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6mm Expanse and ghosting - easy improvement?

Started by jtrobins, 01/03/2004 12:38AM
Posted 01/03/2004 12:38AM Opening Post
Hi, well it's cloudy here and will be for a while so this is a (mostly) untested theory. I unscrewed the bottom section of the 6 mm expanse and was surprised to discover that the inside of the eyepiece tube (upper portion) is very shiny. This can't be good, particularly with the negative element in front of it. I had some protostar paper handy and have now lined the inside. This might not eliminate the ghosts but can't hurt and is easy.

I've attached a photo, the e.p. on the left has been flocked.

Jim

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jtrobins's attachment for post 11952
Posted 01/03/2004 02:16AM #1
That would be interesting to find out if this helps with the ghosting.
Floyd

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 01/03/2004 03:29AM #2
I've done the same to my Antares 5.7mm W70. This may help some with lunar and terrestrial performance, any context where there is a significant amount of bright target area outside the field of view, in which case it is possible that light may bounce off the walls and back into the light path. I think it will do little or nothing with respect to ghosting from planets that fit entirely within the field, although deep sky views may gain a small amount of contrast.

I also discovered that my eyepiece had a fairly un-blackened spacer ring in the upper assembly. Blackening that seemed to make a major improvement in glare from a bright object just outside the view. Nothing I have done has made it a great lunar eyepiece, however. It's sharp, but there is just too much light bouncing around in there, I think because of the coatings. On the other hand, I think it does well with Jupiter and Saturn.
--
Mike
Posted 01/04/2004 01:00AM #3
I've done the same with some cheap Plossls, only with auto underbody sealer - giving it time to dry and cure thoroughly. Along with blackening the lens edges with a black marker, I was able to make some noteworthy improvements in contrast. I didn't notice any significant changes in ghosting - I would guess this is more a function of lens coatings. Although if I coated those with the auto sealer...smile