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Author Topic: Interesting Comparison  (Read 18036 times)
fike
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« on: December 11, 2008, 11:30:18 AM »
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Over the last few months we have been discussing the relative merits of the new high-Mega Pixel cameras.  the 50D gained the dubious notariety of the camera that went "a bridge too far," just too many megapixels for its sensor size.  

I shoot a 30D now, and I've had the 50D in my sights for a few months.  I have been waiting for the stars to align and the price to decline.  But I have constantly had in the back of my mind the issue of more megapixels versus good megapixels.

Now comes the 5dMkII.  It really is a bit out of my price-range.  But that problem of good megapixels keeps bedeviling me.  It occurred to me yesterday that the 5dMkII has the same pixel pitch as the 20D/30D cameras.  

--so here's the controversial statement--

What this means to me is that when I put my 100-400 f/4.5-5.6 L IS lens on a 5dMkII, under ideal conditions and at base ISOs, I will get very similar resolution out of the same cropped field of view subject between the 30D and the 5dMkII cameras.

Yes, color, noise at higher ISOs, dynamic range, and a myriad of other factors will be better in the 5dMkII, but for sheer reach out of a telephoto zoom lens and camera combination, the 5dMkII and 30D will be equivalent. The 50D wins in this narrow category.  What I am really curious to see is controlled comparisons of the previous generation 20/30D and the 5dMkII.  The 5dMkII will obviously be better, but how much?  Will resolution numbers be the same when factoring in the crop-factor?

To get a similar telephoto reach and image quality out of a 5dMkII, you would need to invest many thousands more in a high-quality longer lens.  This makes the price differential even higher between the 50D solution and the 5dMkII solution.

What are your thoughts on my logic?
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« Reply #1 on: December 11, 2008, 04:00:42 PM »
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I also hasve a 30D and would like to see a comparison. as for your longer lens question... you could just use a 1.4 or 2.0 extender. the 1.4 will get you pretty close to the APS-C magnification factor on a full frame sensor.
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fike
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« Reply #2 on: December 11, 2008, 04:13:25 PM »
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Quote from: mike.online
I also hasve a 30D and would like to see a comparison. as for your longer lens question... you could just use a 1.4 or 2.0 extender. the 1.4 will get you pretty close to the APS-C magnification factor on a full frame sensor.

The 1.4x teleconverter is a decent idea, but again, that is a decrease in image quality and a loss of a single stop of light.  Will this cancel out the benefit of the improved body/sensor? Would there be unacceptable increased vignettingand distortion more obviously displayed by the full frame sensor and further exacerbated by the teleconverter.  

So an interesting hypothesis to test would be:

The 5dMkII with a 1.4x teleconverter has equivalent resolution and quality to a 20/30D without teleconverter???
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« Reply #3 on: December 11, 2008, 04:25:12 PM »
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Quote from: fike
To get a similar telephoto reach and image quality out of a 5dMkII, you would need to invest many thousands more in a high-quality longer lens

I don't understand this. You explained just above, that if you crop away the edges of a 5D2 image, you get the same resolution and same angle of view as with the 20D/30D, using the very same lens. The pixel quality of the 5D2 is definitively better than that of the 20D-50D.

So, why would you need a different lens?
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Gabor
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« Reply #4 on: December 11, 2008, 04:33:29 PM »
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Quote from: Panopeeper
I don't understand this. You explained just above, that if you crop away the edges of a 5D2 image, you get the same resolution and same angle of view as with the 20D/30D, using the very same lens. The pixel quality of the 5D2 is definitively better than that of the 20D-50D.

So, why would you need a different lens?

To be more precise, I should have said:
Quote
To get a similar telephoto reach and the full benefit of the improved image quality(and resolution) out of a full-frame 5dMkII, you would need to invest many thousands more in a similarly high-quality longer lens to get the same effective 640mm range at full-frame coverage.

As you probably know, the price differential between a decent 600mm lens and 400mm lens is quite substantial.

This analysis really is predicated on the importance of long telephoto reach.  The opposite argument could certainly be made regarding wide-angle capabilities.  I am obviously weighting long telephoto as more important.
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Panopeeper
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« Reply #5 on: December 11, 2008, 05:33:08 PM »
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Quote from: fike
To get a similar telephoto reach and the full benefit of the improved image quality(and resolution) out of a full-frame 5dMkII, you would need to invest many thousands more in a similarly high-quality longer lens to get the same effective 640mm range at full-frame coverage.

Ok, what do you need the more pixels for?

1. To make larger prints? Is the higher pixel level quality of the 5D2 not enough to print with lower resolution (a kind of upresing)?

2. To downres the image in order to increase the quality? Would that be necessary even with the 5D2 images?

What I am trying to arrive at is, that a crop from the 5D2 image is more worth than a full 20D-30D-40D image, perhaps even than a full 50D image. Keep in mind, that downresing the 50D images reduces not the noise but its visibility, and it does not increase the dynamic range.
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« Reply #6 on: December 11, 2008, 05:44:54 PM »
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Quote from: Panopeeper
Ok, what do you need the more pixels for?

1. To make larger prints? Is the higher pixel level quality of the 5D2 not enough to print with lower resolution (a kind of upresing)?

2. To downres the image in order to increase the quality? Would that be necessary even with the 5D2 images?

What I am trying to arrive at is, that a crop from the 5D2 image is more worth than a full 20D-30D-40D image, perhaps even than a full 50D image. Keep in mind, that downresing the 50D images reduces not the noise but its visibility, and it does not increase the dynamic range.

You have framed the question perfectly.  I would be comfortable saying that a 5dMkII crop would be better than the equivalent field of view from a 20D/30D--similar number of pixels, better quality from improved contrast, color, decreased SNR.  

While I am comfortable saying that the 5dMkII will have better quality, I am interested to see how that difference manifests itself.  

The 40d/50d in that same scenario makes an interesting discussion. I would find it informative to see the same cropped field of view from all the cameras adjacent to one another.  

You have got me pegged. I like to print very large images--24"x56".  I generally shoot panoramic or mosaic, so wide angle capability is not a problem. I can always stitch the image.
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« Reply #7 on: December 11, 2008, 07:35:30 PM »
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Very interesting comparison data at the Digital Picture:

The Digital Picture 5DMKII Review

I find his comparative analysis of DLA--Diffraction Limited Aperture to be very interesting.
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Ray
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« Reply #8 on: December 11, 2008, 11:12:02 PM »
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Quote from: Panopeeper
I don't understand this. You explained just above, that if you crop away the edges of a 5D2 image, you get the same resolution and same angle of view as with the 20D/30D, using the very same lens. The pixel quality of the 5D2 is definitively better than that of the 20D-50D.

So, why would you need a different lens?

How much better is the pixel quality, Gabor? I'd like to see this. In fact, such a comparison would be very revealing of just how much improvement has taken place at the pixel level, during the past few years.

The 40D has very liitle improvement over the 20D, when comparing equal size images, and the 50D has perhaps marginally more improvement over the 40D, when comparing equal image sizes.

The pixel size of the 5D2 is roughly equal to the pixel size of the 20D. Comparing equal size crops comprised of the same number of pixels, a 5D2 image will be better, no doubt. But how much better is the 5D2 pixel? This appears to be an unknown quantity. Can you post some comparisons?
« Last Edit: December 12, 2008, 07:58:45 AM by Ray » Logged
Ray
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« Reply #9 on: December 12, 2008, 08:18:23 AM »
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DXOmark has some interesting information comparing the 20D with the 5D2, which I understand is at the pixel level. According to their graphs, SNR of the 5D2 at ISO 1600 is just 1.4db better than the 20D. That doesn't sound much, especially when you consider that ISO 1600 on the 5D2 is actually ISO 1093 and on the 20D actually ISO 1333. In other words, I take a fully exposed shot with the 20D at ISO 1600, then take the same shot with the same lens on the 5D2, using the same exposure at ISO 1600, crop the 5D2 image to the same FoV as the 20D shot, and that 1.4db S/N advantage disappears because the 5D2 shot is slightly underexposed.
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« Reply #10 on: December 12, 2008, 09:02:05 AM »
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Quote from: Ray
DXOmark has some interesting information comparing the 20D with the 5D2, which I understand is at the pixel level. According to their graphs, SNR of the 5D2 at ISO 1600 is just 1.4db better than the 20D. That doesn't sound much, especially when you consider that ISO 1600 on the 5D2 is actually ISO 1093 and on the 20D actually ISO 1333. In other words, I take a fully exposed shot with the 20D at ISO 1600, then take the same shot with the same lens on the 5D2, using the same exposure at ISO 1600, crop the 5D2 image to the same FoV as the 20D shot, and that 1.4db S/N advantage disappears because the 5D2 shot is slightly underexposed.


That's pretty interesting.  Now what I want to see is how this minor difference manifests itself in images.  Most of the comparisons between full-frame and APS-C have focused on comparing the full-frame to the cropped frame.  What is interesting about the identical pixel pitch and similar SNR is that we can now look at a level playing field by cropping the full-frame sensor down to the APS-C sized field of view.  

I think this will shed light on the issues comparing the 50D and the 40D cameras.

But again, this allows us to view comparison images and see the effect of "better pixels" without confusing the issue with megapixel and pixel-pitch discussions.
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« Reply #11 on: December 12, 2008, 10:12:21 AM »
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Quote from: fike
That's pretty interesting.  Now what I want to see is how this minor difference manifests itself in images.  Most of the comparisons between full-frame and APS-C have focused on comparing the full-frame to the cropped frame.  What is interesting about the identical pixel pitch and similar SNR is that we can now look at a level playing field by cropping the full-frame sensor down to the APS-C sized field of view.  

I think this will shed light on the issues comparing the 50D and the 40D cameras.

But again, this allows us to view comparison images and see the effect of "better pixels" without confusing the issue with megapixel and pixel-pitch discussions.

The graphs at DXOmark overlay an image which appears if you move the cursor to the colored bar on the right. It's easy to see how the noise increases, with all cameras compared, as you change ISO, ie. by moving the cursor up and down the colored bar.

I'd estimate the 5D2 has just under a stop of S/N improvement over the 50D at most ISOs. However, a 5D2 image cropped to the FoV of a 50D image becomes only 8mp. As mentioned before, most of that 3/4 stop advantage will disappear if the 50D images is downsampled to 8mp, or, if the 8mp crop is interpolated to 15mp. The net effect is either better resolution from the 50D or equal noise, approximately.

http://www.dxomark.com/index.php/eng/Image.../(brand3)/Canon
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« Reply #12 on: December 12, 2008, 10:36:06 AM »
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Quote from: Ray
The graphs at DXOmark overlay an image which appears if you move the cursor to the colored bar on the right. It's easy to see how the noise increases, with all cameras compared, as you change ISO, ie. by moving the cursor up and down the colored bar.

I'd estimate the 5D2 has just under a stop of S/N improvement over the 50D at most ISOs. However, a 5D2 image cropped to the FoV of a 50D image becomes only 8mp. As mentioned before, most of that 3/4 stop advantage will disappear if the 50D images is downsampled to 8mp, or, if the 8mp crop is interpolated to 15mp. The net effect is either better resolution from the 50D or equal noise, approximately.

http://www.dxomark.com/index.php/eng/Image.../(brand3)/Canon


I saw that overlay. I assumed that it was merely for representation only...not real data-based images.  

Your conclusion about the 50D having better resolution within the cropped sensor field of view and nearly equal noise is likely to be debated heavily, although I think you are probably right.  As I keep repeating, I want to see what the difference really looks like in the real world.  Everyone wants to uprez or downrez the images to compare.  In this comparison, no resizing is needed.  since a 20/30d share the same pixel pitch cropping is sufficient.  When the 50D is thrown into the mix, then you need to do some sort of resampling, either up for the 5dMkII or down for the 50D.  

Another aspect to this debate is when you start throwing High-ISO into the mix.  How high do you need to go before the 5dMkII overtakes the 50D in cropped sensor area resolution?
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« Reply #13 on: December 12, 2008, 01:15:55 PM »
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Quote from: Ray
How much better is the pixel quality, Gabor? I'd like to see this. In fact, such a comparison would be very revealing of just how much improvement has taken place at the pixel level, during the past few years

I did not qualify my statement (I was blathering).

Those, who need the maximum DR, like landscapers, shoot mostly at the native ISO or in the low range. The DR of the 5D2 seems to be only negligably greater than that of the 40D @ ISO 100.

For those, who are after available-light performance, higher ISO is important. The 5D2 is about one stop better than the 40D @ ISO 1600.

I ordered a Stouffer transmission wedge; as soon as it arrives, I will make measurements of the 20D and the 40D, and I hope to find some photogs in my area, who would come by with their cameras and make suitable shots, so that I can build a large camera base. I am disappointed with the raw files posted at Imaging Resource; they are obviously not using those images for accurate measurements.

I don't believe the more accurate measures will differ very much from those I made until now, but those results are much more reliable. I have such raw files for the 5D (but only ISO 100), the Nikon D200 (only ISO 100) and the D3 (full serie). Those shots prove, that the measurement is very consistent within a small margin.
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« Reply #14 on: December 12, 2008, 09:21:25 PM »
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As I keep repeating, I want to see what the difference really looks like in the real world.

Prints or Plasma/LCD display?

At present, I'm converting a good few of my images to sRGB and 1920x1080 pixels for display on my new 50" Plasma TV. Where I can crop to the 16:9 aspect ratio without spoiling the composition, I do so.

It so happens I have a mounted print hanging on the wall immediately above the plasma screen, to one side. The scene is a wide-angle shot of a temple ruin at Angkor Wat taken with my 5D and printed on my Epson 7600 at 23" x35", no cropping, the full 12.7mp interpolated.

Out of curiosity, I took the same image file that I'd printed at 23"x35", converted it to sRGB and downsampled it to 1080 pixels in height, which resulted in a 5mb file (not 5mp but 5MB which is less than 2mp).

From a 'normal' (or shall we say 'usual') viewing distance of 10 or 12ft, the 5MB file on the Plasma screen looks just as detailed as the 260MB file (after interpolation) that was printed.

I'm a bit flabbergasted. Is there something wrong with my eyesight? I need glasses for close reading, but long distance is no problem. However, medium distances can be a slight problem. I can drive a car at night with no problem, without glasses, but for best clarity on the computer monitor I need galsses with a lower magnification than my normal reading glasses. For best clarity at medium distances, I use the very first spectacles I was prescribed for reading purposes, with a magnification of 1x.

I have no reason to think that this effect I'm seeing is a result of poor eyesight, but it might be. Maybe I'm in a state of delusion.

The other impression one clearly gets, making this comparison between the print of the 260MB file and the 5MB plasma display of the same file, is that the vibrancy and luminosity of the image on the plasma screen completley trounces the relatively dull and flat print. I'm beginning to think that the only purpose of my Epson 7600 printer is to produce very wide panoramas of stitched images that my plasma display cannot accommodate without very severe reduction in resolution and size.

However, I don't want to appear to be exaggerating. The appearance of the print changes with lighting. Sometimes in the evening, with a certain type of artificail lighting, the qualities change and subtleties of tonality are quite enchanting on the print. The plasma display is 'full on', as it were, day or night.
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« Reply #15 on: December 15, 2008, 05:53:52 AM »
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I had a conversation yesterday that kinda gels with with thread.
My new LX3 has an interesting feature, when you select a smaller image size (e.g. 6Mp instead of 10Mp) you get an increased zoom range!
I does this by zooming electronically until the sensor crop shrinks to the desired number of pixels, then it zooms optically.
As well as giving me an extended zoom range it means the sensor is avoiding any soft edge effect from the lens.
Very cunning!

Now imagine if the 5D2 on sRAW gave you the option of either a resized full frame or cropped frame to get the smaller file.
This would give you the option of sacrificing pixels in exchange for a much greater zoom range.

I realise I can do this by cropping in post-processing, but in terms of a composition aid and checking focus it would be great if the cropped image filled the frame.
Maybe the LX3 has something that could useful be applied to DSLRs too!
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« Reply #16 on: December 15, 2008, 07:25:52 AM »
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Quote from: Nacnud
I had a conversation yesterday that kinda gels with with thread.
My new LX3 has an interesting feature, when you select a smaller image size (e.g. 6Mp instead of 10Mp) you get an increased zoom range!
I does this by zooming electronically until the sensor crop shrinks to the desired number of pixels, then it zooms optically.
As well as giving me an extended zoom range it means the sensor is avoiding any soft edge effect from the lens.
Very cunning!

Now imagine if the 5D2 on sRAW gave you the option of either a resized full frame or cropped frame to get the smaller file.
This would give you the option of sacrificing pixels in exchange for a much greater zoom range.

I realise I can do this by cropping in post-processing, but in terms of a composition aid and checking focus it would be great if the cropped image filled the frame.
Maybe the LX3 has something that could useful be applied to DSLRs too!

There is actually an advantage in having that wider view when taking the shot. I find often when using a 400mm lens with a cropped format camera like the 20D it's difficult to locate the target, especially when the tareget is a small bird flitting from branch to branch.
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« Reply #17 on: December 15, 2008, 08:06:55 AM »
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Hi,

I think this is mostly a question of viewing distance. The resolution of the human eye is regarded to be normally about one minute of arc, and be determined by the average distance between the rods on the foeva. If my calculations are right the resolution of the plasma TV would match the resolution of the eye at about 2m (or 6 feet). So if you look at your print at a distance which is shorter than two neters it should be sharper than your plasma TV.

Another issue is that prints need a lot of light, 400 lux or so. Prints also have better permanence than plasma screens :-)

Best regards
Erik


Quote from: Ray
Prints or Plasma/LCD display?

At present, I'm converting a good few of my images to sRGB and 1920x1080 pixels for display on my new 50" Plasma TV. Where I can crop to the 16:9 aspect ratio without spoiling the composition, I do so.

It so happens I have a mounted print hanging on the wall immediately above the plasma screen, to one side. The scene is a wide-angle shot of a temple ruin at Angkor Wat taken with my 5D and printed on my Epson 7600 at 23" x35", no cropping, the full 12.7mp interpolated.

Out of curiosity, I took the same image file that I'd printed at 23"x35", converted it to sRGB and downsampled it to 1080 pixels in height, which resulted in a 5mb file (not 5mp but 5MB which is less than 2mp).

From a 'normal' (or shall we say 'usual') viewing distance of 10 or 12ft, the 5MB file on the Plasma screen looks just as detailed as the 260MB file (after interpolation) that was printed.

I'm a bit flabbergasted. Is there something wrong with my eyesight? I need glasses for close reading, but long distance is no problem. However, medium distances can be a slight problem. I can drive a car at night with no problem, without glasses, but for best clarity on the computer monitor I need galsses with a lower magnification than my normal reading glasses. For best clarity at medium distances, I use the very first spectacles I was prescribed for reading purposes, with a magnification of 1x.

I have no reason to think that this effect I'm seeing is a result of poor eyesight, but it might be. Maybe I'm in a state of delusion.

The other impression one clearly gets, making this comparison between the print of the 260MB file and the 5MB plasma display of the same file, is that the vibrancy and luminosity of the image on the plasma screen completley trounces the relatively dull and flat print. I'm beginning to think that the only purpose of my Epson 7600 printer is to produce very wide panoramas of stitched images that my plasma display cannot accommodate without very severe reduction in resolution and size.

However, I don't want to appear to be exaggerating. The appearance of the print changes with lighting. Sometimes in the evening, with a certain type of artificail lighting, the qualities change and subtleties of tonality are quite enchanting on the print. The plasma display is 'full on', as it were, day or night.
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« Reply #18 on: December 15, 2008, 09:28:21 AM »
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Quote from: ErikKaffehr
Hi,

I think this is mostly a question of viewing distance. The resolution of the human eye is regarded to be normally about one minute of arc, and be determined by the average distance between the rods on the foeva. If my calculations are right the resolution of the plasma TV would match the resolution of the eye at about 2m (or 6 feet). So if you look at your print at a distance which is shorter than two neters it should be sharper than your plasma TV.

Another issue is that prints need a lot of light, 400 lux or so. Prints also have better permanence than plasma screens :-)

Best regards
Erik

Erik,
Yes, it's definitely a matter of viewing distance. Your calculation of about 2 metre's viewing distance seems about right, but in practice I'm usually further away from the print than that, most of the time.

I guess a print would have better permanence than a plasma display which was on all the time. However, Panasonic are boasting that their latest displays will last longer than most of their customers who buy them. They are rated at 100,000 hours which, at 8 hours a day, works out to 34 years. At a more reasonable 4 hours a day, that would be 68 years   .
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« Reply #19 on: December 15, 2008, 11:08:40 AM »
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;-) (Re. permanence)

Quote from: Ray
Erik,
Yes, it's definitely a matter of viewing distance. Your calculation of about 2 metre's viewing distance seems about right, but in practice I'm usually further away from the print than that, most of the time.

I guess a print would have better permanence than a plasma display which was on all the time. However, Panasonic are boasting that their latest displays will last longer than most of their customers who buy them. They are rated at 100,000 hours which, at 8 hours a day, works out to 34 years. At a more reasonable 4 hours a day, that would be 68 years   .
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