The Optical Tube
The Bresser Messier 5″ Tabletop Dobsonian is a Newtonian reflector featuring an aperture of 130mm (5.1”) and a focal length of 650mm. This specification is comparable to several other tabletop telescopes as well as numerous tripod-mounted reflectors of this aperture size. An f/5 Newtonian tends to exhibit minor coma at low magnification towards the edges of the field of view when used with a wide-angle 2” ocular (or if you examine the edge of the field intently with a 1.25” eyepiece). However, considering the Messier 5″ Tabletop Dobsonian’s 1.25”-only focuser, you are unlikely ever to notice this anyway. Nevertheless, it is worth bearing in mind that many inexpensive, low-power, wide-angle eyepieces may display similar aberrations at the edges of the field of view in an f/5 Newtonian, so consider this factor when shopping for additional eyepieces. The primary mirror is collimated without tools while the secondary mirror requires a hex key for adjustment. Collimating the secondary mirror is required very infrequently while the primary mirror seldom needs adjustment but you should be sure to check every time you set up the telescope.
The Messier 5” Tabletop Dobsonian uses a 1.25”, all-plastic rack-and-pinion focuser. This focuser has no real provision for tension adjustment and cannot hold heavy eyepieces without sagging or racking itself in. It is also extremely fragile and its plastic teeth can be damaged fairly easily, while finding a replacement drawtube with teeth is next to impossible to do for a reasonable price.
The Messier 5” Tabletop Dobsonian attaches to its mount utilising a Vixen-style dovetail, which enables you to easily swap it onto another astronomical mount if desired. The dovetail is, in turn, secured to a pair of tube rings, permitting you to slide the Messier 5” f/5 optical tube along the altitude axis for balancing with varying eyepieces or accessories, as well as rotating the focuser and eyepiece to a more comfortable position.
The Bresser Messier 5” Tabletop Dobsonian is supplied with two 1.25” Kellner eyepieces: a 25mm providing 26x magnification and a 9mm for 72x magnification. These eyepieces are of acceptable quality at best, but they do suffer from some edge-of-field aberrations at this scope’s fast f/5 focal ratio and there are certainly sharper oculars available too. The 9mm Kellner also offers very limited eye relief, requiring you to press your eye firmly against the lens to view the entire field, which can be quite uncomfortable. The apparent field of both eyepieces is approximately 50 degrees.
As for a finder, the Messier 5” Tabletop Dobsonian includes a low-cost red dot sight, which is of fairly low quality and challenging to align with the telescope. Moreover, replacing it would necessitate adding an entirely new bracket to the tube, requiring the removal of the optics and drilling some holes. Despite this, the red dot sight is sufficient for pointing this wide-field instrument.
All of the Messier Dobsonian telescopes come with a white light film solar filter, which attaches to the front of the telescope. You have to aim the telescope at the Sun by using its shadow as looking through the red dot finder at the Sun is of course bad for your eyesight. The provided solar filter, with its all-plastic body, is susceptible to detaching from the telescope if it is bumped or caught by a gust of wind, which can be extremely hazardous. The only elements holding it in place are a few small plastic tabs. You need to be absolutely sure the filter cannot blow or fall off the front of the telescope; if it does, you could cause permanent blindness and/or start a fire. Tape, Velcro, or some other jerry-rigged solution will do. The filter itself is perfectly safe and enables close-up views of the solar photosphere and sunspots with this scope.
The Bresser Messier 5” Tabletop Dobsonian employs the same tabletop “Dobsonian” mount design as its smaller counterparts. It worth noting that this is actually a single-arm fork design, in which the telescope pivots up and down on a single bolt and a nylon/felt bushing, whilst also moving in azimuth (left to right) on Teflon pads, sort of halfway between a Dobsonian and a more traditional alt-azimuth mount. The fork arm includes a tension adjustment knob, allowing users to set the appropriate friction to prevent the optical tube from moving by itself if you swap eyepieces as well as for smooth, fine adjustments for aiming at high magnifications. For balance, you can simply slide the tube within the pair of tube rings to adjust its position forward-backward and rotate the eyepiece to a more comfortable position.
Finding a suitable surface for the Bresser Messier 5” Tabletop Dobsonian might be tricky. A milk crate, bucket, or bin works well if you plan to sit in a chair while using the scope, and a picnic bench, saw horse, bar stool, or barrel can also suffice if you need something taller. Unfortunately, few folding or otherwise easily transported tables are stable enough. If you prefer, you can also build a custom stand for the scope.
Should I buy a Used Bresser Messier 5” Tabletop Dobsonian?
You may consider purchasing a pre-owned Bresser Messier 5” Tabletop Dobsonian as a means of saving money on accessories or for other reasons. However, it is vital to inspect any second-hand Dobsonian for potential damage to the mirror coatings or base before committing to a purchase. Reproducing the Messier 5” Tabletop Dobsonian base accurately, let alone sourcing quality materials, is seldom worth the time or effort, and issues related to damaged mirror coatings can be even more troublesome due to the cost of recoating such a small primary mirror usually not being worth the price of an entire new telescope let alone the savings from purchasing a used one. Be sure the mirror is not corroded in any way before purchasing. The loss of light collecting and resolving power from even minor corrosion or damage is too much with a relatively small telescope like the Messier 5” Tabletop Dobsonian.
Dents in the tube of a Dobsonian telescope like the Messier 5” Tabletop are generally not a cause for concern, as they typically do not interfere with the light path of the optics. In cases where dents do affect the optical path by obstructing the primary mirror or tilting components, they can often be pulled or hammered out fairly easily.
The Bresser Messier 5″ Tabletop Dobsonian is one of the best telescopes under 250 pounds aside from the Sky-Watcher Heritage 130P, which has identical optics and performance but features a better accessory kit and a collapsible, open tube which may or may not be preferable.
- The Sky-Watcher Heritage 130P shares the optics and basic design of the Messier 5″ Tabletop Dobsonian, but features a collapsible tube for improved portability and a less fragile, if still rather cheap, helical focuser. In addition, includes a decent quality pair of 3-element, long eye relief 1.25” eyepieces and a better-designed red dot finder than the Bresser tabletop scopes.
- The Zhumell Z114 is a bit smaller than the Messier 5” Tabletop Dobsonian/130P but features a decent pair of starter eyepieces, a red dot finder, and sharp 114mm f/4 optics.
- The Sky-Watcher Heritage 100P is a tiny but still surprisingly capable and affordable 100mm (4”) tabletop Dobsonian with a quality parabolic primary mirror and decent accessories. It can also be used on a tripod if needed, and while limited by its small size it’s still a sharp instrument and easily the cheapest acceptable telescope you can find.
- The Sky-Watcher Virtuoso GTi 150P provides fully motorised tracking and GoTo capabilities, high-quality 6” optics, and the same design/accessories of the regular Heritage Dobsonian telescopes. It can be aimed manually thanks to the mount’s built-in Sky-Watcher FreedomFind encoder system, with the GoTo system being controlled by your smartphone or tablet. The manual Heritage 150P is identical in design minus GoTo/tracking, and is also a great pick, with the same collapsible tube, accessories, and quality 6” f/5 optics as the Virtuoso GTi 150P.
- The Ursa Major 8″ f/6 Dobsonian’s 8” aperture grants it a significant performance advantage over a smaller 6” or 5” Dobsonian, and it features a pair of Plossl eyepieces and a basic 2” single-speed Crayford focuser, along with a 9×50 finder scope. Although it may not be the most well-equipped or well-designed, it delivers outstanding performance for its modest price.
- The Ursa Major 6” f/8 Planetary Dobsonian offers a sharp 6” f/8 parabolic primary mirror, and it’s considerably easier to collimate as well as focus at high magnifications than a fast f/5 scope while also lacking the need for well-corrected low-power eyepieces or a table to set it on. However, it’s not nearly as compact as a tabletop Dobsonian of its aperture and does not weigh much less than an 8” or 10” telescope with more capability.
- The Bresser Messier 6″ Tabletop Dobsonian is hardly much bigger or heavier than the 5” model but boasts a superior 2” all-metal rack-and-pinion focuser along with 20% more resolving power and 40% more light-collecting surface area. However, the provided accessories remain pitifully cheap and low-quality.
- The StellaLyra 8″ f/6 Dobsonian offers well over 2.5x the light-gathering area and substantially more resolving power than the Messier 5″ Tabletop Dobsonian, along with numerous features and accessories. These include a top-quality 2” dual-speed Crayford focuser, an integrated fan, a right-angle finder scope, and two decent eyepieces included in the package. It stands on the ground and is simple to aim due to its smooth Dobsonian base.
- The Bresser Messier 8″ Dobsonian features an exceptionally well-designed Dobsonian mount and 2.5” hexagonal focuser, in addition to excellent 8” optics. However, the provided finder and Plossl eyepiece could be improved upon, as with the other Messier scopes, and the focuser costs extra to convert to a dual-speed unit.
- The Sky-Watcher Skymax 127 AZ-GTi combines the exceptional Skymax 127 Maksutov-Cassegrain optical tube with the versatile AZ-GTi mount and tripod, offering motorised tracking GoTo functionality that can be operated through your smartphone, or simply pushed around the sky by hand thanks to its FreedomFind encoders. The Skymax 127 Virtuoso GTi boasts the same features but is mounted on the Virtuoso GTi tabletop Dobsonian mount, with the option to connect it to a third-party tripod. In terms of performance, the Skymax 127 optical tube surpasses the Bresser Messier 5″ Tabletop Dobsonian when observing the Moon, planets, and double stars, and only experiences slightly inferior performance when it comes to viewing deep-sky objects.
Aftermarket Accessory Recommendations
The Bresser Messier 5” Tabletop Dobsonian’s provided eyepieces will do, but we recommend replacing them with something else. A good 25mm (26x) eyepiece such as the Celestron X-Cel LX or Omegon FlatField is perfect to replace the stock 25mm Kellner for a slightly wider and crisper low-power view.
For observing many celestial objects at medium power, such as the Moon and many deep-sky objects, with the Messier 5” Tabletop Dobsonian, we recommend selecting a between either a 17mm Plossl (44x magnification) or 15mm “redline”/”goldline” (50x magnification) eyepiece. Although the redline/goldline’s simple optical design may not be flawless across the entire field of view at this scope’s f/5 focal ratio, it serves as an affordable and satisfactory wide-field alternative to a Plossl or Kellner-type ocular.
We would also advise opting for a 9mm redline/goldline (72x magnification) to replace the inferior provided 9mm Kellner eyepiece. The redline/goldline eyepiece boasts a considerably wider apparent field of view, around 70 degrees compared to the Kellners’ < 50-degree field, while also affording greater eye relief than the 9mm Kellner, making for more comfortable viewing, as well as improved sharpness towards the edges of the field of view
For even higher magnification, you’ll want a short focal length eyepiece such as a 6mm goldline/redline (108x magnification) and a 2x Barlow lens (achieving 144x/217x magnification when used with the 9mm and 6mm redline/goldline eyepieces respectively). You will probably not find yourself being able to use over 200x with this telescope much due to the turbulence of our own planet’s atmosphere blurring the view, but the Messier 5” Tabletop Dobsonian’s optics can handle up to 250x magnification, at least theoretically. We recommend some sort of Cheshire collimation tool to ensure accurate collimation of the Messier 5” Tabletop Dobsonian in order to enable the sharpest possible views.
Furthermore, a narrowband Ultra High Contrast (UHC)/OIII nebula filter can significantly enhance your views of nebulae, such as the Orion Nebula, when using the Messier 5” Tabletop Dobsonian or any other telescope. This filter also accentuates planetary nebulae by diminishing the brightness of surrounding stars, enabling you to locate them at low power. Moreover, it offers enough contrast improvement to render previously invisible targets like the Crab Nebula and Veil Nebula supernova remnants visible using this telescope under dark skies.
What can you see?
The Bresser Messier 5” Tabletop Dobsonian boasts a sufficiently large aperture to enable impressive deep-sky views. Even when residing in an area plagued by significant light pollution, open star clusters such as the Double Cluster, M11, M35, and the renowned Pleiades (M45) will captivate you with their myriad bright and vibrant stars. Numerous other open clusters display hundreds of stars within them, and a staggering number of individual clusters, reaching into the hundreds, can be observed with a 5-inch telescope under dark skies at any time throughout the year.
Globular star clusters, including M3, M13, M15, and M22, can also be resolved at high magnification (although a different eyepiece than the provided 9mm Kellner is recommended) under suburban or dark skies with the Messier 5” Tabletop Dobsonian, revealing their individual stellar members. However, dimmer globular clusters will still appear as faint smudges, if they are visible at all.
For extensive galaxy observation, dark skies far from sources of light pollution are essential; light polluted conditions will limit you to spotting the brightest ones, such as Andromeda (M31), and only as detail-less “faint fuzzy” blobs, regardless of the telescope in use. A filter, unfortunately, offers no assistance on non-nebula targets. Under dark skies, however, the Messier 5” Tabletop Dobsonian will allow you to discern dust lanes in some of the brightest and most spectacular galaxies like M31, M82, and M104. Moreover, galaxy groups such as the Leo Triplet and the vast Virgo Cluster can be seen, with the latter revealing dozens of galaxies, though the majority lack any discernible detail due to their elliptical structures. With dark skies, the Bresser Messier 5” Tabletop Dobsonian should be capable of showing you over 100 galaxies.
Many nebulae appear stunning when observed through the Messier 5” Tabletop Dobsonian, especially with dark skies and/or a UHC nebula filter. The Orion Nebula (M42) fascinates with its dark lanes, luminous clouds of gas, and the Trapezium cluster at its core. The elusive Veil supernova remnant is attainable with a UHC filter. Large planetary nebulae such as the Dumbbell (M27) are conspicuous even at low power, and a UHC filter reveals further detail, while smaller ones like the Blue Snowball or Cat’s Eye are best observed with high magnification and unfiltered, as they are less influenced by light pollution compared to larger targets and may even reveal hints of their blue and green coloration.
The Messier 5” Tabletop Dobsonian performs admirably when observing the Moon and planets thanks to its high-quality 130mm primary mirror. You will be able to discern thousands of lunar craters, mountains, and ridges, the phases of Mercury and Venus, and the polar ice caps on Mars. During periods when Mars is closer to Earth, you may also be able to identify a few dark markings and any ongoing dust storms.
As with any telescope, the Messier 5” Tabletop Dobsonian will reveal the moons of Jupiter, but 130mm of aperture also allows you to resolve them as minuscule discs, along with their shadows when they transit in front of the planet. Jupiter itself displays colourful, ever-changing cloud belts, festoons, and storms in a variety of shades, ranging from white to pink, blue, and brown. On a clear night, you can also resolve the Great Red Spot using the Messier 5” Tabletop Dobsonian. Saturn’s rings and the Cassini division within the rings can be observed, in addition to a handful of its moons, while Uranus and Neptune are fuzzy bluish dots devoid of detail; Uranus’ moons will require a larger telescope to see while Neptune’s moon Triton is at the absolute limit of what a 5” telescope like the Messier can show you. Pluto will require a 10” or larger telescope to observe due to its faintness, however.