Classic mac CRT fuzzy in the corners?

[8bitbubsy]

I lately got a Macintosh Classic that was mint on the inside with extremely little dust/sot, and the picture is bright with very minor blooming when I set brightness to max. I thought all of this was a sign of a non-high-hour CRT, but the image is a little fuzzy in the corners (like all classic Macs I've had in my collection before!). Is this just how it was on these machines even when new, or is it a sign of a weak tube? I have of course tried to adjust the focus, but I just can't get uniform sharpness. It's either sharp in the corners, or sharp in the middle.

One person said that this comes from lack of dynamic focus, while another person said that he has seen uniform sharpness on these macs before. I feel it's time to find out, because I've been wondering about this for years now!

 

[obsolete]

It's either sharp in the corners, or sharp in the middle.

This describes every compact Mac I've seen in the last 25 years, but I am not old enough to have had one when they were new.

 

[8bitbubsy]

Good to know. I guess the lack of dynamic focus is the key here, if the person that said it is correct.
But at the same time, unsharp corners is often a sign of a high-hour tube in general, so it's a bit confusing... Wish I had a CRT tester.

 

[s_pupp]

My Mac Plus in '86 was sharp both in the middle and in the corners of the displayed picture.

 

[8bitbubsy]

Hm, interesting! So I guess the claim that it lacks dynamic focus is either not true, or that it doesn't matter in practice.