Question on Image Size affect on sensor (Page 2): Yes, I would generally say that, if the sensor size was the same. For example, the D800 can shoot jpeg medium size, which is about...

amehta Loc: Boston

photon56 wrote:

So, from what you're saying, using 6mp on a 24mp camera could look worse than a 6mp photo taken on a 6mp camera.

Yes, I would generally say that, if the sensor size was the same. For example, the D800 can shoot jpeg medium size, which is about 20mp, and the Df jpeg large is 16mp, but I believe the full image from the Df would be better.

amehta Loc: Boston

Gene51 wrote:

You must have special Nikons. The manual is quite clear - the cropped modes are not downsampled, they use the center of the sensor. It is not a full-sensor image that processed to a smaller size.

This is explained on pages 80-82 in the D800 manual. Also, when you use crop modes af sensors fill more of the image, so in the smallest crop mode, the entire area is filled with sensors. This would not be possible if the image was downsampled.

Nikon FX bodies have both crop modes and downsample modes. Keep going in the D800 manual to page 87. This is the "Large / Medium / Small" setting, turn the front sub-command dial while pressing the QUAL button instead of the main command dial on the back.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

amehta wrote:

Nikon FX bodies have both crop modes and downsample modes. Keep going in the D800 manual to page 87. This is the "Large / Medium / Small" setting, turn the front sub-command dial while pressing the QUAL button instead of the main command dial on the back.

The quality option on my D800 (and D700 before it, and D300 before that) is cemented on the raw position. That's why I never saw the jpg/tif image size option. Though it may not be binning, because of that odd 20 mp size, it must be some sort of averaging or other downsampling. I have not come across anything that indicates using a smaller file size option increases signal to noise.

amehta Loc: Boston

Gene51 wrote:

The quality option on my D800 (and D700 before it, and D300 before that) is cemented on the raw position. That's why I never saw the jpg/tif image size option. Though it may not be binning, because of that odd 20 mp size, it must be some sort of averaging or other downsampling. I have not come across anything that indicates using a smaller file size option increases signal to noise.

If someone is using the smaller file size, they are probably not worrying about signal to noise too much, since it will be displayed in a small format.

If it is doing some averaging, and I agree that the random pixel resolution numbers implies that, then I would still rather do it in software later. But it also answers the original question of whether pixels are turned off, they definitely are not.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

amehta wrote:

If someone is using the smaller file size, they are probably not worrying about signal to noise too much, since it will be displayed in a small format.

If it is doing some averaging, and I agree that the random pixel resolution numbers implies that, then I would still rather do it in software later. But it also answers the original question of whether pixels are turned off, they definitely are not.

I would hope someone is not trying to get 24x36 images from the 9mp size. :) That would be a tragedy.

amehta Loc: Boston

Gene51 wrote:

I would hope someone is not trying to get 24x36 images from the 9mp size. :) That would be a tragedy.

The NPS-police should immediately grab the D800 and hand the person a D40! :lol:

Trabor

photon56 wrote:

I am curious how the sensor works when I choose a smaller size. For instance, my camera is capable of shooting 24MP. If I set the size to 6MP (small), does the sensor turn off pixels or does it remove them during the save process to the memory card?

Hey this is a great question! I learned something about JPEG modes
The following is based on my D800 manual

1) Note the difference between quality (amount of JPEG Compression) and size (number of pixels)
2) In both cases it only applies if you want the camera to create a JPEG. RAW files are not affected
3) note that the different "sizes" are in an exact ratio of 3:2
So it is obvious that for example to create a "M" from a "L" one takes 9 pixels (row one column 1, row one column 2, row 1 col 3, row 2 column 1, row 2 column 2, row 3 col 3) and interpolates them, average or median or some other function to create a new pixel row 1 column 1 of the smaller size file

Since each new pixel interpolates 9 old pixels the noise will be significantly reduced (very complicated math here)
Note that no pixels are "thrown away" they are interpolated to create new pixels
3) Crop is something else again, in crop mode pixels not in the defined saved central region are thrown away

Note that for other ratios 2:1 for example as for your camera a similar algorithm applies, this works conveniently for simple whole numbers like 3:2 , 2:1 , 4:1

OOPS it is not clear how to handle the discontinuity between row 4 and 5 but it probably is not visible to the naked eye

dcampbell52 Loc: Clearwater Fl

Trabor wrote:

Hey this is a great question! I learned something ... (show quote)

Yes, the main reasons to use Raw and .jpg on each shot would be if you were going to upload the .jpg to some online service without modifying and also many pros do it at playoffs etc.. They will wirelessly upload the jpg to their ftp server in the arena (ESPN CNN and other pubs) so that the Editors back in the home office can get advanced looks at the images to start doing layouts then they have already planned for the raw files when they get them.

Shooting basic or normal jpg other than that would almost be a waste of the photographer's (and I use that term loosely) time.
It took me 3 years to finally convince my wife to STOP shooting .jpg. (Now, she has been on my other computer since 7:00 am this morning. it is now 2:30 pm, editing yesterday's shoot of our daughter, son-in-law and grand daughter's Easter. lol) I have created a monster.

dcampbell52 Loc: Clearwater Fl

Gene51 wrote:

Yes, in crop mode you only use the center of the s... (show quote)

By the way, here is a really good article on Raw and how cameras work with the file formats.

http://www.digitalphotopro.com/technique/camera-technique/exposing-for-raw.html#.U1Vrbm7D-70

Thanks