I’ve always wanted to put this blogpost together since I started Blogging Behind The Scenes. I remember when first starting our fashion blog about 5 years ago, the first thing we tried our darnedest to achieve was background blur. I’m pretty sure we aren’t alone, as 1.8 and 1.4 50mm lens sell like hot cakes. While Aperture is the most well known tool for background blur, there are two more things you can use to control background blur. Those are Focal Length and Distances. I’ll go through all 3 of these and show the impact they have. It’s worth noting, that in order to better analyze the difference each adjust makes I’ve cropped these images so that the subject (the hat mannequin) takes up roughly the same amount of the frame. Below is what it would look like uncropped.
In the images below, I’ve added the details of the settings.
C-S Distance is the distance between the camera and the subject (the mannequin head)
S-B Distance is the distance between the subject and the background
Based on my experiments, the Aperture setting had the greatest impact on increasing the background blur. The widest Aperture setting on the 50mm lens I used was f/2.0. In the f/2.0 shot, my subject is completely separated from the background. The bags in the background are simply shapes and colors. As I start to narrow the aperture setting you can start making out more detail on the bags behind. If you are looking for a quick way to add blurry backgrounds, make sure you have a lens with a wide Aperture.
While I’ve always known that with everything else held equal, focal length has an impact on background blur. But it wasn’t until I did these side by side comparisons of 35mm and 50mm focal lengths that I really could tell how big the impact is. Take a close look at the bag on the bottom shelf for the f/3.5 images (middle ones), there’s a huge difference between those two images. For those that shoot with zoom lenses, give your longest focal lengths a try when attempting to separate your subject from the background.
This particular experiment was the first time I’d really tested out how distance impacts background blur. I should note that I paid close attention to both the distance from Camera to Subject (C-S) and the distance from Subject to Background (S-B). Based on my experiment, our results were as expected. The highest background blur was achieved by a close Camera to Subject Distance and a long Subject to Background Distance. Alternatively, the least amount of background blur came from a long Camera to Subject Distance and a close Subject to Background Distance. For those that shoot pictures on their phones, the distance is essentially the only thing you can adjust to impact background blur. That’s because focal length and is fixed on a phone and the aperture cannot be changed manually.
Camera to Subject Distance Impact with S-B of 4ft
Camera to Subject Distance Impact with S-B of 8ft
Subject to Background Distance Impact with C-S of 4 ft
When taking pictures, it’s important to consider the artistic effect that background blur has on your photo. Try to make a conscious decision about what you want. Blurry background photos are great for focusing the viewers eye’s directly onto your subject. It makes you wonder more about the story behind that subject. Compare that to a photo of a subject that’s one with their environment. This provides perspective on how the subject belongs there. Take a look at the two photos below, in these, my subject hasn’t changed, it’s still the Cholla Cactus right in front of me. The photo on the left to me feels singular, that particular cactus is what the story is all about, the photo on right on the other hand, it’s about how that one cactus fits into the sea of cacti.
While my findings were pretty clear there’s one thing that surprised me a bit. I noticed that with proportional distances (1:1 ratio) of C-S to S-B, the background blur was very comparable at f/5.6 (see the side by side images below). Which makes me wonder if I tried different distances but kept the proportions the same, what my results would be. Unfortunately, I ran out of room in our office space but I’m curious if 12ft C-S and 12ft S-B would have comparable background blurs to the photos below.