Paracorr and Miscollimation

Does a paracorr help or hurt if the telescope is moderately mis-collimated?

As I understand it, one of the important goals of Newtonian collimation is to aim the optical axis of the primary along the center of the focuser, so the part of the image with minimal coma is centered under the eyepiece.

According to the paracorr instructions, with an F/4.5 primary, only the central 3mm of the image has less distortion from coma than from diffraction. With the paracorr installed, this "sweet spot" enlarges from 3mm to 18mm.

But what if the telescope is miscollimated so the sweet spot is a few millimeters from the optical axis of the paracorr? Could that make the image be even worse than without the paracorr?

I'm sure my scope is never perfectly collimated, even if it is close. How close does it have to be for the paracorr to help?

Perhaps an optical designer with knowledge of the paracorr's design can give us some guidance.

Allen

A Paracorr does not make up for collimation or make it better if miscollimated.
But, the image is improved when it is used with a faster mirror. It does not make it worse from my experience, even when collimation is not spot on.

Paracorr does nothing at the field center, so
whatever miscollimation you have will be the
same at the field center with or without it.

Elsewhere in the field of view, Paracorr will help
in some areas and hurt in others, if you are
miscollimated. For example, where the
(miscollimated) primary mirror optical axis is,
it will hurt because it makes some correction
that is not needed. On the other side of the
field it will make a partial correction and help.

The accuracy needed for collimation is partly
in your question. It would seem you need to
be within the 3mm "sweet spot" for best results.
This is not hard accuacy to get using a Barlowed
laser or star test.