Simulate Alt/Azm movements in Equatorial mounts?


Patrizio Boschi
 

Hi, maybe it's a stupid question, but is it possible to just be stupid and simulate the Alt/Azm movement in Equatorial mounts?

So when you press "N" on the SHC, instead of going "N" and move the DEC axis, it just goes "UP" (towards zenith) moving both axes using some math for coordinate transformation. "S" would go "DOWN" (towards nadir/horizon), "W"/"E" would go left and right on the sky's circle of latitude (or whatever it's called in english).

Does OnStep already include some math/logic functions to do that?

(...And why nobody wants it? Sometimes I just want to relax with visual observations, then I just want to watch "a bit on the left" in respect of the sky when I watch it with naked eyes, and it's very hard to decide what to do when the telescope inverts some directions, the finder inverts some directions, the SHC inverts some directions, then you change position around the telescope, then you change hand which holds the SHC, the RA/DEC axes rotate around invisible references, the brain is freezing, etc. In fact I can do that, but I also would be dead at the first turn if I had to apply the same logics when driving a vehicle.)


kevin_kevin_kevin@...
 

This may or may not be what you are trying to do.
I have just started  used Stellarium to control Onstep via the usb  and using lx200 mode or ascom.
I am new to all this so other progs may do it as well but Stellarium gives you a nice variable "virtual" view of the sky as a hemisphere. It  takes a little getting used to but with the horizon in ( you can even add a wraparound view of your own site). if onstep is set up correctly you can just click on a star and tell the telescope to go to it. if you zoom in an make it central ( space bar) then you can just click the next star over  and go to it. 
Stellerium doesn't give you a cursor pad but is you use Ascom you can then use "Ascom device hub" to give you cursor controls and i have even uses Sharpcap with ascom at the same time to get a second set of cursors. Sharpcap is connected to a couple of cameras as a wided view and a finder on the laptop and jus visual or another camera on the main scope.
I havn't found one yet but there is probably a Ascom hand controller , i may also have a go at using a USB numberpad just to get the keys i want mapped to the appropriate buttons.

Unfortunatly with an equatorial mount my understanding ( may be wrong , all new to me) is that at certain positons "just moving a bit left" actually needs the scope to move up to the celestial pole to flip sided of the pier and then come back down again. i still havn't got my mind clear on that bit .

It may be a silly idea, i was thinking as it for using my EQ for terestrial daytime  as well as stars,  but i was was considering   a "reverse wedge" . normally you add a wedge to an AZ to turn it into a EQ. should be able to  add a "wedge" so the polarscope points straight up? normal mounts wouldn't give the adjustment but  i have access to a EQ5 so it w"should " just be a couple of plates at the correct angle in between the tripod and the mount ( the OTA may hit the legs though at high angles ) .   maybe you can get fabricated a bit of metal to take the offset out (i.e 90 - latitude). Tracking wouldn't work with that though, but it may give you the effect you wan't, i am not sure.


kevin_kevin_kevin@...
 

Another thought. Within the EQ mount restrictions i have no idea if the guiding port  controls would give you the  correct directions locally or if they set to move reasonable distances.?


Robert Benward
 

Patrizio,
Rotate your RA axis to the vertical and you're all set.  Or get a Dob.  

Once I did the reverse. I had an iOptron cube, but the older alt/az only model.  I just told it I was at the North Pole, and then tilted the cube's azimuth axis to my latitude.  It worked well enough that I modified the hand controller to accept ST4 commands and I was able to take pictures with it.

Bob


Patrizio Boschi
 

Hi, thank you all for the replies.

I understand the "reverse wedge" or align RA to zenith thing, but that practically disrupts the possibility to use the EQ mount for other "regular" things during the same session. I would like to keep the mount correctly aligned to celestial pole (because it's an EQ mount) AND be able to decide to move the scope using the hand controller with either RA/DEC or Alt/Azm logic - I mean, to decide it on the fly with a flip of an option. In fact you can already do that on some stellarium programs.

The controller (OnStep for us, but also the commercial ones) should understand that if you want to move "up" it just needs to move the two axes in some manner, and even to do a flip if you are reaching physical limits. It's already doing it whenever you do a GoTo. It just seems to me that the correct LX200 commands are missing, as we have:
  • :Mn# Move north
  • :Ms# Move south
  • :Me# Move east
  • :Mw# Move west
  • :Mp# Move in spiral manner
  • :MA# Move to Az/Alt coordinates
  • etc
But we are missing:
  • :Mu# Move up
  • :Md# Move down
  • :Ml# Move left
  • :Mr# Move right

I've checked OnStep code, and I think the commands could be added and I would like to have the time to try to implement them - I'm however still missing the math step to transform an "Up" command to 2 coordinated guide commands on RA/DEC axes (considering the eventual limiting speeds etc). In fact I see that an even more complex thing was implemented for Spiral Search, so I don't think it isn't feasible (but again I'm missing some of the math).

It's not a critic to any mount controller, I just don't understand why a similar basic function was never implemented by anyone in the world in any mount controller. It's the first thing people want to do when using a telescope - to move it reliably by hand around the human-undestandable reference points.


Kind regards,
Patrizio


 

On Mon, Nov 22, 2021 at 07:27 PM, Robert Benward wrote:
Rotate your RA axis to the vertical and you're all set.  Or get a Dob.  
The Skywatcher AZ-EQ6 Pro (and some other mounts) has this capability.  Essentially, you crank the altitude screw until the RA axis goes vertical.  But it doesn't use OnStep, does it?  


Chris Whitener
 

"Turn Left at Orion"  is a wonderful book.  I understand the question.  I started writing code to work directly with hardware 50 years ago, but I picked up astronomy only a year ago and have been trying Astro photography for 6 months.  I started with a very popular up/left kind of mount from Celestron 8se.  It has to translate its up down left right movements to Equitorial.  I bought a wedge to try to understand the polar alignment thingy.  Then I lucked into some nice EQ mounts and then to Onstep.  After spending a fair amount of time with these systems I realize they are all doing the same thing.
Think of the mount as a peripheral to a computer system.  Like an astronomy camera, it does its specialty very well.  You could jam all the autofocus systems of a DSLR into it, but....

My feeling is that what you want is very reasonable and many manufactures have provided it.  Sky Watcher even makes mounts that can switch from EQ to Alt/Az.  However my suggestion is to do it in either a hand control or an attached system.  the mount needs to (for most purposes) be really good at tracking slowly to image the sky.  Translations of direction and coordinates are better in the User interface.  I don't typically issue serial commands directly. But a hand control like the ones from celestron, orion et.all. can and does offer all sorts of translations and even plate solving.  An app could easily figure out where "Orion" is and move left......


Howard Dutton
 

On Tue, Nov 23, 2021 at 01:12 AM, Patrizio Boschi wrote:
It's not a critic to any mount controller, I just don't understand why a similar basic function was never implemented by anyone in the world in any mount controller. It's the first thing people want to do when using a telescope - to move it reliably by hand around the human-undestandable reference points.
I don't see that I'd ever add this feature to OnStep.  I'd be more inclined to add code to (optionally) have Alt/Az guide on the equatorial coordinate system; wonder how PHD2 would react to that.


Khalid Baheyeldin
 

On Tue, Nov 23, 2021 at 10:39 AM, Richard Shagam wrote:
On Mon, Nov 22, 2021 at 07:27 PM, Robert Benward wrote:
Rotate your RA axis to the vertical and you're all set.  Or get a Dob.  
The Skywatcher AZ-EQ6 Pro (and some other mounts) has this capability.  Essentially, you crank the altitude screw until the RA axis goes vertical. 
I had a Vixen GP-DX mount, and it had that same feature.
The previous owner made a small plug from a piece of wood that makes this easier, and shoved it on the base of the mount.

The handset for the mount, the Vixen SkySensor 2000 PC, had an option to change from Equatorial to Alt-Az, and it worked great.

With the new SWS, OnStep has this feature, and can change from GEM to Alt-Az.

Not exactly what Patrizio is talking about, but really close.

I am with Howard on this though: this is of limited utility and may/will confuse the applications interfacing to OnStep.


Howard Dutton
 

On Tue, Nov 23, 2021 at 09:49 AM, Khalid Baheyeldin wrote:
With the new SWS, OnStep has this feature, and can change from GEM to Alt-Az.

Not exactly what Patrizio is talking about, but really close.
The only official support for doing this exists in OnStepX which is still beta (user testing phase.)

OnStep release-4.24 and earlier can NOT switch between GEM and ALTAZM unless you flash the firmware.


Khalid Baheyeldin
 

On Tue, Nov 23, 2021 at 01:13 PM, Howard Dutton wrote:
The only official support for doing this exists in OnStepX which is still beta (user testing phase.)

OnStep release-4.24 and earlier can NOT switch between GEM and ALTAZM unless you flash the firmware.
I am still confusing 4.24 with the now defunct 5.1.

OnStepX it is ... it coming along speedily enough ...


 

On Tue, Nov 23, 2021 at 12:55 AM, Patrizio Boschi wrote:
(...And why nobody wants it? Sometimes I just want to relax with visual observations, then I just want to watch "a bit on the left" in respect of the sky when I watch it with naked eyes, and it's very hard to decide what to do when the telescope inverts some directions, the finder inverts some directions, the SHC inverts some directions, then you change position around the telescope, then you change hand which holds the SHC, the RA/DEC axes rotate around invisible references, the brain is freezing, etc. In fact I can do that, but I also would be dead at the first turn if I had to apply the same logics when driving a vehicle.)
Once you learn to navigate across the sky, and get used to it, you will see that there is nothing better than GEM and NSEW. The thing is that in the sky (nor in space) the concert of "up" or "down" is meaningless. Everything counts relative to celestial pole, because only celestial pole is always in same place. This way you only need to keep one thing in mind - where celestial pole is, and then you will exactly know which button need to be pressed.

In SkySafari app there is an option to display cardinal directions around scope which helped me a lot in the beginning when same question bothered me.