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Thread started 26 Dec 2012 (Wednesday) 01:21
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to evaluate pictures/lenses -

 
inspectoring
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Dec 26, 2012 01:21 |  #1

To evaluate the sharpness of the pictures - I just put the CF card in PS3 and view them on my 7 year old TV - purchased in 2005 - Sony LED projection 55 inches.

Is this the best way to go about evaluating them?

I have tried viewing them on my PC monitor - but its max resolution is 1600 x something and pictures don't look as good as they do on the TV.


Gear: 7D, Canon 70-200 f8 MK II, 70-200 f4 IS, 24-70 f2.8 and Sigmalux 50 f1.4 Flash: 580EXii

  
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Ilovetheleafs
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Dec 26, 2012 07:51 |  #2

I'd say there's no wrong way to do it. If your photos look better on the TV then use it as a tool. Photography is all about using your creativity to express yourself or to show truth if in photojournalism.


Canon Rebel XS gripped, Canon 18 - 55mm, Sigma 18 - 200mm f3.5 - f6.3 DC OS HSM,Sigma 50mm f1.4 Olympus TG-810 Tough, LowePro Classified 160AW, Canon 430EX II Flash, Kata E-702

  
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melcat
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Dec 26, 2012 23:51 |  #3

Your TV has (at best) 1920 x 1080 pixels, possibly less if it's 7 years old. That has nothing to do with the size. This is far below the resolution of the 7D - to be precise, it's approaching 1/3 the resolution or 1/10 the number of pixels.

But wait, there may be more. If the PS3 is feeding the TV a standard 1080i30, 1080i25 or 1080p24 signal, that uses "chroma subsampling", so that although the luminance is at 1920 x 1080, the colour information is not. Many TVs provide a "monitor HDMI" input that avoids this, but I don't know what your PS3 and/or TV does and how you've set it up.

The TV may *look* sharp because it's doing what's known in the video world as edge enhancement, which is what stills photographers call USM sharpening. This would be why you perceive the TV as "sharper" - a more trained eye might think the opposite.

In summary, displaying the images on a TV is one of the worst possible ways to evaluate their sharpness. Most of the difference is far above TV resolution, and what it can see the TV may be trying to equalise.

EDIT - I am assuming in the above that the PS3 doesn't have a way to "zoom" in to look at the actual pixels (you would be looking at 1/10 of the picture and have to scroll around), but instead just shows the entire picture fitted on to the screen (pillarboxed).




  
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inspectoring
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Dec 27, 2012 00:39 |  #4

melcat wrote in post #15411264 (external link)
Your TV has (at best) 1920 x 1080 pixels, possibly less if it's 7 years old. That has nothing to do with the size. This is far below the resolution of the 7D - to be precise, it's approaching 1/3 the resolution or 1/10 the number of pixels.

But wait, there may be more. If the PS3 is feeding the TV a standard 1080i30, 1080i25 or 1080p24 signal, that uses "chroma subsampling", so that although the luminance is at 1920 x 1080, the colour information is not. Many TVs provide a "monitor HDMI" input that avoids this, but I don't know what your PS3 and/or TV does and how you've set it up.

The TV may *look* sharp because it's doing what's known in the video world as edge enhancement, which is what stills photographers call USM sharpening. This would be why you perceive the TV as "sharper" - a more trained eye might think the opposite.

In summary, displaying the images on a TV is one of the worst possible ways to evaluate their sharpness. Most of the difference is far above TV resolution, and what it can see the TV may be trying to equalise.

EDIT - I am assuming in the above that the PS3 doesn't have a way to "zoom" in to look at the actual pixels (you would be looking at 1/10 of the picture and have to scroll around), but instead just shows the entire picture fitted on to the screen (pillarboxed).


Thank you so much for the detailed response. So Does this mean that I should not be looking at the images on the TV or does it mean that when I look at images on the TV and they look good that means in reality Images are a lot better?

I have an iPad 3 at home. Should I be using this to look at my images? If so what would be the best way to look at them? I've tried transferring images to the iPad and quite frankly it Is very painful.


Gear: 7D, Canon 70-200 f8 MK II, 70-200 f4 IS, 24-70 f2.8 and Sigmalux 50 f1.4 Flash: 580EXii

  
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Bob_A
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Dec 27, 2012 01:02 |  #5

I think that the best way to evaluate sharpness would be to view using Photoshop and your PC's monitor with the image zoomed to 100%.


Bob
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melcat
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Dec 27, 2012 01:08 |  #6

Yes, what Bob said, with the proviso: an 18Mpx camera like the 7D will show some softness and it's OK for it to show more than a lower res camera.

I have the iPad 3 and it is *very* good for looking at JPEGs, provided you drop the screen brightness slightly from its auto setting. You can either use iTunes to get them on the device, or upload the images somewhere and look at them in Safari. I haven't tried to get .CR2 files on there.




  
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