Canon Camera Reviews & Info From 20d to present

[Grady Weed]

I found this information really informative. For those who like to compare features, frame rates, pixels, etc, you will love this review and informational article. The charts was what grabbed me. I saved this to my hard drive for future comparison.

Go here: http://www.the-digital-picture.com/R...ra-Review.aspx

For instance, I thought his information to be of particular interest, as I have never heard this before: Diffraction Limited Aperture) is the result of a mathematical formula that approximates the aperture where diffraction begins to visibly affect image sharpness at the pixel level. Diffraction at the DLA is only barely visible when viewed at full-size (100%, 1 pixel = 1 pixel) on a display or output to a very large print. As sensor pixel density increases, the narrowest aperture we can use to get perfectly pixel sharp images gets wider.

DLA does not mean that narrower apertures should not be used - it is simply the point where image sharpness begins to be compromised for increased DOF and longer exposures. And, higher resolution sensors generally continue to deliver more detail well beyond the DLA than lower resolution sensors - until the "Diffraction Cutoff Frequency" is reached (a much narrower aperture). The progression from sharp the soft is not an abrupt one - and the change from immediately prior models to new models is usually not dramatic. Check out this specific diffraction comparison example using the ISO 12233 chart comparison tool. The mouseover feature will show you the degradation at f/11 compared to f/5.6.

Thanks for looking.

[James Shadle]

For instance, I thought his information to be of particular interest, as I have never heard this before:
Grady,
That's because you haven't talked to Roger.

The diffraction limitations of the D800 concerned me to the point that I'm buying a D4.
I am able to work very close to my subject so I need to stop down to get the DOF I need. I work with converters and like to stop down.
If I'm correct the diffraction envelop on the D800 is F8 +/- and the D4 is F14 +/-

[Roger Clark]

For instance, I thought his information to be of particular interest, as I have never heard this before:
Grady,
That's because you haven't talked to Roger.

The diffraction limitations of the D800 concerned me to the point that I'm buying a D4.
I am able to work very close to my subject so I need to stop down to get the DOF I need. I work with converters and like to stop down.
If I'm correct the diffraction envelop on the D800 is F8 +/- and the D4 is F14 +/-

James,
If you are using the same lens from the same position, you'll simply trade spatial resolution for noise. (D4 16 megapixel versus D800 36 megapixels, so D4 pixels are 1.5 times larger pixels). So a D4 image will have less detail but higher signal-to-noise ratio. You won't gain any more detail on the D4 stopped down over a D800 stopped down. The D800 image will still have more detail, though the difference will decrease as you stop down.

Roger

[Roger Clark]

Grady,
Here are two examples showing the losses due to diffraction:
MTF plot:
http://www.birdphotographers.net/for...018#post773018

and images:
http://www.birdphotographers.net/for...320#post771320

So it is a continuous slide in loss of contrast in fine details as the aperture is closed down. Think of the bars in the test images as the strands in feathers in a bird photo.

Roger

[Grady Weed]

Going back and reading over that thread, I can know get even more out of it. Thanks Roger.

[James Shadle]

Roger,
If I'm at my minimum focus distance with an 800mm lens, I need to stop down a bunch to have any DOF. If an GBH turns it's head towards me, I want both the eye and bill tip to be in sharp focus.

Are you saying that if I stop down the D800 to F16 and compare it to the D4 @ F16, the D800 will still have more detail?
If the detail is the same or slightly better, the D800 would still be noisier?

[Roger Clark]

Roger,
If I'm at my minimum focus distance with an 800mm lens, I need to stop down a bunch to have any DOF. If an GBH turns it's head towards me, I want both the eye and bill tip to be in sharp focus.

Are you saying that if I stop down the D800 to F16 and compare it to the D4 @ F16, the D800 will still have more detail?
If the detail is the same or slightly better, the D800 would still be noisier?

HI James,
Yes, the D800 will still show a little more detail, and the noise per pixel will be slightly higher in the D800 pixels. For every D4 pixel, where are 2.2 D800 pixels. When the images are compared at the same size, most people will choose the image with more detail as the better image, assuming, of course, a sharp lens.

Roger