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I bought a new 24" iMac yesterday and.....
- Thread starter ibizarocks
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Mid-2007 24" iMac, MA878LL/A, S/N: W873447ZX89
MAX:MIN luminance ratio = 2.5 : 1 (about 1.3 f-stops)
...maybe my light meter should take a psych course?
LK
P.S. For photo tech info and more Canon 'optical illusions' see:
http://picasaweb.google.com/TheLooby
.
It's not your stance on the existence of the issue that is causing you arguments. It's you're claim that most all iMacs have the issue, which they clearly do not. Just check the active threads on this board. 2-3 people now posting with problems and 100's posting with great iMacs.
Here we go again. Someone had to go and shout in Leon's cave.
What course does one take to learn the difference between a light meter and a digital camera?
To your credit at least you removed your trademark "One measurement is worth a thousand expert opinions" tagline from this one.
Oh wait, it's still there. It just didn't show up when I quoted the message.
What course does one take to learn the difference between a light meter and a digital camera?
To your credit at least you removed your trademark "One measurement is worth a thousand expert opinions" tagline from this one.
Oh wait, it's still there. It just didn't show up when I quoted the message.
There are 24" panels with bad gradients. Some are bad enough that they clearly show up in digital photos. There are many photos of such screens in threads on these forums as well as Apple's discussion forums. There are also many many photos of 24" iMac screens with little or no gradients at all.
If you have one with this problem and it persists after full calibration and allowing the display to fully heat up I would suggest that the machine be returned to Apple for replacement.
Here we go again. Someone had to go and shout in Leon's cave.
What course does one take to learn the difference between a light meter and a digital camera?
To your credit at least you removed your trademark "One measurement is worth a thousand expert opinions" tagline from this one.
Oh wait, it's still there. It just didn't show up when I quoted the message.
Leon's post seemed fine to me. Someone asked for proof that the gradient issue exists, and he provided one with very little commentary.
It is a 180 degree shift from where we were at in October when there seemed to be a much higher frequency of bad iMacs screens, and some where calling for anyone to post a pic of a good iMac. Now there are so many good ones, that people are asking for someone to post a pic of a bad one as proof that they exist. That alone seems like adequate evidence that Apple has turned the corner on this issue. It still exists, but at a greatly reduced frequency.
I didn't have any problems with Leon's post either, thank you. I don't deny that the machine he photographed has a bad gradient and I said as much. Thanks for your moderation but I am completely aware that Leon is entirely entitled to his sarcastic commentary as are you and I.
Thus I am happy to remind Leon that while his screen clearly had a horrible gradient from those photos he still never actually measured it with a proper luminance meter and so he shouldn't be quoting figures on the ratio.
As for the gradient issue on the iMacs I don't think anything has changed at all. I've already stated what I believe to be the case. Apple is still using the exact same part.
I didn't have any problems with Leon's post either, thank you. I don't deny that the machine he photographed has a bad gradient and I said as much. Thanks for your moderation but I am completely aware that Leon is entirely entitled to his sarcastic commentary as are you and I.
Thus I am happy to remind Leon that while his screen clearly had a horrible gradient from those photos he still never actually measured it with a proper luminance meter and so he shouldn't be quoting figures on the ratio.
As for the gradient issue on the iMacs I don't think anything has changed at all. I've already stated what I believe to be the case. Apple is still using the exact same part.
I'd be interested in your commentary about the obvious decline in complaint threads around here.
Every modern, moderately-priced digital camera is a perfectly good
luminance meter -- plus an "exposure computer." If you turn off the
"computer" all that remains is the luminance meter. It's dirt-simple
if the camera has manual controls:
1) Set the ISO to a fixed speed.
2) Select aperture priority and choose an f-stop
3) Let the metering system determine exposure time
Luminance is inversely proportional to exposure time -- Physics 101.
http://johnlind.tripod.com/science/scienceexposure.html
...my Canon is more accurate than my old Gossen Luna Pro,
LK
i can see the light
thats behind you and to the left. try moving it. btw, mid-2007 is pre-august, which means its a white intel C2D imac, not the alum which people have been buggin out about.
Mid-2007 24" iMac, MA878LL/A, S/N: W873447ZX89
MAX:MIN luminance ratio = 2.5 : 1 (about 1.3 f-stops)
...maybe my light meter should take a psych course?
LK
P.S. For photo tech info and more Canon 'optical illusions' see:
http://picasaweb.google.com/TheLooby
.
thats behind you and to the left. try moving it. btw, mid-2007 is pre-august, which means its a white intel C2D imac, not the alum which people have been buggin out about.
That doesn't parse. If you mean "something" was behind me -- nope.
The photo was taken at night, in the dark. Other than the ALU iMac,
there was absolutely no other light source.
Wrong! And BTW, "Mid-2007" is Apple's terminology, not mine. They
refer to the white C2Ds as "Late-2006" -- and I've never seen a white
iMac with a display anywhere near that ugly.
http://support.apple.com/specs/imac/iMac_Mid_2007.html
http://support.apple.com/specs/imac/iMac_Late_2006.html
LK
OK, here's my story again:
I had an LCD panel on my iMac with a very minimal gradient at best. What it did have, however, was a faint line about 4cm in length almost like a shadow. It was so faint that it did not even occur to me until 5 months into using the machine. It was not noticeable at all on darker screens.
I sent it back to Apple and sure enough they confirmed it as a defect and replaced the LCD panel. There was a minor left-to-right gradient on the old panel that really wasn't noticeable at all unless you took a digital photo and then copy pasted the far left next to the far right (which Leon kindly did for me).
The new panel was a different story. When I first powered it up I about had a heart attack the gradient was so bad. It is especially noticeable on the grey boot screen with the black Apple logo, bright grey at the left and dark grey at the right. I called Apple and scheduled it to go back for replacement and they set it for the earliest pickup which was about 3 days later.
I continued using the machine and decided to run the expert calibration. Right off the bat I was taken aback by how much improvement I saw by doing that alone. As I continued using the machine I thought maybe the gradient was somehow magically dissappearing but what I came to realize was that it was always there and clearly visible when the machine was cold right at startup and gradually as the panel warmed up the backlight evened out. I cancelled the service. This panel may actually be slightly better when its warm than my old one was.
Of course these are only my own experiences but I think the left-to-right gradient may in fact be very much prevalent on these panels and of course is backlight-related. Some don't display this effect even cold and while I envy those who own them I am prepared to live with mine which needs to warm up for optimal quality. I know some have panels where no amount of warming up cures things. Those folks need to send their iMacs back to Apple for service or replacement.
Don't just turn on an iMac and shut it off and send it back if you see a gradient at first. Calibrate it and give the panel some time to warm up is my best advice.
This has been posted a billion times in here but all digital photo luminance testing aside I like this test as an indicator of gradient problems:
http://downloads.zac.ch/imac/imac_gradient_test_24.html
Looking at it now I see almost no difference in the tone of the grey left to right and the white text is equally legible.
Sorry but that's incorrect. The current line of aluminum iMacs is indeed called "mid-2007". I own one I should know.
Leon got a bad one. Did he properly calibrate it and allow it to warm up before sending it back? I will assume so since he seems to be nothing if not thorough.
The 20 does look horrendous out of the box. Supecal can fix it to some degree but the 24 is a superior panel in every way. My 24inch is perfect.
Warm up? Yep, kept the display on continuously for 3-4 days hoping for
a miracle -- no measurable difference. Anyhow, if it needs to "warm up"
for more than a minute or two, sumpin' is seriously wrong.
Calibration? Well, I did calibrate it -- but not with any hope of improving
the brightness gradient. Calibration has exactly ZERO effect on gradients.
- Calibration only tweaks RGB balance and luminance-per-volt (gamma)
response the TFT matrix -- and it affects each-and-every pixel EQUALLY.
- Calibration doesn't touch the source of the problem: FUBAR backlighting.
LK
I don't know, Leon. I think you and Apple have a difference of opinion on this matter:
http://docs.info.apple.com/article.html?artnum=25242
As you can see they say "up to over an hour". A friend in town who is a professor of engineering at a local university who does a lot of research into quality control issues with LCDs concurs. In fact I heard the theory from him initially. Then I saw it in action on my own display.
If you had bothered to read any of the dozens of gradient-related threads on these very forums you would find many photos of evenly backlit iMacs.
I'm looking at one right now.
My advice is to try reading more and posting redundant requests less.
If you had bothered to read any of the dozens of gradient-related threads on these very forums you would find many photos of evenly backlit iMacs.
I'm looking at one right now.
My advice is to try reading more and posting redundant requests less.
You're just being needlessly argumentative with someone who doesn't agree with you now. How old are you?
admin plz lock /delete this thread
admin plz lock /delete this thread
soo far off topic, throw it in the wasteland i think
plz
admin plz lock /delete this thread
soo far off topic, throw it in the wasteland i think
plz
Why has it become my responsibility to search the forums and point you to the threads full of photos from gradient-free iMac owners?? You seem to speak English well enough that you could accomplish this on your own but I'm in a giving mood this evening:
https://forums.macrumors.com/threads/371616/
Knock yourself out.
Taken under the camera settings specified by Leon to not over saturate:
Extreme left and right edges cropped and put next to each other:
Some see it, some do not...........But it is there, it is the nature of the panels used by Apple.
Do not go looking for it, enjoy your new Mac