Forgive a potentially stupid question:

When shooting the D800 in DX mode with a DX lens, does one still retain the ISO performance you get with the FX sensor? While it would be compromising the D800's ultimate high res abilities, it would certainly be an advantage to be able to shoot ~16MP DX images while still having usable ISO3200-6400+ (which I certainly don't have on my D300).

I assume there are more complicated physics at hand that don't allow this to happen though.

-Alex Rosen
www.flickr.com/photos/klrbee25/

Visit my Nikonians gallery.

The image and ISO quality are the same.
What you are doing is cropping in camera instead of post process.
I can think of only three advantages:
Smaller file size, slightly faster frame rate, and being able to use only the sweet spot of a lens.

Visit my Nikonians gallery.

I agree with your points Roger.

But this made me think of a question.

If I take a perfectly framed shot in DX at 15MP and the same shot in FX, with the same FOV as the DX, and then dowmsample both to an 8x10 image size, would there be more,less or the same downsample advantage regarding noise clean-up to both pix?

Seems to me there would be no difference, since the pixel density is the same in both modes... as long as the downsampling advantage applies to the surrounding pixels.

Thoughts...?

Dan

"My most rewarding photos are those that capture something I didn't 'see' in the frame....so just SHOOT."

Visit my Nikonians gallery.

Yes, if you down sample the larger megapixel image you would see very little, if any, difference in the image quality.

On the other hand if you are making larger prints and you need to up sample either or both images to get you final print size then the image with more megapixels (full FX frame) will look cleaner then the lower megapixel (DX frame) image.

Dave
Quad Cities, USA
A Nikonians Team Member
My Gallery
SummersPhotoGraphic.com

Nikonians membership -
"My most important photographic investment, after the camera"

Share, Learn and Inspire

Essentially IQ and noise are the same but...

An image shot (at high ISO) using the full frame printed at 16 x 24 will have less visible noise than an image shot in DX crop mode (or cropped in post-production) because you are enlarging the DX crop image more to get your final print size.

Cropping in-camera or in post will usually cause noise to be more visible particularly when makeing in larger prints.

Dave
Quad Cities, USA
A Nikonians Team Member
My Gallery
SummersPhotoGraphic.com

Nikonians membership -
"My most important photographic investment, after the camera"

Share, Learn and Inspire

> Essentially IQ and noise are the same but...
>
> An image shot (at high ISO) using the full frame printed at
>16 x 24 will have less visible noise than an image shot
>in DX crop mode (or cropped in post-production) because you
>are enlarging the DX crop image more to get your final print
>size.
>
>Cropping in-camera or in post will usually cause noise to be
>more visible particularly when makeing in larger prints.
>

Great replies. Thanks guys. Essentially the noise characteristics are identical but you 'magnify' the noise when printing a lower res image the same size as a comparable higher resolution image.

So, noise levels would look the same at 100% on a computer but there would be more noticeable noise when printed? Interesting.

-Alex Rosen
www.flickr.com/photos/klrbee25/

Visit my Nikonians gallery.

I don't know if I would call the DX image a lower res image if that's what you meant. The DX image has the same pixel density (what I call resolution) in a smaller file size than the FX image has. It is just the center of the same sensor. But the FX image has 36mp in a larger file size. Dave's point above is (correct me if I am wrong Dave), if you upsample the DX image size @ 15mp to say a 24x36 print size you are spreading out 15mp to fill that 'print'. If you upsample the FX image size at 36mp to the same 24x36 'print' size you are spreading more pixels over the same 24x36 but they do not have to spread as much...so the FX upsample will be sharper.

Dan

"My most rewarding photos are those that capture something I didn't 'see' in the frame....so just SHOOT."

Visit my Nikonians gallery.

The various tests that have been done (DXOMark and Bill Claff, for example) suggest that in FX mode you would get a 2 stop improvement over the D300. In DX mode you would get about one stop. That is presumably about the same one stop improvement we would probably get from an updated D300, or any other DX camera that was introduced now (such as the D3200).

>> So, noise levels would look the same at 100% on a computer but there would be more noticeable noise when printed? Interesting.

Comparing D800 DX to FX, same composition, downsized to any similar output size for display on a monitor (such as 1000 pixels wide) you would see the same one stop improvement from FX. The principle is the same as the results from printing.

Oddly enough, the D800 would make for a very good wildlife camera used for deep cropping of high ISO images, which is the same problem as printing high ISO images very large. Not because it's a D800 and FX and 36 mpx but simply because it is new and has a richer feature set than, say, the D3200 . Of course, an FX pixel is a terrible thing to waste

_________________________________
Neil
Nikonians Team
My Gallery

>So, noise levels would look the same at 100% on a computer but
>there would be more noticeable noise when printed?
>Interesting.

That is basically the correct analysis, but I'd add "when printed at the same size."

Or, more generally, any output medium (monitor, print, or whatever) at the same output size gives the advantage to FX. Because at a common output size, you're magnifying the DX image 1.5x more, which accounts for the approx. 1-stop magnification of noise (viewing both 100% on screen, the output size of the FX image is 1.5x taller and 1.5x wider than the DX, which negates the FX advantage).
You can see this with any camera - print a pic, then crop a section out and print the crop the same size as the original pic. As you'd expect, the crop will be more grainy and show less detail.

Larry - a Bay Area Nikonian
My Nikonians gallery

www.tempered-light.com

This was a good read a little while ago, D800 downsampled vs D3s and D800 in DX vs D7000

http://nikonrumors.com/2012/04/10/nikon-d800-vs-d3s-and-d7000-comparison-by-cary-jordan.aspx/

The D800 looks to be a good camera as long as people realize that at higher iso's, print size will need to be smaller(down-sampling). I can't wait to get my D800E whenever Amazon gets them.... (Have had on pre-order from Feb. 6th)

Chris

Visit my Nikonians gallery.