Is it possible to shoot in RAW-only mode yet choose to capture an image file lower in resolution than the full 36MP? It isn't clear to me from reading the manual whether one can choose a lower-resolution mode or if this is only available by choosing DX mode or only available in non-DX mode by shooting JPEGs only. Thanks for any help.
From what I under stand, the only way to get smaller res is either shoot in jpeg modes or in one of the crop modes.... otherwise you can shoot in lossless RAW and files are around 40-45mb vs. 70-75mb....
Not in the camera, but you can convert NEFs to a DNG format on your computer and alter the dimensions of the image downward. The resulting file will be a linear DNG (a bit different as it's been demosaiced), but you'll have the normal editing options you expect with a raw file (white balance, tonal changes, sharpening, color profile, etc.). I've tried it, and it's a viable option if you need smaller file sizes and don't plan to make large prints from certain images. This option works best with Adobe workflows and doesn't work at all with Nikon software.
In addition to what others have said, you can choose lossy compression. Doesn’t lossy compression reduce image quality? Absolutely, but much less than downsampling the image does. Downsampling reduces quality while cropping destroys content.
With my earlier DSLR, the D90, lossy compression was the only available option, yet in practice nobody noticed the quality loss because the effect is minimal. We are only talking about 2:1 to 4:1 compression, and it’s been shown over and over again that JPG images can often be compressed by about 10:1 without noticeable effects.
In #2 Rick mentions “lowering the image dimensions”. I’m not sure if this means cropping or downsampling, but either way, if the image is converted to DNG, it’s not editable with Nikon software (without further conversion to TIF or JPG). Choosing lossy compression has the benefit that the raw files are editable in any software that reads NEF files.