Jeff Blazey article.qxd:1 - Astronomy Technology Today
Transcription
Jeff Blazey article.qxd:1 - Astronomy Technology Today
CONFESSIONS OF A MAK-NEWT FAN A Tribute to a Unique Telescope Design that Really Does It All! By Jeff Blazey There it is again, a fairly extended silence followed by “Hmm,” and moments later a step back from the eyepiece and a careful examination of the scope with the beam of a red flash running up and down the tube. Then the usual question: “Wow, that’s nice, what scope is this?” I give the usual answer, “It’s an Intes MN66.” Without fail, that’s the kind of reaction I get when people have their first look thru one of my Intes Micro MaksutovNewtonians (Mak-Newt or MN). With such almost universal reaction to the image quality of these scopes, why aren’t they more popular? Well, I don’t know. But what I do know is that these Intes Micro Mak-Newts remind me very much of quality refractors – Apos in particular. I’ve been around this hobby for 40 years and even had a small part-time business at one point, buying, selling and trading scopes. I’ve owned and used more telescopes than you can shake a Barlow at and can, by now, immediately tell a good set of optics. What I’ve discovered along the way is that really good scopes all seem to share certain key characteristics and the MakNewts are no exception. First, there’s no ambiguity to focus, just an abruptness or “snap” at focus which is unmistakable. I have never experienced this before with a scope (reflector or refractor) of such a short focal ratio (f/6) and over such a good chunk of the field of view. If you’ve spent some time at the eyepiece of a big, fast Dob, you know exactly what I mean. The next trait involves just how sharp that well-focused image is. To me, what differentiates excellent instruments from the merely good is this characteristic of image sharpness, and the Mak-Newts I’ve used produce that sharpness of detail – an etched, almost chiseled image quality that I’ve come to expect from a highquality refractor. Moon and planetary images are “hard” and sharp with very solid boundaries against the blackness of space. They will readily reveal differences in eyepieces that lesser scopes will, well, quite literally, smudge over. Thus, the Tele Vue Plossls and University Optics orthos work especially well with these scopes. I’ve also noted that these scopes are very “friendly” to my older Plossl, Konig and Erfle eyepieces in the 20- to 40-mm range (my 28-mm RKE is particularly enjoyable in the Mak-Newts), despite their faster f/6 stop. I notice considerably less image distortion towards the edges of the field than I do when using those eyepieces with a typical f/6 Newtonian. For example, using my 30+ year old 2-inch 40-mm Brandon “boat anchor” Erfle in an uncorrected f/6 Newtonian would just about make you sea sick. The outer twothirds of the 70 degree apparent field is a whirlpool of elongated stars. With the Mak-Newt, however, only about the outer third of the field starts to suffer. This gives me a noticeably wider working field of view, again reminding me very much of a well made refractor. Finally, one characteristic surprised me and it was something that these scopes do not do – there is little obvious vignetting of Astronomy TECHNOLOGY TODAY 41 CONFESSIONS OF A MAK-NEWT FAN the light cone in these long focal-length refractors truly strut their stuff over the wide-field eyepieces. The secondary mirIntes-Micro MN66. The Apos are a bit rors in Mak-Newts are relatively small brighter, with a smidge better contrast and given their fast f/6 design (typically around greater capacity to absorb really high mag20 percent on the diameter), and the nifications, but I gotta tell yah, after a scopes usually have a fair amount of back minute’s use, I’ve forgotten those differfocus. In a traditional Newtonian, that ences and am totally involved in the views small secondary produced by and long back the Makfocus would Newts. Like combine to progood Apos, duce an illumiMak-Newts do nated field of nothing wrong, very small diamnor anything eter and signifithat actively cant vignetting interferes with in eyepieces the viewing with large field experience. stop diameters. Quite the Looking into opposite really the optical path – when using of the Makthem, I’ve no Newt sans eyedesire or urge to piece you’ll rush back to the indeed notice The Intes-Micro MN66/Losmandy G-8 Combination Apo. I just sit that there’s a relatively small fully-illumithere and enjoy the views (and yes, you can nated field and would therefore expect to observe with the smaller ones while seated notice some dimming of the outer edges in comfortably). The Mak-Newts don’t leave a wide-field eyepiece, and yes, it is there, me feeling like I’m missing out on anybut not nearly to the extent I would have thing. expected. I have to actively look for it, a Like any telescope design though, they telling testament to the effectiveness of the do have their own unique quirks and pracunique Mak-Newt design. tical considerations. The collimation proIt’s only in direct, side-by-side comparcedures and tools required to carry them isons, under very steady skies and at very out are basically the same as for any high magnifications, that my two (yes, I Newtonian, with adjustments available for have two) Astro-Physics 152 Starfire Apo both the primary and secondary. One 42 Astronomy TECHNOLOGY TODAY CONFESSIONS OF A MAK-NEWT FAN wrinkle is that you can’t, as in a Newtonians. I can still get a sharp image Newtonian, rotate the secondary holder by with small amounts of miscollimation. reaching in through the front of the tube, Even when collimation is slightly off, in because the meniscus is in the way. Instead, and out of focus stellar images are still you have to use your finger tips to rotate a round, exhibiting only a slight mis-centerknurled ring on the front of the secondary ing of the airy disk inside the first diffracholder. There’s not a lot of space between tion ring – with an f/6 Newtonian, coma your finger tips and creeps in much the meniscus, so it’s more quickly under easy to get finger the same condiprints on its coated tions. surface. Just be Cool down careful. time is not an issue Also, these for me, even in the Mak-Newts are extremes of winter. equipped with bafIn fact, my Makfling under the secNewts cool faster ondary and it is so than my Apos. effective it can be That’s because the difficult to see the meniscus and secoutline of the secondary have no ondary against the “power” associated internal diameter with them; the mirof your sight tube. rors are spherical I guess we should and thin, the tubes all have such probare aluminum with lems! However, the effective ventilacollimation adjusttion, and the bafments and locking fling acts as heat The Intes-Micro MN86 mounted features are straight sinks. All good on a Losmandy G-11 forward and effecstuff! I just point tive so that, once dialed in, it takes a pretty the scope down and open the back plate to good jolt to knock anything out of alignallow the warmer interior air to escape. The ment. only thermal issues I’ve experienced have Interestingly, I’ve also found these been thermal plumes coming off of the secscopes to be considerably less “fussy” and ondary and then only when I’ve done more tolerant of collimation error than f/6 something dumb like leave it exposed to Now Offering HyperTuning Services! • Stability TuneUp of your Atlas/EQ6 mounting. • Install complete bearing set including ceramic bearings on both worms. • Mainbolt TuneUp of your Atlas/EQ6 mounting. • Center your polar scope. • Install a V Series Saddle and an Atlas/EQ6 Adaptor - Specify Black or Bronze (Bronze matches color of Brass Hardware on Saddle). • Install 12" Stainless Steel Counterweight Shaft Toe Saver - 2 Stainless Steel collars. • 1 Side By Side V Series Dual Dovetail System with 2 V Series Saddles. Astronomy TECHNOLOGY TODAY 43 CONFESSIONS OF A MAK-NEWT FAN The Compact and Portable Intes-Micro MN55/Vixen GP Combination direct sunlight. The scopes’ weights are completely reasonable for each of their aperture sizes and there are dovetail options a-plenty for any mount. I imagine they would also work very well in a Dobsonain configuration, although I’ve never tried that myself. 44 Astronomy TECHNOLOGY TODAY There has been a lot of carping about the quality of the stock finders and, especially, the focusers. I find both to be completely “serviceable.” But, if you want to upgrade, there’s no shortage of either. I can personally recommend the Starlight Instruments Feather Touch replacement focusers. One last high-performance scope trait I failed to list earlier is that I find Intes-Micro Mak-Newts terribly difficult to part with. I still own three of them (MN55, MN66 and MN86) and only parted with a MN56 because a friend really wanted it. I know of several former MN76 owners who now completely regret selling them. They’re just really nice packages. The f/6 focal ratio is perfect for most applications; it allows use of 40-mm wide-field eyepieces for really low-power work, or high-power viewing using a Barlow, without having to resort to a peephole 4- or 5-mm eyepiece. I specifically purchased a MN55 to fit on my Vixen GP or Meade LXD75 mounts for portability. Low-power deep-sky views are its forte, but the high power views compare well to my old A-P 130-mm f/6 Apo (the one with the “NASA glass”) and that’s really saying something! The MN86 fits extremely well on my Losmandy G-11 mount and the rotating rings (standard on the MN76 and larger) allow easy access to the eyepiece no matter where the scope is pointed. Despite the MN86 being a bit of a beast weight wise (~45 pounds), the MN86/G-11 combo demonstrates excellent damping times – a poke on the side of the tube causes nothing more than a one-cycle, out-and-back motion, with no “ringing” of CONFESSIONS OF A MAK-NEWT FAN the image. This scope does it all by providing stunning high-power views of the Moon and planets, while also providing enough aperture to do some serious deep-sky damage. M42 and M13 are exceptional through the MN86. The MN66 was, if the truth be known, an impulse buy as it looked so cool with Parallax rotating rings. But, it’s turned out to be my favorite Mak-Newt for public gatherings and is mounted on a Losmandy G-8 mount. In closing, as the title says, I’m a Mak-Newt fan. They provide a fat slice of the performance you get from a good Apo (exceptional, stable image quality) and the simple layout of a Newtonian, without the disadvantages of tube currents, diffractions spikes and coma). I consider these scopes to be a tremendous value, even at full list price. The MN76 is a particularly compelling package with its large-aperture, sharp optics and reasonable weight and length. Recommended? No…HIGHLY recommended! This close-up of the meniscus of the MN demonstrates both the relatively small diameter of the central obstruction formed by the secondary and the effectiveness of the meniscus coatings. Note also the internal baffles of the optical tube. Astronomy TECHNOLOGY TODAY 45