Irix lens depth of field and hyperfocal scales

Hyperfocal Distance, the DOF Scale and the Hyperfocal Scale

How Irix Makes it Easy to Maximize Sharpness in Your Images

One of the least understood terms among amateur photographers is “hyperfocal distance”. That’s unfortunate, because it’s one of the most important terms to know if you want to maximize the sharpness of photos with a lot of depth, such as landscape shots. This distance becomes very important for photos in which you want objects in the foreground in focus as well objects in the distance.

One of the reasons that many don’t bother with learning to find the hyperfocal distance in a scene is the fact that the calculations for it are based on a complex formula. Fortunately, there are tools that can be used to find it quickly and easily, so you don’t have to be a rocket scientist to use it. Before we go into that, however, you should understand what it is and why it’s important.

Hyperfocal distance is a term used to describe the closest point to the focal plane of a camera that will be acceptably sharp when a lens is focused at infinity.

“Hyper what?”

Hyperfocal distance is a term used to describe the closest point to the focal plane of a camera that will be acceptably sharp when a lens is focused at infinity. Put simply, setting your focus at that distance can help maximize the overall, “front to back” sharpness. Here’s the problem: the distance varies according to the focal length of the lens and the size of the aperture, so it’s not easy to know exactly where that point is. There are a few solutions, though and some are surprisingly simple.

Hyperfocal Distance Charts and Calculators

Other than doing the math yourself, which can cost you enough time to miss the shot, using one of the many charts or calculators available is probably the most accurate way to find the hyperfocal distance in a given situation. These are available as printed cards, website applications and smartphone apps.

The Depth of Field (DOF) Scale

High-end camera lenses often incorporate depth of field scales that can be used to quickly estimate the approximate range at which an image will be in focus at a various apertures for that lens. The photo below shows the DOF scale on the Irix 15mm f2.4 Blackstone lens.

Note the numbers increasing in opposite directions from the center mark, which indicates the center of focus for the focusing scale above it. These numbers represent the f-numbers for aperture settings. When you focus the lens, these numbers will indicate the approximate range of focus for the shot at those aperture settings. For instance, note that in this photo the focus is set at about 8ft (2.4m). Now look at the number 16 on either side of the DOF scale.

You’ll see that the number 16 on the left aligns with about 3.2ft (1m) and the right one is past the infinity mark. This means that at f/16 and at this focus setting, objects in the photo should be in focus from about 3.2ft away to beyond infinity. Objects that fall within this range should, theoretically, be acceptably sharp. Now look at f/11 on the scale and you’ll see that objects should be in focus from about 4ft away to almost infinity. That’s how this scale scale helps you determine the approximate depth of field in your photos. That’s convenient, don’t you think?

What’s even more convenient is that you can also use the same scale to quickly set your focus at the hyperfocal distance for a given aperture. Here’s an example: Take a look at the photo above. With the focus set at infinity, we see that the closest point that will be in focus (the hyperfocal distance) is about 5.8ft or 1.8m. Now, let’s move that infinity mark to the f/16 mark on the right side of the DOF scale as in the photo below:

As you can see, the correct hyperfocal distance on both the ft and m scales is now aligned with the focusing mark. Try this same experiment with the marks for f/11 and f/8 and you’ll find that it works consistently every time. Pretty handy, huh?

I don’t even have to focus visually!

The Hyperfocal Scale

Irix has made that process even simpler with their hyperfocal scale. Looking again at the photo above, you can see how by just lining up the appropriate f-number on this scale with the focusing mark, you also line up the approximate hyperfocal distance for that aperture size. So, in the example above, if I shoot at f/16 and want to maximize the depth of field in a landscape shot, I can simply line up 16 on the hyperfocal scale with the focusing mark, frame the shot and shoot. I don’t even have to focus visually! It doesn’t get much easier than that! To the best of my knowledge, Irix is the only manufacturer currently including this scale on their lenses.

Learning More

Of course, there’s much more to achieving maximum sharpness in your photos, and focusing at the hyperfocal distance isn’t always going to be the optimum choice. It’s simply a tool to help you achieve a particular result. Like all photographic tools, your creativity will dictate when and when not to use it. In those instances that you do use it, using the hyperfocal scale will help you do so quickly and effectively.

Written by Dana Crandell


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  1. I understand hyperfocus (I have always called it “extended depth of field” – but why is the lens made in a way that you can focus past infinity? Where is the value in that? (I have had my lens for two days now, and love its handling and feel, and the way it clicks at infinity as a safeguard.)

    • Hi, Kirk. Thanks for your comments and your question. The ability to focus past infinity is common to almost all high-end lenses. The purpose, in general is to be able to fine-tune the focus in case the infinity mark isn’t precisely accurate.

  2. I’m trying to understand how this lens relates to the standard depth of field equations, as it looks like it doesn’t.

    I’ve used several DoF calculators, with and without difraction being accounted for, and my own equations.

    Could you please explain what assumptions you have made regarding the CoC when calculating your DoF scales.

    Also, it appears on a Canon your lens doesn’t report distance. This is a pity.



    • Hi Garry. Thanks for your comment and my apologies for the late reply – it seems this comment was lost in the shuffle for a while. In regard to the depth of field scale, I’ll certainly see what I can find out from our engineering department and I’ll do some testing on my own as well. My initial thought would be that it might have something to do with the lens corrections required for rectilinear projection. As for reporting distance, I’m assuming you’re referring to focus distance in the EXIF data. Since the lenses are manual focus, the necessary electronic connections for this simply don’t exist.

  3. Hi, i’ve read some forums that they can’t reach the infinity with the lens. Now i have the same issue with mine, i work with a crop and i’m aware of the +1stop. Do you recomend anything but to change the focusring adjustment?

    • Hi Tom,
      Thanks for contacting us. You didn’t mention where you purchased the lens or how long you’ve had it. As you probably already know, it’s also possible to calibrate the lens yourself. If the lens was purchased from an authorized US dealer, you can send it in for repair or replacement. If this is a problem that has just occurred after using the lens for some time, I would recommend the latter option. Please contact for details.

    • Hello, JJ. A very good point, and thank you for bringing it up. Your assumption is correct and it’s probably time to update this article. Generally speaking, the numbers for an APS-C camera would need to be multiplied by 1.5 or 1.6, depending on the make of the camera. Since Irix lenses technically are manufactured for full-frame cameras, the markings would not be accurate on a crop sensor camera.

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