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CN: Behind the Scenes - TMB Optical

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Here at CN, we realize that many of our readers are equipment junkies, but sometimes it's nice to get a glimpse into the people and the company behind the equipment.  With this in mind, we've decided to launch a new series of articles spot lighting and interviewing some of the better known manufacturers for the amateur astronomy community.  Think of this as a chance to get to know the people who make your favorite toys.

CN: Behind the Scenes -  TMB Optical

This month in CNs Behind the Scenes we've got something special lined up for you - an in-depth interview with Thomas M. Back – the owner and founder of TMB OpticalTMB designs some of the most highly regarded optical instruments on the planet today, for his own company and others.
CN: Welcome Thomas, I know things have been hectic for you lately, so right off the bat, I'd like to say a big thank you for taking time out of your busy schedule to sit down and give us some insight on you and your company.   Lets start at the beginning: Tell us a bit about yourself, your interests and how you got started in astronomy.  I understand you're from the midwest?

I was born in Cleveland Ohio, and have lived in the greater Cleveland area all my life, with a few exceptions, like living in California (Venice) for a short time, and Bowling Green, Ohio. I was not formally trained  in optics, but I did well in Mathematics and Physics. I now live in a suburb of Cleveland, at one of the highest points in Ohio, and I am near a large body of water, which is good for seeing. It's probably one of the best seeing sites in the state, but not from a standpoint of sky darkness, or clear nights during the winter months. However, the summer months have a surprising number of clear nights. The expansion of 24 hour shopping has all but ruined faint object deep sky viewing in my area.   

I've always been very intense about my hobbies, and my interests. I road my first 100 mile bike trip at the age of 11, and won a few races. I got my first telescope,  for Christmas, after seeing the moon and the Pleiades star cluster through an old pair of 7x50 binoculars.  It was a 60mm refractor (a Tasco of course) at the age of 8. Even with the poor optics and images, I was very determined to get a new telescope, that could show the moon and planets with good detail.    

I also enjoy music very much. I have a very high end stereo system, with well over 3500 LPs, and about 1000 CDs, DVD-As and SACDs. Living in Cleveland, we have one of the best symphony Orchestras in the country.Many nights I have heard the beauty of music at its finest at the Cleveland Orchestra.

I've been active in astronomy for forty one years. I guess you all know my age now.

I started to get interested in optics after I could not buy a telescope with optics that I felt were good enough. I won't name any names, but I went through 8 telescopes, some very expensive, and none would show the planets the way I would dreamt. This was when I was a teenager.  I decided to grind and polish my own 6" f/8 mirror. I still  have that mirror. The mirror was fair, and better than all my previous telescopes, except one, a 6" f/15 Mak-Cassegrain, but it would never cool down on anything but the warmest nights. It was a one season telescope, if that, and would often dew up even with the dew shield on.

After I made that mirror, I really became interested in optics and bought nearly every optical book that dealt with telescopes, theoretical optics, and went to many University libraries to make copies of articles that had to do with astronomical optics. I must have copied over 2000 pages of articles on telescopes and optics,  and another 1000 pages on lunar and planetary articles, at both the amateur and professional level over the last 35 years.

I currently have a very extensive library with a complete set of Astronomy and Sky and Telescope magazine, 50 years of the ALPO Journal, the B.A.A journal, plus many others. It contains nearly every serious lunar and planetary book (and a lot of deep sky books and atlases), most that deal with visual planetary astronomy, going back to the 18th century, and the rest are books from professional large telescope research of the moon and planets, and the space missions, starting with the first lunar orbital missions, up to the latest Cassini mission.  

Still not happy with my 6" f/8 Newtonian, this was during the early days of the PC. With Windows 95 about one year away, I bought a Gateway 386-16 with a math coprocessor. In 1990, Mike Simmons, an optical wizard, wrote an optical design program, called IOPD. It was a DOS program, but I was able to master it quickly. I was friends with Roland Christen at the time, and he gave me a copy of the program. Mike was hard to contact, so I could not get his design program from him. Soon, I was sending and showing Roland his own designs. I was very close to his own designs, which at first made him a bit uncomfortable, but later, at the 1991 Astrofest Star Party, he said that I was within a few microns of his production "Star 12ED doublet," and later, his first Super ED triplet, the 155mm f/9 EDT.

I then got into contact with a professional optical designer, Richard Karlson, and with my help, he refined his optical design program, and I then used that program to design doublet and triplet lenses. I now use the program Zemax, a very powerful optical design program, and is the standard around the world, along with Code V. Code V is a better optical design program, the best in the world in my opinion, but with Zemax at $4,000.00, and Code V being a program that you must "rent" for one year at a time, at a cost that is significantly greater, Zemax is by far the better value, and you don't have to upgrade, if you don't want to, or rent it out on your computer, which over the years can add up to a fortune.

Once I was able to design optical systems at or near the level of the Professional designers at that time, I decided to use my optical design knowledge to offer services to the amateur and professional market. At that time, my company was call "APO Optical." I did a few designs for amateurs, and professional optical companies, but I wasn't making enough money to make a living, so I had to keep my day job. Then in 1997, Markus Ludes contacted me by letter, offering to start a partnership together, but at first I said that all I wanted to do is design optics. He agreed to pay me for my designs, and I sent him apochromatic lens designs from 80mm up to 14". To be honest, I was never paid cash, just with equipment, which at the time, was a big mistake on my part, to allow that to happen, but I then decided to sell my TMB telescopes and lenses, so I could quit my job, and work full time, selling TMB designed optical systems. The first two years were tough (not uncommon for a new business), but by the third year, I was making a fairly good living.

 I made that decision 16 years ago, and never looked back.     

CN: Do you prefer to design objectives or eyepieces?  Can you tell us a little about what is involved?

Objectives. Since they are very interesting to design. There is almost always a better design, but no one has found it yet. Finding that "super" design can be very exciting. Modern optical software is trying to find these better designs, and it is called "Global Optimization." You put your best design in, and the global  optimizer tries as many as a billion different possible solutions. To do this, you have to keep your computer on for days, before you can hope that it will find that better design. There are other tricks, but the computer will show that typically these super lens designs have tolerances that are too sensitive to make in production.   

Eyepieces are difficult, because there is the eye itself to consider. You can have a fantastic eyepiece design on the computer, but spherical aberration of the exit pupil can make the eyepiece very uncomfortable to use. Certain glass types that are useful for making eyepieces have a yellow coloration to them, thus making the eyepiece a yellow filter. You have to worry a lot about your supplier's coatings, as with 6 to 8 element designs, coating quality can make a big difference in performance. And the internal baffling can be a real job, as we learned when we made the new TMB Planetary eyepieces.  

CN: Who does the lens figuring for your TMB scopes? Why did you choose them?

A large aerospace firm in Russia, called LZOS. Their master opticians do the final hand figuring, that is so important for sharp and high contrast images. We (Markus Ludes and I) choose LZOS, because they could control every part of making my designs to a very high quality. They make their own glass, curve generate, polish, figure, multicoated all glass surfaces, and finally make a custom temperature compensated cell, that has been a proven performer over the last 9 years. The last issue is always price, and while the lenses are not inexpensive, they are priced so we can be competitive in the high end apo world.  
CN: What was the first scope your company was involved with?

A 100mm/800mm f/8 of LZOS design (our optical supplier). I tested this lens, and have its design on my computer. It wasn't a bad design, but by trying to control the spherochromatism at all wavelengths, no wavelength had a better wavefront than 1/4 wave OPD peak to valley, on the wavefront, including the null (green-yellow wavelength). The TMB 100mm f/8 design, is better than 1/10 wave from 430nm to 800nm, or in other words, from the deep violet, to almost the near infrared wavelengths.

CN: I know I'd never be able to afford it, but I've just got to ask: What's the largest scope you've designed?

A 60" f/20 apochromat, just to see if you had unlimited funds, would the correction be good enough to go ahead with the project. The focal ratio has to be f/20 or greater, if the lens would be color free in focus. The great Alvan Clark was ready to make a 60" achromat for the Mount Wilson project, and wrote a paper showing that the glass would not be the limitation. And he was right. But the cell would be a monster to build, it would have to hold all three elements without strain, and hold the lenses within the tolerance of their optical centers, so there would not be coma on axis, and other optical aberrations.  

CN: Sixty inches?  Wow!

The largest scope I designed that is available from TMB Optical, is a 21" f/12. And I designed a 1000" Ritchey-Chretien, with a field corrector, just to see how large the usable field would be. The readers may laugh, but in the next 10 to 15 years, there will be 1000" class telescopes, with adaptive optics, on mountain tops in the southern and northern hemispheres. These monster telescopes will easily outperform the Hubble Space Telescope.

CN: What's your best seller?

Our TMB 105mm f/6.2 apochromat.   Together, APM-Telescopes and TMB Optical have shipped about 2500 telescopes and lenses. TMB Optical has sold about 500 telescopes and lenses, mostly telescopes. The astronomy retailer Astronomics, my only dealer, has sold many of them, through their retail company. 

CN:  Any planned changes to your line up?

Yes, a 130mm f/7 and 155mm f/7.5 FPL-53 Signature Series, with air spaced triplets, and 4" fully rotatable focusers. In the eyepiece department, we will bring out more focal lengths in the wide angle "Paragon" series, and a new Ultra Wide angle eyepiece, that will redefine the words "space walk," when looking into an eyepiece.

The Paragons will be at the following focal lengths: 16mm, 24mm (1.25" barrels), 30mm, 35mm and the current 40mm. The 30mm and 24mm will be the next focal lengths to be in production. I would rather not give any specific production dates. They will be posted on the Astronomics, TMB Optical, and Burgess Optical web sites, plus the TMB and Burgess Optical Yahoo groups. 

CN: If you could pick only one scope out of your line up, which would it be?

The TMB 12" f/12. But that darn tree would have to be cut down!

CN: Do you observe often?

Before I started TMB Optical, I was out almost every clear night, unless the seeing was poor. I have observing notebooks going back to 1975. I became a member of the ALPO, and the British Astronomical Association, the latter as one of their select Mars Observers. I sent in many drawings of Mars to the B.A.A., and got to know, through correspondence, many planetary observers, that had access to the largest and best planetary telescopes. This included some of the best imagers of the moon and planets too. One person was William Sheehan, a prolific author of many books on the planets. He wrote to me about his visual observations with the Pic-du-Midi 43-inch f/15 planetary Cassegrain. He was able to see the satellite Charon, Pluto's moon, and saw Saturn like the best Hubble shots. Some might say more like the Voyager images, but in any case, very few people have seen the planets at this level of detail and contrast. Another is Sky and Telescope's Steve O'Meara. He sent me photocopies of his drawings and observations of Mars with the Mount Wilson 60" reflector. He was able to see craters in the south of Mare Cimmerium, and the summit Caldera of Olympus Mons. Arsia Mons showed relief -- in his own words: "Arsia Mons lifted off the face of Mars like a blemish." I nearly cried, when I read and saw his drawings.

Later, he gave a speech at the Hidden Hollow Star Party in Mansfield, Ohio about his observations with the Mount Wilson 60", and I was able to talk to him for almost an hour, about his observations, and those of one of the greatest planetary observers, E. M. Antoniadi.
Now, I observe after I star test a telescope, before it is shipped, and at star parties. I miss very much all the great time I spent observing, before I started TMB Optical.

Before anyone says just build an observatory, I can't. There is a huge tree due south (the worse possible place for a large tree), and it is not on my property. The owner will not cut it down, even when I offered to pay for all the expenses. So, I would only get about 30% sky coverage, when you take the trees and the zoning laws that only allow a building to be in a specified area on your property.  

CN: So I guess that's a natrural lead in: What's your favorite setup for observing, gear wise, and your favorite targets?

My favorite telescope is my TMB 152mm f/7.9, on an AP 900 GTO mount, and ATS 54" portable pier. The eyepiece would be my 5mm TMB Super Monocentric, or two, in my Mark V Baader binoviewer. My favorite object is Mars. Deep sky, my favorite target would have to be Globular Clusters. For some reason, the stars look like the tiniest points almost with no dimension. They never look that way when you look at any star field, and I have never heard a convincing argument why this is so. Omega Centauri through a 20" Starmaster at the Winter Star Party, using a Zeiss binoviewer, was one of the views I will never forget. There are two views of the planets I will never forget.  One was with my Astro-Physics 180mm f/9 EDT (Strehl .9975, Roland made a copy of the test report for me), of Mars very high in a splendid sky. It was only 14.5 arc seconds, but I could clearly see Olympus Mons, and this was a time when there was no cloud cover, so I was seeing the actual mountain, not the atmosphere above it. I was using my Nikon 5mm ortho, which gave 325x. The other view I will never forget, was through my TMB 9" f/9 at the Winter Star Party. We had Jupiter in view with again, the Zeiss/Baader binoviewer, a 1.7x corrector and a pair of 1.25" Zeiss orthos, at around 600x. This was the first time I was an eyepiece hog, and I stared at Jupiter for over 15 minutes. Ganymede looked like a small planet, with the bright polar region visible, and Galileo Regio crossing the center of the moon. Jupiter looked nearly like a Hubble image, albeit at a smaller scale. There were 10 to 15 people behind me, and they all called me a "eyepiece hog." I could not help myself, the view was so stunning.     

CN: What do you see that differentiates your company from the other companies on the market?

A focus on design. You may hear that anyone can design optics, with an optical design program. Well, that is almost true. But I will give you an example of a well known designer, and telescope maker, and how for over 30 years, he was not fully optimizing his designs. I told him over 15 years ago about this, as did the famous optical designer Richard Buchroeder. Any designer worth his salt, understands that correct glass choices, determines the color correction, Assuming the glass or crystal elements are of very high homogeneity. In a high quality, triplet apochromatic lens, the only remaining aberration on axis is spherochromatism.
This is where design comes in to play. This other designer, pushed his designs for minimum spot size. This, unfortunately, greatly increases the amount of sphero-chromatism a lens has. By optimizing for minimum RMS wavefront aberration, and using the proper "weighting" of the merit function, a lens will have minimum sphero- chromatism, and therefore, the highest contrast images.  

Another important difference is we offer the widest range of apochromats, in size and focal ratio, and are making the world's largest true apochromat right now, a 21" f/12 triplet.

Our mission is to bring the wonders of the universe to people, it's that simple.

CN: What are your long range plans / goals for the company?

To offer eyepieces and apochromatic refractors that are as good or better than the competition, at a reasonable price. We already have some of these products on the market now, because of the wonderful help of Fred and Mike from Astronomics. Also, Bill Burgess of Burgess Optical is a part of the new goals of TMB Optical.
CN:  Any parting words for our readers?

Don't worry about what telescope you own, or its quality. Just get out under the night sky, and enjoy God's wondrous universe.

CN: Words to live by.  Thanks Thomas!

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