Monitor View at What Size?

I am enlarging an image to 48" and have a 24" monitor. At what size should I view the image to see how the sharpening looks?

If I can see the whole image at 12% at what percent would I be able to see the sharpening results at full size? When I make it 100% the view is way bigger than the printed image would be.

It would depend on what PPI you are using for the print.

I use 360 PPI which is, I think, the native resolution of my printer.

And you monitor is approximately 90ppi so that would mean 90/360 or 25% would be a decent approximation of on screen size compared to print size.

Viewing at 50% gives a good representation of sharpening on the finished print. I generally will view at 25% and 50% and make a judgement of sharpening based on the what I see in both views, 50% will show up sharpening aliasing and other defects better than a 25% view. I just use ctrl + and Ctrl- to toggle from 25 - 50% views and back again.

What I generally do is adjust the sharpening when looking at a portion of the image at 50%, scroll around the whole image to preview what the USM has done to various parts of the image, fine tune the USM, then view at 25% and scroll around again. I tend to make look very slightly oversharpened at 50% as the image will soften a little when printed. More often than not I will seletively sharpen, applying no sharpening to very dark areas, skies etc where noise will potentially be an issue and where there is no detail to sharpen.

You definitely want to be at a whole number magnification either 25 or 50% as other values give you aliasing problems in PS.

Thanks, Chris, much appreciated!