Here’s how to use the crop tool to zoom

I want to talk today about one tool, in Lightroom and Photoshop, that is probably used on nearly every image but is not used to it’s full potential – the Crop tool.

Now, I, like most of us I would imagine, use the crop tool to make minor adjustments to the image – maybe crop out an unwanted tree or post and straighten up the image.

But what if I told you that you can dramatically change the look and feel of your image and even use it to zoom?

OK, you won’t technically be zooming in optically, but you can zoom in digitally. And the maths behind it is quite incredible really.

Firstly, let us talk about the purpose of an image. It doesn’t matter if you are a professional photographer or an amateur, most of the images we take will have the same end point. The great cul-de-sac of Instagram (or other photo sharing site). And did you know that Instagram has an optimal image width of 1080 pixels. And the reason being is because most people will view it on their phone so it has no need to be bigger.

So 1080 pixels wide. Assuming you are using a 4×5 crop that means you will have an image with dimensions of 1080×1350 or 1080×1080 or 1080×864. So, in megapixel terms, the largest image you will need is 1.46MP!

What does that mean in reality? In the 2 examples below, I have cropped in from a full size file on a Canon 5d Mk IV which has an original image size of 6720×4480 (30.4MP). Before studying the images, please remember that these have been scaled down to 1080p wide so if you are looking on a computer, they may look slightly grainy/pixelated.

#gallery-1 {
margin: auto;
}
#gallery-1 .gallery-item {
float: left;
margin-top: 10px;
text-align: center;
width: 50%;
}
#gallery-1 img {
border: 2px solid #cfcfcf;
}
#gallery-1 .gallery-caption {
margin-left: 0;
}
/* see gallery_shortcode() in wp-includes/media.php */

#gallery-2 {
margin: auto;
}
#gallery-2 .gallery-item {
float: left;
margin-top: 10px;
text-align: center;
width: 50%;
}
#gallery-2 img {
border: 2px solid #cfcfcf;
}
#gallery-2 .gallery-caption {
margin-left: 0;
}
/* see gallery_shortcode() in wp-includes/media.php */

So as you can see, you can completely change the image and still retain perfectly sharp and clear images.

But, what if your intention is not Instagram, but a print or some wall art? Well, all we need to do is work backwards from our final product to see how far we can crop in.

The industry standard DPI (dots per inch) for printing is 300. So, if you are printing a 10×8” print, you will need 3000×2400 pixels. In fact, many print houses are more than happy to print at 200dpi. Which would mean 2000×1600 pixels for a 10×8 image

This would still give you plenty of room for cropping, though perhaps not quite as much as for Instagram. The following image was taken on a Sony A7R III which has a 42mp sensor.

#gallery-3 {
margin: auto;
}
#gallery-3 .gallery-item {
float: left;
margin-top: 10px;
text-align: center;
width: 33%;
}
#gallery-3 img {
border: 2px solid #cfcfcf;
}
#gallery-3 .gallery-caption {
margin-left: 0;
}
/* see gallery_shortcode() in wp-includes/media.php */

For the example of the Highland Coo above, I was running a photography workshop and only had a 70-200mm lens but I just felt that I had to capture this scene. I knew that when I took it it wouldn’t form part of my main portfolio, but would certainly work well for my Instagram feed. So all I had to do was get it sharp and in focus and I knew that the crop tool would do the rest.

But, what if you want to have the ability to print big? Well, this is where things get really interesting. Big prints are designed to be viewed from further away. In fact, if you think about where most of your big artwork is in your house, I would image it would be above sofas, tables, beds etc. This will automatically put you a meter or so away In fact, if you visit an art gallery, you will notice most people will view art from 1 metre or even further away. It is for this reason that if necessary, you can print your wall art at 150dpi. Of course the higher the DPI the better, that goes without saying, but you will get more than acceptable results at 150 or 200dpi.

So as a final example I have a picture of a castle. I want to print it at 30×20” to form the focal piece for my lounge wall. That means that ideally I want 9000×6000 pixels. Well… that probably isn’t going to happen for most of us. Yes, the Sony A7R IV and some other cameras could make it work at 300dpi but not most. So, we will just send it to the printers with the highest DPI possible.

But that sometimes means we don’t use the optimum crop. I want my image to look as good as possible and sometimes that will mean sacrificing a few hundred pixels but to me that is preferable. Remember, 150dpi will be fine for viewing from further away. This gives me double the amount of room to play with. So, if I know I can go to 150dpi I now only need 4500×3000 pixels – which the Sony A7R III/Canon 5D Mk IV can handle with room to spare.

#gallery-4 {
margin: auto;
}
#gallery-4 .gallery-item {
float: left;
margin-top: 10px;
text-align: center;
width: 50%;
}
#gallery-4 img {
border: 2px solid #cfcfcf;
}
#gallery-4 .gallery-caption {
margin-left: 0;
}
/* see gallery_shortcode() in wp-includes/media.php */

Of course, everything that I have written here will depend on your camera. If you are working on an older digital camera with, say, an 8mp limit then your ability to crop will be much less than working on a new, professional body.

But by being unafraid to crop your images and to not feel constrained by wanting to retain a 30mp image you will probably find that you will become more creative and produce better, more impactful images.

Thanks for reading.
Matt

About the Author

Matt Ward is a landscape, wedding, and portrait photographer based in Scotland. You can find out more about Matt on his website and follow his work on Instagram. This article was also published here and shared with permission.