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Astro-Physics Fastmax 180 F4.5: An Ideal Telescope

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#1 MDRP

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Posted 13 January 2016 - 02:08 PM

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.

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#2 junomike

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Posted 13 January 2016 - 02:11 PM

Thorough write on an amazing Instrument!

What Tripod is that?

 

Mike



#3 elwaine

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Posted 13 January 2016 - 02:30 PM

Great report. Thanks.

 

I am not jealous.

I am not jealous.

I am NOT jealous.

 

OK...  I'm jealous!


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#4 MDRP

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Posted 13 January 2016 - 02:42 PM

More images of AP Fastmax 180 F4.5.

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#5 MDRP

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Posted 13 January 2016 - 02:45 PM

Cap on rear mirror cell.

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#6 MDRP

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Posted 13 January 2016 - 02:48 PM

Fastmax in aftermarket carrying case. 

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#7 Dwight J

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Posted 13 January 2016 - 03:17 PM

"...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."

 

 An 8" MN is a heavy scope.  Mine weighs about 40 lbs with finder, fan, etc.  I do have a F5 one however.



#8 MDRP

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Posted 13 January 2016 - 04:12 PM

The tripod for Fastmax is a vintage Houston Fearless. I bolted an Astro-Physics mounting plate on the top that accepts both my AP GEM and DM-6. The Fearless is very rigid and, as shown in the posted images, features many of the large, locked triangles that contribute to good performance. How many triangles do you count? Triangular pieces even lock the legs in position.  It was designed for heavy television and 35 mm cine cameras and is an outstanding tripod for astronomical telescopes. It's probably more rigid than most modern premium tripods costing thousands. They are heavy, but not oppressively so, and collapse into a compact unit. I have two of them and use them even for small scopes--no worry about someone kicking the tripod over! A wonderful of feature of the Fearless is its low cost, sometimes free from studios wanting to get rid of old gear.         



#9 MDRP

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Posted 13 January 2016 - 04:57 PM

Dwight,

      I presume that your 8" MN continues the tradition of outstanding Ceravolo optics, and its F5 focal ratio offers the flexibility that I found in my F4.5 Fastmax. Your extra inch of aperture comes at the price of about 10 pounds. Another difference between our instruments is that Fastmax has a closed tube, except for the focuser opening, while your Ceravolo has fans and circulating air in the tube. How necessary are your fans? What happens if your turn them of during an observing session?

      Astro-Physics' adventure into Maksutov optics, both MN and MC, is in part a response the difficulty of making apos larger than 6" and of finding suitable glass. The appearance of low-cost Russian Mak optics made the AP foray into compound systems financially unattractive.      


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#10 Paul G

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Posted 13 January 2016 - 05:46 PM

Congrats! Sounds like a fantastic scope!

 

>>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.<<

 

Same with the AP 10" Mak-Cass, permanently collimated.



#11 Jeff B

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Posted 14 January 2016 - 09:51 AM

MNs don't necessarily have to weigh a lot.  For example, my APM/MW MN86 comes in at a lean 28 pound with the rings and dovetail.  The tube has an open back for quick cooling of the primary.  Collimating of the optics is straight forward...for a MN.  However, the FT focuser lacks provisions for squaring, something I've found it needs and will modify to incorporate.

 

Nice read!  I'm looking forward to more commentary on its performance and use.  ENJOY!

 

Jeff


Edited by Jeff B, 14 January 2016 - 09:52 AM.


#12 Bill Barlow

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Posted 14 January 2016 - 11:26 AM

Beautiful telescope.  I was curious, what was the price when you signed up for it 20 years ago and what did you pay for it today?  

 

Bill



#13 Paul G

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Posted 14 January 2016 - 12:14 PM

Beautiful telescope.  I was curious, what was the price when you signed up for it 20 years ago and what did you pay for it today?  

 

Bill

There was no list for this particular scope, so there was no price, just like the 10" Mak and the 175 EDF. There is a general interest list for scopes over 6" that started when AP stopped production of the 180 EDF's.  When AP has a run of scopes fitting that niche that are ready to ship, people on that list are notified of the existence of the scope, its price, and are given the opportunity to purchase it. Small run scopes like the 10" Mak-Cass (couple dozen) and this Fastmax were snapped up by those on the list. The larger run of more expensive 175 EDFs was not completely sold out to those on the interest list and a few were sold to people who hadn't been on any list at all.



#14 MDRP

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Posted 14 January 2016 - 01:13 PM

I'm an early AP customer, buying a 6" F8 apo in the mid-1980s for $1295. As a big reflector and ATM guy, it was a revelation. Over the years I have upgraded my AP apos as the mechanics and optics have evolved. In 1995, I placed my name on an "interest list" for MakNewts if any were to become available. (I was also interested in the AP 10" MC but that didn't happen.) I was interested in apo-like performance in larger apertures, shorter tubes, and at a reasonable price. A small lot of  Fastmax 180s finally became available 20 years later in 2015 at a price of $7800. Telescopes and other instruments are works in progress as illustrated by the continuing iterations of the elegant AP 130 GT apo and the saga of the AP 10" MC. (The history of Fastmax and other AP scopes is provided on the AP website.) It is obvious that Roland is constantly thinking about products at the system level. Regrettably, not being a production instrument, there will probably not be further refinements of the Fastmax 180. Financial contingencies are significant. What ever the design, precision, elegance and individually testing comes at a price. Even a "simple" closed tube traditional Newtonian of similar F4.5 focal ratio with a super paraboloid with coma corrector (now a cat?) in a precision machined tube would be costly and have a limited market.         


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#15 Dwight J

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Posted 14 January 2016 - 08:19 PM

Dwight,

      I presume that your 8" MN continues the tradition of outstanding Ceravolo optics, and its F5 focal ratio offers the flexibility that I found in my F4.5 Fastmax. Your extra inch of aperture comes at the price of about 10 pounds. Another difference between our instruments is that Fastmax has a closed tube, except for the focuser opening, while your Ceravolo has fans and circulating air in the tube. How necessary are your fans? What happens if your turn them of during an observing session?

      Astro-Physics' adventure into Maksutov optics, both MN and MC, is in part a response the difficulty of making apos larger than 6" and of finding suitable glass. The appearance of low-cost Russian Mak optics made the AP foray into compound systems financially unattractive.      

Part of the weight added is a sliding counterweight opposite the focuser and it is down at the mirror end ostensibly to help with tube balance when using heavy eyepieces and to offset the weight of the finder.  I also have rotating rings which add more weight but really help when operating with a newtonian focus.  For casual poking around I don't use the fan but I do run it when boosting the magnification.  I have turned it off as the night progressed and the temperature has stabilized.  My scope is stored at ambient temp so there usually isn't much of a gradient.  I have noticed improvement in detail in Jupiter's belts and zones when the fan is running and I am over 300 X.  I would conclude that if I want to squeeze out the most that the scope can deliver, running the fan is required, at least for a few hours.  



#16 Scott99

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Posted 14 January 2016 - 08:47 PM

what a scope, congrats!   Coming at this point in AP's history…….wow.  The permanent alignment, the small CO, the cooling wizardy, tube refinement, etc.   It's like a 7-inch Questar that was made in Heaven or something!  

 

So it can do 3.3 degrees….the AP160 can only do 2.3 degrees FOV.  My first thought would be low-power oberving from a dark location…must be amazing.   And it's much smaller than a comparable Mak-Newt but has the same CO - optical alchemy!


Edited by Scott99, 14 January 2016 - 08:51 PM.

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#17 MDRP

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Posted 15 January 2016 - 02:44 AM

As I am gradually becoming familiar with Fastmax, its most striking feature so far may be as a 7.1" RFT. I love scanning star fields, making chance discoveries, and enjoying its remarkably sharp, flat, wide (over 3 degrees), relatively coma-free, contrasty fields at powers from the mid-20s upward. Further, as noted by Scott 99, Fastmax is permanently aligned, avoiding the collimation hassles characteristic of short focus Newts. Aside from cool down, just set it up and you are ready to go. Also, there is no need for coma correction, with Fastmax having 1/10 the coma of comparable, short focus Newtonians. Are you wondering about comparable, big, color-free refractors? How many 180 mm F4.5 APOs are out there? What instruments can provide a comparable wide, high quality field and range of powers? Well, my AP 155 F7 EDF APO would be a contender. Although a bit lighter, the 155 APO is longer, must be positioned higher, and is more challenging to mount than the short Fastmax, and scanning involves a greater shift in eyepiece position. I look forward to comparisons between stubby Fastmax and its more svelte stable mate.    


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#18 turnerjs085

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Posted 15 January 2016 - 07:30 AM

It really is a beautiful scope in an all business way ;) Congrats! (and I'm not the least bit jealous... well maybe a tiny bit lol)

Jeremy
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#19 Scott99

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Posted 15 January 2016 - 01:26 PM

How is the field illumation in this scope?  That is one downside of Mak-Newts or Cass scopes with small COs.  



#20 MDRP

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Posted 15 January 2016 - 02:10 PM

According to Roland, the fully illuminated field of the Fastmax 180 is 14 mm, with illumination falling off gradually to the edge of the 2" field. Although not maximized for imaging, good results have been obtained. For examples of impressive Fastmax imagery with both the 180 F4.5 and the 235 F4.3, see bigcigarastronomy.com. As expected, I have not noticed a fall-off in illumination of the visual field. The effect of CO size on illuminated field is certainly not confined to Maks and other cats and cassegrainians. The CO of Newtonian diagonals is also directly correlated to the size of the illuminated field, with bigger diagonals providing a larger fully illuminated field. Dobs maximized for visual performance do so at the expense of the size of the illuminated field. There ain't no such thing as a free lunch.   



#21 junomike

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Posted 15 January 2016 - 02:29 PM

how does this translate to max Field Stop for visual use?

 

Mike



#22 Bill Barlow

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Posted 15 January 2016 - 04:32 PM

 

Beautiful telescope.  I was curious, what was the price when you signed up for it 20 years ago and what did you pay for it today?  

 

Bill

There was no list for this particular scope, so there was no price, just like the 10" Mak and the 175 EDF. There is a general interest list for scopes over 6" that started when AP stopped production of the 180 EDF's.  When AP has a run of scopes fitting that niche that are ready to ship, people on that list are notified of the existence of the scope, its price, and are given the opportunity to purchase it. Small run scopes like the 10" Mak-Cass (couple dozen) and this Fastmax were snapped up by those on the list. The larger run of more expensive 175 EDFs was not completely sold out to those on the interest list and a few were sold to people who hadn't been on any list at all.

 

 

Interesting..thanks for the information.

 

Bill



#23 TheQuestar7

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Posted 29 February 2016 - 02:05 PM

I have yet to see "first light" as I am deciding on the right visual push to mount such as the DM6 or the Half Hitch FTX to be added to the AP Eagle Pier.  Does anyone have this combination of mounts with the Astro-Physics FASTMAX 180 f/4.5...I sold my Questar Seven last year to compliment my ultimate grab 'n go Questar 50th, 3.5...I am spoiled on the quick peeks it offers with one hand grab and table top legs etc.



#24 MDRP

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Posted 29 February 2016 - 09:35 PM

Do not leave your new Fastmax 180 lusting for photons. (Place your ear near to its case and you can hear the panting.) Put it on a mount and give it first light. With an AP Eagle pier, you have an excellent base for a variety of mounts. As I noted at the start of this thread, if interested in an alt-az push to, the DM-6 works great. (Illustrations provided.) The short (30") tube makes Fastmax mount-friendly, and its substantial 30 lb weight may even improve performance of the DM-6. I see the Q7 in your logo. See how 7.1" of F4.6, primo Fastmax compares. I think that you will be pleased with contrasty images from low, low to very high power. Fastmax is an ultimate RFT. Put it to use while we still have the glories of the winter Milky Way.    


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#25 bierbelly

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Posted 01 March 2016 - 11:53 AM

I have yet to see "first light" as I am deciding on the right visual push to mount such as the DM6 or the Half Hitch FTX to be added to the AP Eagle Pier.  Does anyone have this combination of mounts with the Astro-Physics FASTMAX 180 f/4.5...I sold my Questar Seven last year to compliment my ultimate grab 'n go Questar 50th, 3.5...I am spoiled on the quick peeks it offers with one hand grab and table top legs etc.

 

one of the 11 Astro-Physics Fastmax 180 telescopes

 

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