After a 20 year wait, I was surprised and delighted to finally receive one of the 11 Astro-Physics Fastmax 180 telescopes. It was worth the wait. After ten long viewing sessions over several months, I can share preliminary impressions of what may be the exemplary implementation of the portable, short-focus (F4.5) Maksutov-Newtonian design. Given the excitement of a new scope, I have spent more time looking through than testing the instrument; seeing has not been good and planets have not been well-positioned for viewing. I had anticipated that the 180 Fastmax would provide slightly better resolution and, because of its 26% central obstruction, slightly less contrast than my Astro-Physics (AP) 155 apo. Although I have not conducted side-by-side comparisons with my 155 apo, Fastmax has exceeded expectations and is becoming one of my favorite telescopes. Contrast and resolution are superb, as expected for an AP scope. Each completed optical train is tested via interferometry by master optician Roland Christen, but consistent with AP policy, the degree of correction is not provided. As noted by Roland Christen, this little 30" long (810 mm fl) scope provides refractor-like construction and performance, providing sharp, wide, flat fields from the mid-20X range to well over 400X. Rather like a super-versatile 7" Questar that gives low as well as high powers and without significant cool-down problems. The optics have no provision for alignment, but none is needed for mounting the precision ground optics (parallel optical surfaces/no wedge, round within .0002") in the precision machined cells and tube. According to AP, the precision is such that the corrector and mirror can be removed and replaced without losing alignment. The corrector and primary mirror are spherical. The 180 mm diameter annealed BK7 corrector is 0.8 inch thick. The 7.5" diameter Pyrex mirror is 1.25" thick. The elliptical Newtonian diagonal is a 1.83" quartz flat. The corrector has 3-layer multicoating; the mirrors are coated with enhanced aluminum. Being protected in a closed tube, the coatings should have a long life.
At first glance, the Fastmax 180 looks a bit like a cute little 8" Newtonian RFT with a 30" (10" dia. dew shield not installed), 9" dia. tube, but when you heft it, you realize that you are dealing with a very different beast. When you tap its thick, machined tube, you hear "thunk, thunk." The beefy, machined tube assembly weighs 30 lbs, that when added to its 11 lb. case, yields an awkward 41 lb. box that is difficult to lift into and out of a car trunk. As suggested elsewhere on this Forum, substituting the AP case for a light, handsome, padded Lightwave case (AP provides one for their Eagle tripod) makes everything easily manageable by one person. The short tube, despite its 30 lb. weight, is easily handled by both of my mounts, a DiscMount DM-6 Alt/Az and an AP 600e GTO GEM (now replaced with an AP Mach I), each resting on a sturdy, vintage Houston Fearless tripod in its lowest position. Taps to the tube settle down almost immediately. Set-up time on my DM-6 is about 5 minutes and about three-times as long with my GEM. Not exactly grab-and-go, but all easily fits in the trunk of my High Performance Telescope Transport Vehicle (HPTTV), a Corvette ZO6. (Corvettes have surprisingly large trunks designed to hold two golf bags.)
Once mounted, the mass of the short but heavy tube disappears and it provides ideal viewing positions for a seated observer, from horizon to zenith. Little, if any, adjustment in seat height is necessary to perfectly position the eyepiece. Other tweaks in viewing position can be made via a rotating tube. I particularly enjoyed views provided by my Leica ASPH zoom (17.8-8.9 mm) eyepiece, my most used, that provides 46-91X with an exit pupil of 3.9-2.0 mm. If more power is needed, I switch to a Nagler 6-3 mm zoom that provides 135-270X (1.3-0.7 mm pupil). I am surprised to find myself using zoom eyepieces, but these are very good and are an option that simplifies my observing kit. All of my Nagler (4.8, 7, 9, 20) and Panoptic (19, 22, 35) eyepieces work well. I didn't try my Clave Plossls that would not be at their best on a short focal ratio scope. With powers of 400X and beyond, seeing seemed to fail before optical performance was exhausted. My Panoptic 35 mm provides a good finder eyepiece and impressive 3.3 degree field at 23X but with a larger than desirable pupil of 7.8 mm. I anticipate remarkable views with a 21 mm Ethos and 31 mm Nagler. Focusing is via a low-profile, two-speed, Crayford FeatherTouch unit. As expected with a short focal ratio, high quality optic, images snap into focus. Imagine sharp, contrasty, refractor-like views with 180 mm (7.1 inch) of clear aperture. Brighter globulars are nicely resolved into faint but tiny stars. M-42 is a revelation of complexity and contrasts, bright and dark. M-31 companion M-110 becomes interesting. Views of the Double Cluster, the Pleiades and other large, bright clusters are especially lovely, usually the best on the observing field. Subtle shifts in field brightness in Auriga, Cassiopeia, Cepheus and Cygnus suggest large diffuse nebula that I did not track down. At high powers, the Lunar limb is sharp and crater shadows are inky black. I look forward to the galaxies of spring and the planets now coming into view.
Despite its closed tube, I have not experienced tube currents and other serious cool down problems associated with Maksutov variants; they may be equal to or less than in my 155 apo with its more massive optic. In cold weather, Fastmax is almost immediately useful for non-demanding tasks, but full settle-down with a 40 degree F temperature differential may take up to an hour. I did not notice Fastmax chasing but never keeping up with falling temperatures, a symptom of some larger Maks. With the dewshield in place, dewing of the exposed corrector has not occurred, even when the outside of the tube is wet with dew. So far, no dew-zapper has been required. In fact, none of the anticipated problems of Maks have occurred. Roland has definitely done his homework.
What's not to like about the Fastmax 180? Well, like most AP telescopes, they are essentially unavailable. I waited for 20 years for mine and no more will be made. If you are thinking, "if a 180 is good, wouldn't a bigger one be even better," I would argue against that position if portability is an issue. (My standard of portability is what I can easily lift and fit in the trunk of my HPTTV.) One Fastmax 235 F4.3 prototype has been produced, but I would be reluctant to handle such expensive and heavy hardware in the dark and cold. Just as refractors start to lose their versatility and appeal at around 6 inches of aperture, Mak-Newts may lose theirs at around 7 inches. I have not had experience with other MakNewt systems, most of which have focal ratios of F6, in contrast to the F4.5 Fastmax. The legendary Ceravolo HD 145 is F6.
My Fastmax 180 is still on its shakedown cruise, but preliminary views suggest that it is a remarkable performer that is compact, portable and easily mounted on midsize alt-az and GEM mounts. Consider the desirability of a closed tube, permanently aligned 7.1" RFT that has a tenth of the coma of a similar Newtonian and that yields refractor-like views of double stars, moon and planets. Although my interest is primarily visual, Fastmax has been used to capture some outstanding images which are displayed at bigcigarastronomy.com. I'm not ready to give up my refractors but this versatile and potent little scope has certainly captured my attention. Fastmax would provide an ideal only scope for many observers.