Astro-Rubinar 100

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Brand and Model:Astro-Rubinar 100
Price ($USD):$349.00
Attributes: un-checked Go-To un-checked PEC
Aperture:106mm (4.2")
f Ratio:f/10
Focal Length:1000mm
Electric Power:none
Weight (lbs):5 lbs.
Dimensions (w/h/d):
Description:The ASTRO RUBINAR 100 MAKSUTOV is a highly versatile, very portable telescope manufactured by LZOS of Russia. This scope has absolutely superb multicoated and enhanced optics. The Astro Rubinar 100 fullfills the design intent of a flat field Maksutov and is "diffraction limited." This compact, portable telescope easily outperforms many of the popular mass-produced Mak-Cass, Schmidt-Cass telescopes and even refractors in the 90mm to 125mm class. It is the lowest cost, high quality Maksutov-Cassegrain on the market today!

Vote Highlights Vote
Astro-Rubinar 100
(What follows is a shortened version of the full review which will soon appear on Cloudy Nights. The full article is currently undergoing a peer-review).

Overall Assessment: The Astro-Rubinar is a camera lens that, due to the nature and quality of its construction, functions well as a telescope.

System Evaluated:
-106 mm clear aperture.
-F10 – 1000mm when used “straight-through” near the visual back. F15 (1600mm) when used with a 90 degree mirror star diagonal and depending on the eyepiece.
-OTA is about 7 inches long and weighs just over 5 pounds (2.5 kgs).
-focusing is done by rotating the OTA.
-central obstruction: 13% by area, 34% by diameter

Accessories: (included by ITE)
-screw on metal dew cap/light shield
-full aperture dust cap
-screw on visual back dust cap
-screw on visual back (needed to use 1.25 inch accessories)
-¼-20 camera tripod fitting on an OTA encircling ring next to the visual back
-three full aperture screw on filters (green, red, neutral)
-45 degree erect image diagonal
-32mm fully coated plossl
-soft padded case
-instruction manual
-certification of ¼ wave-front accuracy

Other Components Evaluated:
-Astro-Rubinar as described above
-accessories as described above
-Orion Min-EQ tabletop mount
-cg4 tripod with wood adaptor plate to allow use of mini-eq on top
-Orion EQ-1M single axis drive
-Orion EZ Finder II pointer
-eyepieces: 32mm ITE plossl, 17mm Celestron Nexstar plossl, 12.5mm University Optics orthoscopic, 7mm UO ortho., 4mm UO ortho.
-Celestron mirror star 90 degree diagonal
-Ocular Filters: neutral, light orange, light yellow, medium yellow, light green, light blue, diffraction grating
-full aperture Baader film solar filter

Outward Appearance of the Astro-Rubinar system:
The Astro-Rubinar is a catadioptric design; but it is not a Maksutov or Schmidt telescope. The system includes three full aperture lenses, a primary mirror, a rear surface secondary mirror and a small field flattener lens. The secondary mirror is affixed to the outermost aperture lens. A set of two full aperture lenses is situated between the secondary and primary mirror. The primary mirror is spherical. The field flattener lens is situated in the optical back, behind the primary mirror. The central obstruction of the secondary mirror is 13% of the area and 34% of the diameter of the clear aperture. Light passes through 18 optical surfaces and reflects off two mirror surfaces on its way to the eyepiece. The reason for all of these optical components was to create an excellent flat photographic lens. However, it was discovered that the quality of the components created a good telescope that also has very good near focus capabilities.
Included with the scope is a certificate asserting that the wave-front error (p.t.v.) of the optical system is ¼ wave at 555 nanometers. This certificate is signed by by Mr. Bill Burnett (proprietor of ITE) and by Mr. Mike Palermiti (optical systems evaluator). That the end product is diffraction limited is amazing and a testament to good optical work on the individual elements and good mechanical work on the overall assembly.
The lens mirror alignment creates a light compact optical tube assembly. The scope is 7 inches long with the dew shield and diagonal removed. It weighs just over 5 pounds (2.5 kilograms). This solid metal OTA is painted black with etched in markings. With both attached, the unit is about a foot in length and about 5 inches in diameter.
The scope is attached to a camera tripod or to an equatorial mount by means of a ¼-20 fitting. This fitting is attached to a ring of metal that is affixed to and encircles the scope near its visual back.
This unit has a number of cosmetic imperfections. The metallic ring has a roughened-up look to it; a number of striations/scorings which have been painted over. Further, the markings etched on the scope have a rough though uniform appearance. Finally, at the very edge of the field-flattening lens is a small chip/crack. This appears underneath or right next to the retaining ring. The chip is perhaps 1.5mm by 1mm and can be seen reflected off the field-flattening lens. However, when light is blocked from reaching the chip, the reflection is removed from sight.
A very long baffle tube extends most of the way from the primary mirror central hole to the secondary. Within this tube are many baffle-edges. All interior surfaces have a dull black appearance.

Performance (optical):
The scope has been tested by Mike Palermiti for ITE and a wave-front error of ¼ wave at 555 nanometers has been ascertained.
Appearances of intra and extra focal images of bright stars and of point light sources are strange, even disturbing to the non-optician who has become accustomed to MK, MN or apochromat optical systems. The intra-focal image is a sharply defined elliptical structure with a well-delineated ring forming the very perimeter. The extra-focal image is mushy in comparison, lighter in tone, and elliptical as well. The elliptical shape of the intra focal image is perpendicular to the elliptical shape of the extra focal image. This is an indication of astigmatism. Both images, at a high degree of de-focus both present nearly identically shaped and distinct double rings. Such astigmatism, according to expert opinion, does not compromise the diffraction limitation of this system; either its ¼ wavefront error or 80% strehl ratio.
There are no easily accessible means to collimate the scope. However, the collimation seems to be very close to dead-right-on collimation with only a slight loss of the doubled aspect of the ring-pair in the greatly defocus intra-focal image.
The in-focus image of point-light-sources, when the air is stable and when the scope is thermally equalized, presents a round airy disk and a single diffraction ring of uniform size, uniform distance from the airy disk and uniform brightness. Quite often, the continuity of the diffraction ring is disrupted by four tiny black notches, each 90 degrees away from the next. Sometimes, the diffraction ring is continuous.
The scope functions well on terrestrial objects, providing pleasant views of distant objects and sharp, clear, flat views of objects as near as 4 meters (13 feet).
During times of ambivalent sky stability, with a limiting zenith magnitude of 4.5, the scope reveals stars of magnitude 13.0 with averted vision at 300X (75X per inch). The Great Nebula in Orion gives a very satisfying appearance through a 17mm plossl; as aesthetically pleasing as seen through an MK67. The appearance of the epsilon lyrae double-double is greatly superior to a Celestron F5 80mm achromat refractor and somewhat inferior to the view through the MK-67. Albireo and gamma Andromedae give color saturation views more like an F5 80mm refractor than like the MK-67. In a somewhat stable sky, Castor’s two components can be seen at 50X, though the companion of Rigel is not visible. In a borderline-stable-sky, one can see detail within sunspot penumbra, easily see faculae and detect the presence of rice grain. In an unstable sky the Cassini division of Saturn is detectable but not what would be called, visible. In a stable sky, the division becomes detectable at 90X and visible at 220X (55X per inch) as a faint vague pencil thin line. At moments of good stability the division can be detected through nearly the whole ring, and at moments of very good stability becomes readily apparent. On the moon and on planetary detail, best visual acuity is accomplished at between 20X and 30X per square inch of aperture (80X to 130X in this system) as is true for all telescope systems. Accordingly, though higher magnification may provide more pleasing views of a few objects due to an enhanced image scale, no additional detail can be observed above 130X, even with good orthoscopic eyepieces. Only slightly more detail can be seen at 130X with a good quality ortho, than at 95X with a fair quality plossl.
There appears to be no chromatic aberration at all. None was observed at the terminator of the moon bright planets or stars.
Astronomical views are always dependent on atmospheric stability and thermal equilibrium within the optical system itself. Due to the number and arrangement of the optical components within the system, it can take up to 45 minutes for the scope to “cold soak.” Of course, should the temperature be dropping, “cold soak” may take longer or may be repeated.
This system provides completely flat field-of-view images. In all the plossl and orthoscopic eyepieces the field is flat edge-to-edge. Images are focused clear across the field of every eyepiece from the 32mm plossl to the 4mm ortho. When looking at objects with a straight lined edge near the perimeter of the eyepiece field of view, the line seems to curve away at the ends of the line. This may, however, be only an optical illusion of a line approaching a curved arc-shaped concave edge.
Another very attractive feature for those stargazers who are also scopists, is that extremely sharp images can be obtained of nearby objects. At the near-focus of 13 feet, the level of detail revealed is such that this system can be characterized as a long-distance microscope.
Another outstanding feature is that there is no glare in terrestrial views. This is probably due to the extensive baffling, to the flat black paint and to the optical design. Even at 100X per inch and above, no glare was seen. As a comparison, in the C-90, intrusive and distracting glare appears at 40X per inch and greater. The situation with astronomical viewing of bright objects is somewhat different, though the contrast is very good. When gazing at a gibbous moon, at only a short distance from the dark terminator the field is flooded with a decidedly bluish glare. Again, it does not impact the view of features at the lunar terminator, but it is noticeable. This may be due to the plossl eyepieces used with this system, or it may be an artifact of the coatings and complex optical system. The latter probably explains another curiosity of this system. When a bright planet such as Jupiter is displaced some one or two full fields’ of view width from the eyepieces’ field of view, one sees the faint wide arc of a large circle whose focus is the bright planet so displaced.
Finally, the telescope provides a very wide true field of view (up to 1.7 degrees with a 53 AFOV degree 32mm plossl when viewing occurs near the visual back). When used with a star diagonal, the true field of view reduces to just over one degree.

Peformance (mechanical):
Focusing is accomplished by rotating the tube. Those experienced at using a C-90 will find this scope easy to focus. Some scopists may require adjusting the position of the eyepiece in the diagonal cell. Again, to those familiar with such a focusing style, this is not difficult.
The sweet-spot of best focus is very narrow. This may be a necessary consequence of the optical design of this system that allows a flat field with a very short focal length, or it may be the necessary consequence of a modest amount of astigmatism. If the latter is the case, it may be that in this unit fine focus can be obtained, but at the cost of a bit more effort.
The field-flattening lens is very near the visual back of the scope. So close in fact that one could easily crack or scratch this lens by inserting a diagonal or eyepiece into the screw on visual back. One solution, suggested by Mr. Palermiti, is to shorten the insertion tube on the diagonal so that it does not extend to the field-flattening lens.
The entire scope with the Orion Min-EQ tabletop mount weighs in at less than 15 pounds. The OTA is slightly heavier than the five-pound counter weight. In some positions, the counter balance cannot withstand the force of the telescope weight. However, it does not put undue strain on the equatorial locking screw. Nor does it limit the effectiveness of the EQ-1M single axis drive. The drive is very smooth and accurate. Once the scope is situated relatively near the celestial pole, an object centered in a 4mm orthoscopic eyepiece remains in that field of view without adjustment two hours later. When the drive is turned on, images do not vibrate and thus, do not impact the view of close double stars.
By making a disk of wood 5/8 to ¾ inch thick and a few inches in diameter with a notch at one end and placing it on top of the cg4 tripod head, one is then able to dismantle the screw-base of the Min-EQ and then mesh the rest of the Min-EQ to the cg4 mount. Between the use of the Min-EQ tabletop mount and the adapted cg4 mount, any object can be observed at a comfortable height and location.
With the telescope’s relatively large true field of view, an Orion Star Pointer provides an adequate means for finding objects in the sky if one has a good familiarity with the position of objects in relation to bright stars or has use of a good star chart providing the same information. Another benefit of the star pointer is that it is very light, hardly affecting the balance of the equatorial mount. Further, the pointer has an easy-to-use mechanism for adjusting its position. Finally, the switch that turns the pointer on and off and adjusts the brightness has a very definitive sound and feel. The only drawback of the pointer is that one often leaves it on inadvertently. It would be good if this unit had some type of automatic shutoff function.
The telescope comes with a screw on metallic dew cap/light shade. Care needs to be taken when screwing on the dew cap that the threads are not stripped. Also, in the dark especially, but at any time, care needs to be taken not to let the cap slip allowing its thread edge to touch the surface of the forward full aperture lens. It is also possible to screw the full aperture filters onto the telescope and then screw the due cap onto the filter. Though there is no astronomical advantage to using full aperture filters instead of ocular filters, one can disassemble one of these filters and replace the glass with Baader filter material, thus creating a very convenient solar filter.
The scope comes with a full aperture lens cap that covers the front of the scope when the dew cap is not installed. It would be a nice modification to the current Rubinar design if this lens cap could be modified to fit on the scope with and without the dew cap in place.

Peformance (composite/in the field):
Alan MacRobert is correct; a small telescope will see more than a large telescope because it will get used more often. This is due to the lack of excessive weight and clumsiness. Further, a consideration for aging stargazers is exposure to the cold. The lessened weight and size often eliminates the need for assembling the scope outside or lessens the amount of time this takes. These strengths are true of the Astro-Rubinar mounted on the Mini-EQ1 mount. A second advantage of the low weight and lessened size is the small amount of space that is needed for storage. In the case of this particular scope; it, its mount and drive, and all of its accessories stated above are stored in two 13” plastic tool-boxes, the 15” soft padded bag, and Orion’s smallest eyepiece case. These take up about two square feet of shelf space, can be transported easily in any vehicle and can all easily be carried outside in one trip.

Overall Rating: 9
Optics:9 Mount:9 Ease of Use:9 Value:9
Weight: 5 (Veritable Vote)
Link to this vote:

Astro-Rubinar 100
The telescope comes with an assertion of optical quality from Mike Palermiti. I'm not qualified to second-guess Mr. Palermiti, and the most stringent test I've put it to is viewing the Sun. Granulation was obvious, and nice detail around the sunspots was visible. Nighttime images appear sharp, but I'm waiting for Jupiter and Saturn to be visible.

My main complaints with the telescope are mechanical. Focussing is achieved similarly to a telephoto lens. This makes it impossible to keep the image steady. There is also a very narrow range of travel in which the image is in focus. Combined, these features make fosuccing an exercise in frustration.

With the supplied single ring, the center of gravity of the telescope is well forward. This skews the balance badly, making it difficult to point (on an equatorial mount, the declination axis must be clamped firmly at all times, and even then sometimes the telescope will slip downward). The commercial solution offered by ITE is a custom dual-ring mount, which they sell for $185 (seems a bit steep).

My rating for this telescope is dragged down heavily by the mechanical frustrations. Looking at the optics alone, it would rate much higher.

Overall Rating: 6
Weight: 3 (Unreliable Vote)
Link to this vote:

Astro-Rubinar 100
When connected to my Nikon D-200, the unit was well balanced. True, it takes a little time to focus. Since most of my work is landscape and night time, time is not an issue. This is a camera lens first, telescope second! An I like it's blok!

Overall Rating: 8
Optics:10 Mount:8 Ease of Use:5 Value:10
Weight: 1 (Unreliable Vote)
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Astro-Rubinar 100
I always wanted one of these scopes but never could find one for sale... until I bought a Rubinas lens secondhand and modified it myself.

I paid 200 for the lens (M42 screw) and machined an eyepiece adaptor from Alumimium to suit the 4 fixing points on the lens.

Complaints... it's front heavy as noted and focussing is a fiddle but I find it works very well.

I use mine with 32 and 20mm TV Plossls and it delivers bright flat fields. Very nice indeed. On a decent photo tripod fitted with a Manfrotto head, it works a treat.

Overall Rating: 6
Weight: 1 (Unreliable Vote)
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Astro-Rubinar 100
ITS my second one,planetary and moons views are excelent!!!!!
Bright nebulas are v.good ,too.
The reference of its optic i receive after conect eyepiece to rubinar by short 4 cm str.adapter .(my patent ;))
I agree to Mr.Mike Palermiti - its the best optic quality in 4" economic class.
Mechanically the first and second are good made.
In starry tests no colour and aberr.are visable alike apo.refs.
Starry rings like in books.OPTIC for 10.
Rubi is adapted to First photo tripod and ready for any outdoor usage.

Overall Rating: 10
Weight: 1 (Unreliable Vote)
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Astro-Rubinar 100
If you think the Rubinar might be for you, try ..
Markus Ludes shows how to disassemble this lens. By removing the focus stop and adding an adapter to fit a standard star diagonal, I've made this into a very useful portable scope. Performance is excellent with a perfect star test on each side of focus and no zonal defects.
I felt that my DIY modification to make use of standard accessories was a more elegant solution than the manufacturer's one which uses non-standard eyepieces etc.
I like it a lot. VERY portable.

Overall Rating: No Vote
Weight: <none>
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Astro-Rubinar 100
Well, at first, I was like fallin out of my seat. This was one nice piece of rockdom. The star test was out of this rockdom. The brightness was so rockdomlike I thought Elvis left the building to get some heavy rockdom. The mount is one piece of crap rockdom. All in all, THIS SCOPE IS ROCKDOMLIKE!

Overall Rating: No Vote
Weight: <none>
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