Starsense telescopes versus phone apps.

[col]

I was just wondering if the Starsense type scopes are just a version of an app? and the phone doesnt have any connection to the scope, other than held in place with a mount?

Im thinking if mounting a phone to any scope and using one of those apps that shows you whats in the sky as you point in real time does similar. Or am i missing something?

[DaveL59]

The phone isn't linked into the scope per se, but the holder the phone sits in has a mirror to allow the camera to see the sky so the app can analyse where it and the scope are pointed, then give you directions to guide the scope toward the target you want to look at next. You can do similar with another app, SkEye which doesn't use the camera to analyse so isn't quite as accurate, depending on phone and conditions. 

For the starsense one you do need the app unlock code for the feature to work and that's only available with a starsense scope. Several of us did go buy the cheapest one and either transferred the phone carrier over to another scope or DIY'd our own carrier to suit. In my case I used a prism from a dud 10x50 binocular rather than a mirror and it works just fine.

[Peter Drew]

I bought two of the entry level StarSense refractors and have made fitments to attach the system to 10", 17", 20" and 30" Newtonians.  Not had chance to try either yet but hopeful for the outcome.

The StarSense mirror is considerably larger than a prism from a binocular, I'm surprised that it presents enough of the sky for the app to obtain its "fix".       🙂 

[DaveL59]

6 minutes ago, Peter Drew said:

I bought two of the entry level StarSense refractors and have made fitments to attach the system to 10", 17", 20" and 30" Newtonians.  Not had chance to try either yet but hopeful for the outcome.

The StarSense mirror is considerably larger than a prism from a binocular, I'm surprised that it presents enough of the sky for the app to obtain its "fix".       🙂 

seems to work just fine Peter, not noticed any real difference in time to get a fix. @johninderby used a prism diagonal on his DIY version and that also works well and a cheap alternative if you don't happen to have a bunch of spare/dud binos to steal parts from 😉 

Some on CN I believe even used shaving mirrors to good effect, I did try the long thin mirror that fell off one of those collapsible travel hair brushes and it also worked well but preferred the prism solution for neatness in the DIY carrier I knocked up.

Edited August 25, 2022 by DaveL59

[markse68]

On 25/08/2022 at 20:14, Peter Drew said:

The StarSense mirror is considerably larger than a prism from a binocular, I'm surprised that it presents enough of the sky for the app to obtain its "fix".       🙂 

I think you’d see vignetting in the image if the prism were too small- i’m using a fairly compact prism but needed to find one that was silvered as without got some internal reflection leakage vignetting. I think the mirror is large on the celestron mount to cater for different phones and mounting distance from camera lens?

Starsense is pretty cool Peter. My only issue is the phone i made the adapter for is ancient and doesn’t hold charge so have to run it from a powerbank.

Mark

[DaveL59]

Hi Peter, if you take a stroll thru this thread it covers what John and I had done when adapting ours and then building our own mounts

I blacked the prism sides as well as created and extended hood similar to the OEM mount to reduce any stray reflections and it works fine. Used a prism from a very old japanese 10x50 as its larger, the smaller porro prisms in something like an 8x30 were too narrow, tho perhaps from an old Zeiss pair that may work. Since the phone camera is only a couple mm from the prism edge, vignetting wasn't much of an issue, what there was didn't affect the ability to analyse the sky. John used a cheap mirror diagonal (poor memory as I thought it was a prism) on his.

[markse68]

Regarding @col’s original question, I haven’t tried skyeye or similar but do wonder how accurate they can be. Maybe they are better at utilising the IMU in the phone than Starsense but SS does use the IMU when the scope is moving as the platesolving needs the scope to be steady and takes a few seconds to capture and calculate. I noticed that there’s always quite a jump in the calculated position after a slew as the platesolving locks onto its position. I guess this would also vary depending on phone model.

Mark

Edited August 30, 2022 by markse68

[DaveL59]

1 minute ago, markse68 said:

Regarding @col’s original question, I haven’t tried skyeye or similar but do wonder how accurate they can be. Maybe they are better at utilising the IMU in the phone than Starsense but SS does use the IMU when the scope is moving as the platesolving needs the scope to be steady and takes a few seconds to capture and calculate. I noticed that there’s always quite a jump in the calculated position after a slew as the platesolving locks onto its position.

Mark

SkEye does work reasonably well, but it needs a phone with good sensors, low interference of the sensors which can be problematic with a steel tube scope, electrical equipment etc. Often you can improve its effectiveness by doing the "swing the phone about in a figure-8" before using it. You can set it up to have the phone vertical to the OTA or laying parallel like the starsense (indirect mode) and I was playing with this before Starsense came along. You do of course need a suitable holder and mounting for it.

Found the thread on it:

 

[Louis D]

In my experience, SkEye gets me within a few degrees of the target each time running on an old Galaxy S7.  Once centered, I then realign and it's a bit better for the next target in that region.  Once in the general vicinity, I'm usually good to go finding it in a widest field eyepieces or a RACI.  I can zoom the screen view to see what the immediate neighborhood looks like and match it to the eyepiece view.

I have an aluminum phone holder on a cheap ball mount that doesn't seem to interfere with it:

[markse68]

Will have to try SkyEye out and see how it compares. What's that mount Louis?

Mark

[Louis D]

I cobbled it together from parts I had lying around from previous projects.  The Synta/Vixen finder foot, mini ball head, and cellphone mount all came from ebay back when supply chains were good and prices and shipping from China were quick and cheap.  I couldn't find the exact same phone mount I bought.  The new ones are all plastic, which is probably best for SkEye usage.

I removed the central thumb screw from the mount, discarded the eyepiece clamp part, and screwed it directly onto the ball head where a camera would normally sit.  Luckily, the mount used a standard tripod thread of 1/4"-20.  I can't guarantee the mount I linked to would as well.

Next, I threaded a 1/4"-20 hex socket head cap screw up through the finder foot into the base of the ball head.  I don't recall the exact length since I again had some sitting around, but it was probably about 1/2" to 3/4" or thereabouts.

Edited August 30, 2022 by Louis D

[markse68]

Nice  

And the alt az-mount ?

 

[Louis D]

The alt-az mount is a DSV-2b on a Manfrotto 058B tripod.

[markse68]

Nice!