Someone a few weeks ago brought up the new Orion Expanse lines of eyepieces, which appear to be in the value-priced wide-field category. I was curious too.
I decided to buy one, a 9mm, to try out in my 10" f/8 superplanetary dob. I compared it to my Harry Siebert standard 10mm, another value-priced wide-field eyepiece with similar AFOV and price range. This was by no means a scientific analysis, but I tried it out on the moon and Jupiter with a quick glance at Saturn.
1. Sharpness -- this was pretty close to my eyes, but the Siebert eyepiece was easier to 'snap' to focus quicker to my eye. Seems like my eye has to adjust somehow to 'see' sharply in the Expanse. I don't know how to explain this. Tired eyes?
2. Ghosting -- both eyepieces show some ghosting on Jupiter, but the Expanse is somewhat better so I think the coatings may be better on the Expanse.
3. Eye Relief -- the Expanse has a HUGE eye-lens so eye relief is very very nice for a 9mm wide-field, more than the Siebert. But this comes at some cost:
4. Exit-pupil aberrations ('blackout' or 'kidney bean' effects) -- Severe in the Expanse on something big and bright like the Moon, not seen in the Siebert. The Expanse is hard to use for lunar observing, IMHO.
5. Chromatic aberration, spurious color -- I found this to be more of an issue with the Expanse, especially at the edges. To be expected with the wider lens elements. Moon showed blue & purple flaring all around the edge of the field.
6. Field integrity -- both are pretty good at f/8.
7. What you see -- personally I found I saw pretty similar levels of detail on the Moon, but it felt like I saw detail on Jupiter better with the 10mm Siebert. I should note that conditions were less than perfect and moments of steadiness were fleeting. Anyone else tried these?
I decided to buy one, a 9mm, to try out in my 10" f/8 superplanetary dob. I compared it to my Harry Siebert standard 10mm, another value-priced wide-field eyepiece with similar AFOV and price range. This was by no means a scientific analysis, but I tried it out on the moon and Jupiter with a quick glance at Saturn.
1. Sharpness -- this was pretty close to my eyes, but the Siebert eyepiece was easier to 'snap' to focus quicker to my eye. Seems like my eye has to adjust somehow to 'see' sharply in the Expanse. I don't know how to explain this. Tired eyes?
2. Ghosting -- both eyepieces show some ghosting on Jupiter, but the Expanse is somewhat better so I think the coatings may be better on the Expanse.
3. Eye Relief -- the Expanse has a HUGE eye-lens so eye relief is very very nice for a 9mm wide-field, more than the Siebert. But this comes at some cost:
4. Exit-pupil aberrations ('blackout' or 'kidney bean' effects) -- Severe in the Expanse on something big and bright like the Moon, not seen in the Siebert. The Expanse is hard to use for lunar observing, IMHO.
5. Chromatic aberration, spurious color -- I found this to be more of an issue with the Expanse, especially at the edges. To be expected with the wider lens elements. Moon showed blue & purple flaring all around the edge of the field.
6. Field integrity -- both are pretty good at f/8.
7. What you see -- personally I found I saw pretty similar levels of detail on the Moon, but it felt like I saw detail on Jupiter better with the 10mm Siebert. I should note that conditions were less than perfect and moments of steadiness were fleeting. Anyone else tried these?
