19 mm Panoptic - HELP!!!

Hi, all, I recently purchased a used 19 mm Televue Panoptic eyepiece. I had my first chance to try it in my 13.1” f/4.5 dob last night. And the images were terrible! Only the middle quarter of the FOV was sharp, the rest showed progressively worse and worse coma as you got further out to the edge. Thinking it’s just showing the coma in my fast Newt, I tried it in a friend’s Televue TV60 (60 mm f/6). Even that showed comatic stars near the edge of the field. We then tried his 24 mm Panoptic in my 13”, and the star images at the edge of the field were much better than with the 19 mm, which is not what one would expect if it was simply revealing the coma inherent in the Newtonian design.

There’s definitely something wrong with this eyepiece. I’m wondering if a former owner took it apart and re-assembled it wrong. Are there any online resources where I can find out what the lens layout ought to be? I imagine I could send it back to Televue for repair, I’ll give them a phone call tomorrow to find out what they might be able to do for me. But I don’t expect it to be cheap

Anyone else have experience with this eyepiece, good or bad? In particular, in fast, large dobs? Any other advice? Right now it’s a dog. I could have saved myself a lot of money and bought an Orion Expanse for these kind of images.

Thanks,
Doug

i know it sounds weird
but you might want to check your colimation

i noticed the same problem
when i went to very wide fields
with a 24 mm pan or wide binoviewer
using my SCT

stars were points to the edge after colimation

i'm a bit of a newb, so take it with a grain of salt
but you might want to check it before getting too riled up

Perhaps the EP was disassembled to clean it and was reassembled incorrectly.

I finally got a chance last night to try the 19mm Panoptic in both my scopes last night. Again, lots of coma in the 13" f/4.5, but sharp right to the edge in the 8" f/8. As I suspected, I think I'm simply seeing the coma inherent in the fast dob - it's not the eyepiece's fault. I also was borrowing a friend's 27mm Panoptic, and in the 13" that was showing a lot of coma too. I think I'm just spoiled by my trusty old 28mm Pretoria, which is designed to remove coma, which it does very well. It only has a 50 degree apparent field and a lot of distortion, though, which is why I was considering the 27mm Panoptic. I may have to reconsider that.

Doug

Well, the clouds parted temporarily tonight and I had about 15 minutes to do a critical evaluation on the 19mm Panoptic in my 13-inch f/4.5. I was comparing it against another 19mm Panoptic that I borrowed from a fellow observer. And as we expected, the views were identical in each eyepiece. So my original statement that "There’s definitely something wrong with this eyepiece" was premature. The chances of both of them being defective are almost nil. And this should also put to rest any thoughts that somehow the seller was trying to pull a fast one.

Stars were good and sharp near the center of the field, but about one third of the way from the center of the field to the edge I could just start to see some coma. About half way to the edge coma was becoming more obvious, about two thirds to the edge it was obvious, and near the edge it was ridiculous. This eyepiece definitely needs a Paracorr in a fast scope. But in an f/8 or slower scope, it's a gem all by itself.

I also tried a borrowed 24mm Panoptic, and just like in my original evaluation, coma is much less pronounced across the entire field, despite it's larger true FOV. Not perfect, but pretty clean to within I'd say four fifths of the way from the center to the edge. Near the edge the coma is visible but not terribly objectionable. Being a newer design I guess it's just better corrected than the 19.

So, it's going up on AM. Keep in mind that it will work great in an f/8 Newt or an f/10 SCT. But in a fast scope expect to see some coma.

I'd be interested in hearing from anyone else who has done a critical evaluation in fast scopes to see if you get similar results.

Best regards,
Doug