Small apertures

xenocide72 · Dec 23, 2014

hello,

Have been seeing some photos on some online photo sites lately where the photographer uses small apertures like f/16 to shoot normal landscapes that don't necessarily need a wide depth of field. I've also seen advice to use f/16 to shoot night shots of Christmas lights. Previously I had thought that the smallest aperture you should use is f/11 unless you want extreme depth of fields or sunburst effects

Any input would be appreciated.

weepete · Dec 23, 2014

I have used f16 in a fair few of my landscapes unless I've not had enough light.

In my head its to do with the hyperfocal distance and using a smaller aperture lets me get more of the foreground in focus before the diffraction becomes a big deal at really small apertures (like f22)

Usul · Dec 24, 2014

I use small apertures quite often even if it makes pictures softer. It gives nice star looking lights and allows to use slow shutter speed if you have no ND filters. If I don't need slow shutter speed I prefer f5.6-f9 for wide angle lenses it gives enough DOF for landskapes and delivers the best sharpness for most of lenses.

Designer · Dec 24, 2014

xenocide72 said:
hello,

Have been seeing some photos on some online photo sites lately where the photographer uses small apertures like f/16 to shoot normal landscapes that don't necessarily need a wide depth of field. I've also seen advice to use f/16 to shoot night shots of Christmas lights. Previously I had thought that the smallest aperture you should use is f/11 unless you want extreme depth of fields or sunburst effects

Any input would be appreciated.

The aperture that you select will affect some different aspects of your photo, and will be informed by several conditions.

You already mentioned DOF, and in some situations you would want to maximize the DOF.

Another is the inherent IQ rendering of the lens in question. Some just seem to yield better results at a certain range of aperture.

Another (as you mentioned) is the amount of light available. The photographer selects the aperture to work with the shutter duration and the sensitivity of the sensor.

I don't know where you got the idea that the smallest aperture should be f/11, but take all such suggestions in context of what else is being written, not just an absolute.

TCampbell · Dec 24, 2014

xenocide72 said:
hello,

Have been seeing some photos on some online photo sites lately where the photographer uses small apertures like f/16 to shoot normal landscapes that don't necessarily need a wide depth of field. I've also seen advice to use f/16 to shoot night shots of Christmas lights. Previously I had thought that the smallest aperture you should use is f/11 unless you want extreme depth of fields or sunburst effects

Any input would be appreciated.

Use any f-stop you want. They all have trade-offs.

Landscapes are usually shot with a broad depth of field and that usually means using a high f-stop value... f/16... f/22.

As you stop down to higher f-stops, the camera becomes 'diffraction limited'. Light doesn't technically focus to an individual point (due to it's wave nature). It focuses to something called an Airy Disk (nothing to do with "air" -- it's named for the astronomer who discovered it... George Airy.) Anyway, as you push light through a tinier opening, the size of the Airy Disk gets bigger. There is a point where the size of a small aperture increases the size of the Airy disk to the point where it can not fit on a single "pixel" (sensors don't really have "pixels", but that's another thread so I'll stick with "pixel" for simplicity.) This means that a single Airy disk spills across adjacent pixels leaving you with softer focus than you might get at a high f-stop.

So that's the idea... but it turns out we often don't use all the pixels available to us when we create output. The image is resampled to a smaller size for output and that means it's no longer even possible to tell that the camera was shooting at higher "diffraction-limited" f-stop.

The bottom line... you probably don't really need to worry too much about those high f-stops unless you know you plan on using a very high output size and the image will be subject to close inspection.

You can learn more about diffraction limits here: Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

Meanwhile... there's a reason you might deliberately want to shoot at a very high f-stop.

It turns out that when you shoot at high f-stops, the tight aperture size causes each point of bright light in the image to throw diffraction spikes. You only get these at high f-stops and the higher you go, the more noticeable they become. These can be very attractive in night-scapes and city-scapes shot at hours when the lights are on.

See: Tip: Star Bursts | StarCircleAcademy.com llc

runnah · Dec 24, 2014

There are very few cases where there is a "right" and "wrong" aperture. There is no universal "rule". Things like "sunny 16" and so forth are good starting points when you are learning. Eventually you'll learn more and end up breaking every rule you learned.