Why They Call It The "Planet Killer" | MAK Telescopes Explained

If you have been following the channel, you know that I've taken some deep dives into the telescope world, breaking down the raw light gathering power of Newtonian reflectors, the sharpness of refractors, and the versatile jack-of-all-trades, the Schmidt-Cassegrain. Today we are shining a light on a design that often gets called the planet killer. Of course, I'm talking about the Maksutov-Cassegrain or simply the Mac. Let's dive in and see what makes this optical design so special. Before I get into the optics, you might have noticed things are looking a little different around here. I have a brand new logo and a bit of a channel revamp thanks to my good friend Sophia, who did an absolutely awesome job bringing this vision to life. If you have a project of your own and need some top-tier design work, Sophia is currently open for new projects. I've put her contact information in the description below, so definitely reach out to her. To understand the Mac, we have to go back in time to the mid-17th century, when the French mathematician and priest Laurent Cassegrain invented this type of telescope design. But since everyone pronounces it as Cassegrain, I'll continue doing it as well, just to avoid confusion. Classic Cassegrain telescopes are a type of reflecting telescope, which means they use mirrors to gather and focus light instead of lenses like refracting telescopes. While very clear, indeed, this optical design unfortunately also suffers from optical errors like spherical aberrations. Fast forward to 1941, Russian optician Dmitry Maksutov wanted to solve this exact problem without making the telescope impossibly long or expensive. His solution was the meniscus corrector plate. By placing a deeply curved bowl-shaped lens at the front of the mirror, the light bounces off the primary mirror at the back, travels up to the secondary reflective surface, which is often just an aluminized spot right on the back of the front lens, and then bounces back down through a hole in the primary mirror to the eyepiece. This results in a beautifully folded light path that packs a massive focal length into a remarkably short tube. But what does that actually mean in terms of real-world applications? Well, that ingenious design gives the Maks some serious superpowers. When evaluating the Maksutov Cassegrain, its advantages become most apparent during high-magnification observations. The foremost advantage is image contrast and sharpness. Responsible for these traits is the closed-tube design that minimizes internal air currents once the telescope's optics have reached thermal equilibrium, and the front meniscus lens which effectively corrects for spherical aberrations. This combined with a relatively small surface occupied or blocked by the secondary reflective surface results in pinpoint stars and high contrast, making this optical design highly effective for lunar observations, resolving planetary details, and splitting tight double stars. Additionally, the MAK design is essentially capable of eliminating chromatic aberrations, unlike standard achromatic refractors, which often display a purple or yellow halo around bright objects. The MAK is a catadioptric system that relies primarily on mirrors to gather and focus light. While the front meniscus lens does introduce false color, it is negligible. On the other hand, it ensures that all wavelengths of light arise at the same focal point, which is its true strength. Another significant benefit is optical stability. In standard Newtonians, collimation, the process of aligning the mirrors, is a regular maintenance task. In most commercial MAKs, however, the secondary mirror is simply an aluminized spot on the inside of the meniscus lens, and because of this, it is fixed in place, meaning the telescope holds its alignment exceptionally well, requiring virtually no user adjustment, even after frequent transport. Even if collimation does eventually become necessary, the process is straightforward since you only have to adjust the primary mirror. Finally, there is the advantage of physical compactness. The folded optics allow for a focal length of 1.5 meters or more to fit within a tube that is only a fraction of that length. This compact form factor significantly lowers the payload requirement for equatorial or alt azimuth mounts. It provides a highly capable, long focal length instrument that remains easy to store, to handle, and transport to dark sky locations. Alright, but just like any other telescope design, there are trade-offs as well, which should be carefully considered before getting one. While the MAK is an exceptional tool for high magnification tasks, it is not a universally applicable instrument. One of the most notable limitations of the MAK is its thermal acclimation, commonly referred to as cooldown time. The thick glass of the front meniscus corrector plate acts as a highly effective insulator, trapping ambient indoor heat inside the closed optical tube. When moved to cooler outdoor air, this temperature differential creates internal thermal currents that severely degrades image quality. Depending on the size of the telescope and the ambient temperature drop, the MAK can require anywhere from 45 minutes to well over an hour to fully stabilize and deliver sharp views. Optically, the system is constrained by a naturally narrow field of view. Most MAKs operate at slow focal ratios, typically between f12 and f15. While this long focal length provides the magnification necessary for planetary observations, it heavily restricts the maximum true field of view. Consequently, framing large deep-sky objects or extensive nebulae is often optically impossible with this design, even when utilizing low-power, wide-field eyepieces. Additionally, the front corrector plate sits entirely exposed at the end of the tube, making the system highly susceptible to deformation during humid nights. This is why you typically must factor in extra equipment relying on active dew heater bands or custom 3D-printed dew shields to manage moisture and keep the optics clean throughout the observing session. Early I mentioned the stability with regard to collimation, but this can also work the other way around when looking at different variations of the design, such as the RUMAK Maxotov variant for example. Here the reflective spot on the back of the meniscus is replaced by a fully functional secondary mirror. And while this opens up the possibility of using quality glass and coatings that can deliver superior image quality, it also introduces complexity which is noticeable when trying to align two mirrors instead of just one. This process becomes unfortunately exponentially more cumbersome thanks to this. Finally, the design does not scale efficiently. The meniscus corrector plate must be very thick and requires precise deep curves that are difficult to manufacture at large diameters. As a result, once a mech aperture exceeds six or seven inches, the weight of the front element becomes substantial, affecting balance and the manufacturing costs increases exponentially. For this reason, large aperture mechs are rare, as other catadioptric designs such as SCTs become more cost-efficient and lighter at those sizes. One of my favorite budget mechs has to be the 102mm SkyMax from SkyWatcher. Not only that it's largely available and affordable, but in true fashion for a mech, it is also very portable whilst being capable of delivering sharp and well-corrected views up to a magnification of 140-160x depending on the scene conditions. And this is perfectly enough to observe some of the brighter planets like Saturn and Jupiter. If you plan on getting one, please make sure to get the revised model, which features collimation screws at the back for the primary mirror. This will allow you to realign the optics down the line should it be necessary. The initial version of this telescope did not feature these screws. If you plan on getting something a bit bigger with better light-gathering capabilities and resolving power, then take a look at the MK127 from SVBONY. It's a very capable instrument for its size. The reason for this is partially thanks to the RUMAK-MAXUTOV optical design, which compared to the traditional mech, features a fully-fledged mirror instead of an aluminized spot on the back of the meniscus. This feature allows for better optical fidelity with a higher reflectivity. The reflectivity of the whole optical system is therefore very high, over 95%, which for a complex reflective design such as this one is just excellent. All this has however a downside. The RUMAK-MAXUTOV design and therefore the MK127 is particularly difficult to collimate. Well, at least in my experience it is. While normally there are no collimation screws for the primary mirror, at least in the case of the MK127, there aren't. There are a total of six adjusting screws for the secondary mirror in a push-pull configuration and getting the collimation just right on a very slow optical design like this one proved quite the challenge. It's definitely doable, but it takes a lot of time and fine adjustments to get it right. Alright, if you set your eyes on this particular optical design and money is no issue, you might want to check out the SKYWATCHER SKYMAX200DX. As the flagship 8-inch model in the SKYWATCHER's Maxutov-Kasagrain lineup, it shifts away from slower traditional F-15 mech designs to a faster aplanatic F-10 system. This specialized RUMAK optical design also suppresses off-axis coma. It delivers a completely flat, aberration-free 44mm image circle to comfortably support full-frame camera sensor without needing an extra corrective field flattener. Two-inch wide-field long focal length eyepieces are also fully illuminated for maximum immersiveness. This gives it unique performance advantages, though its weight and specialized nature mean it's not an all-rounder, nor is it for beginners. But if you want one of the best corrected images in this class, give the SKYMAX200DX a thorough look, because this telescope excels at lunar and planetary observations. Anyway, that's been it for now. I hope you all enjoyed this video. Let me know what you think about Maxutov-Kasagrain telescopes in the comments below. Do you use one as your daily driver? I'm very interested in reading your opinions. I've also added affiliate links to the description for all the telescopes mentioned in this video. Using them to buy your new telescope won't cost you more, but will help this channel out, so thank you for considering this. Also, thanks for watching and catch you guys in the next one!