so, I guess i enjoy getting myself mad for some reason, I have been watching a bunch of videos of people replacing old magnetic ballasts with LED lights or an electronic ballast, and one thing they almost always say no matter if they are "upgrading" to LED or an electronic ballast is that they don't hum or flicker like a magnetic ballast does. now almost all of my fixtures have a magnetic ballast, be it a rapid start or a preheat, some of them do hum, but not so loud as for it to be any annoyance at all, and most of them are quite silent, so i guess for really sensitive people i could understand that magnetic ballasts do sometimes hum. but what I do not understand is that they always say magnetic ballasts flicker, i have argued with people who say they do and they don't care about facts they just think old is bad. but every fixture i have, and i have quite a few with magnetic ballasts. none of them flicker at all that you can see. so why does everyone say magnetic ballasts flicker? I have seen quite a few electronic ballast flicker when they are dying pre-maturely or when they are burning out a lamp that probably would have a few years left in a magnetic ballast. and LED lights always flicker even when working properly, but they become strobe lights after like a year, but unless there is a really burned up lamp, I have never seen a magnetic ballast flicker. so where does the idea that magnetic ballasts are so horrible and flicker come from? 

Some people are sensitive to 50/60Hz flicker, (I’m also not one of them), but I think that’s what their referring to?, I suppose for someone that is though, it must be like a magnetic choke circuit with a failing tube as you say.

People have been programmed to think the old stuff is bad by the way the new stuff is marketed. It's really a shame. Its to the point where people think a brand nee integrated LED fixture will serve them better than a fixture with a socket.

yep,I for one am getting tired of the "old=bad new=good" mentality that most everyone has these days, and it is not just one thing, it is everything. most people would rather have anything new even though old stuff does the job better, lasts longer and normally looks better.

Both Ria and myself are in favour of using the good old stuff when we can. 

 Some of few people can see the flicker on florescent tubes esp  when there rectifying.  But I can pick up 120 Hz flicker in my side vision it not to point that it annoys me.  But some people say they get migrain headache from them as well.  Those are the senstive type of people that do complain.   What drives me nuts was a very old plant that have very old 25 Hz westinghouse industrals 3 phase 240 volt 25 Hz the whole building looked like a very fast xmas light chaser set.  There are LED flickers so badly as led is a recifier lighting diodes
 That your seeing 60 Hz flicker instead of 120 Hz  flicker of a florescent.  A light collector Silverliner wittness this when I went
To a Autozone store in Semi Valley.  That  I did not want be in there very long.  So some cases led is actually worse than fluorescent.
 

I'm not usually bothered by a typical line-frequency ballast, but a lamp such as a Design 50 or Chroma 50 or other phosphor without much persistence can be a bit bothersome.  They're generally acceptable when operated on two-lamp ballasts with stroboscopic correction.

I can sometimes sorta see the normal 60hz flicker with a magnetic ballast, but its not like its enough to bother me or anything.
Patrick makes a good point that its more noticeable with some lamps..

Most lamps on a line frequency ballast don't bother me and plus I don't really see flickering unless I look directly at the tube and squint. Well the exception would be Chroma 50 and Design 50. The low persistence phosphors on those mean that I'd probably need to use a lead lag or electronic ballast to use them.

Now the old 25Hz line frequency though, at frequencies that low even incandescent lamps have a slight flicker to them. Can't imagine what fluorescents would have looked like.

what exactly is a chroma 50? I have 2 f15t8 lamps that are and they just look like cool white to me.

what exactly is a chroma 50?

Just a dim 5000k fluorescent.
like this one

They're supposed to significantly render colours more accurately compared to the halophosphates commonly used in T12 lamps and the basic triphosphors used in T8 at the time. Now with tightened energy regulations, I think a lot of fluorescent lamps still on the market have fairly high CRIs in the 80s and 90s so the appeal of the C50 isn't as high as before.