Back in March of this year, I bought a collection of Orion Expanse (6mm, 9mm, 15mm, & 20mm) eyepieces for ~$120. On the C8 SCT, and more recently, the Orion ED80T CF (f6/480mm) refractor, I found them very clear, sharp to the edges with good contrast, comfortable to use and with nice wide views.
Having read how well a good triplet refractor can handle extreme magnification, I decided to test it out while viewing bright objects like the moon, Jupiter and Saturn. I found good deals on a clean Orion Shorty Plus 3-Element barlow ($60; great performer, BTW) and a new Explore Scientific 4.7mm 82 degree eyepiece ($125). I've always wanted to try "less than budget" eyepieces and this seemed a good opportunity.
Last night marked our first clear night in several weeks, so I broke everything out to try it for the first time. A principle goal, other than testing the limits of the refractor, was to compare the Orion Expanse 6mm to the Explore Scientific 4.7mm and see if a $125 eyepiece delivered better views and/or was more comfortable to use than a $25 eyepiece. Here are my impressions:
- Clarity/sharpness: Both are equally very clear; in terms of sharpness, the Explore Scientific may be a little bit better around the edges where stars are visible, but it’s negligible. Clarity and sharpness of the central bright object is indistinguishable between the two.
- Contrast: No discernible difference between the two. Both allow the refractor to do what it does best.
- Eye relief/blind spots: No discernible difference between the two.
The Explore Scientific 4.7mm provided more magnification and was a bit dimmer, as one would expect given the 1.3mm difference in focal length. Performance of both eyepieces was as described both with and without the barlow.
Overall, as a test of the ability of the Orion ED80T CF to handle magnification, last night was a success! It had views that rivaled those of my C8 with excellent sharpness and contrast. I’ll be keeping the Explore Scientific 4.7mm, as I find it has the perfect minimum focal length for the Orion ED80T CF when combined with the Orion Shorty Plus 3-Element barlow.
As far as $25 VS $125 eyepieces go, the argument could be made that a 1.3mm difference in focal length with no difference in eye relief/blind spots means that the Explore Scientific 4.7mm is superior, but that may be stretching things; whether it's worth $100 is subjective. Perhaps a longer focal length eyepiece would be a better object for comparison on a f6 refractor, or perhaps my eyes and/or brain are just incapable of discerning fine differences.
Edited by ayadai, 27 September 2021 - 08:27 PM.