos, those have been amazing. ?I¡¯ve watched them all so many times my wife walks into the room and says ¡°are you watching that again?¡±
I¡¯ll solicit some advice. ?If anyone has any wisdom on what I should make sure I do before I race to assemble and use the new mount when it arrives, I¡¯m all ears. ?
Thanks again for what seems like a great resource and community.
Bill
|
Re: Gemini 2 response to pulses that are smaller than minimum
Hi Ed
>>>seems a bit pointless to set a minmov to a value that the mount can't accommodate. What do you think?
I agree, but as you pointed out, there's no harm in doing that.
I'd rather just stick with the recommendations of the guiding assistant and let it set the min move. If you ever move to G11 DEC you won't have to remember adjusting that.?
Your imaging scale of your primary OTA may also dictate how important are these small differences.?
Brian
|
Re: Gemini 2 response to pulses that are smaller than minimum
Ed,
Two things I suggest you evaluate:
You have the option of using ASCOM pulse guiding (sending commands to the Gemini to move) or using the ST4 port (the autoguide camera sends electrical signals to the Gemini).
I've always read they work identically, but I think it's worth it for you to do a comparison.? I tried both mothods and found good results from either way.? But since you are experiencing some problems perhaps one method is superior and minimizes your issue.
The other factor you might try is this: eliminate the SLW movement if your DEC uses this spring system.? You only need to adjust the worm for smooth jam-free rotation into the ring gear, then tighten down the bottom two worm block mounting bolts so the DEC assembly cannot shift in the pivot hole (left block) and cannot shift in or outward (right block).? This will cut the hysteresis time needed for those motions. Compare your autoguide results.? Use the best method for real practice and don't be concerned about theory.? (Again, friction matters here and for lowest friction of the worm to ring gear I suggest CRC Brake and Caliper Grease ...that has the best technical ratings and I feel the smoothest worm behavior (no chatter) on my G11T RA worm.)
All the best, Michael
On Sat, May 22, 2021, 12:23 PM Edward Beshore via <ebeshore= [email protected]> wrote: Hi Brian,
I was mostly concerned about the Dec axis with my GM811.
The default minmov for PhD2 in Dec is 0.2 pix. I am using my 480mm Pronto (206.265/480 = 0.43"/¦Ì?plate scale) and a Lodestar 2 (8.6?¦Ì?pixels) for my guidescope setup which yields 8.6 ¦Ì * 0.43"/¦Ì?= 3.7"/pix. With a 0.2 pix min move that is 0.2 * 3.7" = 0.74" in Dec. Seems like I should be setting my Dec min move to ~1.15 " / 3.7 "/pix = ?0.32 pix?
Given Paul's response, it sounds like the Dec move commands would be getting ignored until the error gets past the minimum step. In the final analysis, that may be fine, since the error will eventually move past that and a correction will make it through but seems a bit pointless to set a minmov to a value that the mount can't accommodate.
What do you think?
Cheers, Ed
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Re: Gemini 2 response to pulses that are smaller than minimum
Hi Brian,
I was mostly concerned about the Dec axis with my GM811.
The default minmov for PhD2 in Dec is 0.2 pix. I am using my 480mm Pronto (206.265/480 = 0.43"/¦Ì?plate scale) and a Lodestar 2 (8.6?¦Ì?pixels) for my guidescope setup which yields 8.6 ¦Ì * 0.43"/¦Ì?= 3.7"/pix. With a 0.2 pix min move that is 0.2 * 3.7" = 0.74" in Dec. Seems like I should be setting my Dec min move to ~1.15 " / 3.7 "/pix = ?0.32 pix?
Given Paul's response, it sounds like the Dec move commands would be getting ignored until the error gets past the minimum step. In the final analysis, that may be fine, since the error will eventually move past that and a correction will make it through but seems a bit pointless to set a minmov to a value that the mount can't accommodate.
What do you think?
Cheers, Ed
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Re: DIY Spring Loaded Worms for the G11
Made a couple of minor changes...
Painted the worm block assembly black.?
Changed to button head socket screws.?
Added very thin washers so the button head screws don't get stuck
in the paint.?
Added nylon washers under the pivot bottom bolt.
Added a longer bolt and spring under the bottom sliding bolt to
apply constant pressure.
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Jamie Amendolagine
ACorkill
Michael Herman