- COUNTING SUNSPOTS WITH A $10 OPTICAL TUBE ASSEMBLY
- Hubble Optics 14 inch Dobsonian - Part 2: The SiTech GoTo system
- iStar Optical’s Phantom FCL 140-6.5 review
- Who’s Afraid of a Phantom: Istar Phantom 140mm F/6.5, that is?
- SHARPSTAR 94EDPH APOCHROMATIC REFRACTOR
- My Losmandy G11T review
- FIELD TEST: THE NOH CT-20 ALT-AZ MOUNT
- SkyTee-2 Alt/Az Mount Review
- SharpStar Askar ACL200 200-mm f/4 astrographic telephoto lens
- A review of the Unistellar EVscope
- Astrotrac 360 tracking platform – first impression
- FIELD TEST: CARL ZEISS APOCHROMATIC & SHARPEST (CZAS) BINOVIEWER
- Omegon 32mm 70º SWA eyepiece review
- Review of iPolar hardware and software for polar alignment
- Review of the Hubble Optics 14 inch, f/4.6 Premium Ultra Light Dobsonian Tele...
CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.
I encourage anyone with a minimum of technical facility to build their own vintage solar telescope, and join with me on the sunspot counting journey. Next to the study of Earth-grazing asteroids, I can think of no more important branch of astronomy. Aside its obvious ties to climate change science, solar astronomy is extremely important to our understanding of, and ability to predict flares and coronal mass ejections, which have the potential to devastate modern society (google "Carrington Event").
I have gotten some use out of them, but I had to get used to some things. They are still available on the used market, but I don't think they are currently
The DMK 21AU04.AS is a B&W cam from imaging source answering the call for an inexpensive cam that offers good performance for beginning imagers to moderate imagers on a limited budget
Believe it or not, there’s a little-known thin film solar filter on the market that is remarkably inexpensive and provides excellent performance
For years I've been primarily a deep-sky observer, with a recent interest in at-the-eyepiece sketching.
This is one observer's attempt to look at these eyepieces as objectively as possible and rate them "head to head". I've got good eyesight and see coma and other optical imperfections quite easily, so I think I gave
The Coronado Personal Solar Telescope (PST) is a 40 mm (1.6 in) refractor designed for observing the sun. It contains an internal hydrogen-alpha filter. At $500, the PST has brought h-alpha observing within the realm of ordinary mortals. Before Coronado, most h-alpha systems were prohibitively expensive.
Amateur astronomers have shown a growing interest in solar observation ever since Coronado introduced their line of solar H-a filters to compete with the industry stalwart, Daystar, several years ago (other solar H-a filters are made by Hardin Optical and Baader Planetarium). However, amateur solar observers too often neglect another instrument – the spectrohelioscope. Spectrohelioscopes were invented by G.E. Hale in the 1920s and have steadily been improved and made more accessible to amateurs over the years. Fredrick N. Veio’s authoritative book “The Spectrohelioscope” established his reputation at the vanguard of amateur solar astronomy. This book, as well as myriad designs, photos, discussions, articles mentioned below and other information can be found at http://spectrohelioscope.net. I recently asked Fred to compare the performance of a spectrohelioscope to commercially available H-a filters. The remainder of this report presents (with minor edits and additional material on my part) Fred’s observations on the benefits and weaknesses of each type of instrument for solar observation (Chris Westland, 22 May 2004)
Since I bought the “Herschel Prisma” as Baader names it, one wonders what a “Prisma” or prism has to do with solar observing, well as a matter of fact, the Herschel is a peculiar type of prism that reflects about 4.6% of the light you pass through one of the prism faces that is flat to 1/10 of a wave, the rest that is 95.4% of light and heat goes into the prism and exits through the other face and out the backdoor of the housing, thus the excess light and heat is dispensed and not used for observing.
As I watched a plane flew across the H-alpha disk. As it crossed the flaming limb, racked by prominences, the exhaust caused the solar limb to shimmer momentarily. I wished I had a camera to capture the almost uniquely 21st century moment, a stunningly beautiful conjunction of two pieces of advanced technology which I felt truly privileged to witness.
Lately I've been enjoying my 3rd Daystar filter. My first a .6ATM, second was a .5 ATM, my third a .45 University. Since I began into this long road of astronomical equipment, I always wanted an H Alpha filter. It finally happened, and now I'm sold on Solar.
A little about my Solar Observatory. The main instrument is an 6" f/12 Astro- Physics Triplet "Superplanetary" refractor, built with the NASA glass. This superb refractor telescope was given to me as a gift by Joseph. H.C. Liu, a well known Chinese astrophotographer and friend. It is mounted on an equatorial HGM-200 Losmandy with the Gemini system.
The normally good day seeing, made me decide to buy from Mister Thomas Baader two more solar accessories; a Herschel wedge built around a Zeiss prism, and the Mark-IV Coronagraph. As for the Herschel wedge, well I must confess that after receiving it I have never used again my other filters, not even the one made with the Baader film. The vistas that the wedge delivers are incredibly crisp and contrasty. The neutral filters that come with the "Herschel Prisma" are at least ¼ wave flat. The Herschel itself is a work of art. All the hand set screws hold the eyepieces or the heavy CCD or 35mm cameras easily and with no wobble, you just have to tighten lightly to keep them secure, an eerie feel.
What is the purpose of the NearStar? It is basically an elementary hydrogen-alpha telescope that cannot easily be disassembled or otherwise made unsafe without completely breaking it. It is a small, portable, instrument in a compact case. It is made to be a portable resource, perhaps belonging to a school system, that can be easily set up and used by persons unfamiliar with its operation with a high chance of success. One can't see Doppler-shifted gas using a tilt adjustment, but at the same time teachers who have checked it out can't bungle a class session if they haven't been informed that such an adjustment should be made. The H-alpha image looks best right in the center of the field, so you don't have to fish around for the best view. Coronado has a 60-mm MaxScope as an alternative to the NearStar.
H-Alpha System on a Budget Mount??? It looks like it will shake crazily - but it does not! The scope (thanks for the reviews, Dave Novoselskyi) is blissfully short. Even with the Extender-Q and the Tele Vue Binovue in place, the inexpensive tripod and AZ3 mount absorb all vibrations in 1 to 1.5 sec. The slow motion controls allow me to follow objects with precision and comfort. The Coronado 90mm filter and the mounting ring are not light, but the Extender-Q with the BinoVue balances it almost perfectly at the horizon. Near the zenith, the scope has to be balanced with a counterweight. I devised a simple counterweight system using a standard ¾" shaft, which is held by a bolt right through the mounting plate.
After my recent purchase of a Coronado Instruments ASP-60 Hydrogen-Alpha solar filter system I found myself 'hooked' on H-alpha solar observing. Before going any farther, after I posted the last review, I got more than a few notes saying, "okay, what the hell is H-alpha, and why is it so much more expensive than white light observing." The short answer is as follows, cribbed from the Coronado website (www.coronadofilters.com):
The Coronado Instrument ASP-60 Solar Filter is a Hydrogen-Alpha solar filter set designed for use with the Tele Vue Pronto. (It will work with other telescopes "with a suitable adaptor.") The ASP-60 offers performance similar to the dedicated solar scope offered by the same manufacturer (Coronado), the Helios 1, but costs about $300 less. Since I already had a Pronto, I opted for the ASP-60 set rather than the Helios. I ordered my set through Jim Kendrick at Kendrick Astro. He was quite helpful in assisting me in wading through the ins and outs of the various solar viewing possiblities, and helped me decide on this particular setup.
Recently Del Woods (DayStar Filters) sent me a 0.3 Angstrom ATM H-alpha filter to try. It is a prototype filter that is a narrower bandpass than the normally available DayStar line of filters to date. The filter stack is housed in the same style filter oven as both the University and normal ATM series using a 12 watt oven at 115 volts AC to keep the filter on band at 6562.8 Angstroms. The filter oven is 3 inches in diameter and 2 inches in length. The clear aperture of the filter is 32 mm. The Energy Rejection Filter (ERF) can be up to 150 mm (largest RG610 Schott glass blank is approximately 165 mm) provided that at least an f/30 beam is provided through the filter. The ERF blocks about 80 percent of incoming light including ultra-violet. Long-term exposure to ultra-violet radiation can bleach the filter, blue-shifting it so that it no longer can isolate the H- alpha spectral line. This particular prototype filter utilizes an enhanced infra-red blocking filter coating that adds to the optical density on the long side of the H-alpha line. This enhanced coating is a new addition to the filter that will hopefully eliminate the need to replace the blocking filters over time.
I have been a solar enthusiast for 12 years now, and have owned a Lumicon, and several DayStar H-alpha filters. I recently took delivery of a new Daystar 0.45a ATM system, and a Coronado AS1 90 / BF 30 filter. I thought it would be an interesting comparison, and being familiar with the design and function of the Daystar, was eager to compare the new Coronado.
There are currently several Hydrogen-Alpha solar filter systems available on the market. The best known system, and the one that has been the most sought after by amateurs, is the Day Star system. (One of the Day Star products was reviewed elsewhere on this site.) Another company has developed a system that first became available only in the last few years, a system that works quite differently from and makes an interesting contrast to the existing Day Star system - the filters now sold through many US and Canadian dealers and manufactured on the Isle of Man in the United Kingdom by Coronado Instruments. Their ASP-60 (a 60mm, <0.7 A system) and the AS1-90 (a 90mm, <0.7 A system) were reviewed by yours truly also here at Cloudy Nights. (I purchased the ASP-60 first, got myself well and truly hooked on Solar, and now use the AS1-90 exclusively and am selling the smaller unit.)
When I heard about the new Solarmax H-alpha filter from Coronado I was a bit skeptical. 40mm aperture, modestly priced, sub-angstrom performance, sounded too good to be true? Well, I am a solar nut, having owned several h-alpha filters over the years, and familiar with Coronado Instruments Group's (CIG) AS series filters, I could not wait to get my hands on a Solarmax to evaluate.
The active face of our nearest star, the Sun, is interesting to watch with the proper white light solar filter. However, with a narrow band filter tuned to the wavelength of the Hydrogen-alpha light (6562.8 Angstroms), the Sun changes from a well-mannered star with an occasional case of acne, to a huge seething angry red ball of gas in almost constant turmoil. To view the fascinating spectacle of the Chromosphere requires a very narrow and fairly expensive filter to eliminate all but the Chromosphere's contribution to the image. One filter which does this fairly well without exactly breaking the bank account is the DayStar "T-Scanner", 0.7 Angstrom H-alpha filter. With it, the door to the wonderful world of H-alpha is opened a crack, allowing the amateur a peek at a vista which was once reserved for only professional solar astronomers
In 1981, with a newly purchased full aperture solar filter, I turned my C8 telescope to the Sun for the first time. I was absolutely amazed that one could actually view the fiery surface of our daytime star. I was also amazed at how quickly it changed. It only took a year to add a hydrogen-alpha solar filter to my observing arsenal. I was hooked forever on solar observing.
A small and light 90mm set up: Takahashi Sky 90, TeleVue BinoVue, and Coronado H-Alpha filter on an AZ3 Mount with a counterweight and comfortable slow motion controls. Do not forget the adjustable observing chair and an old fashioned parasol or a beach umbrella!
I have become a confirmed Hydrogen-Alpha addict since my purchase of a Coronado Instruments ASP-60/Prom-15 T combination last year to use on my Pronto, an addiction that reached chronic levels when I sold the 60mm filter and purchased the half-again as large AS1-90 a few months later and added that and the BF-30 2" blocking filter as a combination to be used with my TMB 100 f/8 in the second generation William Yang OTA.