Irritating angular brightness shifts & other issues - picking a monitor for a visually impaired person

[midix]

Hi all.

 

TL;DR or short story:

 

I'd like to ask you to take a look at a video and suggest some ideas, what are the root cause why an IPS monitor which is new, more expensive and feature rich shows so bad brightness shifts when looking at various angles, when compared to an older, less expensive IPS monitor.

 

 

Sorry for the quality and shaking, I didn't have a good camera at that time. I hope the quality is good enough to clearly show the issue.

 

I would really appreciate technical details and explanation, so I can gain more knowledge what should I look for when buying a new monitor. 

 

Is this shift caused by the fact that the bad monitor has LED backlight but the good one has CCFL? Or is it some fault in backlight vaweguide (if that's the right term; English is not my native language)? Or is it AG coating? Or is it caused by IPS LEDs themselves, in which case I wonder how can I know beforehand which IPSes are free of this issue?

 

What's confusing - a similar model to the bad monitor in my video in TFTCentral reviews received high scores for brightness uniformity. I suspect that the results might be different, if the test had included brightness shift measurements at different angles. 

It would be great in the future to have such test for each monitor to evaluate vertical and horizontal radius at which brightness shift exceeds some value which might feel uncomfortable for users, and repeat the test at multiple distances from a monitor. I guess, near-sighted people would be grateful for such tests. Currently there are images of different viewing angles in each review, but they usually show an image of a beach, and it is hard to evaluate if the monitor is free from bad brightness shifts when looking at a colorful photo. The brightness shifts are most irritating when reading a text on a white page.

 

The long story.

 

I'm visually impaired since birth (nystagmus + astigmatism + near-sightedness). It's so bad that I have no chance to get a driving license. But despite that, I am really interested in computer programming - it got really serious and now I have master's degree in software development and now I have been programmer and software architect for 8 years.

 

Choosing a monitor has always been great frustration for me. To be able to work I have to have my eyes located closer to my monitor than "average user" (to avoid leaning forward and having bad posture, I'm using ergonomic arm which brings my monitor closer to my eyes and adjusts it the way I need). Also I have to use lower screen resolution. Such usage scenarios allows me to notice various kinds of flaws in monitors and graphics cards. As the result it is really hard to find a monitor which is comfortable to my eyes, so I can work for hours.

 

At first I thought that I should avoid flickering backlight because I'm in general very susceptible and notice flickering where "average people" don't. Therefore when I read in reviews that ASUS PA238Q monitor has higher backlight frequency, I thought - yes, that's the monitor which should be comfortable for my eyes. Also, knowing that it is IPS monitor, I put high hopes on its color and brightness uniformity and viewing angles because the Internet raved about it. Of course, I was aware that IPS panels have some other issues like pink/blue/gray backlight bleeding, especially noticeable on dark images, but I thought that I can live with that.

 

So I bought PA238Q and was somewhat pleased with it. Still, it had some brightness patches and shifts, especially noticebale from my normal viewing distance (30cm), and it had blotchy backlight bleeding, but I thought - oh, well, then IPS technology is not that far from TN, and I had too high hopes. 

 

But then one day in my office I had a chance to work on Viewsonic VP2365WB and somehow subjectively felt much better. I immediately organized a test with both monitors and was really surprised how bad my new, relatively expensive PA238Q turned out to be compared with VP2365WB. Reading a page of text on VP2365WB felt much more like reading a text on a printed evenly lit page, while reading the same page on PA238Q felt like reading on my old TN monitor. Also, backlight bleeding on VP2365WB was much more even without distinct patches.

 

I went even further - I exchanged my PA238Q for another one with a hope that I got a bad device, but the new monitor was even worse - it had even more distinct backlight patches.

 

As the result I bought VP2365WB and gave my PA238Q to my sister who is using it as a TV - at a far distance this monitor is pretty good.

 

Now I'm afraid to think what will I buy in case if my VP2365WB dies. VP2365WB is discontinued and I'm not sure if new Viewsonic models are as good as this one. Maybe Viewsonic has some special know-how which they are sticking to, and the angular brightness uniformity is one of the things they try to provide in every model? At least, it's nice to see Viewsonic web site to advertise some eye-care features like flicker-free and blue light filter, and also their SuperClear description claims to have special attention for wide-viewing angles, but I'm not sure if they have done anything in addition to what IPS panels already provide, in which case they might have models with bad IPS panels which suffer from bad angular brightness shifts.

 

I'd like to try a flicker-free monitor (thanks TFTCentral for the flicker-free monitor database) but I'm not sure, how to find a model which is not only flicker-free, but also free from such irritating brightness shifts and blotchy backlight bleeding.

 

Thank you for reading this long text and I really hope someone with technical monitor knowledge will give an advice how to find out if a monitor has problems with patchy backlight and angular brightness shifts, even if reviews claim that it is fine.

 

Happy new year!

[xernos]

Probably I won't give you answerer for all your question in that post, but I try give for a few.

 

 

Is this shift caused by the fact that the bad monitor has LED backlight but the good one has CCFL?

New display have diodes mounted on up and down edge of panel, and old display probably have this diodes mounted on back behind panel (that requires more diodes).

 

d--d--d--d--d                   -d---d---d---d-

-----------------                  ----d---d---d---

-----------------                  --d---d---d---d

-----------------                  ----d---d---d---

d--d--d--d--d                   --d---d---d---d

 

 

IPSes are free of this issue

Probably only selected panels with display for graphic work ...

 

What's confusing - a similar model to the bad monitor in my video in TFTCentral reviews received high scores for brightness uniformity. I suspect that the results might be different, if the test had included brightness shift measurements at different angles.

 

Different production, country, revision, providers ,storage and transport (sometime one product is produced by, a few manufactures and sells as one product)- many factors have really important influence on that.

 

I'd like to try a flicker-free monitor (thanks TFTCentral for the flicker-free monitor database) but I'm not sure, how to find a model which is not only flicker-free, but also free from such irritating brightness shifts and blotchy backlight bleeding.

You can consider buy display that use AMVA+ panel technology (uniformity problem is less common), or try again luck in IPS lottery.

 

Happy new year!

[midix]

Thanks, xernos, the explanation about backlight positioning makes sense.

 

The disappointing moment is that a monitor which has higher price and higher review ratings in real life might turn out much worse (in backlight aspect) than some other monitor, and there are no reliable parameters to watch before buying.

 

And considering that CCFLs are dead and LEDs rule, I guess most of new monitors will have that "bad" positioning which causes angular brightness shifts.

[xernos]

Thanks, xernos, the explanation about backlight positioning makes sense.

 

The disappointing moment is that a monitor which has higher price and higher review ratings in real life might turn out much worse (in backlight aspect) than some other monitor, and there are no reliable parameters to watch before buying.

 

And considering that CCFLs are dead and LEDs rule, I guess most of new monitors will have that "bad" positioning which causes angular brightness shifts.

Sadly I share similar situation as yours, on my desk was 3 displays (i2369vm/EW2440L/P2314H) and any of them can't compete on panel uniformity field with my old Benq FP93G (TN that working ideally up today, only lack resolution and panel size). For my next draft in lottery probably will be EV2450 or EV2336W, also thinking about something with true 8 bit (i.e. U2413). Only one thing is inconvenient for me, I bought GTX 960 (too week for IPS with 1440p), and radeon probably will be cheaper in that price tag (for buy display with freesync).

[midix]

I have an idea which would help me a lot.

 

I ask all owners of IPS monitors who can spend some minutes: 

 

I would be grateful if you could shoot a similar video to mine and publish it somewhere (Youtube, Dropbox, Google drive etc.). The process is simple and will take just a few minutes. Open any image editor (Paint etc). and fill it with single color (yellow works the best, in my experience). Then move your camera up and down to detect any brightness shifts, if they are present.

 

It would be even better if you have two or more monitors and can put the side by side to compare which one has more uniform brightness when viewed solid color backgrounds. There are comparison videos on Youtube, but they use colorful images, which do not give any real representation, what will I experience when reading documents and web sites with solid, white backgrounds.