image quality issues FX vs DX image area on D800

[fhmillard]

<p>for example, should i expect the same image quality from my 28 mm 1.8 G on D800 in FX image area as in DX image area? OR, is DX image area really just a "cut out" of the FX sensor?</p>

[dan_brown4]

<p>Exact same pixels, exact same image quality. It's just a question of how many pixels are cropped off. Just like cropping an image during post processing.</p>

[ShunCheung]

<p>Right, the DX mode on an FX body such as the D800 is merely a crop at the time of capture, and the area of the crop is fixed to approximately 24x16mm in the center of the 36x24mm FX frame.</p>

<p>In most situations, you are much better off cropping in post processing to maximize your flexibility, e.g. you can crop to an area larger than 24x16mm on the sensor, you can move the crop away from the center .... However, there are a couple of exceptions:</p>

<ul>

<li>The DX crop mode will give you a smaller image file. If your memory card is low in space, you may prefer those smaller files.</li>

<li>In some configurations, the DX crop mode can give you a faster frame rate.</li>

</ul>

[lwg]

<p>As you say the DX is just "cut out" from the full FX sensor. So it's the same image quality, but to make the same sized print you will be using fewer pixels, so a 16x24 from the DX portion will have noticeably lower sharpness than the same sized print made from the full FX sensor.</p>

<p>Set the camera to DX mode and you can see the cropping in the viewfinder. If you also turn off the AF Point Illumination (A5) it will shade the outside area to make it clearer what is included in the image.</p>

[fhmillard]

<p>thank you all, that had to be the case,since all the pixels lined up in both modes , as 28 mm and "virtual" 42mm.</p>