|Orion ED 80 (80 mm Refractor) Review|
|By: Sam Pitts 2008|
The Orion ED80 used in this review was purchased from Company Seven (http://www.company7.com/home.html) and it arrived in perfect condition. The appearance of the OTA is good, finished with a coating of gunmetal gray paint. You can not and should not compare this inexpensive scope with fit and finish of the premium refractors made by Takahashi, Astro Physics, TMB, Telescope Engineering and other makers of some of the best APO refractors built. This review will not compare this scope to such pedigree scopes, as they are in class of their own. The Orion ED80 and its clones fit a special niche of inexpensive doublets that produce APO like views. A true APO (Apochromatic) refractor will produce excellent color correction, void of false color, halos, etc. on bright objects. (See note below)
I am an avid amateur astronomer for 45 years and enjoy visual viewing, while my main endeavor is imaging and this review will cover both.
The first night out with the ED 80 exposed it to Oregon skies to see how it would hold up to skies with high moisture content. The testing took place at one of Eugene Astronomical Societies favorite observing spots called Eagles Rest. This is a dark sky sight at 2700' with dark skies allowing naked eye observations of M31 and M13 on a good night. This was a very good night and objects down to 6th magnitude were readily visible to the un-aided eye. Conditions were good and steady so a group of fellow observers were on hand. The ED 80 was fitted onto a CG4 mount using scopes rings and Losmandy plate with and adapter for the mount. The scope was allowed to acclimate to ambient temperature and a 2" William Optics Dielectric Diagonal was inserted and TeleVue Radian eyepieces were used for this evaluation.
The views were great. The scope was trained on Saturn using a 6mm Radian which produced 100x in magnification. Saturn was nice and sharp with a black background. The slow-motion control kept Saturn in view for a prolonged viewing session. The contrast, due to sharp image and black background, would let moments of steady seeing reveal nice details with the Cassini Division readily apparent. No false color around Saturn was detected.
Fellow club members had setup an 8" Schmidt Cassegrain and 10" Dobsonian telescopes and were viewing Saturn as well. These two scopes were set at similar magnification and used to compare views. We all took turns and while Saturn appeared brighter in the larger apertures, the general consensus confirmed the Orion ED80 produced a noticeably sharper image.
The OrionED 80 was then pushed to 200x magnification with a 3 mm Radian. This exceeded the common Dawes limit of 50x the diameter of the objective in inches or 150x for the ED 80 (actually 3.15" & 157x). It is understood and my experience, that a true APO refractor will exceed such limits while lesser optics are restricted to such limits. High quality APO refractors routinely allow at 80-100 times the diameter when seeing conditions allow.
The nearby 8" SCT and 10 Dobsonian were taken to 200x magnifications and the images compared. The larger apertures were brighter but the overall consensuses again favored the Orion ED 80 with a sharper view that revealed just as much detail as the larger scopes just not as bright. The little ED80 had more contrast and at times of good seeing sharper detail was evident.
Taking the scope to double stars produced pinpoint stars throughout the field (back at 100x) and no noticeable false color. Training the scope on bright Vega, the fifth brightest star, revealed a slight halo of false color. The view still revealed very pleasant pin point refractor like stars one can get used too. The Orion ED80 was later tested on the moon revealing great detail and sharpness with some color fringing evident around the edge.
The Orion ED80 is a real performer for the money spent for an imaging scope. My first night out was a little frustrating as the stock focuser would not handle the heavy load of a DSLR or CCD with a color filter wheel. View some of the images of M31 and the Horse Head nebula take with this scope (Deep Sky Image Gallery). While color correction is not in the excellent category of top end refractors the somewhat bloated stars are very acceptable. This scope with a DSLR or CCD camera will provide you with pictures suitable for framing.
Adjust or replace the focuser for imaging and general observing pleasure. I used a William optics 2 speed focuser that just screwed directly in. You may have to shim new focuser in place, I did not. I took all three screws out and took the stock focuser out. The William Optics focuser went right in; I replaced each screw with evenly distributed tightening till all three were in. The final tightening was even and just enough to hold securely, don't over tighten. My test showed the collimation to be satisfactory as evident by star tests and later imaging. Always use a high quality diagonal with any scope. Some diagonals have only an 85% reflective rating.
Visually this is a great scope for an aperture of only 3.15" and may exceed the 50x the diameters rating (Dawes limit) of 150x (157x). I usually use it a 50 -120x but can push it to 150 or even 200 when seeing allows. Deep sky objects are nice but brightness is limited by the aperture. This scope is excellent for lunar, planetary and double star observing. Imaging is very good for deep sky objects. This is a great scope to start imaging with, especially using the TeleVue TRF-2008 0.8 field flattener & reducer. Don't expect too much from a 3" scope. The 3" aperture can punch through average seeing that may limit larger aperture scopes.
The Orion ED 80 is a very affordable way of getting a refractor that is superior in performance to the multitude of Achromatic refractors out there at similar prices. Whether the Orion ED80 is a true APO or semi APO is subject to debate by many, one thing is certain, it is well worth the price tag of under $500.
| Check this site out
for improving the stock focuser.
| Orion Specifications
Part # 09895 ( http://www.telescope.com/control/main )
80mm ED Apochromatic Refractor
Optical tube: Seamless aluminum
Objective lens diameter: 80mm (3.1")
Objective lens: Achromatic, rear element made of ED glass (FPL-53), air-spaced
Objective lens coating: Fully multi-coated
Lens cell: Machined aluminum
Focal length: 600mm
Focal ratio: f/7.5
Focuser: Crayford, accepts 1.25" or 2" accessories and camera T-Ring
Mounting: 1/4"-20 mounting block, optional tube rings
Weight: 5 lbs. 11 oz.
|Horsehead taken with Orion ED80 by author||M33 taken with Orion ED80 by author|
Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus in the same plane.
Apochromatic refractors have objectives built with special, extra-low dispersion materials. They are designed to bring three wavelengths (typically red, green, and blue) into focus in the same plane.
| This review is a personal
opinion and should only be used as a guideline and is not definitive.
|/ Home / Photo Gallery / Astronomy / Astrophotography / Equipment /|
|[ Back ]|