December 19, 2014, 07:30:35 PM

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Messages - Jackson_Bill

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16
and finally the sheep ...
the boys are feeling amorous, the ewe, not so much.

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and, of course, the moose...

18
and the goat ...

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no deer handy, how about a couple of elk...

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bison...

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I can't pass up this topic...

antelope

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Animal Kingdom / Re: BIRD IN FLIGHT ONLY -- share your BIF photos here
« on: October 28, 2014, 02:44:55 PM »
I'm guessing these are immature golden eyes - anybody have any other thoughts?
Oh yeah,
7d, 500 f/4 IS USM, ISO 400

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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 24, 2014, 12:35:50 AM »

If you have a larger sensor with the same pixel count, the shot noise per pixel is lower.
True, because the pixels are larger and the standard deviation of the photon count is proportional to the square root of the count.

You can use software (noise reduction and downsampling) to trade all that extra resolution for much lower noise in the overall image with the same sharpness (resolution), and in fact that's what you end up doing when you compare the two images at the same final size.
That's something else again. This discussion was related to the discussion regarding the intensity and total quantity of light and whether how that was affected (if at all) by the size of the sensor [before post processing].

All those photons that are collected by all those extra pixels count in the total signal (sharpness) to noise (noise) of the final overall image, and that's the reason that a larger sensor out-performs a smaller sensor in low-light despite having the same sized pixels.
No, those extra pixels don't count (again, before post processing). Consider a FF sensor with pixels that are the same size as an APS-C, taking a photo of a uniform 18% gray background and that APS-C taking the same photo under the same conditions. There will be no difference in the shot noise between those photos.

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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 11:03:46 PM »

SNR = sqrt(photon count)

True, but I believe that's photon count per pixel. I'm trying to understand how the the total photon count on the sensor matters.

If you only look at one pixel, the per-pixel photon count would be all that matters.  If you look at a whole image, the whole image photon count is what matters.

I don't think so. You've probably seen this before
http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/

For the shot noise, its only a function of the number of photons captured by a pixel. Its the physics of why the crop (smaller pixels) shot noise can never be as low as the FF.
My impression is that the read noise is also per pixel but I can't back that up.

[Where's jrista when you need him?]
:-)


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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 09:27:11 PM »

Yes, if a FF pixel and a crop pixel are the same physical size (and technology) the individual pixels will be identical in terms of signal and noise.

If both images were shot with the exact same lens, the same settings, and the same distance, the central 40 percent of the FF pixels would be exactly the same as the crop pixels.
My point exactly!

In real life, with your equal size pixel scenario, we would try to frame the two pictures the same, so that means either a 1.6X longer lens on the FF camera, or walking closer until the image filled the screen the same. Either way you look at it, that gives you 2.56 times as many pixels of equal quality on the target, so when you "normalize" the FF picture for the same number of pixels as the crop image, you end up with better quality pixels on the FF image. You are choosing between more pixels of the same quality, or the same amount of pixels but of better quality. There is no way for crop to win in that scenario.

In the real world, with the cameras Canon makes now, FF wins the IQ contest in all but one scenario... and that scenario is when you are focal length limited, can't move any closer, have a GREAT lens, and good lighting. Under those conditions (happens a lot with small birds) the quality of your crop pixels is fairly close to your FF pixels, but you have more crop pixels on target so you end up with a better image from the crop camera.  Everywhere else, FF wins.


No argument with any of that either. In fact, I think that's another good version of the summary that Eldar was asking for.

Sorry I got us off track with that amount and intensity of light thing.


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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 09:20:36 PM »

SNR = sqrt(photon count)

True, but I believe that's photon count per pixel. I'm trying to understand how the the total photon count on the sensor matters.
Although I'm beginning to regret going off on this tangent.
:-)

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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 07:32:22 PM »

True, but the 2.56x greater area of the FF sensor will gather more total light.  Comparing noise at the pixel level isn't the same as comparing noise at the image level.

There's shot noise, which is clearly related to the size of the pixel and I thought that the signal processing to convert the analog to digital was done on a pixel-by-pixel basis, which would make the read noise related to the pixel photon count, too.  Is that so? If so, what else would make the image level noise different? In other words, how does the total amount of light collected by the sensor come into the noise calculation?



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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 10:19:05 AM »
I don't agree with this "amount of light" argument. Consider a full frame sensor and an APS-C size sensor with pixels the same size as a full frame taking photos with the same lens at the same f-stop and the same distance from the subject. The signal to noise ratio for each pixel in the APS-C sensor will be the same as the S:N ratio as the corresponding pixels in an APS-C sized area of the ff.

True, but the 2.56x greater area of the FF sensor will gather more total light.  Comparing noise at the pixel level isn't the same as comparing noise at the image level.

You lost me on the image level noise, Neuro. It seems that an APS-C sized crop of the FF image and the APS-C image in this case would be identical. The number of photons hitting each pixel is the same and assuming the downstream operations are identical, what's the difference?

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EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 09:47:06 AM »
I must have misread. I was under the impression that some people were arguing that 2.8 lens let in the light of an f8 when on the micro 4/3 mount.
Jarrod
...

A greater intensity of light is what's needed to make a smaller area receive the same amount of light. Simply cutting/cropping out some light, and then magnifying/enlarging what's left afterwards results in less light captured. That's otherwise known as a lower signal, which requires more amplification/enlargement, typically resulting in more noise.

I don't agree with this "amount of light" argument. Consider a full frame sensor and an APS-C size sensor with pixels the same size as a full frame taking photos with the same lens at the same f-stop and the same distance from the subject. The signal to noise ratio for each pixel in the APS-C sensor will be the same as the S:N ratio as the corresponding pixels in an APS-C sized area of the ff.

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EOS Bodies - For Stills / Re: What card(s) will you use for the 7DII?
« on: October 22, 2014, 09:46:58 AM »


As a precaution I shoot in both RAW and JPEG in different card. RAW in Sandisk 32gb 160mb/s UDMA 7 CF Card and JPEG in a Sandisk 16gb 120mb/s SD card. Both formats in high resolution
That is my general intention, shoot raw to the CF and jpeg to the SD.  Not sure of the sizes yet but your method seems good.

Are you actually writing the RAW and jpg both on every shot? It seems that would seriously impact the high speed frames per sec.

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