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And now for something totally different — a Refractor Review!

A few months ago, a remarkable 100mm refractor found its way to my front door and landed in my hands.  Now it’s no secret that long focal length refractors attract me like a moth to a front porch light, but in this case there were a few other factors involved — such as a long black tube, a gleaming brass dew shield and finder, and above all else, the aura of 19th-century England which surrounds it in the same way an elliptical galaxy is encircled by a glowing nebulous cloud of stars.  For those not familiar with the age, the late nineteenth and early twentieth century was an era when high quality achromatic refractors, crafted by Thomas Cooke & Sons in England and Alvan Clark & Sons in the United States, ruled in many observatories in both countries and in continental Europe.

So to get to the point, I was asked by the person who hand-crafted that refractor, Richard Day of Skylight Telescopes, if I would be interested in doing a review for Astronomy Technology Today — and the rest is now history.  The review has been published in the current issue (March-April, 2012) of that magazine, along with an account by Richard of how he became involved in the art of building hand-crafted refractors.

With the blessings of Gary Parkerson, the editor of the magazine, I’m posting my original draft of that review here.  If you have a subscription to the magazine, you can download a .pdf version of either the entire current issue, just my review, or even Richard’s piece, by going to the ATT website.    But — you need to be a subscriber to have electronic access to the magazine — and,  if you’re not, you can subscribe to the digital edition for the current  reduced rate of ten dollars.  I’ve been a subscriber almost since the magazine first came out in 2007, which should say all there is to say about my high opinion of it.

So ………. without further ado, and a little inspirational help from the gracious and very dependable Admiral William Henry Smith …………..  here we go!

*********************************************************************************************

The Skylight 100mm f/13 Refractor: A Different Experience

Rats! Rain and more rain! Enough to drive a starlight addict into a photon deprived fit!

I sat back in my chair, opened my well worn star atlas, and began to plot new paths through the double star studded heavens as the rain beat against the windows and the wind rattled the doors and roared through the trees — again.  Let’s see now, this is day nineteen — twenty-one more to go and we’ll reach forty.  Maybe I better get back to work on that ark I started last year.

I worked my way across the middle of Gemini, and then down into northern Orion, circling and plotting as I went, making lists of magnitudes, separations, and position angles, and then laid my notes aside, closed my eyes, and began dreaming of clear dark skies filled with jewel-like points of starlight ……………

Click on this or any of the other photos for larger views!

……………  And then I heard the sharp scrape of a chair being dragged across my observing deck, just outside the window. I jumped up, walked over to the door, opened it carefully, and peered into the moonlit darkness — and over in the corner where I normally set up my telescope, I saw a figure in an old black frock coat, wearing a tri-cornered hat and holding a long-stemmed pipe, peering intently into a highly polished black tube with a gleaming brass finder just a few inches from his hat-covered head.

Hmmmmm, I hummed — that guy looks vaguely familiar, even a bit like the much admired Admiral William Henry Smith of mid-nineteenth century British astronomical fame.

I grabbed a coat, walked outside, and quietly started toward him. As I got closer, he looked up from the eyepiece, with blue-white starlight sparkling in both eyes, and in a heavy nineteenth century London accent with an aroma of sea salt hovering about it, said, “Something I can do for you, m’good man?”

“Yes, you can,” I began hesitantly.  “You can start by telling me who you are, and how you got here.”

He stood up, took off his hat, and with a low bow and a flourish of his coat, said, “Allow me to introduce m’self, m’dear sir.  I am the good Admiral Wm. H. Smyth, well known author of that best selling 1844 compendium of the stars, A Cycle of Celestial Objects, of which you twentieth-first century folks typically peruse only the fragment known as The Bedford Catalog!”

. . . the brilliant white light of the moon was busy beaming its bright rays off of a beautiful brass dew shield.

“I thought that might be the case,” I replied a bit distractedly, still wondering how he got here. It was that telescope — I couldn’t take my eyes off of it. The long, gleaming black tube literally shimmered under the brilliant white light of the moon, which was busy beaming its bright rays off of a beautiful brass dew shield.

“Mind if I take a peek into that thing?” I inquired.

“Certainly not, m’boy! Please, peer into this heavenly one hundred millimeter instrument!”

I positioned my eye carefully in front of the eyepiece, reached for the focus knob …………………

…………….. and suddenly a strong gust of wind rattled the entire house and sent a refractor length tree limb crashing into the deck. I shook myself out of my stupor, looked around in a slight daze, got up, walked over to the door, opened it, and looked outside —- nothing there but a large limb over in the corner of the deck where I normally set up my telescope.

Very strange. I ought to know by now not to eat oysters and sardines this late at night.

That long black tube, with the gleaming brass dew shield, and the brass finder ............. there it was!

A few nights later — it was still raining, and the wind was still blowing, and I was scrupulously avoiding the sardines — I was inspecting the internet for possible purchases of an astronomical nature, and suddenly I felt my breath catch.  That long black tube, with the gleaming brass dew shield, and the brass finder ………….  there it was!  The telescope in my dream!

I didn’t hesitate for a tenth of an arc second.  I placed the order, and three days later it arrived in a large brown truck and was carried up to the front porch while I stood in stunned silence.  Under clear skies, even.

Now, the truth is, when I placed that order, I was a bit more than a bit concerned about a telescope of that length surviving the journey from London to southern California to Oregon. So I opened the stout outer box very cautiously, then a similarly stout inner box, and removed enough molded foam and bubble wrap to float that ark I never finished all the way to Hawaii.  Very impressive work.

Finally, after what seemed like a short version of eternity, I lifted a long bubble-wrapped tube out of the box.  And then I saw it — a red sheen on the other side of the bubbles! A red scope? I thought this thing was supposed to be black!

Slowly, carefully, cautiously, and with my cup overflowing with concern and curiosity, I unwound the crackling bubble wrap — and there, beneath all of it, was a bright red blanket wrapped carefully around the entire length of that long tube! Nice touch!

I unwound it, too, and carefully as well, and as I did, the long black gleaming tube and shining brass dew shield of my dream emerged into the admiring low afternoon daylight of northwest Oregon.

Inside the box I found a Baader Steeltrack focuser and that glowing brass finder I had spied in the moonlight when the Admiral was visiting. It didn’t take long to attach either of those, followed by a pair of Parallax rings I ordered separately, then my dovetail plate, and then  ……….. with visions of frock coats, tri-cornered hats, wool vests, and the remembered aroma of pungent tobacco wafting my way from the Admiral’s long-stemmed pipe, I hoisted the whole thing on to its mount, edged the dovetail carefully into the saddle, tightened the knobs, and proceeded to stand back in admiration  …………. and stared  ………..  and walked around to the other side  …………  and stared  …………  and walked to the front  …………  and stared  ………..  and then to the back  ………..  and, well,  ………….  I stared.  A lot.  While walking in circles.

The photos I had looked at on the internet were good, but not as good as this. The admirable Admiral was right — this was heaven.

*********************************************************************************************

So how does it perform?

Imagine the delicate strains of the Second Movement of Chopin’s Second Piano Concerto drifting across an open field on a late summer afternoon in early September, while the slanting rays of a low sun stream through the dappled rustling leaves of a tall stand of poplars.  Sublime it is.

Being that the skies were clear and cooperative that night, I lined up the mount and that long black tube on Polaris, and initiated my one hundred millimeter Skylight f/13 into the world of multiple star light.  With an 18mm Radian (72x) perched proudly in the diagonal, I gingerly dialed in that first light focus — and there was that beady little gleam of ninth magnitude secondarial light, looking me right in the eye from a jet black sky.  I could hear the Admiral’s voice again:  “Please, peer into this heavenly one hundred millimeter instrument!”

The waxing moon was out that night, shining at about 70% of full power.  Ignoring it for the moment, I swiveled the long black tube through that shimmering moonlight to the Orion Nebula just to take a peek.  I bent down to the finder, watched the three gleaming pools of light that decorate Orion’s sword come into view, put the center pool under the crosshairs, and then sat down and leaned over to peer into the 18mm Radian.  Despite the moonlight, the nebula stood out almost as if it was three dimensional.  The contrast was simply amazing — shades of light and dark gray ran randomly through the center and out to the edges — and there was just a very slight hint of color, dark red, dark pink even, very subtle, and beautiful beyond description.  And the four stars of the Trapezium looked like they were etched into crystal.  Wow.

There are two double stars in the vicinity of M42 that I’ve been eyeing periodically over the last few years, which can be a challenge for a four inch scope.  One is Σ 750, located at the north edge of that northern pool of light (NGC 1981).  The magnitudes of that one are 6.4 and 8.4, with a short 4.2″ of distance between them.  The other one, Σ 754, is at the southeast edge of the southern pool of light (NGC 1980), and it has magnitudes of 5.7 and 9.3 separated by 5.3 seconds of arc.  Both can be a bit difficult because the secondaries are mere phantoms of light that tend to suffocate under the glow of their primarial parents.

At 72x, each of those elusive secondaries was as distinctly separate and pinpoint sharp as could be.  There were no intermittent bursts of ravenous photons leaping from the primaries with intentions of swallowing the secondaries — just round, sharply defined primarial orbs with very delicate micro dots of white light perched impossibly close by, shining sharply on their own.  I sat and stared at each of them for about fifteen minutes.  Then I went back and forth between them several times — I simply couldn’t believe I was seeing what I was seeing at that relatively low magnification with no strain to my visual apparatus.  I’ve seen them like that in a five inch refractor at similar magnification, but not in a four inch.  Pure gold.  Pure undiluted, unaltered, unbelievable gold.

When I recovered, I scanned the sky in search of old favorites, and never met with anything anywhere near disappointment.  Sitting at the rear of that immaculate gleaming black tube with the moonbeams bouncing from the brass dew shield, I was ready to sell every scope I own and live happily ever after with just this one.  I can’t ever remember a reaction like this to a telescope.

Now I’m not going to rattle off esoteric mathematical formulas and phrases here.  I know optical gold when I look through it.  I checked the collimation that first light evening, first with a Cheshire tube — it was dead center — and then toward the end of the night on several first magnitude stars.  I looked closely at the in- and out-focus images of each of them and detected what might be a very slight over-correction, but if so, I wouldn’t touch this lens for all the Naglers in a Televue warehouse.

What about that dreaded two letter designation for color, CA?  Not much, I can tell you.  Jupiter shows a slight bit around the outer perimeter when out of focus, none when in focus.  That bright, 70% illuminated lunar orb flashed a bit of yellow around the edge, but just barely — I had to look for it to catch it.  The detail along the terminator was sharp, the shadows were jet black, and the rough edges of craters had that granulated texture which is characteristic of sharp optics.  There were flashes of color when Regulus was out of focus, but almost none when it was focused precisely.

Plastic plug? Nein! How about brass instead?

The only aspect of this beautiful refractor I can point to with any concern is the coarse focus adjustment on the Baader Steeltrack focuser.  It’s much too stiff when attempting to coax it into motion from a standing start.  That can be adjusted out, although it would be a huge help if Baader would get a data sheet on their web site with adjustment information.  But the fine focus knob is as smooth as a sharp knife passing through a succulent oyster, and contributed immensely to my success with the two double stars described above.  And it’s a very heavy duty piece of equipment that should easily hold a large two inch diagonal and a monster eyepiece, such as the 31mm Nagler or the 21mm Ethos.  I had a very heavy two inch Takahashi diagonal plugged into the focuser, and at one point I loaded it with a 5mm Radian, pointed it at the zenith, and it held firmly in place.  No horizontal sag, no vertical slip.

Oh, and one more thing about that focuser.  You know the little white plastic plug that fits into the end of the 1 1/4″ adapter?  Not on your life.  How about a heavy brass plug.  Neat.

As I’m writing this, the infernal rain has returned, and the starlight I’m addicted to is hiding on the other side of the scudding gray clouds streaming past overhead.  So I think I’ll amble over to my comfortable old chair, plot a few more courses through the heavens, and then lean back, close my eyes, and see if I can get in touch with the good Admiral once more.  I need to find out where I can get a black frock coat, a tri-cornered hat, a wool vest, and a long-stemmed pipe.  I’ve got an old stash of Whitehall tobacco I’ve been saving for a long, long time, waiting for the right moment — and I do believe I’ve finally found it.

Clear Skies!

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8 Responses

  1. Excellent review John. If my skies didn’t require a larger aperture telescope this beautify would riding on my mount. The brass plug is a very class finish to an excellent telescope.

  2. Hi John. Congratulations on that awesome scope, she sure is a beauty. I recently received a 100mm f/13 OTA built by Dan Crawford of Crawmach that has one of Sheldon’s Carton objectives. An extremely nice long refractor indeed. Do you know if Skylight is using the same Carton 100/1300 objectives for their refractors?

    I also read that you also happened upon a 5″ D&G recently?

    You and Greg keep up the good work!

    Clear skies
    Brandon
    Cordova, TN

  3. Thanks for the comments, Brandon!

    I don’t know what lens was used in the Skylight f/13. All I can say is that it’s unlike any other achromatic lens I’ve ever looked through. I have a 50mm and a 63mm Zeiss, which have a snap and crispness that are unique for an achromat, but it’s impossible to make any comparison between them and the Skylight because of the differences in aperture — except to say that that same snap and crispness is there to a greater degree (which is due to the aperture).

    It does seem as though something has been lost over the years with regard to the fabrication of achromatic lenses. When I read the comments made by famous double star observers such as S. W. Burnham, it’s obvious the lenses made by Cooke and Clarke were of a different caliber than what’s found on the typical achromat sold today.

    Burnham discovered at least 1450 doubles with a six inch f/15 Clark refractor built in 1870, and had this to say about it in 1900:

    “It is hardly necessary to say, in view of the discoveries made with it . . . that its performance on the most difficult objects was simply perfect. Many of the stars discovered with it are by no means easy to measure with the largest telescopes now in use.”

    The D&G finally got some extended use this past weekend, and I can say I’m very pleased with it as well. But it’s so long I have to be careful not to catch the corner of the roof with it when I’m on the second floor observing deck!

  4. I finally was able to get the Skylight 100m f/13 out this morning for the first time since I wrote the review above. To be honest, I’ve wondered more than once if I didn’t over-do the description in it of the pair of double stars in Orion — as in too much of the new scope euphoria.

    Nope. Not one bit. Not one single bit.

    I spied Rasalgethi climbing over the roof of my house, so I pointed the scope at it — and I absolutely did not budge except to wake my foot up once. I have never, ever — and I mean NEVER — seen it like that. The primary was a very sharply defined round ball of orange light, and the secondary — you just have to see it to believe it.

    Every now and then the secondary would waver a bit when the seeing slipped a little, but then it would come back, just as sharp and bullet-hole precise as it could be. Both of those stars were so sharp that the difference in visual size was a study of contrasts in diameter. I don’t know how else to describe it — I was really struck by that. Apart from the color, it was the dominant aspect of the view, the one that just reaches out and grabs you by the neck and shakes you. You see two stars of different sizes, you notice it, and you move on — but in this case, I was stunned speechless — and motionless. And there was that delicious thin slice of black space between the two stars that just accented that contrast.

    As if that wasn’t enough, I moved up to Delta Herc, the Ring of Fire, after a good thirty minutes of drooling all over Rasalgethi — and I drooled some more. A lot more, in fact. The secondary, just barely a dust mote of light — I mean if it was any smaller it would literally disappear from sight — was very clear, very sharp, very intense, and it was just sitting out there far enough away that you could almost say it was all alone — yet it was within twelve arc seconds of the primary, barely far enough to escape most of the white glow.

    I described those Orion doubles in the scope review as shining sharply on their own, which is exactly what they were doing — and that’s exactly what Delta Herc’s secondary was doing, too. That is not a literary embellishment — it’s exactly, precisely, what those stars were doing! You literally have to see it to understand what those words mean.

    All that time I thought I was using a 14mm Radian in the scope, which would have provided 93x. When I finally overcame my stunned state long enough to think about switching eyepieces, I discovered I had been using an 18mm Radian — 72x. Not a huge difference, but still it came as quite a surprise.

    What a night! What a night!

    • Hi John, that is a beautiful scope and a great review I also
      like the mount it is on, what is it looks very sturdy.

      Pat.

      • Hi Pat,

        The mount is the basic T-Rex (no encoders), with a small counter-weight I added to the side opposite the scope. The tripod was built by a guy in Arizona, Jeff Morgan. I would love to take credit for it, but it’s all his creation. It is really a work of art. I would guess the tripod alone weights about 20 pounds. As long as the mount head is detached, it’s no problem to carry from inside the house to the deck. It’s by far the most stable wooden tripod I’ve ever used. Sure does eliminate the vibrations at the eyepiece.

        Clear Skies!

        John

  5. Hi John

    I finally got around to posting here. I bought one of these fine telescopes from Richard Day pretty much on the strength of this article. I have not been disappointed! It has, I believe, a carton objective. Whatever it is, the scope is a truly beautiful instrument both as a work of art in its own right as well as in optical performance. Even in my novice hands it has shown itself capable of some wonderful things. Your description of M42 is so like my own experience under the freezing skies of an English winter few days ago! I thought I was dreaming as those merest hints of colour flitted across my sight, so it is good to know that someone else can see them (or at least shares my dreams…).

    I live in York, and work in an office ot 100 metres from the original workshop that wonderful master telescope maker, Thomas Cooke! It seems fitting that at least one Skylight, whose very essence is a tribute to Cooke’s work, now resides in Cooke’s home city.

    Thanks for your article, and may I say I very much enjoy the site (and the work and writings of yourself and your colleague, Greg).

    Clear skies!

    Mark

    • Hi Mark,

      Glad to exchange notes with another owner of the Skylight f/13!

      You’re right, there really is something special about the lens in that scope. The only way to truly appreciate it is to actually look through it. I was tempted many times before I bought one, but after actually experiencing first hand how well it performs, I wished I hadn’t waited so long. It hasn’t disappointed me yet.

      Clear skies to you as well!

      John

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