Ghosting with Expanse EP (6mm)

Hi,
I received a complete set of Orion Expanse eyepieces for Christmas. I had them out last night and found the 20, 15, and 9 to be o.k. for the money. They might displace my plossls, time will tell. However the 6mm has the worst ghosting I have ever seen. The moon ghost completely blocked out the middle 20% of the field of view. Is this a general problem with this EP or did I get a bad one?

Jim

Thanks Bob, I will try that. I do suspect the negative element is the main culprit. I used the e.p. without it and the ghosting disappeared. Of course that was also at much lower power.

Jim

One thing about these eyepieces, and the new Antares 70 degree models is that they are employing some kind of coating technology designed to LOOK like good multi-coatings without actually BEING good multi-coatings. These are pretty coatings that look green from some angles and blue from others. People who don't know what to look for will then note that the coatings look very good, but in fact they are horribly inefficient, probably far less efficient than single-layer MgFl2 coatings. When I look almost straight down at these coatings, I get the green reflection where I should be getting blue, and the reflection is bright enough to shave with. Holding one up side-by-side to a Tele Vue 20mm Plossl shows just how bad it is, despite how pretty they look.

Here's a photo of a cheap Russian binocular eyepiece, a 20mm TV Plossl, and a 5.7mm Antares W70. As I recall, the coatings on Expanse-type eyepieces were similar in nature. Note that the camera is directly above the midpoint between the 20mm Plossl and the Antares W70, and the lens surfaces are at the same height. I tried various camera positions with similar results.
--
Mike

Attached Image:

If you read Orion's description of their Expanse eyepieces, you will see that they are not fully multi-coated. Meaning some air-to-glass surfaces are multi-coated, some (probably most) are not. It's a conscious trade off in favor of low price that they admit to.

I would expect to see ghosting in all FLs. My guess is the 6mm just happens to be worse.

Regards,
Doug