Making the most of cloudy winter nights with a new mount and scope
With my new GM811G, I have been working through setup details. When the scope came, we had three clear nights and I was able to be out, getting familiar with the new mount.?I love it!!
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My experience and equipment: I¡¯m still pretty new at visual work and brand new at AP.??I am on my second scope and mount, having swapped out a TV 100 ED doublet for an ES 127 triplet 2 months ago, and an ieq30 for a GM811G two weeks ago. Lots to learn on the new scope and mount. Then my ASIAIR Pro (AAP) and my ASI290mm-mini and my?ZWO 30mm mini Guide Scope all arrived, and I¡¯ve been working on connecting them?to my Gemini 2 and a GL-iNet Mango mini router.?I think it works. Whew!
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What I would love to do is practice, practice, practice. But the skies are likely to stay cloudy for more weeks, maybe all next month.?
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Q: Let¡¯s say I have more weeks of cloudy weather, and I want to hit the ground running when the skies clear. What can I do now that will make both viewing and beginning AP easier then?
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My goals by summer:?
¡¤??????Continue visual observing. Been using ¡°left Turn¡¡± and SkySafari+ to get around with my goto. I want to learn the constellations and the sky much better.
¡¤??????Learn my setup routine both local (often) and remote (occasional).??The GM811G seems miles deep in its competencies, and there is a lot to explore
¡¤??????Learn to PA and guide with the ASIair Pro, camera and scope.?
¡¤??????Learn how to use my Fuji XT3 on my mount for both widefield (with fuji lenses) and deep sky (through my scope). I have attachments.
I know that processing is a whole other area that lies in the future, but I¡¯d rather leave it alone for now and develop some competence with what I have.?
What can I practice with my scope and mount setup now that can get me ready for clear skies when they come? What do you all do on cloudy weeks when you want to do something to build your skills???Any advice would be welcome!!
Geoff Chapman
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Re: Useful tip for G11 Digital Drive owners: https://nova.astrometry.net/
Robert,
Nice tip. I'll bookmark the site for use at home - I can't use it in the field but it is nice to have the option at home.
The way I have gotten around this problem is to use a flip mirror on my finder/guider and then at the start of the evening (I have to set up and tear down every night) verify that the imaging scope and the guider are co-boresighted so the finder/guider is always pointed at the same spot in the sky as the imaging scope (usually 1100mm with an APS-C sized CCD chip so my FOV is roughly the same as yours). I slip-focus the eyepiece (if used) in the imaging scope when I do this so I don't have to touch the focus knob on the imaging scope. That way I don't have to radically re-focus the imaging scope after installing the camera for the evening - I do a one-time focus tweak of the camera each evening or between shots, if required. Such is the price of working from the trunk of car.
The guider is set up so the guide camera and the eyepiece of the flip mirror on the finder/guider have a common (para-) focus. Doing this requires enough in-focus of the guide scope but the 80X500 short tubes commonly used have a lot of that.
When imaging at shorter focal lengths (under 700mm or so) I just use a modified 8X50 finder. There I had to hacksaw off about an inch from the tube to get the required in-focus. See:
I also built a slightly bigger (and marginally more expensive) version from one objective cone of a 15X70mm Celestron Skymaster bino and a Vixen flip mirror, using the other objective cone to make a wide-field scope.? I bought the binos decades ago (when the price was $58) and didn't use them much. Re-used both eyepieces as well.
Regards,
Mark Christensen
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Re: RA Divisor on Gemini 2 G811 mount.
Eric - Many thanks for this. A nice addition to my small, but growing trove of useful Gemini documents!
Ed
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Useful tip for G11 Digital Drive owners: https://nova.astrometry.net/
Hello - I do astrophotography on a Digital Drive G11 - one problem I have had in the past is that if I use the finderscope of my telescope to find a bright star, then centre it in my main telescope, set the setting circles to the star's coordinates, I then have to refocus the main and guider camera, before moving to the position of the object I want to photograph.?
Maybe it is obvious to others but I have now started to use??- you simply point your main telescope in roughly the right direction of the DSO, and take a photograph. Then you upload the photo to??which after a minute or so tells you the exact RA and DEC coordinates of the middle of the photo. You can then set the setting circles to these values and can then quickly move to the DSO coordinates.?
This does depend on you having internet access on your computer when you are observing, but is a neat trick for those G11 owners that don't have Goto.?
My main telescope has a focal length of around 700 mm (or 500 mm with a focal reducer) and when coupled with a ZWO ASI 071 camera, the field of view is about 2 degrees by 1 degree, so the above method should enable you to get the DSO in the field of view of the camera, and you can then use the hand controller to centre it.?
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Re: Used GM-8 Guiding Help
Thanks for the response! Weather permitting tonight I hope to get a good hour+ worth of unguided data (8min periods for GM8) for PE Analysis, I was mostly concerned with all the sharp spikes but agree with your advise of getting a starting baseline. As for polar alignment, tonight im going to try using my polar scope for a rough alignment then fine tune with gemini polar assist since drift guiding isnt very reliable for me right now (I believe due to high RA drift rates and noisy data in general). I have played with aggressiveness in PHD2, I can get Dec guiding half decent (1.7rms) but in RA even with aggressiveness at 100 and guide rate of 0.8 it drifts quite a bit (3+rms) hoping the periodic error analysis will help make some sense of this! I'll try adding a small amount of grease on the oldham, and make the balance east biased see if that helps. I did end up pulling the trigger on getting new bearings and belleville spring for the mod Michael has shown in other posts, should be able to complete this weekend! Thanks for all the input! I'll keep this updated as it comes along, I think the main thing at this point is to be as methodical as possible and get a baseline, which sounds obvious but I may have gotten too excited with my new (to me) mount ?
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Re: Used GM-8 Guiding Help
Hello Nick - have you measured the periodic error of the mount - you can do this by running the Guiding Assistant for 5 or 6 turns of the worm (I have a G11, whose worm turns in 4 mins, so if you run the Guiding Assistant for 20-30 minutes you can usually get 5 or 6 worm periods included).
The Guding Assistant also gives you advice on recommended paramaters for min movements in RA and DEC, and what to set for the DEC backlash.?
I have found that if the mount is accurately polar aligned, then DEC movements are mainly due to the seeing. The default PHD2 parameter for DEC aggressiveness is 100%, and I found I had to reduce this down to 60 or 70% to stop DEC constantly responding to changes in seeing. I also found that if there was a large DEC correction, it tended to cause a reaction in RA. Playing with decreasing the aggressiveness settings and increaing the min move parameter (and also increasing the exposure time of the camera to 3 or 4 seconds to average out the seeing helped). I also found it was worth running a guiding session for 20 or 30 minutes, since for my mount it does tend to settle down.?
I also believe the Losmandy mounts are better with higher loads - if you have a fairly small telescope, you may want to deliberately load the scope so it is east heavy. I tend to get a smoother periodic error curve when I put a 12" Newtonian on my G11 mount (which probably comes in at 35 lbs with tube rings and camera etc.) compared to when a put on a 102 mm refractor (which is only about 15 lbs).?
I have also been learning how to use PHD2 for autoguiding, and can now get RA errors down to around 0.8" and DEC errors down to around 0.6" on a good night, but I think I am limited by my seeing conditions as I live on the outskirts of a city.
I also recently stripped down and regreased my mount - I also put a small amount of grease onto the metal rods in the Oldham couplers - if for any reason these "stick" you may get stick-slip effects which I'm pretty sure could cause spikes in? guiding. You also need to be careful to not put too much grease on - this could also cause problems (e.g. the excess grease could make its way to the clutches, which you don't want. It is also possible to change the bearings in the worm blocks fairly easily - they are R4 ZZ 1/4 inch bearings.
Hope this helps? ?
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Re: RA Divisor on Gemini 2 G811 mount.
Ed,
The comet tracking reference Brian provided above is for Gemini 1. Gemini 2 uses a different clock so the calculations will be different. I do not do comet tracking, but have a look at the attached document for an explanation of the clock divisors for Gemini 2.
Eric
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Hello everyone!
I'm a relatively new owner of a used GM-8 Gemini 1 with the LW tripod, steel worm (not brass), and original worm block (not OPW). Also I have the old motors, not maxxon or tucked etc. My guiding setup is a 50mm f/4 WO scope piggybacked on my WO Z73 refractor using a ZWO ASI120mm for guiding. Both mount and guide camera work using ASCOM gemini drivers and PHD2. My initial issues were with tight spots in the worm where I would get RA motor lags errors in the same spots. I'm very mechanically inclined and pulled apart the mount after countless hours of research on here, everything was extremely caked in grease I believe from a previous owner, it appeared to be a very good moly grease and nothing was seized etc. I decided to fully clean the mount and all the grease out and re-grease everything using superlube with teflon (typically recommended here). I was able to find high spots in the worm gear (using a 3d printed hand knob connected to the oldham coupler) and adjust the worm block so there was no more tight spots and no play in the worm. I also widened the gear box mounting holes to help align the worm and gear box shaft best as possible. I was successful in getting rid of the RA motor lags, however I am having a very hard time getting decent guiding. I've tried tightening RA axis and leaving it loose (but where clutch doesnt slip), I've tried various PHD2 settings, I've pulled apart the mount 2x now for cleaning, greasing and aligning (out of fear not using enough grease the first time), and I feel I've gotten the process down decently, but still have wild jumps in guiding. My testing days thus far haven't been ideal seeing conditions and intermittent clouds, but I have yet to see even a glimpse of "okay this will work its just a bad day". I'm just hoping someone can give me some guidance on what all these spikes may be, if it's possibly a bad bearing, not enough grease, oldham coupler alignment, bad motor, stiction? I still have several things to test for troubleshooting but want some other input as well to know I'm on the right track. These spikes also make using drift align very difficult and not very reliable, would it be better to use the gemini polar align assist for now? I've attached a PHD2 log just for some substance/visual, I really appreciate any input, I'm trying to avoid spending hundreds on upgrades but would be open to new bearings and the belleville spring mod if it would help.
Thanks everyone!
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Re: RA Divisor on Gemini 2 G811 mount.
Thanks for digging a bit on this Brian. The reference you sent refers to the serial line protocol, which I investigated and it definitely suggests the command set for Gemini supports this if you know the correct tracking rate divisors and other physical parameters for the mount. Im guessing the divisors on the handset are effectively this value, but using the handset for this repeatedly or on a regular basis may be a pain.
My new G811 is still on order so I can't noodle around with it myself yet. As you say, my AP could do this, but its not very portable :-)?
I am assuming I can set a non-sidereal rate in the TheSkyX, as there is a provision for that there, although I have not used it, I will give it a try and report back on my findings.
Thanks to all for their help.
Best, Ed
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Re: Orientation of pier/riser relative to legs
Hi Geoff,
I have never extended my HD tripods legs.
And the stability is still awesome.
About the only place the 12EX might not be a good idea is if you were using a Newtonian Telescope for observation.
I'm basically only interested in imaging. And only use a refractor.
So each has to think about what OTA they wish to use.
--
SonnyE
(I suggest viewed in full screen)
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Bit of fun adding RGB color to a duo band mono luminance shot with a QHY9/FSQ106N. Technically the duo band is 34nm Oiii and 12nm Ha emission lines. I don't have any Ha/Oiii channels but had some RGB from previous years with colors that overlap the duo band spectrum.
I have posted both mono and colours along with the filter specs so you know what I did. The Oiii overlaps and clips the transition from blue to green so the brown still makes it through and the Ha is a subset of the red.
Full res fields are Here: -
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Re: RA Divisor on Gemini 2 G811 mount.
Hi Ed,
this page may be interesting to you, particularly the section on?Coordinate Controlled Tracking.?
Looking at the Gemini interface, it's changed a bit so now you enter the delta RA and Delta DEC over a specified Timespan, but may be more what you're looking for
On Mon, Jan 25, 2021 at 7:41 AM Edward Beshore via <ebeshore= [email protected]> wrote: Hi Brian -
Thanks for the link. I am looking at a more ¡±production¡± oriented approach to asteroid followup that would preclude independently determining track rate by watching the object over 4 or 5 minutes.? I will get rates of motion from JPL Horizons and would like to enter the RA/dec rates of the object or some tracking bias to track the asteroid.?
I would greatly appreciate ?some authoritative guidance on how one would do that.
A humble request please. Gemini needs a proper manual. As it is, information is spread out among multiple webpages with no particular organization, YouTube videos from more than one source, and of course, posts on iogroups.
Kind regards,
Ed Beshore
-- Brian?
Brian Valente portfolio
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Re: Orientation of pier/riser relative to legs
Sonny,
Have a Q about those 12" pier extensions... do you - or do some others - ever leave your tripod legs retracted as you use a 12" extension? I have thought of that as I have moved my observing chair (a catsperch kit I built) around through a night. If the tripod legs were not so wide, it would be a lot easier. But then I suspect that a tighter base might reduce the stability of the OTA? Thoughts?
Geoff
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Re: RA Divisor on Gemini 2 G811 mount.
The Gemini ASCOM driver (and the ASCOM standard) supports setting variable tracking rates. It's entirely possible for software using ASCOM to set the Gemini divisor programmatically, so it's really just a question of finding the right software using ASCOM-provided commands to tell Gemini to track at a speed different than Sidereal. What software does it, I couldn't tell you, but it's totally doable :)
Regards,
? ? -Paul
toggle quoted message
Show quoted text
On Mon, Jan 25, 2021 at 02:18 PM, Brian Valente wrote:
Hi Ed
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I will look into this some more, but for the Losmandy Gemini, afaik training is the only way Gemini supports custom tracking rates.?
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If you are looking to do something like import Horizons data, mounts like Astro-Physics have that capability via their APCC/Horizons software.?
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there may be third party software available to do this with an ASCOM connection, though i'm not aware of any for comets
?
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Brian
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On Mon, Jan 25, 2021 at 7:41 AM Edward Beshore via <ebeshore= [email protected]> wrote:
Hi Brian -
Thanks for the link. I am looking at a more ¡±production¡± oriented approach to asteroid followup that would preclude independently determining track rate by watching the object over 4 or 5 minutes.? I will get rates of motion from JPL Horizons and would like to enter the RA/dec rates of the object or some tracking bias to track the asteroid.?
I would greatly appreciate ?some authoritative guidance on how one would do that.
A humble request please. Gemini needs a proper manual. As it is, information is spread out among multiple webpages with no particular organization, YouTube videos from more than one source, and of course, posts on iogroups.
Kind regards,
Ed Beshore
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--
Brian?
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Brian Valente
portfolio
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Re: Orientation of pier/riser relative to legs
I¡¯ve finally settled on the standard one leg to the north and the Gemini unit to the south (under the polar scope). ?
Having the Gemini off to one side just bugged me aesthetically. ?It looked unbalanced. ?In the uncommon case where I need to use the polar scope, I will just unplug the cables so they are not in my face.
Then for reference, the Losmandy logo on the tripod is set due South. There doesn¡¯t appear to be anyway to have the Losmandy log also to the south since there is only one set of mounting holes for the Gemini brackets and that leaves the logo in the northwest. ?Maybe your extensions give you more flexibility.
I¡¯m satisfied and am not going to worry about it further. ?Now with the single leg to the north, it is also easier to find CWD (which is how this whole discussion started).
Bill
Hi again, Bill.
Yes, when assembling and using my GM811GHD, I tried different locations for the Gemini II, and decided I liked having towards the South, between the two legs, and a single Northward leg.
But to a tinkerer like me, the brilliant configurability of the latest tucked motor design gives a wide array of ways to finally assemble your mount.
Removing, turning, and replacing the 3/8" button head screws as I was deciding on a configuration I felt worked best for me. (I say that because everybody seems to have their own selection of equipment, telescope sizes and configurations, wants, needs, and custom problems.
I always thought I wanted a pier type configuration, so I got a 12EXT with my mount when purchased. The EXT's allow for the Gemini II to be mounted onto them, and I eventually found my spot for mine. At first I had it towards the East, with a single tripod leg pointed due North. But I was uncomfortable with my wiring and swing of my telescope in use. So sitting in the house waiting out 2020's torretial spring rains, I had a lot of days to tinker and think through different configurations.
My current one is the best for me.
I have the HD tripod, but it doesn't really matter. A tripod is a tripod, 3 legs. I set mine so one leg is due North. Then for reference, the Losmandy logo on the tripod is set due South. It is of little consequence, just explaining the picture. ;^)
Each piece of extension offers a 3 bayonet type mounting on one end, and a Hex hole pattern on the other. The Bayonet gives 120¡ã positions, and the Hex pattern gives 60¡ã points of rotation. Ample to configure the rotational axis of the mount to suit each. it's a matter of setting up the tripod, then determining the place for your next piece of the puzzle.
The Male to Male fittings to attach the extension to the MA provided with the mount. Or the RA head to the MA with 60¡ã orientations.
I'd suggest you set up your tripod inside where you have room to look at it and walk around it. Orientate your tripod as it works best for you. Mine is single leg North, Gemini II controller South.
If you don't have a/any extensions, locate the RA head so it points North Axis. (But same thing if you do use a/an extension.)
My RA is buttonhead screwed to the three bayonet slots, semi permanent, and my EX12 attaches to the standard MA with TKS hand screws. The hand screws are my separation point.
Anyway, just try turning and looking at your configuration until you get it aimed the way it works best for you.
Our mounts are really brilliantly adaptable to configure to work for us, if we want to set them up to our liking. ;^)
--
SonnyE
(I suggest viewed in full screen)
--? Bill Tschumy Otherwise -- Longmont, CO
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Re: Orientation of pier/riser relative to legs
Hi again, Bill.
Yes, when assembling and using my GM811GHD, I tried different locations for the Gemini II, and decided I liked having towards the South, between the two legs, and a single Northward leg.
But to a tinkerer like me, the brilliant configurability of the latest tucked motor design gives a wide array of ways to finally assemble your mount.
Removing, turning, and replacing the 3/8" button head screws as I was deciding on a configuration I felt worked best for me. (I say that because everybody seems to have their own selection of equipment, telescope sizes and configurations, wants, needs, and custom problems.
I always thought I wanted a pier type configuration, so I got a 12EXT with my mount when purchased. The EXT's allow for the Gemini II to be mounted onto them, and I eventually found my spot for mine. At first I had it towards the East, with a single tripod leg pointed due North. But I was uncomfortable with my wiring and swing of my telescope in use. So sitting in the house waiting out 2020's torretial spring rains, I had a lot of days to tinker and think through different configurations.
My current one is the best for me.
I have the HD tripod, but it doesn't really matter. A tripod is a tripod, 3 legs. I set mine so one leg is due North. Then for reference, the Losmandy logo on the tripod is set due South. It is of little consequence, just explaining the picture. ;^)
Each piece of extension offers a 3 bayonet type mounting on one end, and a Hex hole pattern on the other. The Bayonet gives 120¡ã positions, and the Hex pattern gives 60¡ã points of rotation. Ample to configure the rotational axis of the mount to suit each. it's a matter of setting up the tripod, then determining the place for your next piece of the puzzle.
The Male to Male fittings to attach the extension to the MA provided with the mount. Or the RA head to the MA with 60¡ã orientations.
I'd suggest you set up your tripod inside where you have room to look at it and walk around it. Orientate your tripod as it works best for you. Mine is single leg North, Gemini II controller South.
If you don't have a/any extensions, locate the RA head so it points North Axis. (But same thing if you do use a/an extension.)
My RA is buttonhead screwed to the three bayonet slots, semi permanent, and my EX12 attaches to the standard MA with TKS hand screws. The hand screws are my separation point.
Anyway, just try turning and looking at your configuration until you get it aimed the way it works best for you.
Our mounts are really brilliantly adaptable to configure to work for us, if we want to set them up to our liking. ;^)
--
SonnyE
(I suggest viewed in full screen)
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Re: RA Divisor on Gemini 2 G811 mount.
Hi Ed
I will look into this some more, but for the Losmandy Gemini, afaik training is the only way Gemini supports custom tracking rates.?
If you are looking to do something like import Horizons data, mounts like Astro-Physics have that capability via their APCC/Horizons software.?
there may be third party software available to do this with an ASCOM connection, though i'm not aware of any for comets
Brian
On Mon, Jan 25, 2021 at 7:41 AM Edward Beshore via <ebeshore= [email protected]> wrote: Hi Brian -
Thanks for the link. I am looking at a more ¡±production¡± oriented approach to asteroid followup that would preclude independently determining track rate by watching the object over 4 or 5 minutes.? I will get rates of motion from JPL Horizons and would like to enter the RA/dec rates of the object or some tracking bias to track the asteroid.?
I would greatly appreciate ?some authoritative guidance on how one would do that.
A humble request please. Gemini needs a proper manual. As it is, information is spread out among multiple webpages with no particular organization, YouTube videos from more than one source, and of course, posts on iogroups.
Kind regards,
Ed Beshore
-- Brian?
Brian Valente portfolio
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Re: RA Divisor on Gemini 2 G811 mount.
Hi Brian -
Thanks for the link. I am looking at a more ¡±production¡± oriented approach to asteroid followup that would preclude independently determining track rate by watching the object over 4 or 5 minutes. ?I will get rates of motion from JPL Horizons and would like to enter the RA/dec rates of the object or some tracking bias to track the asteroid.?
I would greatly appreciate ?some authoritative guidance on how one would do that.
A humble request please. Gemini needs a proper manual. As it is, information is spread out among multiple webpages with no particular organization, YouTube videos from more than one source, and of course, posts on iogroups.
Kind regards,
Ed Beshore
|
Re: Orientation of pier/riser relative to legs
That is the way my GM8 is and I was a bit surprised when the G811 came differently. ?I *think* it came that way from the factory. ?I don¡¯t recall putting the riser on myself, but possibly I did and did it incorrectly.
The only problem with having the Gemini unit to the south is that it makes it hard to use the polar alignment scope. ?The cables sticking out of the Gemini get in your face while trying to look through the scope.
What is the orientation of the Losmandy logo? ?Where should it be facing?
Bill On Jan 24, 2021, at 4:24 PM, Brian Valente < bvalente@...> wrote:
There is no "right way" as any of those work
but the generally preferred and accepted "normal" way is to have one leg pointing north and the Gemini mounted to the opposite?(south) side.?
it does not make any difference in performance, though you have to look at things like motor cable lengths to ensure things will connect up
the picture you mention is out of date - you can see it's the older gemini in there?
Brian On Sun, Jan 24, 2021 at 2:53 PM Bill Tschumy < bill@...> wrote: A day or two ago I asked how best to achieve CWD position.? Sonny replied
> When beginning with everything plumb from the tripod up, it is natural for the weight shaft to be centered on a North pointing tripod leg.
I just realized that my tripod is set up so the counterweight shaft is between two legs, it can¡¯t be over a leg.? Not that it matters that much but I think my short pier was put on incorrectly.? I can take our the 6 bolts and rotate it 30? (??) so that I can put the head on with the shaft over a leg.
Can someone tell me what is the correct position?? Is the Gemini 2 unit supposed to be on the east or west side?? The way mine came, the unit would be on the south side.
The picture here seems to indicate it should be on the west side (actually north-west).
Bill
--
Bill Tschumy
Otherwise -- Longmont, CO
-- Brian?
Brian Valente portfolio
--? Bill Tschumy Otherwise -- Longmont, CO
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Re: Orientation of pier/riser relative to legs
The main thing you will notice with the CW over the tripod leg, is that if you have the upgraded aluminum RA knobs to attach the RA to the tripod, the knobs will be close to the Az and Alt adjustment knobs on the RA.
This MAY make it a little harder to get a good grip on those knobs, certainly not really difficult to access, but completely different than the other orientation which places all the Az/Alt knobs away from the RA /tripod attachment knobs/screws.
ALSO, when you orient the CW shaft over the tripod leg, (partially limiting some access to the Az/Alt knobs) you gain the benefit of having the Gemini controller mounting ears positioned so you can mount the Gemini controller due south, instead of at an angle on one side, which MAY affect the limit setting you can use on that side.
It would be awesome if Losmandy were to drill the holes for the controller ears, in both orientations, 1: as is currently, and 2: a new set of alternate (extra) holes, so the RA / tripod aluminum knobs can be oriented so they do not intefere with the AZ/Alt adjustment knobs, while still allowing the Gemini controller to be mounted due south...
The motor cables seem long enough for either orientation...?
Since the ear holes are drilled and tapped at an angle, it is a lot harder to add these without a jig. This may be beneficial for both the main 4" tripod adapter, as well as all of the extensions.
Just a 'wow, it would be great if...' observation...
Astronut Tim
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Paul Kanevsky
Bill Tschumy