newtonian view

[Ray Andrews]

So, I was out with my tablet last night using hand-held mode, and I tapped or swiped something by mistake and ended up leaving Skeye.  When I came back to it the display was upside down.  After some fiddling around the display righted itself. 

Now, this 180 degree rotation is obviously of no use in hand-held mode, but I noticed that the rotated display was a perfect Newtonian view of the sky!  In other words, it is exactly what I'd want to see if I was comparing what I see on Skeye vs. what I see in my eyepiece instead of what I see by direct observation.  So, I'm wondering how I did that, and how I might get it back!  I couldn't duplicate it deliberately.  'Newtonian View' could be an interesting feature.

[Alva Couch]

My tablet has an "auto-rotation" feature on the tablet that can be turned off in settings. It's not in Skeye or Skeye Cam. Thus, you can decide whether your tablet is displaying in landscape or portrait and then adjust how your tablet is held. This should in theory solve your problem. Hope this helps. 

On Fri, Aug 5, 2022 at 12:20 PM Ray Andrews <rayan...@eastlink.ca> wrote:

So, I was out with my tablet last night using hand-held mode, and I tapped or swiped something by mistake and ended up leaving Skeye.  When I came back to it the display was upside down.  After some fiddling around the display righted itself. 

Now, this 180 degree rotation is obviously of no use in hand-held mode, but I noticed that the rotated display was a perfect Newtonian view of the sky!  In other words, it is exactly what I'd want to see if I was comparing what I see on Skeye vs. what I see in my eyepiece instead of what I see by direct observation.  So, I'm wondering how I did that, and how I might get it back!  I couldn't duplicate it deliberately.  'Newtonian View' could be an interesting feature.

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Alva L. Couch
18 Clinton Street
Woburn, MA 01801

[Ray Andrews]

Thanks Alva, I'll give that a try next time I'm out.  It would make a cool feature tho, no?  And dead simple to implement.

[Harshad RJ]

Thanks Alva and Ray for the ideas.

The maths of this is simple; I just need to add a rotation to the view. However, I haven't yet been able to plan the user experience around the feature.

For example, let's consider a Newtonian on an Alt-Az mount, pointed at the horizon. We expect the view in the eyepiece to appear rotated by 180° with the sky on the bottom and ground on top. This assumes that we are holding our head upright, but that may not be convenient when the eyepiece is very low. We usually also assume that the focuser is oriented such that its optical axis is parallel to the ground and perpendicular to the OTA axis. However, this need not always be the case. My Dob for example has a focuser which points slightly up, as I find it more convenient. So, I am not sure whether a rotation of 180° always makes sense.

Secondly, as the user moves the telescope in Altitude, the angle of the eye w.r.t to the eyepiece changes. I am not yet sure how to model that.

And then thirdly, there are other types of telescopes and mounts.

To keep this simple, I am thinking of the following:

When in aligned mode, add a way to rotate the map view by an angle. The app then continues rotating the map view with this angle, irrespective of the current orientation of the OTA. To be effective this requires the screen orientation to be locked to either portrait or landscape mode. The user can tweak the angle whenever required, to adjust for the angle of their heads, etc.

Does this make sense? Are there other ideas?

The next level of this idea is to let the user specify equipment details and automatically adjust the rotation angle, field of view, etc.

thanks,

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Harshad RJ

[Ray Andrews]

On 2022-08-13 20:23, Harshad RJ wrote:

Thanks Alva and Ray for the ideas.

The maths of this is simple; I just need to add a rotation to the view. However, I haven't yet been able to plan the user experience around the feature.

For example, let's consider a Newtonian on an Alt-Az mount, pointed at the horizon. We expect the view in the eyepiece to appear rotated by 180° with the sky on the bottom and ground on top. This assumes that we are holding our head upright, but that may not be convenient when the eyepiece is very low. We usually also assume that the focuser is oriented such that its optical axis is parallel to the ground and perpendicular to the OTA axis. However, this need not always be the case. My Dob for example has a focuser which points slightly up, as I find it more convenient. So, I am not sure whether a rotation of 180° always makes sense.

I suppose the first thing would be to make a trial version to experiment with.  You may have noted several problems, but a test version will make things more clear.  As it is I can only use SkEye to point the scope by direct naked eye reference.  I point my dob using a laser to the place in the sky that matches where my target is supposed to be as shown on the SkEye view of that part of the sky.  But when I try to match the SkEye view to what I see thru the eyepiece, of course the latter is upside down and I'm not smart enough to make the inversion in my mind.  In practice this means that I can only use a zoomed out SkEye view to compare what I can see with my naked eye -- accurate to maybe 30'.  Zoom in, trying to find some target in a field of faint stars, SkEye will show me the faint stars alright, but it's all upside down versus the eyepiece view.  I'm not sure, but right now I'd say that a simple 180 inversion would be effective.  Obviously this is only for Newtonians and of course you'd want to be able to switch it on and off very easily since when you go back to naked eye comparisons the inversion is no longer wanted.

Secondly, as the user moves the telescope in Altitude, the angle of the eye w.r.t to the eyepiece changes. I am not yet sure how to model that.

And then thirdly, there are other types of telescopes and mounts.

To keep this simple, I am thinking of the following:

When in aligned mode, add a way to rotate the map view by an angle. The app then continues rotating the map view with this angle, irrespective of the current orientation of the OTA. To be effective this requires the screen orientation to be locked to either portrait or landscape mode.

Yeah, that gets back to what Alva was saying.  Maybe a dotted horizon line would help.  That is, a line parallel to the horizon even when the horizon itself is not visible, just to let you know which way is up no matter the orientation of hardware.  Mind, there's already the grid but the line would be simpler.

The user can tweak the angle whenever required, to adjust for the angle of their heads, etc.

Does this make sense? Are there other ideas?

So difficult to model this in the brain!  Better make a test version and see how it goes down.  As you say, the simple 180 inversion is mathematically trivial.

==================================

The next level of this idea is to let the user specify equipment details and automatically adjust the rotation angle, field of view, etc.

thanks,

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Harshad RJ

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[Harshad RJ]

On Sun, Aug 14, 2022 at 8:23 PM Ray Andrews <rayan...@eastlink.ca> wrote:

Yeah, that gets back to what Alva was saying.  Maybe a dotted horizon line would help.  That is, a line parallel to the horizon even when the horizon itself is not visible, just to let you know which way is up no matter the orientation of hardware.  Mind, there's already the grid but the line would be simpler.

The bulls-eye reticle has lines that indicate the orientation of the horizon. See the lines connecting N-S and E-W (which of these is shown depends on where you are pointing). Mentioning it because they are easy to miss, especially when the opacity of the reticle is set low.

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Harshad RJ

[Harshad RJ]

On Tue, Aug 16, 2022 at 12:21 PM Harshad RJ <harsh...@gmail.com> wrote:

The bulls-eye reticle has lines that indicate the orientation of the horizon. See the lines connecting N-S and E-W (which of these is shown depends on where you are pointing). Mentioning it because they are easy to miss, especially when the opacity of the reticle is set low.

Ooops, sorry, these lines are not always parallel to the horizon. (They are based on the great circle passing through the center of the view, but what we want is the small circle parallel to the horizon). The Alt-Az grid will give a better idea of the horizon.

Aside, the grid lines can look a bit confusing, because both line directions have the same color. I will try to draw the grid lines parallel to the horizon in a different way.

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Harshad RJ

[Ray Andrews]

On 2022-08-16 00:00, Harshad RJ wrote:

Aside, the grid lines can look a bit confusing, because both line directions have the same color. I will try to draw the grid lines parallel to the horizon in a different way.

I don't normally use that Alt-Az grid because it gets to be a mess when the celestial grid is used too -- they 'fight' for my attention.  The more I think about it the more I like the idea of a simple line that is always bisecting the screen and is always parallel with the horizon.  Optional of course.  Even then I'd bet the simple rotation of the screen 180 would be very useful all by itself.

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Harshad RJ

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