Perhaps as my first post I should pick a less volatile subject than the 36MP sensor size on the D800 but I really wanted some feedback on whether I am “getting” it or not on this issue. I have a D300 which has treated me well for several years but I have the bug to upgrade. When I compare the sensor size & effective pixels of the D300 to the new D800 the pixel density is about 28% more even though the effective pixels are 3 times greater. Do I have that math right? If so, it’s about the same as the D7000 today.
I also use a Sony NEX C3 (I know; I shouldn’t mention this) and its pixel density is a tad higher than the D800 with half the pixel count. Very decent results particularly in low light, but a different animal all together.
My question would be isn’t the pixel density every bit as important as the raw pixel count as we conjure with how this new beast is going to operate and how touchy it may be to camera movement or sloppy focus techniques etc.

Nick, you're basically on the right track on all counts.

The only idea in your logic I'd refine is that it's really greater enlargement reveals flaws in technique. This is only related to pixel density in that people expect greater pixel density to allow greater enlargement.

If you make, for example, 24x36" prints from your D300 and a D800, and view these at the same distance, all things being equal I'd expect the D800 print to be more forgiving of flaws in equipment and technique despite the greater pixel density, because the larger FX sensor means you're enlarging less, and by extension enlarging your flaws less as well. The "all things equal" is a real rub here however, since the larger sensor will require larger lenses and be less forgiving of lens performance in the corners, and a million other details we could discuss, but the basic idea is that it's enlargement that magnifies your flaws, not pixel density.

Larry - a Bay Area Nikonian
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>My question would be isn’t the pixel density every bit as
>important as the raw pixel count as we conjure with how this
>new beast is going to operate and how touchy it may be to
>camera movement or sloppy focus techniques etc.

Pixel density and pixel count are inextricably related. It is the pixel count in within a finite area which determines the density.

If you have very large pixels - hence fewer - within the same finite area (FX), resolution is lower because fewer pixels are available to record detail. At the same time, very slight movements of the camera (e.g., while shooting handheld) do not normally result in very much blurring when shooting at 1/125s and using average technique.

If you have very small pixels - hence many more - within the same finite area (FX), resolution is higher because more and smaller pixels are available to record detail. At the same time, very slight movements of the camera (e.g., while shooting handheld) cause blurring when shooting at 1/125s using average technique. Each incrementally higher shutter speed you try for the same shot, using the same technique, will usually result in increasingly sharper images up to a point at which the shutter speed is high enough to overcome most of the effect of any slight movement, but where increasing shutter speed any more will compromise your exposure (i.e., you run out of both appropriate aperture and usable ISO).

Another way to look at it is purely by considering pixel density. Take the case of an FX 12.3mp sensor and an FX 36mp sensor being used sequentially to shoot the exact same subject at the exact same focal length, framing, shutter speed, aperture andn ISO. If your slight, handheld camera shake move the camera +/- a millimeter or two, the 12.3mp sensor may record some blur. Shoot with the 36mp sensor though, and the same amount of camera shake will affect many more pixels - ergo, more apparent blur than in the 12.3mp sensor.

The thing to keep in mind is just that it's not the camera sensor or its AF system which is causing the blur. It's the shaky photographer.

Another way to look at it is that the more pixels that are available to record information in a defined area, the more easily the camera can record blur caused by shake, tremor, pumping, wind, etc., along with finer detail in the scene/subject being photographed.

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Howard Carson, Managing Editor
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Hi Howard,

Your explanation about pixel density/sensor size seems logical and is in accord with my limited understanding of that subject. However, point and shoot cameras are marketed in large part by the number of pixels, with the marketing telling the consume the more pixels the better the camera. Since the size of the sensors in those cameras are quite small, why are those cameras not difficult to shoot, i.e. why is camera shake not an issue (at least not a significant issue)?


JDT

Camera shake in high pixel count P&S cameras would be a big issue if the users tried to make big prints or were pixel peepers. Noise would also be a big issue under those conditions too. However most P&S users just produce internet size images or 4x6 prints. The averaging of many image pixels for one pixel on the screen or a small area in the print hides many problems with technique and pixel size

Gary in SE Michigan, USA. Co-organizer of the Southern Michigan Chapter
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Hi Gary,

That makes sense. Thanks for the post.

JDT

It's exactly as Gary states. Despite the tens of millions of high mp point & shoots sold each year, the vast majority of them aren't used to produce photos for anything but email, 4"x6" prints, Facebook and MySpace posts,Tweets and so on. Resolution and blur simply aren't noticed.

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Howard Carson, Managing Editor
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Gary & Howard you are exactly right and I see this first hand on the 16mp Sony which if handled VERY carefully can produce good detail but the ergonomics are not in your favour when holding the darn thing out in front of you so you can see the screen which is the issue with almost all P&S cameras I guess.

OK Howard, you and Gary have answered my question. I do expect the D800 to challenge me to use better technique, and that is something I should do anyway. It will be interesting to see how it works out in the real world. Thanks for the post.

JDT

It's not the pixel density but the angular pixel density that determines susceptibility to shake. The D800 has 100 pixels per degree, the D7000 only 67. However, down-rezing the D800 file to 16MP in theory should more than compensate for this. In practice, it's never quite that simple. The actual characteristics of the blur, including contrast, come into play. I think we're just going to have to wait and see.

Jim

>It's not the pixel density but the angular pixel density that
>determines susceptibility to shake. The D800 has 100 pixels
>per degree, the D7000 only 67.

How do you figure that?

Look at it this way... if someone can make an 30x20" enlargement with a 200mm lens on a D7000, then you should have no problem making a 45x30" enlargement with the same lens on a D800. Additionally, you should have no problem making a 30x20" enlargement with 300mm lens on a D800.

Simple as that.

--
RL

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The figures Jim quotes (from Thom Hogan, if I'm not mistaken) assume that a lens of equal angle of view is used on the two cameras. It would be helpful to state our assumptions...

Brian
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Yeah,

I guess I just see the pixel/per degree number as something that varies with each focal length so it's best to qualify those numbers somehow.

--
RL

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Thom calculated it with a 24mm lens on an FX camera, and a 16mm lens on a DX camera. But the relative density: 100 vs. 67 will hold up for the same field of view regardless of the focal length(s) chosen. The upshot is that susceptibility to shake depends on resolution, not pixel density.

Jim