When you think of lens aperture on your camera – do you think about exposure, or do you think about artistic interpretation?

Yes, aperture is one third of the exposure equation (with shutter speed and ISO making up the other two variables), but your choice of aperture should primarily be an artistic choice.

If you’re moving up to a DSLR from a mobile camera, you probably haven’t really thought about aperture too much (since phones have a fixed aperture) – or if you have, it’s in terms of bokeh (wider aperture = more bokeh…yay bokeh), but your choice of aperture has a big impact on the look of your captured image (beyond just bokeh).

In this article, I will show you the difference between using a small, closed aperture and a big wide open aperture when it comes to sun flare and specular highlights.

What is Lens Flare?

I think everyone knows what sun flare is (when you shoot directly at the sun). However, if you’re not familiar with specular highlights, they are the bright spots of light that reflect off of shiny objects when illuminated (think sun glinting off of water).

When the light from these bright, hard sources enter your lens from the front it bounces around on the way through, resulting in flare.

With modern optics, it can actually be pretty hard to intentionally capture lens flare, but with practice, you can learn to see lens flare in your viewfinder and make an artistic choice on how much or little flare to capture.

(Here is a good tutorial on how to capture sun flare images.)

Once you’ve decided to add lens flare to your images, how the flare looks on the captured image depends a lot on the lens aperture that you use – you can specifically choose glow or sparkle.

Want Glow? Use A Big Aperture

If you want your lens flare to have a nice soft warm glow, use a large aperture (small number). There is no magic number and results very depending on your lens, but anything at f/4 or under tends to produce a soft diffused glow for both sun flares and specular highlights (f/4, f/2.8, f/2, f/1.4).

Here is an example of a sun flare taken at f/2.8, ISO 100, 1/125th with a Nikon D800 and Sigma 85mm f/1.4.

And here is an example with both sun flare and specular highlights (on the water) taken with a Canon 28mm f/2.8 at f/2.8.

Want Sparkle? Use A Small Aperture

If you want a more defined sun-star or star shaped sparkles, you need to use a small aperture. Again, there is no specific aperture to use, but usually at f/8 and above you start to see the lines of stars and sparkles (f/8, f/11, f/16, f/22 +). By using a smaller aperture you will also usually get a more contrasty image as the definition isn’t as washed out by the flare.

The smaller the aperture, the more defined the stars and sparkles will be.

If you’re photographing a night scene, you can also use this technique to produce individual little sun-stars on each bright light in the image (such as streetlights).

Here is an example of a sun flare taken at f/11, ISO 3200, 1/125th with a Nikon D800 and Sigma 85mm f/1.4 (the exact same scene from the image above except at f/11 instead of f/2.8 with the ISO changed to balance the exposure).

And here is an example that is similar to the above lake scene with specular highlights on the water – taken with a Nikon D800 and Sigma 35mm ART f/1.4 at f/16 (can you see all the individual sparkles?)

Glow or Sparkle – What Do You Prefer?

Do you use a big aperture for glow or a small aperture for sparkle?

Do you have a preference?

When would you use glow? When would you use sparkle?

Leave a comment below and share your thoughts!