The two most significant factors in the optical look of a lens would be focal length and depth of field (aka how the lens focuses). We’re going to look at what those two terms mean and how we can accurately replicate those effects in our digital art to create a deceivingly ‘photo-real’ look.

 

We're going to get quite technical here, so I'd highly recommend watching the above video - it'll make the most sense! However, for our 'learning by reading' viewers, you can find the most essential info below:

 

Let's start with the essential theory.

 

All About Focal Length

Focal length is the most basic description of the lens–it determines a lens’:

• field of view (FOV)

• and thus, its distortion

• and the amount of compression that it will render.

It’s expressed in mm. The smaller the number (such as 14mm), the wider the FOV and the more extreme the distortion. A fish eye lens, for example, is usually around 6mm, which is why it has an extremely wide FOV and a lot of distortion. However, as we increase the number, going from 35mm, to 85mm, to 150mm etc., the image will become more telephoto, having a narrower FOV and looking more magnified.

 

Wide lenses will distort in a convex way, creating a barrelling effect, whereas telephoto lenses will ‘squeeze’ the image to create a pincushion effect. The 6mm fisheye lens example below really demonstrates this ‘barrelling’ look.

You’ll see in the fisheye example that not only are the lines curving in a convex way, but they are also seeming to protrude towards us in a 3D sense, especially when they are close to the camera. This is because wide lenses increase the distance between objects, making the background seem further away than it is in real life. That’s why your phone makes your forehead look really big and your landscape photos look really small and underwhelming; things that are close become closer and things that are far become further.

In the opposite way, you’ll find as you increase in focal length and become more telephoto that the image looks more ‘compressed’. Things that are close become a little further and things that are further become magnified - the image feels more 2D. Take a look at the comparison above between a super wide 6mm fisheye lens, and a much more telephoto 75mm lens.

The way that wide angle lenses distort and increase the distance in the photo means that they an be great for creating a sense of scale or for creating dramatic, intense or comedic feelings.

 

Conversely, telephoto lenses are more flattering for portraits because they don’t give you big foreheads and noses (aha), and their pincushion effect can slim as well. FYI, if you’re looking to create a natural image with a normal amount of distortion, 35mm-50mm is generally believed to be the closest match to the human eye.

 

Which one looks more dramatic to you?

We've got a few tools up our sleeves when it comes to creating these effects in Clip Studio Paint.

 

With the new fisheye ruler included in Version 2, it's easy to create dramatic wide-angle looks, but don't forget to pair this with the Perspective function in the 3D Object tool to get even more out of the effect.

 

 

Here's me using it to match the perspective of the table with a 14mm and a 75mm reference photo.

You can also use the Liquify tool to create more fine-tuned adjustments–specifically the Expand function for barrelling and the Pinch function for pincushioning. Just don't forget to magnify or reduce the background to follow suite.

 

Now let’s talk about Depth of Field

Depth of Field (DOF for short) is how in focus the foreground and background are in focus when something is in focus (usually the subject).

 

A deep depth of field is generally when the subject and the background are relatively in focus, whereas a shallow depth of field will mean only the subject will be in focus with the background and foreground out of focus.

 

With a very shallow depth of field, only a small section of the image will be in focus. Overall, depth of field is really just about how lenses focus.

 

Depth of field is about how much of the image over a distance is in focus but is also relative to how close the subject is to the camera, with closer subjects producing more defocused backgrounds.

 

There’s also a relationship between focal length and depth of field: the longer the lens, generally the shallower the depth of field, whereas wide angle lenses will have a deeper depth of field. So when you’re doing your fisheye scenes, remember that meaningful depth of field ONLY occurs in wide lenses when the subject is CLOSE, like in your face close.

But the focus doesn’t just cut off and then the background is blurry, there is a transition, a graduation from in focus to out of focus and this is known as focus falloff - the focus, falls off. With a shallow depth of field, you’ll find that parts of the subject that are further away will begin to blur into the background, not completely out of focus but not in focus either.

 

And just like with your eyes, anything very close to the camera will become so defocused that it becomes ‘translucent’. You can see this effect in the example below - the flowers right in the foreground have a lowered opacity effect. Only what is bang on that narrow 10cm mark is in focus, and you can see that because the flower’s stem is further away from us, even that is not in focus.

Since depth of field inherently involves 3D space, it is a great way to add dimension and texture to your art.

 

Here's a link to a great DOF simulator that you can use to visualise depth of field vs focal length: https://dofsimulator.net/en/

So when it came to applying these concepts to create a realistic photographic focus in my painting, I used a variety of tools and techniques:

 

• The Blur and Blend tool.

• The Airbrush tool (on low opacity for the most part.)

• The Soft Eraser tool ((on low opacity for the most part.)

• Gaussian Blur.

• And the Tone Curve to bring in more contrast to help the image retain sharpness while still having blur.

 

 

Since the background is so out of focus you only need to worry about values and hue, so just blob in the colours and blend them together. I’m using a watercolour-style blush but you do you. Once you’ve got it in a good place go to Filter>Blur>Gaussian Blur and defocus the background. If you need to make any touchups after this effect has been done, you can use the Airbrush tool.

 

For objects in the far middleground, like the branches of tree, just paint out the form, with the middle of the shapes darker to help create that focus falloff effect. You want the edges of the brush to have a lower opacity which will help that effect along. Apply Gaussian Blur again to a lesser degree, and then use the Blur tool and Soft Eraser to ‘defocus’ the parts of the branches which are further away.

 

You can also use the G pen on a very low opacity to "ghost in" those edges.

 

For any section that is semi out-of-focus, you can also use the G pen on a very low opacity to create a kind of bokeh effect by overlapping dots to create a 'blobbed' look.

 

To create a focal falloff effect, pay attention to what is close to the camera and what is further away, and the adjust the strength of the Gaussian Blur accordingly. Use Airbrush and Soft Eraser to finish off the effect of it blending into the background.

Continue these techniques for the rest of the subjects in the painting - and then we're done!

 

If at any point you feel that the painting lacks definition, you can use the Tone Curve tool (Edit > Tonal Correction > Tone Curve) to introduce more contrast while maintaining the defocused effect you have established. This is actually how lenses work in real life - many of them will have coatings on the glass elements that deepen the blacks to help them look sharp but also smooth and buttery (aka the focussing).

 

I'd highly recommend practicing these techniques with a reference image so that you can wrap your head around these concepts before jumping into a work off imagination.

 

 

I'm always happy to answer questions, so if there is anything you'd like me to elaborate on, comment down below!

 

Thanks for reading! :))