Orion Observer 70mm Equatorial Refractor

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The Review

I always regretted giving away the 60mm refractor that I owned as a kid. A gleaming white tube with uncoated optics and dim, narrow views, it sat on a flimsy mount that never quite locked the tube position where you needed it.  I loved the thing, despite the tiny eyepieces, wiggly Barlow, and scary sun filter. It became a fixture in the corner of my room, always ready for an impromptu trip to the back yard for half an hour of viewing.

When I returned to astronomy after many years, aperture fever gripped me. I bought a 10" Dobsonian reflector. While it shows me lots of faint fuzzies, nothing about it connotes “impromptu.” Carrying the thing outside requires three trips for base, tube, and chair. Once planted, forget moving the scope around the yard to dodge trees and lights. The mirror needs a fair amount of time to cool down and the optics usually require an alignment tweak. One also needs a strong back to use this kind of telescope on a regular basis, and my finicky back dictated a smaller, lighter telescope for regular use.

I pined for the ease and immediacy of a small refractor on an alt/az mount. Setting myself a $200 limit, I bought a Bushnell Northstar 80mm refractor (see review on this site). With a built in computer this scope delivers a lot of bang for the buck. Negatives include substandard optics (uncoated), a poorly-placed finder scope, low quality modified achromat eyepieces, and a mount that proves difficult to handle at high powers.

I began looking at other small refractors below $200. Orion telescopes listed a 70mm achromat model in their catalog that seemed well-equipped: it came with a small equatorial mount, one included eyepiece, and a probably worthless finderscope. At $159 it still looked like a bargain. I ordered one just before Christmas and in January it arrived as promised, in one box, evidently packed by a surgeon. Every piece came in a separate inner box with protective bubble-wrap inside that.

The equatorial mount looked beefy for this small a scope. I assembled the aluminum tripod with the provided tools, attached it to the mount, and set it for alt/az mode. Small equatorial mounts make fine alt/az systems. Just discard the declination axis (the screw-in pole) and counterweight, loosen the latitude scale (the pivot at the base of the mount) and retighten it
after making the right ascension axis vertical. The right ascension axis now becomes the azimuth pivot and the declination axis the altitude pivot. This configuration gives you a low weight alt/az mount with both coarse and fine movement (using the hand knobs on flexible stalks). It easily holds a small scope without the need for a counterweight, plus it suspends the scope’s tube slightly to one side of the mount, giving you the clearance to view objects directly overhead. (The picture of the scope shows the mount in this orientation.)

I bolted in the two metal tube rings (both with rubber linings to keep from marring the scope’s finish) then attached the telescope itself. When I opened the finder scope box I found, instead of the wimpy plastic unit I expected, an actual EZ Finder II red dot reflex sight with a custom mounting base. It attached easily, aligned easily, and even came with fresh batteries installed. More surprises lay in store as I discovered that the scope came with not one but two quite serviceable eyepieces (10mm and 25mm), of a nice Kellner design (Orion actually sells them separately as their Explorer II line). Another box contained a standard 1 & 1/4 inch mirror star diagonal.

A look down the telescope’s objective showed a well-coated, deep purple lens free of reflections. The aluminum tube contains three spaced circular metal baffles. Orion uses plastic for the lens shade and the focuser housing, but metal for the focus mechanism itself.

I decided to run through the usual astronomical suspects for a small telescope. Giving the scope the acid test for cool-down time, I carried it from a 70 degree house to a 16 degree backyard. I pointed the red dot finder at an object typically hard to resolve in a small scope, the trapezium in Orion, then put in the 25mm eyepiece. Even at this magnification (28x), I clearly made out four perfect points of light with no trace of flaring (a sign of pinched optics). The tight focuser provided enough range of movement to achieve crisp focus quickie, and the tripod dampened vibrations in under one second. I popped in the 10mm eyepiece for 70X magnification. Still crisp and gorgeous. I then dipped into my other eyepieces and tried an 8mm Plossl with a 2X Barlow for 175X. Even at 63X per inch of aperture, the image remained crisp. I rate the optical quality as truly outstanding for such an inexpensive instrument.

Next I tried a really big target, the Pleiades. The 25mm Kellner eyepiece resolved the core nicely, but it took a 45mm Plossl to reveal all of the cluster. With excellent seeing on such a calm, cold night, I slipped in an Orion Ultrablock narrowband filter to look for nebulosity around the key stars. Not a trace. Perhaps seeing it remains beyond the capabilities of a 70mm scope? Jupiter sat very low in the sky and the image boiled from atmospheric turbulence, but Saturn winged high overhead, close to the full moon. I pushed the power up to 175X again for grins, but decided that my 8mm eyepiece gave the sharpest view at 87X. Racking the focusser in and out alternatively ringed the planet with faint green or faint violet, but in focus the image remained free of spurious color. I think I made out the Cassini division, but Saturn remains pretty small in a 70mm scope. I also admit that the 16 degrees Fahrenheit air temperature prompted me to rush things a bit.

Before my fingers went numb I panned around the full moon. The brilliant white edge of the disc revealed no false color. While not an ideal phase for observing, I pushed the power back up to 175X and panned around the surface with the slow motion cables. The moon took high power very well, and the cables gave me the precision to steadily move up and down the walls
of large craters with no vibration. I give the scope very high marks for lunar observing.

Negatives

This scope needs a higher profile in Orion’s catalog!

Positives

The optics show little to no false color. The overall quality of the optical system seems appropriate to a $500+ pseudo-apochromat. Orion includes a first class mount and accessories. You wind up with a very lightweight, very portable unit. Orion also includes a star chart current for the month of delivery, plus a CD-ROM with a full-featured version of
The Sky.

Conclusions

Now my favorite telescope, this 70mm marvel puts spontaneity back into star gazing. It transports me back to my parent’s back yard with my first telescope. It leaps into my hands at the slightest encouragement: a break in the clouds, a cancelled Boy Scout meeting, a squirrel on the back fence. With zero cool-down time, no collimation hassles, and crisp edge-to-edge
images, I call it the best bargain in small scopes today. Someday I plan to send Televue about $5000 of my money, but for right now this little scope gives me 90% of the apochromat experience at 1/30 of the cost!

Submitted by Scott T. Schad - stschad@hotmail.com