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Celestron C80ED vs Orion 102mm Maksutov

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Celestron C80ED refractor and Orion's Apex 102mm Maksutov-Cassegrain

The Pros and Cons

Celestron C80ED Pros

1. Widefield viewing: can get 2.5 degree field of view with a 40mm 1.25 inch eyepiece which is enough to give a nice view of the Pleiades.
2. Works very well on Orion's AZ-3 mount.
3. At 150X on a yellow star the star does not become orange from the chromatic aberration (CA) like seen in Orion's 90mm f/10 refractor; handy when you are doing double star viewing.
4. Great quick look scope as cool down time is minimal.
5. Price: excellent for its outstanding optics.
6. Has the standard 90mm tube diameter which makes it a little lighter than Orion's 80ED which uses the 100mm tube when standard tube rings are used.
7. No noticeable diffraction rings around the stars when looking at the Double Double at 150x (Vixen 4mm LV).
8. Much sharper view of Mars at 100X or more than Orion's 90mm f/10 refractor.
9. Much better on the Moon than Orion's 90mm refractor at high powers (tested up to 150X) as I did not notice any discoloration even on the edges.
10. Portability, especially when compared to an 8 inch Dobsonian.
11. Can use Orion's right angle, correct view, 6X30mm viewfinder.
12. Albireo looks very nice at 15X.
13. The focuser is screwed into the tube unlike Orion's 80ED which is only inserted into the tube and then held with three screws. I feel, and it seems to be proven by my experience and by others, this gives a much greater chance that the collimation is right on from the factory.

Celestron C80ED Cons

1. Not really a travel scope since the dew shield is fixed when compared to many of the 80mm f/6 refractors that are available in this price range.
2. Does not come with a crayford focuser but its focuser is smoother than the typical Chinese made focuser like on Orion's 90mm f/10 scope.
3. Price, when you consider you can get an 8 inch Dobsonian instead.
4. The objective cover falls out too easily even when adjusted. It inserts into the dew shield instead of around the dew shield.

Apex 102mm Maksutov-Cassegrain Pros

1. Portability: a 1300mm focal length in such a short tube.
2. Price: significantly cheaper than the C80ED. The difference in price will almost pay for a new AZ-3 mount.
3. Showed the clouds on Mars more often than the C80ED as the seeing conditions fluctuated.
4. A better travel scope than the C80ED as it comes with a nice travel case and is shorter in length. Both scopes weigh about the same; around 5 pounds.
5. The use of eyepieces with greater eye relief at high powers when compared to the C80ED. (A barlow could help here but I do not use barlows).
6. Is noticeably better on Deep Sky Objects like nebulas and galaxies than the C80ED.
7. Works very well on Orion's AZ-3 mount.
8. Very good on the Moon. 200X or more is available based on seeing.
9. Focusing is very smooth especially when compared to Orion's 90mm F/10 scope and a tad better than the C80ED.
10. Can use Orion's right angle, correct view, 6X30mm viewfinder.

Apex 102mm Maksutov-Cassegrain (Mak) Cons

1. Cool down time compared to the C80ED. I try to have the Mak outside at least an hour before viewing to insure its stability for high power use. The C80ED is usually ready in about 15 minutes or less.
2. Price: You can buy a 6 inch Dobsonian for about the same price.
3. Field of view: about 1 degree is about the maximum available. The Pleiades are about 2 degrees in size.
4. Shows the first diffraction ring around the stars when looking at the Double Double at about 150X. This is not a defect in the optics but caused mainly by the central obstruction.
5. 33X is too high, for me, for a nice view of Albireo. This is the power given by a 40mm eyepiece.

If I had to choose between these scopes I would probably choose the C80ED as for my viewing habits it is more useful. I like being able to go down to 15X and then go to 150X with no noticeable CA. The Mak doesn't show CA either but its small field of view is the key reason I wouldn't keep it over the C80ED. But these scopes complement each other very well therefore I have decided to keep both of them.

Blair Slayton
November 05


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