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Alt-Az programmable mount for landscape astro panoramas

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#1 nathanm

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Posted 15 July 2020 - 12:49 PM

I am looking for a mount that can be programmed to go to alt-azimuth positions.

 

That is NOT the same as a "go-to" mount, which typically means RA, Dec positions to find an astronomical object.  

 

This is for making a terrestrial mosaic (panorama) which includes the sky.  

 

I have Gigapan and Roundshot commercial mounts,  but I want to use this for heavier lenses than they take.  Plus they are internally programmable but you can't externally tell them what to do.  

 

I also have one I made myself, along with software to control it.  But I need an additional and heavier duty version so I was hoping to buy something that would work, or that I could modify.

 

Instead of an alt/az interface, I could also interface directly to stepper motors for alt, az.

 

The iOptron iPano AllView Pro https://www.ioptron....duct-p/3600.htm  mount almost is what I want.  It looks very similar to Gigapan, with almost identical interface.   It can be remotely programmed in a sense but only with their app, which is more of a remote wireless interface to the same commands available on the display.  I could reverse engineer what the protocol is, but that seems like a waste if there is something better.

 

I I have built a mount like this already have all of the software to control it.   I just need to get an additional, heavier duty mount so I am hoping there is a product I can buy.

 

Several mounts have an alt-azimuth mode.  That includes Rainbow RST-135,  Hobym and Avalon Instruments.    I have been unable to download the RST-135 manual.  The Hobym manual does not say - apparently you can go RA-Dec go-to in alt-az mode, and you can use the hand controller to do up down, left, right.

 

However it is hard to find information from them on how they are programmed in alt-az mode.    Of course most astronomical users want to use RA, Dec coordinates for convenience, but that is not what I am after here.

 

The same is true for mounts like iOptron AZ Mount Pro,  and similar from Sky-Watcher.  They have an alt-az mount with steppers, but it is unclear to me how to interface with it.

 

One possibility would be a manual alt-az mount that was easy to motorize.

 

 



#2 rk2k2

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Posted 15 July 2020 - 01:35 PM

I don't know how much 'control' you are seeking, and from my understanding, not all equatorial mounts go up to 90 degrees,  But I recently used my old mount (an EXOS2, still in the garage so I could take this pic) as a stable platform to take some 360 degrees panoramas of my viewing location.  Fortunately for me, it's lowest position was close enough to 0 degrees- no biggie since you can just as well adjust the tripod legs to where the RA axis is parallel with the ground.

 

In this configuration you simply rotate the RA axis  I don't remember why I didn't, but you can also set the altitude to 0 degrees (also adjust legs if it doesn't go all the way down to 0) and just pan with the DEC axis  I guess maybe because I was intending to shoot the tree lines above where the 0 degree pan was?  I THINK it was because the one of the motors interfered with  360 degree rotation.

 

I'm certain there are better alternatives but I already had this mount laying around.

 

 

EDIT:  So I reread your post (particularly the TITLE), and I now assume you want this for astro photography?   I was thinking you wanted to use it for  some large video camera or regular camera with large lenses for pan and tilt.  I certainly hope you are NOT looking to take long exposures (meaning tracking) AND include the terrain.

 

P7150104.JPG


Edited by rk2k2, 15 July 2020 - 11:00 PM.


#3 nathanm

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Posted 16 July 2020 - 01:25 PM

No tracking.   Just a programmable X-Y mount, so I can shoot the ground portion of a panorama / mosaic.  

 

So this would be:

 

1.   an Alt-Az mount that has Alt-Az programmability.

2.   An alt-az mount where you can access the stepper motors directly

3.   A manual alt-az mount with a stepper motor  add-on kit.



#4 rk2k2

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Posted 16 July 2020 - 01:59 PM

Since you program, simply get a mount that meets your physical requirements that will communicate with Stellarium or other open source equivalent.  Then modify code to meet your needs.  No sense in re-inventing the wheel. 

 

EDIT:  perhaps easier, get a mount that supports ASCOM (also open source BTW) , then use ASCOMs POTH to do your movements.  That of course is assuming your objective isn't more complex than simple moves, ie you're not programming in sequences of movements, in which case, it's all open source, modify code to meet your own requirements.


Edited by rk2k2, 16 July 2020 - 02:16 PM.


#5 nathanm

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Posted 18 July 2020 - 05:25 PM

ASCOM, so far as I know, is meant to be used with RA, Dec coodinates, not alt-azimuth.



#6 rk2k2

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Posted 18 July 2020 - 06:36 PM

Irrelevant.  You're going to program so it's an extremely simple task to include an ALT/ AZ to RA/ DEC coordinate conversion if you must input ALT/ AZ cooridinates

 

But your assumption is incorrect.  If an ALT/ AZ mount has ASCOM support then obviously ASCOM supports IT.



#7 rk2k2

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Posted 18 July 2020 - 09:49 PM

I just looked up some of the products (GigaPan, etc) to get an idea how much MONEY you were thinking of/ perhaps comfortable with)  Since you were mentioning products upwards of $3000, I assume you aren't looking for a low cost solution (on the cheap).

 

You found the AZ Pro which I assume you were considering.  There are other options, but it has ASCOM support (years back I had considered it but knowing I might want to get into AP, I went for my cheap EXOS2)  .  Meaning if needed you can do whatever programing you need to do without the need for low level workings of the mount. 

 

I'm not familiar with GigaPan or the others but I assume at the cost, they provide sequencing to do the entire panorama capturing for you (no manual intervention).  This will be an area you would have to develop yourself.

 

Personally, I would use my EXOS2 at 90 degrees where the RA is essentially azimuth/ DEC is altitude and manually slew with hand controller as needed, stopping at necessary points to make a shot.



#8 OzAndrewJ

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Posted 18 July 2020 - 10:07 PM

Gday Nathanm

 

Pretty much any of the Meade fork mounts will do what you want.

Very easy to fully remote controll via your own code ( no ASCOM reqd ) if you dont want astro functionality.

They even have inbuilt functions to pre program a series of landmarks and they will happily go to them

or you can interactively send terrestrial coords and move using simple rs232 comms.

You could also use any of the skywatcher mounts ( even a std EQ5 / EQ6 can be made to drive in AltAz

very easily, as long as you dont want astro tracking.)

Again, very easy to remote control via a homebrew app using very simple commands.

All the low level motor commands are freely available in several locations.

 

Andrew Johansen Melbourne Australia



#9 nathanm

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Posted 19 July 2020 - 04:44 PM

OK, so let me see if I understand.   

 

rk2k2,  are you saying that ASCOM protocol has a provision for a  "GoTo  Alt, Az" command?    If so that is great!  I haven't found a good description of the ASCOM protocol, but I would look.

 

Saying that my code should do Alt - Az to RA, Dec conversions is a little odd.    Alt-Az is a local coordinate system to the telescope mount.   If I say go to Alt  30 degrees,  Az 310 degrees that is relative to

 

RA, Dec is a global (well, universal, I suppose) coordinate system for the sky which moves relative to the earth.    This assumes that the telescope is properly oriented.  If you want to find a particular object in the sky, say Andromeda galaxy  M31, you to go to its RA, Dec.    Historically, the big breakthrough in Go-To mounts was to put the local coordinate system of Alt -Az "under the covers" so to speak so one could ask for objects by their RA, Dec coordinates, and just go to the object  (as long as it is above the local horizon etc.).

 

Putting my Alt - Az in terms of RA, Dec is possible but very inconvenient, since the coordinates change moment  by moment.   It is not a very nice way to make a terrestrial panorama compared to issuing Alt - Az commands.

 

Also, I would be happy to get by on the cheap, but given that I want this for long-ish focal lengths that likely isn't going to happen.

 

OzAndrewJ   - thanks for the tip about Meade fork mounts.   I will look to find their protocol described.



#10 OzAndrewJ

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Posted 19 July 2020 - 05:24 PM

Gday Nathanm

For the Meades in alt/az + terrestrial mode

 

Interactively via the rs232 port,

you can use the :Sa and :Sz commands to set a "Target" Alt/Az,

and then the :MA# command to slew to that point.

 

You can also manually enter this data via the handbox on the fly

but if you have a known set of points,

what you need to read up on is the "LandMark" functionality

 

Landmarks  stores  the  location  of  terrestrial  points  of  interest  in  the  permanent  AudioStar  database.

IMPORTANT NOTE: To use the Landmark function, the telescope must be located and aligned exactly as when the landmark was added to the database.

• Select:  To  select  a  Landmark  already  in  the  database  (see  ADD  below), 

                 choose  the  “Select” option and scroll through the list. Press ENTER to select a Landmark,

                 then press GO TO and the telescope slews to the object

.• Add:     To add a Landmark, choose the “Add” option.

                Enter a name for the Landmark.

                Locate and center the Landmark in the eyepiece, then press ENTER

Andrew Johansen Melbourne Australia


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#11 eblanken

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Posted 19 July 2020 - 06:06 PM

No tracking.   Just a programmable X-Y mount, so I can shoot the ground portion of a panorama / mosaic.  

 

So this would be:

 

1.   an Alt-Az mount that has Alt-Az programmability.

2.   An alt-az mount where you can access the stepper motors directly

3.   A manual alt-az mount with a stepper motor  add-on kit.

Hi NATHANM,

 

Interesting need you have that is "opposite" of mainstream astronomy community. Have you considered starting with something like a Losmandy AZ8 Dual Alt./Az. Mount and add your own motors and controllers ? That would give you a solid mount that could handle any task up to 30 pounds of payload on each side. You would have a simple task to give you all the control that you desire, but none of the "working against" the bias that astronomers bring to the table with RA & Dec. coordinates that are always "spinning" relative to the earthbound co-ordinates you want to work with. Maybe you could whip up a Raspberry Pie that could do the interfacing easily ?

 

Just some thoughts,

 

Ed (aka eblanken)


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#12 rk2k2

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Posted 19 July 2020 - 09:32 PM

OK, so let me see if I understand.   

 

rk2k2,  are you saying that ASCOM protocol has a provision for a  "GoTo  Alt, Az" command?    If so that is great!  I haven't found a good description of the ASCOM protocol, but I would look.

 

Saying that my code should do Alt - Az to RA, Dec conversions is a little odd.    Alt-Az is a local coordinate system to the telescope mount.   If I say go to Alt  30 degrees,  Az 310 degrees that is relative to

 

RA, Dec is a global (well, universal, I suppose) coordinate system for the sky which moves relative to the earth.    This assumes that the telescope is properly oriented.  If you want to find a particular object in the sky, say Andromeda galaxy  M31, you to go to its RA, Dec.    Historically, the big breakthrough in Go-To mounts was to put the local coordinate system of Alt -Az "under the covers" so to speak so one could ask for objects by their RA, Dec coordinates, and just go to the object  (as long as it is above the local horizon etc.).

 

Putting my Alt - Az in terms of RA, Dec is possible but very inconvenient, since the coordinates change moment  by moment.   It is not a very nice way to make a terrestrial panorama compared to issuing Alt - Az commands.

 

Also, I would be happy to get by on the cheap, but given that I want this for long-ish focal lengths that likely isn't going to happen.

 

OzAndrewJ   - thanks for the tip about Meade fork mounts.   I will look to find their protocol described.

You might start doing more research.  REGARDLESS of RA/ DEC coordinates being based up on time or site location or whatever, that is PART of your algorithm.  In fact, the code is readily available, you don't even need to write it.

 

You might want to download and install Stellarium and play around with it  Familiarize yourself with all  it's features.  Not for the purpose of using it for whatever you have in mind, but to broaden your imagination towards what you might be able to do  .For example, ocular setup in the top/ right corner.  Define a telescope (your lens) and a sensor (your camera), select a celestial object.  View in 'Ocular' and click the sensor icon.  Voila, you have a nice overlay that displays the area your pic will be.  Also note when an object is selected there is all sort of info in the upper left regarding that object, in particular, where it is in both RA/ DEC and AL/ AZ format.   How does it do that?  Most likely using a conversion algorithm.

 

OZ mentioned it with regard to Meade, they don't do a MOV X,Y directly by command, they move (slew) relative to where they are.  Neither does Stellarium (when set to control your mount).  It simply slews from its current position to the desired location.  It is up to the user to first synchronize where the mount is pointing to where Stellarium thinks it is pointing.  Its pretty much the same as doing star alignment- the mount goes to some 'object' (where it believes that object is), and the user 'manually' (through the system interface) moves that object to 'center'.  From there you're '1 star aligned', any future GoTo's are hopefully 'good enough' (especially for visual). 

 

I'm not saying one way or the other whether ASCOM takes 'commands' of ANY sort.  What I am saying is the ASCOM platform, in particular the POTH, takes user data entry in coordinate format and uses that to define what it sends to the mount.  WHAT it sends is irrelevant as long as the mount does what you want.

 

 

 

 



#13 OzAndrewJ

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Posted 19 July 2020 - 09:47 PM

Gday rk2k2

OZ mentioned it with regard to Meade, they don't do a MOV X,Y directly by command, they move (slew) relative to where they are.

Yes and no and maybe :-)

The Meades are very flexible under the hood, and deal with terrestrial panoramas better than ASCOM, which pretty much assumes Astronomical use.

You are correct that the Meade would need to be set up so its internal datums work, but that is very easy

and doesnt need to know anything about date/time, location, RA or DEC.

Also, there are multiple ways to "move" when terrestrial.

If you define landmarks, you just issue a goto ( no matter where you are currently ) and it goes there.

If you want to manually slew using up/dn/left/right, you can also do that.

Lastly, many years ago, a different group of users wanted to do "video" panoramas where they could make the scope

track at set speeds in each axis, but independent of the sky, ie they wanted to use their own rates.

That can also be done, but for Autostar/Audiostar mounts, it needs patched firmware.

 

ie None of it "requires" any knowledge of RA/DEC and can be done without ASCOM.

If the user wants to use a planetarium app to aid in creating the panoramas,

then ASCOM may work but im not sure if it works happily in non astronomical mode.

You would need to look at each driver to see how it works.

 

Andrew Johansen Melbourne Australia


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#14 rk2k2

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Posted 19 July 2020 - 10:52 PM

Gday rk2k2

Yes and no and maybe :-)

The Meades are very flexible under the hood, and deal with terrestrial panoramas better than ASCOM, which pretty much assumes Astronomical use.

You are correct that the Meade would need to be set up so its internal datums work, but that is very easy

and doesnt need to know anything about date/time, location, RA or DEC.

Also, there are multiple ways to "move" when terrestrial.

If you define landmarks, you just issue a goto ( no matter where you are currently ) and it goes there.

If you want to manually slew using up/dn/left/right, you can also do that.

Lastly, many years ago, a different group of users wanted to do "video" panoramas where they could make the scope

track at set speeds in each axis, but independent of the sky, ie they wanted to use their own rates.

That can also be done, but for Autostar/Audiostar mounts, it needs patched firmware.

 

ie None of it "requires" any knowledge of RA/DEC and can be done without ASCOM.

If the user wants to use a planetarium app to aid in creating the panoramas,

then ASCOM may work but im not sure if it works happily in non astronomical mode.

You would need to look at each driver to see how it works.

 

Andrew Johansen Melbourne Australia

I think you got the wrong impression.  I'm not suggesting to use Stellarium (or any other), especially not in release state, to help create his panoramas, only for Nathans own creativity/ inspiration of what he could possible do for whatever software (or firmware) he intends on writing (if he needs to).  And yes, if he wanted something 'spectacular', he could use open source Stellarium as a base.  Throw out anything and everything non essential (like simple things like 'eyepieces' etc).

 

Again, wrong impression, I'm not suggesting he DO use ASCOM, I'm merely stating he COULD.  I started simple post with pic- a CHEAP equatorial simply set at 90 degrees- you now basically have an AL/ AZ for landscape photography.  It doesn't even care WHERE it is- camera viewing 'Tree Landscape 1', take pic, rotate RA or DEC (through hand controller) to frame for next pic (OR, with knowledge of my frame area, through the hand controller slew by that many degrees and framing is unnecessary) ....  ASCOM comes in cuz that cheap mount supports it  If I want to control from my laptop- connect via ASCOM.  With POTH, hand controller is right there (there are other apps for that so no ASCOM isn't essential).

 

At that point, if he want's MORE, he could modify open source ASCOM (Nathan said from the start he's willing to program if necessary).  Perhaps he wants to do more, like say "I want to enter the area of the  lpanaorama, the size of my camera/ lens ( the size of ONE pic), and hit enter, and it does everything from there on out.  It's up to him, but since his first post I have thought of (as well as opened) Stellarium with regard to what it can,  and I thought of some fantastic things he could achieve- assuming he's open to doing some serious programming or MONEY he wants to spend

 

Finally, with my 'approval' for the AZ Pro and my mention of it having ASCOM, the intention is if it DOESN'T prove to he the turn key solution he'd like, he has the fallback of using ASCOM for communicating with the mount.  Nice thing about ASCOM, you don't need to know anything about the driver if you only want the mount to move. 



#15 OzAndrewJ

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Posted 19 July 2020 - 11:59 PM

Gday rk2k2

 

At that point, if he want's MORE, he could modify open source ASCOM

If we are talking Meades, then nearly all the old drivers are written in now unsupported languages

hence why they dont work with some of the newer models, and arent easily "tweaked".

If he only wants simple terrestrial AltAz ability, the ASCOM is probably an overhead he doesnt need.

ie you can sit a camera on a rock and get good "startrails"   :-)

We can offer possibilities, but only he can tell what suits his needs.

Based on what he is proposing, i would think a synta mount on a bodged mount would be ideal

as you get to control the motors at a very low level, ie you can do what you want.

 

 

Nice thing about ASCOM, you don't need to know anything about the driver if you only want the mount to move.

In theory, yes, but many drivers dont always do what you want.

As noted, i just dont know how well the Meade drivers handle terrestrial mode work.

Most are written "assuming" you will be using it for astronomical work.

 

Andrew Johansen Melbourne Australia


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#16 rk2k2

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Posted 20 July 2020 - 08:06 PM

Nathan,

 

after considering what possible telephoto you may be speaking of, I figure it must be at least a fast 300mm up to an 800mm.  Based upon that and a 'reasonably possible' panorama up to only 180 X 30 degrees, you're talking a panorama of 500, 1000, 2000 shots or more.  So either you are a patient saint willing to do that manually or the obvious, you want it just as automatic as a GigaPan.

 

With that assumption, if it were me (a happy Losmandy owner), I'd look hard into what eblanken suggested, which BTW, in my eyes would make a very clean and beautiful platform:

 

 

Hi NATHANM,

 

Interesting need you have that is "opposite" of mainstream astronomy community. Have you considered starting with something like a Losmandy AZ8 Dual Alt./Az. Mount and add your own motors and controllers ? That would give you a solid mount that could handle any task up to 30 pounds of payload on each side. You would have a simple task to give you all the control that you desire, but none of the "working against" the bias that astronomers bring to the table with RA & Dec. coordinates that are always "spinning" relative to the earthbound co-ordinates you want to work with. Maybe you could whip up a Raspberry Pie that could do the interfacing easily ?

 

Just some thoughts,

 

Ed (aka eblanken)

Cost would probably be between $1500 and $2000, plus your time.

 

The AZ Pro with 2" tripod is $1300 and who knows what time and possible aggravation you might have to 'invest'.  Ignore my 'on the cheap' ideas, go for the gusto!  (But of course before you make the plunge, investigate other alternatives).
 



#17 luxo II

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Posted 20 July 2020 - 08:40 PM

I am looking for a mount that can be programmed to go to alt-azimuth positions.

 

That is NOT the same as a "go-to" mount, which typically means RA, Dec positions to find an astronomical object.  

 

This is for making a terrestrial mosaic (panorama) which includes the sky.  

Another gadget that does this was the Skywatcher All-View mount https://www.bhphotov...View_Mount.html

 

It's an ugly duckling and much overlooked IMHO  - but it does work well and includes several brackets for attaching cameras.

 

Having had one I can say the mount itself is fine, though the tripod supplied is too flimsy - with a big heavy lens or a 70mm scope there's a fair bit of flexure when it slews. Solve that though and its good (I put mine on a larger steel tripod with 2" legs).

 

if you are prepared to do some DIY surgery to motorise it, the Hercules mount is a candidate - https://www.aliexpre...2950373036.html - the belts are driven by a simple pinion with 6mm shafts; replace these with a small gearbox and motor (see for example www.pololu.com). The belts provide 8:1 reduction.

 

Beyond that, if you want something more substantial, there is the Rowan Astro AZ100 which can also be motorised, this would be easier IMHO than the Losmandy AZ8.


Edited by luxo II, 20 July 2020 - 08:48 PM.


#18 nathanm

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Posted 21 July 2020 - 12:01 PM

So either you are a patient saint willing to do that manually or the obvious, you want it just as automatic as a GigaPan.

 

I neither patient, nor a saint, so YES, I want to do this automatically as with a Gigapan.

 

I have a Gigapan and also Roundshot, another panorama mount.  They are too lightweight even for a 200mm telephoto.

 

I have also built my own panorama mount using precision rotary stages, and have written the software to drive it to Alt, Az positions.  But mechanically, that mount was also built for shorter lenses.   

 

The idea of using a Losmandy mount as the base and motorizing it is definitely one approach to the problem.   It has two drawbacks that I was hoping to avoid.

 

First, you can't put the entrance pupil of the lens (sometimes called the "nodal point" or "no parallax point") at the center of rotation  http://www.janrik.ne...rallaxPoint.pdf

 

That is necessary to prevent parallax in panoramas taken with the mount.    

 

A fork-style Alt - Az mount does have the center of rotation at a place where one could put the lens entrance pupil.    So I would prefer that.    A single arm offset fork - like a Wimberly gimbal head for telephoto lenses https://www.borrowle...-a-gimbal-head/, would also work in that regard, except that they are neither motorized or gear driven so are more difficult to modify than an astronomical mount which is usually both.

 

For a long lens shooting foreground which is far away, the amount of parallax caused by the Losmandy Alt-Az mount (or similar mounts by Stellarvue, Rowan and others) may be tolerable, but I am hoping to find a one or two armed fork mount.

 

The second problem with this approach is just laziness on my part - I was hoping I could buy an already motorized mount without going through the hassle of motorizing it.   I say this because having built a mount from scratch, I know what it takes.

 

There certainly are dozens of motorized Alt-Az mounts on the market - it is just a question or getting the right programming access.    

 

However, I would rather motorize a manual mount than try to reverse engineer what happens inside an integrated product.  So I have looked at various motorization kits.

 

The good news about motorizing a manual mount is that I already understand how to program stepper motors to get what I want.

 

I don't entirely follow the suggestions that I play with Stellarium to enhance my creative thought process. 

 

Ideally I want a mount that supports an Alt-Az go to command.   

 

The Sky Watcher AllView looks like a possible candidate.  It might, or might not be sturdy enough.   It is a single arm fork so it might be possible to get the entrance pupil over the axis of rotation.  

 

I would classify the Sky Watcher AllView as an integrated product that  I probably do not want to reverse engineer.  So it comes down to this - does it support  Alt-Az go to?

 

I want to thank everybody for the responses so far!


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#19 nathanm

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Posted 21 July 2020 - 12:07 PM

The Hercules mount is kind of cool, and would be a candidate for modification except for the parallax issue mentioned in my post above.   

 

If the attachment point to the telescope is on the wrong side of the azimuth drive.

 

Thanks for the suggestion!



#20 rk2k2

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Posted 21 July 2020 - 01:57 PM


The Sky Watcher AllView looks like a possible candidate.  It might, or might not be sturdy enough.   It is a single arm fork so it might be possible to get the entrance pupil over the axis of rotation.  

 

I would classify the Sky Watcher AllView as an integrated product that  I probably do not want to reverse engineer.  So it comes down to this - does it support  Alt-Az go to?

 

I want to thank everybody for the responses so far!

From what I hear from people, Skywatcher makes great products.  I've also looked at GigaPan and they also look like great products.  So you having one and having on hands experience, I'll have to take you're word they (or at least the one you have) have trouble with even a 200mm lens. When you mentioned telephoto panoramas and weight issues I was thinking  something more than a 150-600mm with DSLR (what I have)  or some prime with comparable weight.  Mine total weighs just under 10 lbs (without scope rings and dovetail) so I would have thought a GigaPan would handle it.  Sounds like it's not the weight issue, its the length GigaPan can't handle?

 

Maybe the AllView is more stable but the 2 have the same rated payload capacity. 
 



#21 nathanm

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Posted 21 July 2020 - 02:18 PM

The gigapan (epic pro, largest model) has a very shallow fork.    

 

The shallow fork means it can't point very high in the sky for a long lens - the camera end hits the control unit.

 

You can sort of see the problem in this photo I found online  https://i.ytimg.com/...xresdefault.jpg  . The telephoto works at the inclination it is at in the photo, but if the guy in the photo tried to incline the head to say 40 degrees, the camera would hit the control unit.

 

This even happens with a long wide angle lens.  With the Samyang 24mm f/1.4 lens, positioned with the lens entrance pupil at the center of rotation, I can't point higher than about 45 degrees altitude.


Edited by nathanm, 21 July 2020 - 02:23 PM.

  • rk2k2 likes this

#22 OzAndrewJ

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Posted 21 July 2020 - 03:57 PM

Gday Nathanm

 

but I am hoping to find a one or two armed fork mount.

Based on wanting to remove parallax, the best fit Meades will be the LT or LX65s ( one armed forks )

that you could knock up a simple cradle for.

I recon there are probably a few LT bodies around second hand you might get cheap??

 

Andrew Johansen Melbourne Australia.



#23 rk2k2

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Posted 21 July 2020 - 07:59 PM

Purchased for the 2017 eclipse, a Manfrotto 393 to handle my 150-600mm lens.

 

Manfrotto-393.JPG

 

 

I thought, why I can attach TWO cameras for the eclipse, just buy another mounting plate (not there now)  just have to swing it 'on top'.  So I had a camera on top, one on the bottom, AND a video camera mounted on the side- that I forgot to turn on!:

 

Manfrotto-393-swung-up.JPG

 

Wishful thinking to believe it would fit inside a GigaPan (8.75" w).  Perhaps the GigaPan can be altered in such a way to 'put on top'?  Else I am pretty certain you could jury rig something, or even have the necessary metal fabricated for $100 - $200.  At least to test.  An issue you might have is with the Y axis (elevation) torque ability to hold the mass in place.  From what I understand what you want (your no parallax point), you'll need counterweight any way when you have such an unbalanced setup.

 

Just a riser bloc was my first thought but your no parallax requirement applies to BOTH axis, correct?



#24 luxo II

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Posted 21 July 2020 - 09:22 PM

rh2k that cannot be motorised...



#25 luxo II

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Posted 21 July 2020 - 09:32 PM

 

The Sky Watcher AllView looks like a possible candidate.  It might, or might not be sturdy enough.   It is a single arm fork so it might be possible to get the entrance pupil over the axis of rotation.  

 

I would classify the Sky Watcher AllView as an integrated product that  I probably do not want to reverse engineer.  So it comes down to this - does it support  Alt-Az go to?

I used one of these for a while as a grab-n-go rig with a 70mm APO and knew it quite well. IMHO its quite a bargain at its price point, trying to assemble the equivalent in any other way will cost a lot more.

 

If using a camera, yes the brackets supplied with the SW All-View do allow you to position it laterally over the axis of rotation. However, there is no means to axially slide it (lengthways) to get the front node over the axis - this means as it rotates, parallax issues will be visible for foreground objects.

 

It does support altazimuth GOTO, both in panorama mode and when used astronomically. 

 

The Synscan handset for this also includes a key feature - "Daylight alignment" which was specifically added for the 2017 solar eclipse. This allows the mount to calibrate its azimuth bearing using a single celestial object (Sun, Moon, Planet or any bright star in its catalog) and from that it will track the sky reasonably well, provided the base has been accurately levelled, and you have entered the correct position (longitude, latitude) and local time. Note that errors in levelling, position or time will translate to errors in GOTO position and produce drift in tracking over long time intervals.

 

Even with a camera doing astro shots, if you centre an object in the camera and use that to calibrate, subsequent GOTO's will work well.

 

Lastly - if you want to do panoramas and parallax is an issue for you, you will need to make a slide of some sort to shift the camera back to put the entrance pupil (ie the front node of the lens) over the axis.

 

There is a gadget that does this - Jasper Engineering's Pano head https://www.stereosc...r/panorama.html

I have one of these and use it for panos, it does do a great job - with this stitching is remarkably accurate and quick.

 

You could cannibalise the nodal slide from one of these, bolting it on the All-View via an L-Bracket on the V dovetail.


Edited by luxo II, 21 July 2020 - 09:40 PM.



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