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The Beginner Photographer’s Guide to Understanding Resolution

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resolution1 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials

It happens to everyone, and it makes us all crazy. You spend months honing your skill, shooting in manual, perfecting light, diligent editing and finally having an image you want to print HUGE for your living room…and then it arrives all blurry and you are crying in the floor. Oh, that was just me? Huh, well, moving on…

Through the graces of a wonderful human being and local printer who took pity on me and my obvious lack of knowledge, I was given a sit down course in making the transition from camera to print and it simplified my life greatly. No more worrying about cropping images before loading into ROES. Yes, you heard me correctly. So, how does that work? By understand the relationship between PPI, DPI and somehow…PSI.

1. Forget DPI for now.

This is for printers. Dots Per Inch. Of color of ink. This does not correlate directly to your photo resolution when cropping and resizing.

2. PSI…think of this as a typo…

PSI has nothing to do with photographs. PSI is actually a measurement of pressure, used for the air in your tires for example. Somewhere along the line, photographers started using PSI to mean *Pixels per Square Inch.*  Think of PSI as a way to confuse newbie photographers. Just don’t use it.

3. PPI. Pixels Per Inch.

This is what you are looking at when resizing and cropping your photos. Here’s the thing, looking ONLY at the PPI will CONFUSE you. Why? Because in most cases, your camera is taking a large image size at a lower PPI. For example…  21inx14in @ 240ppi OR 72inx48in @ 72ppiBoth these sizes, though they have very different PPIs, are high resolution images. In fact…they are nearly identical…wanna see?

Look at the top two numbers for the first image size, 21inx14in @ 240ppi…

pixels1 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials

 

Now for the second set, 72inx48in @ 72ppi…

pixels2 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials

 

The results:

Uhm, wait a minute…they are EXACTLY the same size!!! 5184×3456. Meaning they have the exact number of pixels in both images, despite their obvious size and PPI differences.

  • Both will produce high quality images.
  • There is no reason to resize these images before loading into ROES to place orders.
  • When you load these high res images, ROES will then allow you to crop, tilt, rotate, etc. and still maintain the high resolution you are after.
  • If an image needs a stretched background, some cloning to straighten, those sorts of things, you may need to make those adjustments ahead of time.

Lesson:

You run into problems with resolution when you try to increase BOTH size and ppi at the same time. For example, taking an 8×10 @ 72ppi to a 20×30 @ 300ppi…is not going to work, but when going DOWN in size, you have much more leeway.To get a visual image of how this is works…think of it like this. You have 3 squares in front of you. Large, medium and small. In the medium square, you have 16 Lego bricks (don’t tell the children I played with their toys, then they want to play with mine!), your pixels, lined up in rows and they fill the square perfectly.IMG_1128 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials Now, you can take these bricks and still fill the small square perfectly. There are even bricks to spare, but this smaller square is still nicely packed tight with bricks.IMG_1129 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials But, if you take those same 16 bricks and try to fill the large square, you are going to have more space between them, more blank space showing through.

IMG_1130 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials

Printing problems:

This is where your printing problems come in. As you try to use these same number of pixels to fill a large surface area, you are left with gaps. In order to fill those gaps, your computer is going pull from surrounding pixels sort of *guessing* what is needed to fill it up. This is where it starts to get *fuzzy* and not print well.

Okay now you are thinking…”so what does this mean when I crop and resize?” 

  • If I am taking an image that is the aforementioned 72×48 @ 72ppi, I can easily resize to a nice print that is 20×24 or other large size at 300ppi. Why? Because I am going down in physical size which allows me to use those extra pixels to fill up the resolution to 300ppi.
  • But again, I do NOT have to do this before I load to ROES. If I take my full size high res images, edit and save them just the way they came out of my camera (assuming I am taking RAW or high res JPEGS) I can simply load them into ROES and use their tools to do my cropping. The resizing will be done on the other end from my large file.
  • But their Q&A section says to resize to 300, right? Yea, I know… they say that because it is a frequently asked question, and they are answering based on the idea that you are going to do your own *pre-cropping,* in which case, they want you to do it at the right resolution. But if you just load it up and use their tools, all will be fine.

So now that you understand that, you find you have a slightly different problem…a client ordered a photo in different sizes, and while the small wallets look great, the desk print is slightly blurry and the wall print just looks bad.

  • This is normally more of an issue with your photo itself. It was probably slightly out of focus to begin with. But why do the smaller ones look okay?

Back to our squares…and now, that DPI I told you to forget temporarily. When printing, bigger isn’t always better. Sometimes you can get away with passing off a slightly not-so-perfect image off in a smaller size because smaller again means packing tighter. Now that we have moved over to the print side, we are looking at dots…as in dots per inch. ( Now this technically has to do with both DPI and PPI, but for the purposes of illustrating what’s happening, we are going with the dots).

With our squares again, we see what the image as an 8×10 looks like…

IMG_1131 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials
Now, if I go DOWN in size, I can almost make it look better overlapping those areas that were previously gaps….

IMG_1132 The Beginner Photographer's Guide to Understanding Resolution Guest Bloggers Photography Tips Photoshop Tips & Tutorials

So my wallet size actually ends up looking better, even though it is technically the exact same photo. And then when I take that *so-so* photo and go bigger…well….let’s not do that okay? It doesn’t end well.

{This is where I insert my disclaimer: Yes, those who have more in depth understanding of resolution and printing know this isn’t *exactly* how it all works, but for the purposes of helping beginner photogs understand what is happening to their photos, these visualizations work}

In the end if you have your camera set to take high res files, RAW or JPEG set to large file format…you are going to be just fine, no adjustment needed before loading to ROES, or even online consumer sites. If you MUST make adjustments, just be sure when you are done, your pixel dimensions, those numbers in the screenshots above, are in the THOUSANDS for good images, preferably the 5000×3000 range.

Kimberly Earl is the owner of K. Lynn Photography in Charleston, WV, a wife and mom to four kiddos. She has been snapping at the world since 1993 and been in business since 2007. You can follow her on Facebook, but she is currently on a short hiatus.

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  1. carri on October 16, 2013 at 10:22 am

    how do i know if my camera is metering off of spot or focus points? I have canon 60D?

  2. Amy on October 16, 2013 at 10:41 am

    Carri, Canons meter off the focus point in evaluative metering mode only. If you are in any other mode, it is metering off a portion of the viewfinder. In spot metering, it is using the circle in the center of your viewfinder as the metering area.

  3. Nancy on October 16, 2013 at 4:18 pm

    Thank you so much for this post, and the previous one too!! It explains so much to me, things I have struggled with, and have never understood. I would use spot metering, and assumed my Canon followed the focus point, and I would have horrible results. Finally, I get it! Thanks!!

  4. Kara Spillman on October 17, 2013 at 9:35 am

    Thank you for all of the information you post – it is so helpful! I have a Nikon D5000 and I have my AE Lock button assigned for focus. If I it is set up this way then I presume locking the exposure won’t work, is that correct?

    • Amy on October 17, 2013 at 9:55 pm

      Hi Kara. I don’t shoot Nikon and am not 100% familiar with them. If you see my answer to Rachel below re. her Canon, I know that some Canons like mine have AF and AE lock on separate back buttons but others do not. As I advised her, I would check your camera manual to see how you would work this. It may be able to be assigned via a custom function.

  5. Samantha on October 17, 2013 at 1:49 pm

    Hi! I currently have a Canon Rebel T3 but plan on upgrading soon. I have been struggling with the AE lock button. From articles that I’ve read, it looks like you should be able to use AE lock when in manual. But mine doesn’t. I even took it to the camera shop and the owner said I had to be in P, AV or TV mode. Is this just my camera or can you use the AE lock in manual on other cameras? Also, my camera has partial metering mode instead of spot. (When in one of the acceptable modes instead of manual) Does the camera use the center area for metering even if one of the outer AF points are selected? I ask because if my center AF is selected to meter, then I hit AE lock and try to change the AF point, I lose the AE lock. The AE lock in manual and understanding the partial metering without using the center AF point for my subject has really been tripping me up. Any help would be greatly and sincerely appreciated!!!! Thank you!

    • Amy on October 19, 2013 at 5:26 pm

      HI Samantha, the answers to most of your questions are in this blog post and the previous one about metering. You can NOT use AE lock in manual mode. You can only use it in P, Av, and Tv. There is no need for AE lock in manual mode, because when you are in manual, you can meter, set your settings, and then recompose and your settings will not change. If you are in P, Av, or Tv, if you meter, your settings will change when you recompose because you are not in control of all of them but if you use AE lock, it will lock your settings. Metering is not connected to the focus point on Canon cameras except in evaluative metering. If you are using spot metering (or partial, as your camera doesn’t have spot metering; partial metering is the same idea but the area of the viewfinder that meters is larger than with spot metering), you are metering off a percentage of the center of the viewfinder (NOT the center focus point). I am able to change my focus point after I use AE lock, but I know some Canons have only one button on the back rather than two, and the one button is AE lock and also activates the selection of focus points, so it probably makes sense for you to choose your focus point FIRST, spot/partil meter, then recompose, focus, and shoot. Again I would recommend re-reading this article and the previous one about metering because it does contain the answers to most of your questions (and maybe some answers to some questions you didn’t even know you had, ha ha!)

  6. rachel on October 17, 2013 at 5:14 pm

    How does AE Lock work if you are using back button focusing? So that button is now assigned a different task. I think I can make my shutter release the AE lock, but it seems like once you set your exposure and lock it, the back button focus doesn’t work while you are holding the AElock/shutter button.

    • Amy on October 17, 2013 at 9:52 pm

      On the Canon cameras I have, the AE lock and back button focus are on two different buttons, though I know this is not the case on all Canons. On the cameras I have, if I can use AE lock on one button to lock the exposure then use the (other) back button to focus. If you do happen to have one of the Canons where both are on the same button, I would consult your camera’s manual to see how you can configure these options.

  7. Bailey on October 26, 2013 at 10:34 am

    Thanks for this great post. I use Nikon which has the option for the AE button to also be AF. Are you familiar with this and would you use it? I have been trying to transition to using back button focusing, so I wouldn’t be able to use it as AE and get correct focus and exposure if I understand it correctly. Is that true?

  8. Amy on November 7, 2013 at 1:41 pm

    Hi Bailey, if your camera has just one button that can be assigned to both AE-Lock and autofocus, you would need to check your camera manual to determine if there is a way to use both functions on that button, or maybe someone who has a camera like yours can chime in. In my case, I can assign the functions to different buttons on the back so I am not super familiar with how it works with one button.

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