Sky Rover Solar Prism 1.25”

[Jim L]

I recently received a 1.25” SkyRover Solar Prism, for which I paid $214 U.S. shipped to my residence in Northern California. The solar prism is manufactured by Yunnan Tianhu Optical Technologies under the Kunming United Optics (KUO) house brand Sky Rover, which might or might not be associated, affiliated, subcontracted by, or a part of KUO.

Here’s what arrived at my doorstep this morning after 15 days from placing my order:

 

So well packed and protected in a good quality cardboard box within thick, dense, foam. Unable to read Standard Chinese, I have no idea what the documentation is about beyond the small middle pamphlet which contains, I suppose, a description of the solar prism features. If I were to guess, the documents to either side are concerned with providence and quality assurance, but that’s just a guess.

The light and compact body of the solar prism appears to be manufactured and machined from a single piece of aluminum extrusion purpose designed and made, and from which are attached the aluminum nosepiece, rotatable filter holder assembly, translucent ceramic heat dissipater, and eyepiece holder. Aluminum side plates affixed with three 1.3mm machine screws each provide access into the body of the solar prism when removed.

 

We’ll dig a bit into the guts in the next post or two…

 

 

Edited May 26 by Jim L

[Jim L]

Removing the eyepiece holder reveals the rotatable filter holder containing, nosepiece side first, a ND3.0 and CPL (Circular Polarizing) filter. The thumbscrew prevents or allows rotation of the filter holder as required to allow the CPL filter to adjust light throughput.

 I was very keen to be able to permanently install a IR/UV filter within the solar prism, for which purpose I chose the very inexpensive but reputably quite effective SvBony piece. The following photographs show the filter holder before and after installation of the IR/UV cut filter, which threads directly into the underlying CPL filter.

With the eyepiece holder, which is of the brass sleeve type, reinstalled there is 24mm distance between the top of the holder and the IR/UV filter substrate. The filter body also provides an effective barrier between an inserted eyepiece nosepiece and the filter glass.

Removing a side plate provides access to the wedge prism for cleaning or other maintenance. Also visible is the side of the ceramic heat dissipater which is fairly thick and should be quite durable.

The fully kitted solar prism, with the IR/UV filter and dust caps installed, weights 200 grams.

The assembly, with eyepiece, ready for viewing.

The next post will address, albeit incompletely, optical quality and overall impressions…

[Jim L]

Ok then, my semi-final contribution to this thread, and arguably the most important.

Let me first begin by saying that by the time I had taken the photos, installed the filter and 12mm eyepiece onto the GSO John Wall style focuser, and moved everything outdoors and under the sun, the weather had grown blustery and the sun had a pronounced moisture haze encircling it. Never mind; onward!

The view through the solar prism was very promising and in brief moments of relative calm very good detail, including hints of granular features, could be observed. At this point not much more can be said concerning optical quality except that I expect that better seeing and transparency will likely reveal detail similar to that of the excellent 2”Baader Cool Wedge Solar prism, but in a package a small fraction of the size and weight and compatible with my 1.25” Takahashi focusers.

I played with the externally adjustable CPL which provided a range of infinitely adjustable brightness between slightly too bright to slightly too dim, which tells me the designers got the various optical components correctly matched to provide the most useful range of light throughput for most visual observations.

Concerning manufacturing, fit, and finish, all are excellent in the manner the APM 30mm UFF is excellent.

I will reserve final judgement on the SkyRover Solar prism until I’ve had more time looking through it under more favorable conditions, but in the meantime those interested can find it for sale here under the Starfield branding from the forum sponsor First Light Optics:

https://www.firstlightoptics.com/solar-filters/starfield-125-herschel-solar-wedge.html

 

Cheers!

Edited May 26 by Jim L

[Highburymark]

Nice review Jim - thanks for posting it.

[JeremyS]

Very interesting review. Will be keen to hear more when you had a chance with better conditions.

If you really want to read the Chinese instructions, simply use Google Lens and point the camera at the page. It will translate in real time.

[Chaz2b]

I would be extremely interested in a side by side comparison against the Lunt Herschel wedge 1.25”, as I have one, this sounds promising.

chaz

[JeremyS]

2 hours ago, Chaz2b said:

I would be extremely interested in a side by side comparison against the Lunt Herschel wedge 1.25”, as I have one, this sounds promising.

chaz

I thought the Lunt was a premium device. Is there something you don’t like about it that you seek in the Sky Rover?

[Louis D]

So, maybe I'm a bit thick headed, but how do you rotate the CPL after loosening the thumbscrew?  Do you grasp the knurled ring and rotate it?  Doesn't that also rotate the eyepiece holder, or does it stay put somehow?  If so, this wouldn't work very well with binoviewers.

I'm wondering if KUO also made my Hercules Herschel Wedge due to the similar appearance.

Edited May 26 by Louis D

[Jim L]

I’ve had an opportunity to observe through the SkyRover Herschel wedge this morning and I’m now in a position to comment in it’s optical performance. But first, some book keeping:

Following Jeremy’s suggestion to use Google Lens to translate the Standard Chinese I discovered that the two documents I’d speculated about are a quality inspection and one-year warranty. Next, I discovered that the solar prism is manufactured by Yunnan Tianhu Optical Technology, which may or may not be associated, affiliated, or a part of KUO. I apologize for my unsupported and very possibly erroneous attribution of provenance, and have corrected the original post.

Louis, the eyepiece holder DOES rotate when you adjust the internal polarizing filter, so bino users will need to loosen the eyepiece holder’s grip on the bino nosepiece when making brightness adjustments.

We all love photos of new optical gear disassembled in flagrant contravention of the warranty terms and conditions, so here are some of those:

Yup, it’s a bonafide wedge prism in there, and my observations this morning suggest it’s of excellent quality.

Speaking of quality, I did a side by side comparison of the SkyRover Herschel wedge with a 2” Baader Mk II Herschel wedge using a Celestron 102 AZ achromat refractor and a SvBony 135 7-21mm zoom with, and without, a GSO #56 green filter. The sun was low, about 25°, transparency was fair, and winds were 25 mph gusting to 30 mph. Seeing seemed fair to almost good. With this equipment, and under these conditions, the views through the two solar prisms were very nearly identical in sharpness and contrast. Very nearly so in that the Baader was perhaps 2% better, though I suspect, although unverified, that the difference had more to do with the difference between the $11.95 GSO #56 filter and the $199 ($119 in 1.25”) Baader Continuum filter than the wedge prism.

I imagine that outfitted with equivalent ND3.0, CPL, IR/UV cut, and 7.5nm Continuum filters there would be no discernible difference between the Baader and SkyRover solar prisms. Pure speculation on my part, but given the differences between the optical components of the respective solar prisms, and the very minute differences in the views through them, I think my supposition reasonable.

Let’s compare the two prisms size and shape:

Pros go to the SkyRover for ease of use and lightweight mount and tripod friendliness. The SkyRover did not exhibit any sign of excessive heating, or indeed any sign of heating at all in my 102mm refractor, but the Baader is said to be capable of handing the light input through a larger refractor, so we’ll give that pro to the Baader.

This last photo I post with great hesitation. It’s a view through the SkyRover through my ancient hand-me-down Apple phone camera, and worst yet, significantly obstructed by a cypress tree the sun inconveniently ducked behind unnoticed. With those caveats, and keeping in mind the actual view, unimpeded by the dense foliage of a tree, was an order of magnitude or more better, here goes:

Too bad I botched the photo, but it’s all I’ve got. Feel free to ignore it as unrepresentative of the SkyRover’s extraordinary capability.

Y’all now know about as much about the SkyRover/Starfield 1.25” solar prism as I do. I unhesitatingly and unequivocally recommend this solar prism for anyone interested in a light, compact, and very well designed and made prism at a reasonable price.

My last and final comment is that because the SkyRover prism is of the wedge design rather than the right-angle design used in the Hercules solar prism and it’s analogs, there is a significant improvement in contrast between the former and the latter. The sky behind the SkyRover is completely black, while the sky behind the Hercules has a distinct glow for some distance from the sun. The difference is such that it’s immediately apparent and obvious.

 Cheers!

Jim

 

Edited May 26 by Jim L

[Don Pensack]

Tianhu is a big maker of astro goods in China, but is not KunMing United Optics, so it is likely a sub-contracted piece made for KUO under their Sky Rover house brand.

Edited May 26 by Don Pensack

[LondonNeil]

What thorough reviews,  thank you.   It seems worth considering unless you are chasing the very very best!  

BTW, I've read the hercules wedge is designed for imaging and unless modified to change the filter its not suitable for visual