Orion Optcis (U.K.) DX300

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Orion Optcis (U.K.) DX300
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I have been interested in astronomy for over 30 years now but only started more serious telescopic observation in the last 3-4 years. I bought a second-hand DX300 OTA about 15 months ago, trading up from an Orion Optics 250mm Newt. It was in excellent, as-new condition.

I have used it fairly frequently now on a range of objects. I use mainly TeleVue Nagler e/ps and have had the scope mounted on a GP-DX and latterly, a GM8. I prefer the Losmandy clutch arrangement to Vixen's.

It gives splendid, bright views of DSOs, even from my location near the centre of the City of Chester. M27 appears to be more circular than dumbell-shaped with plenty of detail visible. M31 and its companions make a stunning sight in a WA e/p.

The relatively short focal length gives wide true FOVs with just over 2 degrees from a Nagler 31mm; great for viewing the open clusters. Bright globulars are generally resolved right to the core.

Planetary views are also good but careful collimation and cool-down are more critical here. Cool-down time is at least an hour for steady views. Once cool, however, the views are probably better than my Tak FS128 in terms of detail, certainly when seeing is good. I haven't looked at many close doubles but the 'double-double' is easily resolved. Again, cool-down is important.

There is a lot of back-focus on this model for a Newtonian. You will need an extension tube for most (or all?) TeleVue eyepieces. This means, however, that binoviewing is possible. I use a Takahashi Twin View with two 19mm Panoptics. (See excellent Binoviewer review at www.weatherman.com.) The unit has a built-in 2.1x Barlow which gives about 130x. I find using this makes big difference to detail visible on DSOs and particularly planets/lunar viewing.

The 'scope seems to be sensitive to eyepiece design at lower powers. The Nagler 22/31mm are sharp more or less right to the edge of field, but in a Meade SWA or Vixen 42mm Superwide the image deteriorated markedly towards the edges, even with a Paracorr.

Mechanically the 'scope is adequate. The 2" focuser (Vixen I think) is fairly smooth with no backlash but feels 'gritty' compared to the focuser on my Tak.

The two-legged spider is not that rigid and is probably the reason the 'scope needs quite frequent collimation. One useful modification I've made is marking the centre of the mirror with a sticky paper ring. This makes collimating with a laser collimator quick and easy. However, Orion could do this for practically nothing.

The cradles hold the OTA firmly but moving it to balance heavy e/ps is not that easy.

The finder has a large field of view but almost no eye-relief. The reticle is actually a pin stuck through the wall of the eyepiece. It works, but..... The Vixen or Tak 7x50 finders are streets ahead. The e/p is in a standard 1.25 inch diagonal so a illuminated reticle guidescope e/p might be a good alternative. I use a Celestron red-dot in conjunction with a Tak 7x50 finder, a combination which works well for me.

Adjustment of the primary mirror cell is easy using wing nuts, which are inside the tube and clear of the floor. (On the 250mm the nuts were mounted on the back of the 'scope which meant re-collimation if the tube was stored vertically resting on them.)

The stout metal rings at each end of the tube are excellent. I dropped the 'scope heavily and dented one badly enough that I had to give it a good belting with a hammer to 'fix' things. If the ring had not been there it would have been the mirror which absorbed the impact (ouch!).

The relatively light weight and short tube means that the GM8, or GP-DX (as supplied) are suitable for visual and photographic use, although in a wind a G11 might be a better bet for photography. I've rated it a 7 on this basis but perhaps that's a little unfair? I'll admit that I prefer the ergonomics of the GM8, maybe I'm biased against the GP-DX.

To sum up, I've found this to be a great 'scope optically, cheap for what's on offer, and still portable enough that it actually gets used!

Overall Rating: 9
Optics:9 Mount:7 Ease of Use:9 Value:10
Weight: 10 (Trustworthy Vote)
By: Richard
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=128853

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