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I had been using a Nikon D3400 with aperture priority mode. I received a Nikon D750 as a present and am in the process of upgrading to FX format lenses. I am looking at a Nikon AF-S Nikkor 24-70mm f/2.8G ED lens, which has constant aperture. Can I still work in aperture priority mode with this lens?

  • Nikon 24-70mm f2.4. Recommenced by someone. – GMC Aug 1 '18 at 18:30
  • What camera are you intending to use with this lens? Also, which Nikon 24-70mm f/2.8? There have been several different models over the years. – Michael C Aug 2 '18 at 6:49
  • Sorry, wasn’t too clear in my response. I have a Nikon d750. The lens am looking at us 24-70mm f2.8G ED. I was using a D3400 for a long time. I got this D750 as a present and am in the process of gradually upgrading to FX format lenses. Thanks. – GMC Aug 2 '18 at 13:24
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Yes.

Constant Aperture is a reference to a zoom lens' maximum aperture at all focal lengths.

It does not mean that it is the lens' only available aperture setting. That would be a fixed aperture lens.

It some ways it is easier to shoot in aperture priority exposure mode with a constant aperture zoom lens than with a variable aperture zoom lens.

(The following is applicable when using any Nikon digital camera with a Nikkor/Nikon lens, or third party lens in the Nikon F-mount, that does not have an aperture ring, such as the lens in question, the Nikkor AF-S 24-70mm f/2.8G. It is also the case if you are using an older Nikon or third party lens that does have an aperture ring but the camera body you are using requires the ring on the lens to be locked at the narrowest aperture setting.)

Let's say you are in a low light situation and you want to use the widest aperture at each focal length of a variable aperture 70-300mm f/4-5.6 lens. If you start out shooting at 300mm the widest you can set the aperture is f/5.6. When you zoom out to 70mm, the camera will preserve the f/5.6 aperture you selected at 300mm. You'll need to reset the aperture to f/4 while the zoom is set to 70mm. Then, when you zoom back in to 300mm the aperture will be forced back to f/5.6.

On the other hand, a constant aperture zoom lens allows the same maximum aperture at any focal length setting.

In manual exposure mode the advantage of a constant aperture lens is even more obvious. If you set the 70-300mm f/4-5.6 lens at f/4 with a shutter time of 1/250 second at 70mm, when you zoom in to 300mm, the aperture will be forced to change f/5.6, but the shutter time will not be automatically compensated and will remain at 1/250 instead of lengthening to 1/125 to preserve the same exposure value.

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    "When you zoom out to 70mm, the camera will preserve the f/5.6 aperture you selected at 300mm" - minor correction. If you leave the aperture wide open, the camera will automatically keep it wide open both at 300mm and at 70mm, there's no need for manual intervention. – JonathanReez Aug 1 '18 at 18:27
  • @JonathanReez If the aperture is set to some other value (say f/8), and you set it to f/5.6 while at 300mm, it will not change to f/4 when you change the focal length to 70mm. Only if you set it to f/4 while at 70mm before you zoom to 300mm and do not change the setting will it return to f/4 when you zoom back out to 70mm. – Michael C Aug 2 '18 at 5:19
  • @JonathanReez SInce the vast majority of NIkon F mount cameras sold in the last 10+ years are in the D3x00 and D5x00 series, the aperture ring (if the lens even has an aperture ring) must be set to the minimum aperture (maximum f-number) and locked there for the camera to function in automatic exposure modes. Thus the aperture value is set digitally by the camera, not by the position of the aperture ring on the lens. Neither the Nikkor AF-S 24-70mm f/2.8G nor the Nikkor AF-S 24-70mm f/2.8E VR, the two most recent F-mount 24-70/2.8 lenses, even have aperture rings. – Michael C Aug 2 '18 at 6:56
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Yes.

Usually, the f/2.8 notation just tells you the maximum aperture (greatest diameter), but it does not say anything about the smallest aperture (smallest diameter).

E.g. a 70-200 mm f/2.8 can keep its maximum aperture all the way from 70 mm to 200 mm, but you can always choose a smaller aperture, e.g. f/4 or f/11 (just two random examples - usually, you can choose them in the usual 1/3 steps)

Yet even if your lens has only a constant permanent aperture of f/2.8, you could still use aperture priority mode - it should still be able to change the shutter speed (and ISO, if your camera can do that) like it would with a non-permanent f/2.8 lens.
That said: I cannot rule out that some camera I have not yet heard of does block using aperture priority if it cannot detect the aperture value of the lens (which would make sense, as a lens that cannot change its aperture most likely would be a fully manual lens).

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    "Yet even if your lens has only a constant permanent aperture of f/2.8, you could still use aperture priority mode - it would, however, have no advantage over going fully manual." - Using manual lenses, using A mode allows the camera to automatically change the shutter speed for exposure. In M mode you have to do this by hand. – sjakubowski Aug 1 '18 at 13:12
  • What if the camera enables you to set ISO to 'auto'? – laurencemadill Aug 1 '18 at 13:14
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    @sjakubowski You are right - I mixed up Av and Tv, as "aperture priority" is called "zeitautomatik" in German (my native language)....I always mix them up. Correcting it now - thank you! – flolilo Aug 1 '18 at 15:50
  • @laurencemadill Included auto-ISO in my answer. Thanks! – flolilo Aug 1 '18 at 15:55
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There are two misunderstandings in your question.

  1. As covered already by Michael and flolilolilo, "constant aperture" means that the widest available aperture (smallest f-number) is constant across the zoom range; it doesn't mean that the lens can only shoot at f/2.8.

  2. Suppose that you did have a hypothetical lens that could only shoot at f/2.8. Then you would be forced to use aperture-priority (or full-manual) mode. Remember that aperture-priority means that you choose the aperture and the camera chooses the shutter speed to give a correct exposure. With this hypothetical lens, your only option would be to choose f/2.8 and let the camera choose the exposure. You wouldn't be able to shoot shutter-priority (you choose the shutter speed and the camera chooses the aperture) because the camera would only be able to select the right aperture for one shutter speed (the one that gives the right exposure at f/2.8).

Frank points out in a comment that actually there are lenses that can only shoot at one fixed aperture: mirror lenses. They're rather rare, these days, and they'd typically have their aperture somewhere around f/8 or f/11.

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    An example of a lens that has one aperture is a mirror lens which typically has a fixed aperture of f/8. – Frank Aug 1 '18 at 18:01
  • There are also some mirror lenses that have a fixed aperture of f/5.6. There are even a rare few that have variable apertures such as the the Ohnar 300/5.6 Mirror (also sold under other names such as Hanimex, Makinon, Panagor, etc.). – Michael C Aug 2 '18 at 5:23
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    There is also the "toy lenses"/pin hole lenses like Holga. It has f/8 and terrible quality (if quality is sharp images and correct colors). I believe someone also said the Holga is actually f/22. But not sure. It's a fun toy in bright light for probably 10 minutes, then it's placed on a shelf. – Andreas Aug 3 '18 at 9:45

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