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 did eventually purchase a larger reflector, the ‘101 was and 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 company owner, is among the most accessible notables in the amateur astronomy and telescope business.

The Televue Pronto is my grab-n-go and autoguide 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 G-11 mount. I can also easily mount it 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 finally purchased a light bucket, the Meade LX850 12″ OTA in May of 2015. It is a lot to handle, but I have developed a technique that employs what is arguably the largest muscle that I have – my brain – lift it up onto the mount. I have a MoonLite SC motorized focuser for precision focus.

Mounts

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 like Cloudy 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. I have not found this to be a problem as I have developed a technique that uses 15 – 18″ of power and USB cable slack between two attachment points on the base and Ra axis of the mount, and still easily access the entire sky. 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. Although well-suited for the NP101, the carrying capacity of the GM-8 does not permit use of larger telescopes.

My astrophotography mount is a Losmandy G-11 with Gemini II goto. I was so good at manually finding objects with the NP101/GM-8 I thought for a while that I would never need a goto capability. It does take extra time to manually find an object with, even with the NP101’s wide FoV, and I realized that having a larger telescope with a narrower FoV would increase the time required to acquire an object – not ideal when trying to be productive on the observing field. Although purchased for, and concurrently with the Meade LX850 OTA, the TeleVue NP101 can often be found riding here for astrophotography. In addition to the extra payload capacity, this mount is easily driven by Stellarium (coolness factor plus great situational awareness before and during slews) and PHD via the ASCOM platform.

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