Telescope optics modification for interactive astronomy project

[Julian0]

Some of you were very helpful with removing the objective lens on my 120mm Sky-Watcher 'Star Travel' telescope. Thanks again for that! I was able to do it without destroying my telescope.

Now for a new thread relating to my project.

I am not an astronomer by any stretch, however I am concerned with the loss of visibility in our night skies. In my lifetime I have seen satellites and night lighting (esp LED) reduce my own ability to view and marvel at the cosmos. I'm making a project that will tour internationally that in a large part seeks to draw attention to this issue.

To do this, I am fitting a small circular screen into a refractor style telescope attached to a small embedded computer that shows an automatically generated starscape. By way of sensors, when moving the telescope on its axes, the generated starscape can be tracked as though looking at the real cosmos. I'd rather not go into any more specifics as to the project, so as not to derail, Rather, I'd now like to talk about the challenge I'm having regarding optics. I'm hoping that someone here that understands how refractor optics and the market for after-market lenses might be able to assist.

In short, I would like the circular screen to be in place (or in the tube, as needed) of the objective lens in a refractor telescope, visible through the eye piece. It is clear simply replacing the objective lens at location with the screen will not work due to eyepiece and objective focal points. I am wondering if replacing the eye piece lens with an alternative, such that putting the circular display in place of the objective lens, might allow for clear in-focus view of the circular screen with a 'telescope-like' viewing experience. Does this sound feasible? If not, might there be another way to do it?

Edited March 19 by Julian0
Grammar

[Julian0]

A quick follow up that I've just ordered a collection of convex lenses of varying focal depth relative to the dimensions of the telescope to play with. They'll arrive in a few days, and I'll start playing around to see what can be done.

[gajjer]

When we do astrophotography we do something similar, in that we capture an image of the night sky - but not necessarily a live view. Am I right in thinking that you want to clean this up of satellites etc and display that on a monitor screen. 

It's not really clear to me what you are trying to do. You talk of a 'screen' in the tube. Do you mean a display? And do you really want the embedded computer in the tube too? So are you trying to capture an image, process it and show the result on a display, all in the telescope tube?

cheers

gaj

 

 

 

 

Edited March 19 by gajjer

[Elp]

Sounds a bit like the electronic eyepieces you get on smart scopes but I don't get the generated artificial starfield being made presented through a telescope. Why not just look at the real stars? Or use a planetarium on a computer?

[happy-kat]

Reads like viewing a dynamic planetarium at the telescope eyepiece that reflects a step back in time to what our great grandparents would see as their night sky if they were looking down the same eyepiece

Edited March 19 by happy-kat

[Cosmic Geoff]

It occurs to me that Apple's new Vision Pro smart glasses (see PC Pro magazine, April 2024 issue 355) would do what you want.  You'd just need to produce your own software, as before.  They cost $3499 though.

If you want to produce your own telescope-like device, you would need a LCD screen (120mm in diameter???) and an achromatic lens of about a quarter of the focal length of the ST120 objective (ie about 150mm) to project an image of the screen into the eyepiece plane.  Or to simplify things, just have an eyepiece that focuses directly onto a smartphone screen.  Note that a lot of eyepieces won't do this so you might have to make or modify one.

Also there are commercially available digital setting circles which will give a readout of where in the sky the attached telescope is pointing - see Nexus DSC.

Edited March 19 by Cosmic Geoff
Nexus

[Julian0]

Thanks all, no need to go into the specifics of the project, other than the optics challenge. I did some tests yesterday with a concave lens I have here and was able to get a telescope-like experience looking at my circular display in-tube, albeit at a focal length shorter than I would need. I hope my 250-500mm FL lenses coming in a few days will give me some more play, effectively replacing the objective lens with my 1080p circular display. I am enjoying learning about refractor telescope optics along the way. The project has to be done with a 120mm Sky-Watcher I have, for the overall format and look, adding an interesting layer of constraints!

Edited March 19 by Julian0