Nikon D2x - Using Non-CPU Lenses
© Darrell Young
Nikon D2x Discussion Forums

When you've spent a lot of time with a certain camera or lens, you sort of develop a relationship with it. You become familiar with its sharpness, field-of-view, and contrast, and know when to use it for taking the best images.

But, over time, technology changes, and camera bodies have become more intelligent. Since your old favorite lenses can't electronically communicate with the new bodies, they might have been sadly relegated to the bag in the back of the closet. Surely, you didn't sell any of your old faithful AI-S Nikkors, did you?

There are several older autofocus-capable Nikon film bodies that will fully or partially meter using non-CPU lenses (non-CPU = no electronic chip in lens). Many of the newer Nikon film and digital bodies won't. Instead they will disable the light meter, and turn our expensive computerized cameras into completely manual models as soon as a non-CPU lens is mounted.

The reason Nikon chose to do this is simple. A non-CPU lens has no microchip inside to inform the camera body of lens settings. If you'll notice, many of our newer AF lenses have no mechanical coupling to engage the camera body aperture control ring. In fact, many of our new lenses (G-Type) do not even have an aperture dial. Instead, the aperture and shutter speed functions are controlled by the command dials. On most of the newer Nikons, the aperture control ring is not even there any more.


Return of the Ring (or the Aperture Ring of Power)

Ignoring my lame Tolkien references above, look at figure 1. Notice the aperture control ring on my old Nikon FE (circa mid-1980s), and the connector notch on the lens. How long has it been since you thought about this old mechanical feature? Until I wrote this article, I didn't even notice that it was missing on the newer camera bodies. I checked my D100 and D70, but it's just not there!

Now, in comparison, look at the D2x aperture control ring below. It looks very similar to the one found on the old Nikon FE above. It is clear that the D2x is prepared to mount AI-S Lenses.


Since the aperture control ring remains on the D2x, D2h, and F6 cameras, they can tell when we change the aperture on an old non-CPU lens. But, the old lens has no micro chip inside to tell what the maximum aperture is. And without the CPU chip, the camera doesn't know what the focal length of the lens is, either.

So, the cameras have a relatively simple means to let their bodies know those values. You use the FUNC button on the front of the D2x, and the command dials, to inform the D2x of maximum aperture and focal length. It only takes a few seconds, and allows the D2x to use Matrix Metering with your old faithful non-CPU Nikkors.


This article is written from the perspective of the D2x, but virtually all of this information also applies to the D2h and F6.

Why not get your D2x, an old favorite AI or AI-S Nikkor lens, and your D2x manual, and let's examine how this works. It's a lot easier than the manual makes it look!

The procedures below work best on single focal length lenses, or zooms with a constant aperture across the zoom range. You can use zoom lenses with variable apertures, but there are some minor difficulties, which we will discuss later. On pages 128-131 of the D2x manual, you'll find detailed information on these procedures. Also, pages 3-5 of the manual shows the names and locations of the various controls used in Method Two below.

There are two ways to set the lens specifications. We'll consider the two methods below:


Method One – Setting Lens Specs by Using the Shooting Menu

Below, you'll find both a quick summary and detail on how to set the lens specs using the camera menus.

Method One Summary:

  1. Open the Shooting Menu
  2. Select Non-CPU lens data
  3. Set the Focal Length
  4. Set the Maximum Aperture

Method One Detail:

Now, you'll need to set the Focal length , then the Maximum aperture . See Figures 2 and 3 for the steps.

As in figure 2, select Focal length from the menu. The next screen will give you a series of focal length ranges, these are 6-45, 50-180, and 200-4000. Select the range into which your lens best fits. (Examples: a 50mm or 135mm lens fits best in the 50-180 selection, while a 300mm or 600mm lens fits best in the 200-4000 selection)

If you are using a zoom lens, there is no difference in the setup. Simply enter the minimum focal length, and there should be good results across the entire zoom range. (Example: an 80-200mm zoom would go in the 50-180 range, since the MINIMUM focal length is the important number!)

In figure 3, we see how to set the Maximum aperture. The selections run from f/1.2 to f/22, with an N/A selection for specialty lenses with no aperture settings. Look at your lens, see what the largest aperture is, and set it in the menu. For instance, my AI-S Nikkor 50mm has a f/1.8 maximum aperture. If there is no exact match, use the one closest to your lens' actual maximum aperture.

Once again, with a zoom lens, just enter the maximum aperture as you would on a prime lens. As long as the zoom is not a variable aperture zoom, which most pro lenses aren't, you'll be fine. Variable aperture zooms are discussed in the Conclusion section at the end of this article.

Remember that we are only concerned with the MAXIMUM aperture. The D2x will take the Maximum aperture menu setting and detect the position of its aperture ring to know what aperture is in use. As you turn the aperture dial on the lens the D2x will adjust the meter accordingly.


Method Two – Setting the Lens Specs by Using Camera Controls

Below, you'll find both a quick summary and detail on how to set the lens specs using the camera controls. Figure 4 shows the location of the controls we'll use to set the lens specs.

Method Two Summary:

  1. Open Custom Setting menu
  2. Select custom setting f Controls
  3. Select f4 FUNC. Button
  4. Select FV Lock/Lens data
  5. Close menus
  6. Hold down FUNC button and turn rear Command-Dial to the Focal Length of the lens in use. The focal length changes will show on the Top Control Panel LCD. (See figure 4 for controls)
  7. Hold down the FUNC button and turn the front Sub-Command dial until the maximum aperture matching your lens appears on the Top Control Panel LCD. (See Figure 4 for controls)

Method Two Detail:

I find method two to be my favorite way to set up old lenses. But, I do not often use the FUNC button to turn on High-speed Crop mode in the D2x. If you need to use the FUNC button for something like High-speed Crop, or Spot metering , then you'll probably need to use Method One to set your lens specs.

In order to use the camera's controls to directly input the lens specs, you must assign the FUNC button to FV Lock/Lens data using Custom Setting f4 . If you decide that you use older lenses frequently enough to change the FUNC button to that setting, then, first we'll set Custom Setting f4 to FV Lock/Lens Data.

As you look at Figure 5, find the Custom Setting Menu then select f Controls from it and scroll right. Next, select f4 FUNC. Button and scroll right. There is quite a list of things you can select for the FUNC button to do. Scroll through these until you find FV Lock/Lens data and scroll right. Now the camera is ready to accept input from the FUNC button and Command Dials to set your lens specs.

Setting the Focal Length: Hold down the FUNC button and turn the REAR Command Dial as you watch the focal length selections scroll by on the Top Control Panel LCD. Stop on the focal length closest matching your lens.

Setting the Maximum Aperture: Hold down the FUNC button and turn the FRONT Sub-Command Dial until the maximum aperture closest to your lens appears in the Top Control Panel LCD.

Congratulations! By using one of the methods above, your D2x is now ready to use your faithful Nikkors of olden times.



Many of the old Nikkors are extremely fine lenses, and the cost on them was quite high. It's a shame to simply abandon the use of lenses like a Nikkor AI-S 600mm, or a 55mm AI-S Micro Nikkor. The D2x has returned a measure of functionality to us that many have missed.

The fact that we can now use matrix, averaging, and spot metering with our older Nikkors is marvelous. You can use prime and zoom lenses with this technology, although it's best to stick to zooms with apertures that do not vary across the zoom range.

The D2x manual on page 130 states: "Lens data are not adjusted when non-CPU lenses are zoomed in or out. After changing the zoom position, select new values for lens focal length and maximum aperture."

But, it has been my experience, and the experience of others, that zooms work just fine WITHOUT adjustment, as long as they are not variable aperture. If you use a variable aperture zoom, please realize that the camera has no way of knowing that the aperture is varying since a CPU chip is not there to inform it. So, if your variable aperture zoom varies by one stop, which is common, you must allow a stop of extra exposure, either manually, or with the exposure compensation controls.

If you set the one-stop variable aperture zoom to f/8, then zoom to its maximum setting, the aperture actually equals f/11, but the camera's aperture control ring is still reporting the f/8 setting, and the meter is metering accordingly. These are only minor difficulties, and ones that anyone who has used a medium format or bellows type camera is very familiar with. If you are using a variable aperture zoom, simply add exposure on the long end.

It is possible to have a CPU chip placed in your favorite old Nikkor lens if you would prefer, and that might be the best course to take on an expensive AI-S variable aperture zoom lens. But, for a single focal length prime lens, it's so fast and easy to set the lens data that it may not be necessary to add a CPU chip. You decide!

One D2x user reported to me that he is successfully using Hasselblad lenses with a Fotodiox® adapter and in stop-down mode. Imagine using matrix metering with a medium format lens. The point is that the D2x is a flexible professional camera with the ability to do what YOU want to do with it.

In any case, Nikon has overcome a rather difficult obstruction to our using older non-CPU lenses. By pro consumer demand…the old AI-S Nikkors are back!

Keep on capturing time...

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