Does dot size matter in CRT monitor?

sforza

Hello,

I'm getting a new monitor and I was pretty sure I wanted this one (MITSUBISHI FE991SB) but I realized it has variable dot size, 0.25 at center and 0.27 at the corners.

The next model is this one (MITSUBISHI DP930SB) wich has 0.24, I suppose that applies to all the surface.

The price difference for me is 90€, approx 110$.

It's worth it? Am I willing to notice the difference?

thanks in advance.

TheSmJ

IMO it is. .27 is rather large.

Caxus

Get this one instead.

http://www.merkortech.com/product_view.aspx?product_id=255

Its bigger. Its higher quality. It's cheaper.

If you're worried about the fact that its a refurb don't be. I've never met anyone on this planet who's more picky about their monitors than myself. I never thought in a million years i'd ever buy a refurb but i was talked into it and it was one of the best purchase decisions of my life. Their grade A monitors are basically brand new. Trust me.

SimGuy

You'll notice it slightly, especially around the edges when reading text on a bright background.

Quite honestly, for any Trinitron/DiamondTron-based CRT, 0.24ag pitch should be considered the absolute minimum and cannot be directly compared to the dot pitch on standard ISM monitors.

IMHO, the Mitsubishi DP930SB is the best 19" DiamondTron/Trinitron-based CRT monitor currently available, even beating the highly-regarded Iiyama Vision Master Pro 455.

TheSmJ

I second the refurbed P1100. I got one from Merkortech myself over a year ago, and couldn't be happier.

Thrax

I third the P1100. I got one for myself about 9 months ago, and I'll probably never buy a brand new monitor again.

RADA

.27 is old technology. For a CRT you should be around .22 - .25. Of course the smaller, the better, the more expensive also.

Straight_Man

Some folks sell grade A refurbs as meaning mfr refurbs as opposed to third party refurbs. Merkortech appears to be one such for some of the major mfr monitors they sell and class as Grade A refurbs. Mfr's have to sell returns as refurbs if they sell in US. They have to sell minor blemed monitors that might be perfectly functional inside as refurbs. Epson does this for printers.

I would echo the P1100 as a good choice.

as to the thread starter's Will I notice and Should I care questions:

Yes, here's a rough table for dot pitch to effective pixels per inch, rounded a bit and squared (some onitors, in fact many, might have non-square PPI values based on how exactly the pixels are matrixed in tube or flat panel:

.28--.27 dot Pitch typically yields an effective 72x72 to 75x75 PPI.

.26-.25 dot pitch typically yeilds ABOUT 80x80 PPI plus or minus about 8 PPI either way (X or Y planes, X is horizontal, Y is vertical, just like a graph)or both ways(both X and Y, though a perfectly square monitor PPI is an oddity to say the least) depending on matrix structure of pixels. Some mfrs use dot pitch in a CRT type monitor to refer to TRIAD pitch, IE a set of one each Red, Green, Blue dots, and run the triads in an interlaced matrix (not interlaced video, every other triad is triangularly bottom flat, and the alternating one between can be triad flat on top, thus the matrix is triad-interlaced and the effective PPI is interesting to calc in reality, but A KDS monitor I had like this was actually able to put out a true 80x81 PPI with a .26 Dot Pitch spec that actually refered to the width of the bottom of the right side up triads).

My LCD here, to illustrate a flat panel in terms of PPI, is a slower refresh, but very tight pixel LCD. I wanted close to 96x96 PPI, settled for about 96x90 and smaller Y PPI means taller pixels in an LCD. It is a NEC, and given Dot Pitch is .25 (its actually more like .24x.25). Dot pitch can be in mm or even in cm in very old monitors of CRT type. Modern ones use mm but note that it is SO hard to get square displays that mfrs do several things.

First, they use variable dot pitch monitors, but the way they do that gives not a sudden endge spread usually, but a center-out dot pitch increase in measurement. This results in blurry edges or strange artifacts at higher than ideal refresh rates. Monitor have NATIVE refresh and res modes, typically are supre calibrated to ONE mode if we are talking a monitor that is not just VGA (which might be a .29 or .31 or bigger dot pitch, NOT what is wanted, SMALLER is better for dot pitch, BIGGER for PPI and close to even for X and Y values in true PPI is a very good thing). in the past, I have seen .37 mm Dot Pitches or bigger yet measurements.

CRT's use guns, typically a single-gun CRT has the "gun in the center of picture tube if you think of things as to X and Y offset and ignore the Z effect (gun is a distance from front of screen in CRTs, that is your Z plane). Further gun is away, or the poorer it can variably focus beam as it moves from one edge, to nearer part of screen to gun in center, and then in Z plane AWAY further as it scans toward right edge, results in edge blur and sometimes brightness loss at edges or color distortion at edges. Wrong pixels can get charged, or two can get partly charged, if aim and intensity and focus are not varied. OR, the front of the tube can be larger pixels to avoid color as you get nearer edges, and result is a lrge dege spec and a small center spec and this helps keep tiny parallax aim effects from yielding wrong colors to eye at adges, or other things like ghosting at edges with some video cards.

More than just PPI or dot pitch is involved, and if the size spread is tiny, some mfrs of cheap monitors (Gold Star has done this) publish an average Dot pitch and no PPI at all, as the PPI WILL vary in real cheap monitors, across boht X and Y planes, from center out and increasing as you get close to edges.

Earliest VDU displays were in fact round edged (circular to slightly oblong), not squared at all, and the display lense was not an ultra-flat like my KDs is, BY ANY MEANS. IInstead, front of display was in fact curved like a searchlight or headlight lense is on older bulb-type ehadlights that are round (just curved, no freznel-like planes on inside as those headlight bulbs sometimes had to allow perceptive intense light area shaping). Those displays were mono, and from edge to edge were more focussed with more primitive controlling circuits (read tube circuitry for lots of functions except in some cases for power control to tubes). BUT, the human eye close up could not judge distance well nearer edge as opposed to center of the VDU. There was X and Y bullseye distortion present that is similar to what a so-called fish-eye lense effect gives now.

Hope that is not way too much info overkill for all of you, but it should explain some issues and where hardware design and shortcuts taken to make the results in mfring much cheaper to do alone (as a set) can explain them.

sforza

Thanks for all the inputs.

First of all, that P1100 from Merkortech is great, but sadly I can't consider it because I'm from Spain (Europe) and shipping it overseas, if possible, would be terribly expensive.

I know 0.27 is too big if you hear that info alone. The same if you hear the other info Nec announces, 0.25, then everyone can say is pretty good. Take all the info together.

What I really wanted to ask was "Is having variable dot size noticeable?"

At the customer reviews at newegg some people stated what Straight_Man said about slightly blurry image at the edges. That dissappoints me a bit.

Reading the specs again, I found the recommended resolution to be 1280x1024 @ 85Hz. That's the one I wanted. Maybe a little higher refresh freq would have been ideal.

About your post Straight_Man, was very informative.

I have drawn this, I tried to make a little example in 2D of the problem with trying to make the screens 100% flat. You need the gun to be placed quite far of the screen. And when you want to get a short CRT monitor to not fill up all your desk, you fall into the problem this monitor has: not constant dot size.



If we draw imaginary lines of the same size from the center of the gun to the edge of the inner side of the screen, we'd got obviously a circunference sector. If we take the gun far enough, then we could say what we are projecting is approximately flat. It's the same as the horizon: we know it's round, but when given a great radium it looks flat.

but if we have that too near gun, and project its signal on a flat screen, it's clear we have bigger points at the edges than the center of the screen.

So, what's the tecnology behind a CRT that announces 0.22 dot size in ALL the screen?

Well, I think I am right in what I have explained, I have written it down the best I could; thinking in spanish is easy and the idea is very clear for me but I don't know if I have explained it right in english.

My current monitor, from where I'm writing this, is a flat KDS Trinitron AV-7TF 0.24 dot size. I'm going to the shop in an hour. I'll see the Mitsubishi with my own eyes at its recommended resolution and if it's acceptablily near of my KDS, I'll get it. Other chances here to buy are LGs and Phillips in the same price range. So...

See you later.