The Equipment

Upon deciding to get really serious about astronomy in February 2011, I had the great fortune to meet Martin Cohen, the owner of Company Seven in Laurel, MD. He spent over an hour with me, questioning me about my interests. Based on this discussion, he recommended the NP101/Losmandy GM-8 combination. Skeptical at first, I went home and read extensively about this equipment and about Martin, and I decided that I would buy on his recommendation. This decision surprised me, because I fully expected that I would “need” a 10″ reflector. Although do I want a larger reflector, the ‘101 has been a joy to own and operate, and I do not believe that I could have picked a better first telescope. I suspect that it will be years, if ever, before I become bored with this fine instrument.

Telescopes

The TeleVue NP101is is a wide-field astrophotographer’s dream telescope! The field of view is greater than 4° (the width of eight full moons) with the TeleVue Panoptic 35mm eyepiece. This telescope is widely acclaimed among amateur astronomers as being among the best in its class. It is a 101mm (4 inch), fast (540mm, f/5.4) apochromatic telescope. The ‘is’ designation stands for ‘imaging system.’ This means that the rear aperture can be configured to accommodate imaging sensors up to 2.4 inches diagonal measurement, and it employs a extra-stable ring mounting system for cameras. Everything about the look and feel of this telescope is high-quality in both fit and finish. Al Nagler, the telescope designer and the TeleVue owner, is among the most accessible notables in the amateur astronomy and telescope business.

The Televue Pronto is my grab-n-go telescope. It is a moderately fast 70mm, f/6.9 refractor. It is a very capable telescope in a very small package. I have seen many Messier objects with it, and it provides impressive views of the Moon. Although no longer made, I was able to pick up a used one for a very reasonable price. This is a great instrument for teaching beginners the basics of handling a telescope. Best of all, it is compatible with all of my TeleVue accessories such as the StarBeam red dot finder, and the piggyback adapter for mounting a camera/lens on top of the telescope. The Pronto is light enough to ride piggyback on my TeleVue NP101 as a autoguide scope, and the two TeleVue scopes make for an impressive pair on top of the Losmandy mount. I can also easily mount it the Pronto on a camera tripod or use it as a finder scope for a larger telescope. The rear aperture accepts eyepieces and accessories up to two inches.

I bought Vixen ED80sf for autoguiding, and I used it as my grab-n-go before picking up the Pronto. It provides good views of the Moon and many Messier objects with its 80mm, f/7.5 optics. Its light weight appealed to me, because the NP101’s substantial weight prohibits anything heavier co-mounted on the GM-8 mount. The combination of its light weight and its good optics make it an attractive grab-n-go telescope as well. Much of my imaging time of late has been spent perfecting drift alignment, so this telescope does not get too much use as an autoguider these days. When I begin to spend time on autoguiding again, I will evaluate the Pronto. It it proves to be suitable, I might be willing to sell the Vixen. Although the fit and finish of the Vixen is acceptable, it comes nowhere near the overall quality of either of my TeleVues. The rear aperture accepts eyepieces and accessories up to two inches.

Celeston C11 UltimaIn January 2014, I made it another step closer to becoming one of those amateur astronomers who has x number of telescopes…that his wife knows about. Celestron marketed the C11 Ultima, an 280mm f/10 telescope, in the mid-1990s, and I picked it up second hand at Hands on Optics for a very reasonable price. The telescope weighs 22 lbs. Since this approaches the maximum capacity of my mount, I am already thinking about my next major purchase.

Mount

Losmandy GM-8The Losmandy GM-8 is arguably the mount that is most often used in combination with TeleVue NP101 telescopes. Moreover, the mount is so widely used that much has been written about it on Web sites likeCloudy Nights for astronomers unafraid to perform their own modifications or do their own maintenance. This mount is not as “high-tech” as some of the more recent mounts on the market as it does not, for instance, permit wire cables to be run through the mount’s interior. It performs solidly, and being among the most accurate mounts around makes is a great value for the price. I modified mine by replacing the stock clutch knobs with Bob’s Knobs – a very worthwhile investment. I bought the mount without a go-to capability so that I would have to learn how to use my own wits to find objects. Today, I can find most objects without too much difficulty, and I continue to improve this skill. I intend to add a go-to capability by upgrading to a Gemini II control panel and servos in the future. Although well-suited for the NP101, the carrying capacity of the GM-8 does not permit use of larger telescopes. Right now, I am pretty sure that I will buy a Losmandy G-11 or Titan to carry the Meade LX200 that I intend to buy.

Cameras

Canon EOS 60Da The EOS 60Da is a full featured, CMOS-based DSLR that is modified for astronomy. I selected this camera for price and features, and because it would not need an after-market modification to photograpy objects in the Hydrogen alpha (Ha) wavelengths. The EOS 60Da is an exact duplicate of the EOS 60D, except that the IR cut filter transparency to Ha (656nm) light is about three times higher than an unmodified filter. This permits increased sensitivity red wave lengths, which is essential to capturing the reds of emission nebula. The CMOS sensor resolution is 5184 x 3456 pixels, which results in 18 megapixel raw images. The sensor format is APS-C (1.6x crop factor compared to a 35mm film frame), and the sensor size is 22.3 x 14.9mm. This sensor size when paired with the NP101 at prime focus covers a 2.3° x 1.5° area of the sky. I was able to capture some pretty amazing results my first few times out with this camera, and I am hopeful that better results are yet to come.

Eyepieces

TeleVue
Panoptic 35mm

TeleVue
Radian 5mm

TeleVue
Plossl 13mm

TeleVue Nagler
Type 4 17mm

Pentax SMC-
XW 20mm

Accessory Lenses

TeleVue
.8x Reducer

TeleVue
2x PowerMate

TeleVue
4x PowerMate

© James R. Johnson, 2014.
jim@jrjohnson.net

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The Astronomical Musings of Jim Johnson