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So over black friday I bought this bundle, which is the Nikon D3500 two kit lenses.

I was wondering, I keep hearing people talk about aperture and using F11-F16 but on those lenses that I have, all I can go up too is like F2.4-F6.3.

If I want to be able to get F16 aperture, do I need to purchase a better lens? Are there some recommended ones that won't break the bank on a amateur photographer?

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The f-number is defined as F/D, where F is the focal length of the lens and D the diameter of the physical opening for light to pass through (the "entrance pupil"). As D grows, the f-number gets smaller. Thus an f-number of f/2.4 or f/6.3 corresponds to a larger opening than an f-number of f/11 or f/16. If your lens is capable of f/2.4, it is also (almost certainly) capable of f/16. Contrary to your assumption, you end up paying the big bucks when you want a lens with a small f-number, i.e. a larger physical opening relative to the lens's focal length. See this illustration:

Illustration of apertures and f-numbers

(Image credit: KoeppiK, CC BY-SA 4.0)

Having said that, there is no magical aperture that results in the optimal photo in every imaginable circumstance. A smaller aperture (hence a larger f-number) results in a greater depth of field, rendering more of your scene in focus. A larger aperture (hence a smaller f-number) allows more light in and thus facilitates low-light photography, plus you can use it to artistic ends to render parts of your photo significantly out of focus ("bokeh"). Most lenses are sharpest at an intermediate aperture. The following combination of two photos illustrates the difference between a small (upper triangle) and a large (bottom triangle) aperture:

Small and large aperture examples

(Image credit: Autopilot, GFDL 1.2)

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It is the other way around: The smaller the minimum aperture number (which means maximum opening) is, the more expensive the lens is - check prices for a f/1.2 vs a f/2.8 35mm prime and you will see.

Almost every lens (unless you are working with something like adapted projection lenses) you can get can be stopped down to f/16. ANY lens that will fit a modern DSLR or DSLM without any further work can be stopped down to f/16 or more. Use aperture priority ("A" or "Av" on the wheel) or manual ("M" on the wheel) mode on your camera to have manual control of the aperture.

Going higher than f/8 without a good reason (eg if you absolutely need that depth of field) is actually NOT advisable with a DSLR/DSLM - f/16 already tends to suffer from diffraction effects, AND it makes inevitable sensor dirt frustratingly visible in the result.

Also, unless your subject is strongly lit, high (in number) apertures can force you to use too slow shutter speeds (you get camera shake) or too high ISO settings (you get noise and lose saturation and clarity).

If your intent is to have an extreme depth of field - go DOWN in focal length if composition allows, for example by using the 18mm setting of the shorter lens in that bundle or even by adding a 16/14/12mm lens.

By the way, on the "low" end of the scale, f/2.8 is usually the smallest you get in a zoom lens, f/1.4 on a prime, f/1.2 to f/0.85 are rather specialised lenses, below 0.85 to 0.65 is experimental territory (strictly adapted too, can't buy this kind of lens as a ready to go camera lens), below 0.5 is physically impossible.

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  • Re, "below 0.5 is physically impossible." Does that mean practically impossible with existing design tools, techniques, and materials? or does that mean theoretically impossible (as in, even if I could obtain "glass" with any index of refraction that I desired, and could perfectly form it into any shape...) If it's theoretically impossible, then what happens at f0.5? – Solomon Slow Dec 9 '19 at 22:14
  • Impossible unless you are using the lens immersed in a non-air,non-vacuum medium..... – rackandboneman Dec 9 '19 at 23:23
  • Hmm... Found this discussion: photrio.com/forum/threads/aperture-bigger-than-f1.68503 Looks like some heavy-duty math. I think the upshot is, a lens with f-number smaller that 0.5 can focus light from one point on one side of the lens to one point on the other side, but you can't make it focus light from all of the points in a plane on side to the corresponding points in a plane on the other side. (i.e., you can't use it to form an image.) Something to do with violating the Abbe Sine Condition – Solomon Slow Dec 9 '19 at 23:46

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