Dreamcolor, although expensive, is still less expensive than high end Eizos
Not here. It's 24", and calibrator is extra. List price is significantly higher than the Eizo CG245; the one with the built-in colorimeter. And it's way beyond the CG 243.
The Dreamcolor is an interesting beast. And coming from hp, of all places. The next one down is the LP2475W; in the Dell U2410-class.
A factor to consider is exactly how the led's are powered series or parallel? In series, one led goes out and you lose a bunch more.
I can make a guess. LED light output is proportional to current. Led current is exponentially related to voltage. The consequence of these facts is that the only practical way to drive LEDs is with a current source - not a voltage source. For luminance uniformity without tweeking you want the same current going through the diodes, that is, hooking the diodes in series. There is a practical problem, however. Hooked in series the rail voltage of your current source goes up with each diode added. Just about the worst thing you can do as a subsystem designer is to drop another regulated power supply voltage demand on the system. So they will almost certainly stick with whatever the existing high voltage is in the system, which is typically 12 or 15 volts. This would allow putting 3 or 4 LEDs in series so you wind up with multiple series or a series/parallel arrangement.
Modern LEDs, which have gone through a decent burn-in test have a MTBF much in excess of the cumulitative hours of use expected of any monitor. Thus LEDs in series is not really a concern.
They are comparably priced in the US, but the Eizo is a CCFL light source. Check Amazon and enter a US zip code for our pricing. (97210 is a Portland zip). On second thought, don't do it! It will only p*ss you off!
Thanks for the feedback from Eizo about running the CCFL units at low light. I'll check out their white papers and see if there is more information available.
To tell the truth, so long as my prints match or exceed the screen, I won't worry much over color. But with B&W, that's another story. I may have to resort to the same technique used with Weston and Luna Pro light meters...dual range measurements. Bright for the shadow values, dimmer overall for general use.
Or spend money! I can wait a bit as well (hopefully!) as there are LED monitors from EIZO in a better price range. Just not here in the US.
An LED is a diode, and as such, has a forward voltage drop, somewhere around .35 to .6V, depending on materials.That voltage is steady, so if you want to control the output, you must either use a current source or a series resistor from a voltage source. But because the actual voltage drop, when forward biased, varies slightly, you cannot run a bunch of diodes in parallel and expect them all to light, as the diode with the lowest voltage at conduction will limit the rest from firing. However, if you string all the diodes together, one diode opening will kill the entire string, so a small parallel resistor, dropping probably no more than .25V or so will provide continuity, but increase the overall power needs.
What I meant by running in parallel is that a small number of diodes be grouped in a series form, then the group run from a single power source in parallel, as you indicated. I would expect that each string have it's own current source as well, possibly in the form of a current mirror.
Just a bit of "Back of the envelope" thinking here.
An LED is a diode, and as such, has a forward voltage drop, somewhere around .35 to .6V, depending on materials.That voltage is steady,
While an LED is a diode, it is not a silicon or germanium diode, which have low forward voltages as you mention. LEDs are typically made from III-IV materials and the forward voltages are in the approximate range of 2V to 4V depending on color and specific materials used.
While this is interesting stuff, it is a bit esoteric for this forum and probably sleep inducing for many.
Hmm, I assumed that the forward drop for white LED's around that value because both my flashlights, using white LED's, use a standard 1.5V AA battery, and consist of several bulbs; one of them has 12 bulbs! Interesting. Time to dig back into that technology.
Thanks, Paolo. Sometimes these discussions do go into esoterics, and with some of them, I do go to sleep!
There are whole forums full of tweakers working to get the most out of LED flashlights... A while back I followed someone who went by the handle "MillerMods" and who was pioneering some new circuit designs, so you could probably find some of his stuff via a web search. I bought some of his stuff back then, but the commercial companies have since exceeded his efforts.
My favorite pocket LED flashlight, which I carry at the moment, is a Fenix LD10 Q5, which on a single NiMH AA cell puts out 120 lumens in turbo mode. It is now somewhat old technology, though... There are MUCH brighter models, including those that run off slightly larger cells that put out much more current (e.g., laptop type 18650 cells).
I've been looking myself since posting last. Some of the circuitry is rather involved. But all that I found at the moment required 2AA cells. I have an original white LED flashlight ( a sales sample, not yet out then and one of the first on the market) that runs on a single AA cell. So some of this stuff may be proprietary.
The $9 unit I purchased lat week puts my big Mag Lite to shame! (Also the original 12 bulb unit)
Returning to monitors per se, after the marathon re-installation of the OS and all necessary applications, I found out that X-Rite actually has an updated driver and application for the i1. (Check for updates always returned only an update for Mac). With it, I can now calibrate the crt to less than 1cd/m^2 color accuracy, and upped the brightness to close to 70 cd. This also produced a better separation of shadow values in grayscale. In one instance, it showed better separation than what actually printed, whereas earlier, it was the print that had the open values. The print did not change, (I didn't reprint it) only the relationship to the monitor image.
The downside is the need to constantly re-calibrate, maybe once a week now, otherwise I see the fold-over in red on the vertical edges degrade as time goes on. That red gun is going south!
What was it, 2 years ago I first suggested you upgrade to LCD?
That red gun is going south!
I know the tan you've been getting from all the x-ray radiation probably looks nice, but it's time to move on!
Actually, I've found, through my own experimentation, that it's a LACK of cash flow that's worse.
Perhaps you should set up a web site to sell fine art prints... Seems to me I've seen some nice stuff you've done.
I've taken the Eizo S2243, freshly arrived, for a spin around the corner, kicking the tires, so to speak (why do people do that? Are they checking if the wheels are about to fall off?)
I was very interested in how the PVA panel behaved, but there was no need to worry. As for the dreaded "black crush" there's hardly any. There is a perceptible shift in the deep shadow values as you move your head across the screen, but considerably less than the old Eizo, and it seems the head-on view is correct. Comparing to the IPS panel of the 2335 showed no significant differences.
The Easy-Pix calibrator works well. It has fewer options than Color Eyes Display Pro, but it seems accurate enough, and it's nice to know that it bypasses the video card and goes straight to the monitor (and it does make a profile for Photoshop to use). There was just a slight hint of color banding after first calibration, gone after second, which goes to show how important warm-up is before you calibrate.
The EX-1 puck is just a rebranded Spyder3, which is known to perform well with wide gamut. I think I can learn to love wide gamut - proofing to ISO Coated took on a whole new meaning since it is covered 100%. Adobe RGB coverage is 95.
Oh, and panel uniformity is excellent <relief>.
All in all, a very fine monitor. Time to get to work
art by accident wrote:
kicking the tires, so to speak (why do people do that? Are they checking if the wheels are about to fall off?)
DO people actually kick tires on cars? It's a descriptive metaphor but I can't honestly say I've ever seen anyone in real life actually do it. If they do, I suppose one day they might find a tire that blows up (or a wheel that falls off)... That won't be good for the sale of that particular car (or the kicker's foot).
Not long ago a friend of mine, who has a VERY good relationship with his Cadillac dealer, was offered a chance to drive a new CTS-V model for a day. He didn't kick the tires, but he DID actually take the car to a drag strip! He managed a respectable 13 second quarter mile time, and he says the car has even more in it. He thinks he'll be buying it...
They do! Not exactly kicking, but placing the foot on the upper half of the wheel and...giving it a push, just enough to make the car rock a little bit. The aim of this test seems to be that if the thing doesn't fall apart instantly, it's passed. Quality control on a very basic level.
Take a closer look next time a congregation of taxi drivers assess a new car...hmmm...well, looks sturdy enough...
It's not available here.
Amazing because it's been on the market in Europe for over a year.
I guess it depends on what you mean by "here". You can certainly get one from B&H Photo in New York City:
You might also look at the SX2262W at about 1100 USD
Interesting because I did a deliberate search for that model on Google, asking price, where to buy etc and nothing came up! For Google?
I also checked Amazon-they didn't have it. But I didn't go further like B&H.
The SX series is what I am looking towards, but I am really holding out for the LED models. I only get one shot financially at this and it's gotta be right! It is the series the Eizo tech rep suggested because it is one step down from the Color Edge versions.
The LED models for the S series is in Japan, but not here until the older versions sell down to some acceptable levels in the US, so I am told.
By the way, since you have previously mentioned both LED backlights and your "white" LED flashlight it may be useful to know, if you do not already, that there are no true white LEDs - at least in commercial production. They are blue LEDs witht a yellow phosphor on top. While that makes it look somewhat white you will find a blue spike in the spectrum (good) plus a broad contribution in the longer wavelengths (not so good). That is why you do not get colors as saturated when "white" LEDs are used in backlights.
I found all that out during my latest foray into "white" LED's.
Let's face it. Nothing replaces a hot black body for spectrum continuity. (Nothing replaces a hot body for other things as well, but that's another story! ).
I lean towards the LED's for shadow separation uniformity at lower outputs. The LED curves confirm this, showing close to first order linearity, with a break in the slope at the lower levels, but still linear. CCFL's need a fixed peak voltage to be able to light off as well, so the dimmers are designed to control the integral value of the power curve, that is, the shape of the curve changes, but the peak value does not. Pretty difficult control, probably requiring a feedback loop to linearize it.