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Re: Ye old Pan 24mm

Started by wpaolini, 07/12/2006 05:47PM
Posted 07/12/2006 05:47PM Opening Post
Greg Nowell said:
Imagine my surprise then when I popped it into the f/6.5 refractor to check for color on the moon. The moon was in a waxing crescent phase and you could see the full outline "the old moon in the new moon's arms". My jaw dropped as I moved the moon off axis and watched it become elongated like a football.

Greg,
2 evenings ago there was a full-ish moon so I went out with my 10" f/5 Dob and chose the older 24mm TV Wide Field wich gives me a degree fov +/-. It's a wonderful EP for full moon viewing. Dead center in the field it looks great. Then I did as you did and slewed it to the edge and holy cow..it looked like it was going thru a carnival mirror it became so distorted. Literally looked like it was being reluctantly sucked out of the fov! So I guess your Ye old Pan must of inherited those genetics from its father, Ye old Wide Field. I was surprised it was so dramatic. I typically just use this EP for scanning...the pincushion is obvious in scanning, just never realized how dramatic until I did it on the moon!
-Bill
Posted 07/13/2006 07:46AM #1
I see the same distortion in my 22mm and 19mm Panoptics and in my 13mm Nagler. In fact I've seen it in every TV Nagler, Wide Field and Panoptic eyepiece since the first ones I bought twenty years ago. I think the worst side effect from this distortion is loss of real field. The increasing magnification and distortion of shapes toward the edge causes around a 10% loss of real field compared to what a distortion free eyepiece with the same apparent field would yield. Naglers produce about the same real field as 73-75 degree distortion free eyepieces and Panoptics' real fields equal about 61-63 degree distortion free eyepieces.