BBC Sky at Night Magazine

Orion Monster Parallelog­ram mount & 25x100 binoculars kit

A well-balanced and versatile observing system that delivers deep-sky results

- WORDS: STEVE TONKIN

Well-mounted large aperture binoculars are a joy to use, especially for the larger deep-sky objects, so Orion’s new binocular and parallelog­ram combo piqued our interest. The GiantView 25x100 binoculars, which come in an aluminium case, have a Porro-prism individual-eyepiece focusing design that is covered with a thin rubber armour. There is a longitudin­al bar that connects the hinge to cuffs on the objective cells. This bar increases the rigidity of the binoculars and carries a sliding mounting post that enables you to achieve perfect balance when you mount them. But, at the point of perfect balance, it obstructs the minimum achievable interpupil­lary distance (IPD) – the distance between the pupils of your eyes – to 66mm.

When we looked down the objective tubes, we saw that the prisms are secured in proper cages, not merely clipped to the housing, so they should not become dislodged by minor bumps. The entrance to the prism housing does not restrict the light path, so that light from the full 100mm aperture is transmitte­d to the eyepiece. This examinatio­n also revealed that the insides of the objective tubes are smooth and without light baffles, although they are stepped where the objective tubes join with the objective cells and delete prism housings. This means that stray light is not well controlled, to the extent that it is intrusive when, for

example, a first quarter Moon is within about 5° of the

target area of sky. We didn’t notice this stray light from any stars, but it must cause some reduction in contrast.

Enjoying the sights

We thoroughly enjoyed our first stargazing outing – as

we put the binoculars and mount to the test – and targeted the constellat­ion of Orion, the Hunter. The

Orion Nebula, M42, was bright, with a structure that

seemed to increase in detail the longer we examined it.

The Trapezium Cluster was cleanly split as we moved it over the central third of the field of view. We found the

colour rendition was very good with recently dimmed

Betelgeuse looking ruddy. We also tried some galaxies in Ursa Major: the Whirpool, M51, revealed both of its core structures, and the Pinwheel, M101, was easy to see despite its low altitude. Open clusters, however, are the real strength of these mounted binoculars. While the Pleiades, M45, was as stunning as we expected, we spent a long time enjoying the Messier clusters in Auriga and Gemini and had to drag ourselves away from the Milky Way’s Cassiopeia region.

Perfect balance

Given the weight of these binoculars, this enjoyment was only made possible by Orion’s Monster Parallelog­ram mount. It has some nice touches, one of which is the facility to vertically adjust the mounting bracket in order to achieve perfect balance: you won’t

find any positions in which the binoculars refuse to stay

put without you over-tightening the mount’s joints. This

makes it easy to achieve that ‘floating binocular’ effect

that is the hallmark of a good parallelog­ram mount. The helpful instructio­ns are detailed and well-illustrate­d.

The tripod is a Synta-made model with 1.75-inch diameter legs, and a north pin (initially for equatorial mounts) which is used to prevent the parallelog­ram from unscrewing itself. The mount arms measure 57cm between fulcrums, giving a vertical range of 75cm, making it easy to share views with people of various heights. There is some vibration when you change target, but this dies down in seconds. There are two counterwei­ghts and you can experiment with their positions to achieve a short vibration-damping time.

When the binoculars are pointed vertically with the tripod extended, the eyepiece height is a maximum of 148cm. Orion suggests purchasing an extension pier for the mount, but you can use a garden recliner, as lying back makes high-altitude observing more comfortabl­e.

This is a complete observing system that will suit anyone who wants a reasonably priced step-up to big mounted binoculars, using a mount that can take other astronomic­al instrument­s and which has the versatilit­y to make it ideal for sharing the night sky with others.

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