Meaning of 1:1

OK, I'm going to ask a real newbie question. When you open a photo in LR5, and increase magnification to 1:1, what does that mean, exactly. If I were to print the 1:1 photo, what size would that resulting print be?

1:1 means pixel to pixel. Each pixel of your image occupies a pixel on your monitor.

Printing is a little different. Usually you go for 150 to 300 pixels per inch (PPI) to print. so you take the overall dimensions of the file and divide by the PPI to see what size the print would be.

Of course you can manipulate the image in software to change it's pixel dimensions so much larger is possible.

As said above, 1:1 (aka 100% in some software) means pixel to pixel rendition and is only related to viewing on the monitor. (In printing, other parameters come in to complicate matters).

1:1 magnification is used often, because it displays the most faithful rendition of what the camera created, since there is no resizing to distort that view.

You must be aware that when you view an image of 5760 pixels on the long side on a monitor with 1280 pixels on the long side (a 5D3 image on my 17" monitor) at 1:1, you are viewing a section of an image, that's 4.5x wider than your monitor screen. That's pretty close scrutiny.

Eddie, do you "get" what's being said?

Granted, to "newbies" this can be a bit confusing at first, but then it works out to be not that complicated!

tonylong wrote in post #16527229
Eddie, do you "get" what's being said?

Granted, to "newbies" this can be a bit confusing at first, but then it works out to be not that complicated!

What I "get" is that there really is no correlation between 1:1 magnification and the size that a photo is printed. Correct?

Be aware of 1:1 in the crop module, that will crop your image into a square like 6x6 medium format ir the likes of instagram. Then there's other terms in photography that use 1:1 also, like Lightning ratios and macro magnification,etc...

I would have thought for printing 1:1 would mean the object is printed so it is the same size in print as it is in 'real life'. Sort of like a 1:1 macro is when the object size on the sensor is the same as in 'real life'.

I've never really heard it used for printing though - only for macro and perhaps monitor display, although that is usually called a '100% crop' - but I don't use LR, so I guess they use 1:1 rather than 100%.

eddieb1 wrote in post #16528159
What I "get" is that there really is no correlation between 1:1 magnification and the size that a photo is printed. Correct?

Correct.

They are two different "pipelines" or more literally two different cables and what goes down them is data that can be very different, not only in terms of image size but also the color data can (and should) be different, because the way liquid crystals render colors is different from ink on paper.

eddieb1 wrote in post #16528159
What I "get" is that there really is no correlation between 1:1 magnification and the size that a photo is printed. Correct?

Yeah, a 1:1 or 100% view/magnification relates to viewing on your screen. Most modern monitors have a resolution of "about" 100 pixels per inch, and so that's what you see when you view an image at 1:1, you see around 100x100 pixels for each square inch. Given the high resolution of our modern cameras, if you plot out an image at that viewing resolution, you get a very large image! That's why here you see people asking for a "100% crop" when discussing things like fine detail and image noise and such: you can't post a full-size image here at 1:1!

For printing, like you said, talking about "1:1" or "100%" isn't a practical consideration. Sure, for a large print you may print at, say, 100 pixels per inch, and in that case, it would look pretty much like if you viewed it at 1:1/100% -- that can be a consideration when viewing preparing to print, although most of the time we will print at other resolutions, typically higher resolutions!

Nope. No connection. 1:1 in macro means that the image on the sensor is the same size as the object in real life. It has no connection to the number of pixels. 1:1 in editing, as several people said, means enlarging the image so that one pixel in the image maps to one pixel in the display. It is essentially like putting a film negative under a magnifying glass so that you can see individual grains.

paddler4 wrote in post #16529915
Nope. No connection. 1:1 in macro means that the image on the sensor is the same size as the object in real life. It has no connection to the number of pixels. 1:1 in editing, as several people said, means enlarging the image so that one pixel in the image maps to one pixel in the display. It is essentially like putting a film negative under a magnifying glass so that you can see individual grains.

Ah, and Macro brings in a whole different subject!

This is because macro lenses have a different set of "specs" that have nothing to do with how you view or print images!

For example, a "true" Macro lens that will shoot a "1:1" image will capture a subject in which it will be "fully framed" at its actual size on the sensor. It's a "special scenario", but it can be special indeed for those of us who love macro shooting! But it's more about the lens, not about how we view the photos!