Televue eyepieces corrected to f/4??

While Televues are certainly better than many (most) eyepieces, that doesn't meant they produce "sharp to the edge" and "pinpoint" images across the entire fov in *fast* scopes. For example, while a 22mm Panoptic is markedly better than an old Celestron 20mm Erfle in a dob at f/5.4, there is still noticeable coma and field curvature in much of the outer portions.

I think it is important to stress this because otherwise less experienced observers may rush out to buy expensive $$ high-end eyepieces thinking they will work miracles. A lot depends upon the observer's standards, their sensitivity to distortions, how fast their scopes are, their eyesight, the eyepiece's field of view, and collimation.

I found that a 21mm Pentax did just as well as the Pantopic, cost a bit less, & had better eye relief for eyeglass wearers. 8O

And, if one is willing to sacrifice the wider field of view, but still have more than a Plossl, the 22mm Epic is quite good for little money. (Admittedly, though, many find the Epic's 20mm eye relief too much.)

As evidence their eyepieces do not correct the entire fov in fast scopes, Televue sells the Paracorr to help fix the coma inherent in speedy mirrors. While most swear by it, people do differ as to how much improvement they feel it makes and whether it is worth the $ and balance issues.

As long as you have reasonably decent eyepieces, focus on what you can see and not on the problems in what you see!

Enjoy the views rather than fixate on their flaws!

Yes, I'm trying to remind myself.

I believe the 'corrected to f/4' statement refers to the astigmatism caused by eyepieces themselves at fast f/ratios. This is utterly independent of coma inherent in parabolic mirrors.

Much of the distortion seen at fast f/ratios is not only the coma from the scope but also due to astigmatism occurring in the eyepieces themselves that have a hard time pulling together light coming from such a wide-angled light cone. f/4 is tough on eyepieces.

Those rushing out to thus buy Televue eyepieces will not get major miracles but may get minor miracles -- the absence of astigmatism at the edge of the field from the eyepieces makes the coma inherent in the scope much more tolerable. When I had an f/4.5 dob and a handful of naglers, I found coma unnoticeable -- of course, I wasn't exactly looking for it either.