University Lowbrow Astronomers

Refractor Madness!!

by Clay Kessler
Printed in Reflections: June, 2000.

It all started out innocently enough. I was looking for a “super finder” for my 12” Split Ring Newtonian. I was on a trip to Ohio when I came across a dealer that had an Orion Short Tube 80 in stock. After looking it over I purchased it and took it home. It turned out to be too large for the Newtonian but looking through it was strangely satisfying. The wide field of view was, somehow, “clean” looking and the short tube made a great guide scope for my equatorial camera platform.

Orion Short Tube 80

Orion Short Tube 80.

I did not think too much about this. I just enjoyed the views and perched the short tube wherever it was handy - the top rail on my 8” SCT was used frequently as a short tube mount. After a while I began to get strange urges for a wide field astrograph. Looking over the options it was clear that many of the astrophoto “big guns” used refractors in the 4” f6 range for wonderful astrophotos. The only problem with these is the cost. The high end APO refractors are expensive. There must be a mirror based solution! Lets see... an 8” f6.3 SCT... no, the field is too curved over a 35mm frame, and forget medium format. How about a Takahashi Epsilon 160 - only $4,500.00.... OK - so that is a little steep. Maybe a Ceravalo Mak-Newt, lets see $2,000.00 and a two year wait.... I don’t think so. Maybe I should look - just look mind you - at refractors.

Elsewhere on my web site you can read about the 4” f6 BW Optik refractor that I built from a kit. [See Clayton Kessler, “The BW Optik 4” f6 Refractor Kit.” Printed in Reflections: September, 1999.] This has turned into a very nice astrograph and can take much better pictures than I am capable of. What is odd, to me, is how satisfying this little scope is to look through. Star clusters take on a rich look of diamonds sprinkled on black velvet. Many nights, despite my best intentions, the cameras never get mounted and the entire night is spent with an eye glued to the eyepiece. This is by no means a planetary scope but the wide field views are spectacular.

4 inch f6 BW Optik Refractor

4 inch f6 BW Optik Refractor.

Somehow my whole attitude about refractors has turned around. What started as a feeling that these were basically glorified “department store trash scopes” has turned into an appreciation of affordable precision optical systems. This is not to say that we should throw away our SCT’s and Newtonians. Aperture is still king and a 12” or 16” or 20” refractor is not very practical. Still, this new crop of achromatic refractors that is showing up in astronomy stores lately have a lot going for them. I have had the good fortune to look through several of these scopes lately and I have been quite impressed. The “Short Tube 90” from Orion takes the “handyness” of the 80mm and adds 10mm of aperture. I was able to peak through Charlie Nielson’s and I was amazed at how easy it was to split double stars and the higher power views showed very nice diffraction rings. I understand that there is now a 102mm f5 version of this scope with a 2” focuser. I have not seen this one but internet reports are very favorable.

All of this peering through refractors, and a timely income tax refund, got me all fired up and I found myself perusing the internet and looking at reviews of different refractors. The “itch” got real bad when I found some lens blanks on eBay. I now have some 5” ED glass blanks that may turn into an f7 triplet astrograph at some unidentified future time. Unfortunately, I do not know anything about grinding lenses. I can, however, make all of the mechanical parts and I am looking for a lens grinder who wants to “buddy up” on a pair of refractors (hint - hint).

Looking at un-ground lens blanks was exciting for a while but it has not satisfied my itch for a larger refractor. I like my 4” f6, any new refractor must do duty as a photographic instrument and not duplicate the functions of my existing equipment. The next logical progression would be an instrument of about 1200mm focal length. I had a chance to look through the new Celestron 6” f8 refractor and I was doomed. I have read a lot of reviews of this new 6” scope and the “twins” marketed by Skywatcher and others. The reviews are almost universally favorable, the optical quality of these achromats is really very good. What bothered me were the mechanical aspects. All of these scopes are made in the same Chinese factory and the mechanicals may not be up to the demands of serious imaging. For example, my Short Tube is a very nice scope but there is some slop in the focuser and it does not lock tightly. I started reading about a scope offered by Photon Instruments - the Photon 127. This is a nice 5” f9 with a 1147mm focal length. Reviews on the internet mention not only the optical quality (reported to be better than the Celestron / Skywatcher clones) but also the well made mechanical systems.

I eventually weakened and paid a visit to the Photon Instruments web site. After I reviewed the info there the next step was a call to Owner Warren Kutok. Warren gave me the hot skinny on the genesis of the Photon 127. Warren prototyped the design of the scope in his Mesa Arizona shop. Once the design was perfected the production work was contracted out to a Chinese optical company (not the same one that makes the Celestron / Skywatcher refractors). This company makes high quality lenses for the scope but they also make the mechanical systems to Warren’s specifications. The tube, focuser and cell are all aluminum including the dew shield. The system employs multiple baffles (3 I think) in the tube. I was quite impressed with the focuser. While it is not as large an Astro Physics 2.7” the design is similar in that adapters are threaded into a 60mm diameter thread. This will allow me to make a special adapter for my Taurus Tracker and keep the Tracker/camera combination as short as possible. The 60mm thread diameter means that I will have a large “hole” for the light path to get to my camera. This will minimize vignetting.

Before I finished talking with Warren he had performed a “credit card-ectomy” and I was anxiously awaiting my new Photon 127. Waiting is always the hardest thing. We astronomers always seem to be waiting for something, a clear night, the new moon - even just waiting for darkness! Well, I made the most of the wait - I ordered the Losmandy adapter plates needed to mount this scope to my trusty G11.

Well, the big day finally arrived. The box was somewhat larger than I thought it would be - a tribute to the careful packaging. Once I removed the beast from its packing material I was impressed with the good looking and well made telescope that I received. It came with the 30mm and 15mm Plossl eyepieces that I requested, a nice finderscope (it did need to be focused) and a 2” mirror diagonal. I do have a minor gripe - why don’t these things come with end caps? It was a simple matter to attach the supplied rings to the Losmandy universal plate and I am in business, or am I?

As I look out my office window I notice that the once clear and sunny sky has clouded over and now threatens rain! A bad case of “new telescope storms” appears to be imminent. As I wait for better weather I can fondle the accessories and dream of the great images I will take through this scope.

Saturday dawned bright and clear, and after work and helping a friend with a kitchen remodel job I set out for Island Lake [located near Brighton, Michigan] and first light. Of course, as I set up the G11 the clouds started rolling in and I earned some wisecracks from some of the solar observers out there. After dark fell there were some holes and I was able to get a peak at Vega near the horizon. Despite the very low altitude and the rolling atmosphere I could see a nice round set of diffraction rings both inside and outside of focus. A peek at the “double double” showed a rolling pair of “figure eight’s” at 88X and considering the poor seeing I am very happy with this. Hopefully next weeks trip to the UP [short for the Upper Peninsula which is the Northern part of Michigan] and Boon [located near Cadillac, Michigan] will allow me to make a more comprehensive evaluation and try some astrophotography with the system.

Man, this thing came with the worst set of “new telescope storms” that I have ever seen (maybe THAT was why the box was so large)! I suspect that this is how the weather stays so good in Arizona, they ship out the bad weather with the telescopes! Four days in the Upper Peninsula and not one good night. Fortunately Boon did not let me down. I finally got “First Film” on Friday June 2nd.

Photon 127

Photon 127.

Star 21 and M104

Star 21 and M104.

The Boon trip yielded a wonderful night on Friday. The sky was very dark and transparent - perhaps the best that I have seen in Michigan. I was able to focus the scope with the Taurus Tracker installed and my worst fear was alleviated. I managed to take four one hour exposures in about 5 hours of darkness - not too bad for a first use of a new scope. My shots did exhibit some slight trailing - or field rotation, I have not yet determined which. I suspect that I need to tighten the pick off tube on the Taurus. I shot STAR 21 - an asterism that included M 104 in the frame, STAR 20 - another asterism, The Swan Nebula (M 17) and NGC 6960 - the western part of the Veil Nebula. As you might expect with an achromat, the brighter stars were somewhat bloated. The extended objects however were wonderful. M 104 was small but distinct with a sharp dust lane, easily recognizable as the Sombrero Galaxy. M 17 was wonderful showing both the main nebula commonly visible in a telescope and clouds of nebulosity around the field. The Veil was dim, it could have used more exposure, but it showed very nice color and lots of delicate filamentary detail.

Swan Nebula

Swan Nebula.

This scope is a real winner. While I have not looked at any planets yet - or even the moon (next week for sure) the photographs tell the tale. I will try to find a filter to cut some of the “star bloat” in the images but even if I cannot correct this it will be well worth while to take lots of astrophotos with this setup this summer. I am very pleased with this relatively inexpensive refractor and I think it represents a very good value for my telescope dollar.

Links

Copyright Info

Copyright © 2013, the University Lowbrow Astronomers. (The University Lowbrow Astronomers are an amateur astronomy club based in Ann Arbor, Michigan).
This page originally appeared in Reflections of the University Lowbrow Astronomers (the club newsletter).
This page revised Sunday, March 9, 2014 4:30 PM.
This web server is provided by the University of Michigan; the University of Michigan does not permit profit making activity on this web server.
Do you have comments about this page or want more information about the club? Contact Us.