Today’s Question: Is viewing a file at 1:1 in Lightroom the same as viewing the same file at 100% in Photoshop? I have read, and heard, others say that most images don’t look sharp at 1:1 and should be viewed at 1:2 in Lightroom.
Tim’s Quick Answer: The “1:1” zoom setting in Lightroom is a 100% view, with each pixel in the image being represented by a single pixel on your monitor display. Just as in Photoshop, the 100% zoom setting is best for evaluating sharpness, though you may want to zoom in further to evaluate fine details (such as when checking for noise). It is important to keep in mind, however, that the most accurate preview for an image will be seen in the Develop module, not the other modules.
More Detail: The previews in Lightroom’s Develop module are created differently compared to the previews shown in the other modules, such as the Library module. In the Develop module the preview is based on a full rendering of the original image, while in the Library module the previews are based on JPEG renderings of your images.
At a 100% zoom setting the differences will be very subtle, but you can see some variations with close examination of the image when switching between the Develop and Library modules.
So, the Develop module should be used for all critical image evaluation. When evaluating sharpness, you should view the image with the 1:1 setting (100% zoom) so you are getting an “actual pixels” view, where one pixel in the image is represented by one pixel on the monitor display.
For evaluating noise and other fine details where you want to be able to see those small details better and aren’t as concerned about visible sharpness, I recommend using the 4:1 (400%) or higher zoom setting. And for evaluating the overall composition and framing, of course, I recommend zooming out to the Fit option, so you can see the entire image.