Cropping a Full Frame Image

Forgive me if this has been asked and answered. I have searched everywhere. Using Photoshop or Lightroom, I want to crop a full frame (36x24) image to the same dimensions of a DX (24x16) image. I know I can easily change the size of the image but that doesn't result in a crop. I want to compare the cropped image using the PS or LR to the same image using the D850's crop feature. Thanks for your help!

Just use the Resize Canvas command in the Image menu (Command-Option-C on a Mac). Then enter the pixel dimensions corresponding to a DX crop for your camera sensor.

I think 4x6 does the trick, at least if I remember my maths.

I don't remember how to directly crop it but I generally do this.

Create a new file with the pixel dimensions for the new format. Copy the entire original image then paste into the new file. Move the image to center it.

T

Forgive me if this has been asked and answered. I have searched everywhere. Using Photoshop or Lightroom, I want to crop a full frame (36x24) image to the same dimensions of a DX (24x16) image. I know I can easily change the size of the image but that doesn't result in a crop. I want to compare the cropped image using the PS or LR to the same image using the D850's crop feature. Thanks for your help!

 

They will be the same . . .

 

All you have to do is change the canvas size of the full frame image to the number of pixels in the camera's DX sized image and indicate that you want all four sides cropped (keep the center of the image).

 

This is pretty much what the camera does itself. Depending on HOW the camera does it, the metering and the color balance might be a little different between the two but I suspect that it will be subtle enough that you will rarely see it.

 

What are trying to look for?

Thanks to all. Just changed the canvas size as chulkim described above. Works great! Ed_farmer, I am comparing images using the 1.5 crop mode in the D850 to FX images cropped in Photoshop. Using different lenses and a 1.4 teleconverter. Trying to determine if one method of cropping results in sharper images than another.

When you are using the TC, the images taken with it will not be as good. When using either the camera or PS to crop, the images will be the same.

The easiest way to extract a "cropped" image is with the Rectangular Marquis tool. You can set it to a fixed size (e.g., 24x16 mm), move it to any part of the FF image you wish, copy (ctl-C) and paste (ctl-P) in a new image. When you create a new image, it defaults to the size of the image you just stored in the Clipboard. When you paste, it forms a new layer. You can keep the layers, or flatten them to save the results.

 

You can also draw a border on the original marquis and use the FF image to illustrate the difference between FX and DX. Et cetera.

 

You can also use the Crop or Canvas Size tools, but the Marquis tool is more flexible with regard to composition.