thumbnail-still-blurry-backgrounds

How to Get Blurry Backgrounds in Video (Bokeh)

Paul Shillito backgrounds, Cameras 6 Comments

Now having just bought a Sony A7s I wanted to show one of the main reasons why i bought it and that was the ability of a full frame sensor camera to get the deeply out of focus backgrounds or Bokeh over a large frame as they say in the photographic circles.

One of the main reasons for wanting this was because I wanted to hide the crap in the background which constitutes one of my main working areas, so I could talk to camera in a more normal environment without having to resort to a white background or roll out the green screen or a major clean up and loosing things in my carefully chronologically ordered desk.

The closer you are to your background the more of a shallow depth of field you need in order to hide it. Now there are many that say you don’t need an f1.5 lens and full frame cameras to get good “Bokeh” but they don’t have to work in the small space that are involved with  home studio’s. Shoot outside or in dedicated larger studios and they are correct to a degree but that’s not where I and many other are forced to work from.

This was one of those things I wished I had the capabilities to do since I started expanding my camera range. Firstly there was the Black Magic Cinema Camera, great ProRes low compression output and RAW if you can handle it.

Then the Panasonic GH4 , my first 4k camera, fantastically sharp and detailed images, great for chroma-key work too, better than the BMCC because of the extra resolution. But because both of these have large crop factor sensors and the wide angle lenses I was forced to use to get shots I needed in my small studio, there was little in the way of creating that really strong background blur.

I could have got some expensive,  low f number lenses or used a metabones SpeedBooster, also expensive,  with  some cheaper lenses but there is still a lack of  wide, low f number lens around. However after factoring in all these extras i decided to go with the Sony A7s because it just made things easier.

YouTube video link

Getting the A7s with the full frame sensor means no need to worry about crop factors any more and there are cheaper cine lenses from Samyang or Rokinon are available like the 35mm f1.5 I have at the moment. There is a 4K output (if you have a recorder) and a super clean low noise output that can work in very low light. Just look in the video at 9:30 where I have the lens set to f22 in a normally lit room and it is set it to an ISO of 10,000 with almost no noise, and no tweaking was done in editing either, try doing that with a BMCC or GH4 or in fact almost any other video camera.

So now I have this extra ability I think that the BMCC will be making an exit soon as it just doesn’t now do enough to justify keeping it.

So anyway enjoy the video and any questions please feel free to ask.

——————————————————

 

{TRANSCRIPT}

Watch almost any film or TV program and you’ll see shots with a blurry defocused background, now these not only look more professional and cinematic but they also help focus the viewer’s attention by isolating the subject from the background. In this video I’ll show you what you need to get that cool effect and also the best way to achieve it.

Now almost any camera can create this blurred out background but some can do it to a much greater degree than others, now if you’re into photography you’ve probably already heard and seen this and its is called Bokeh or Bokay.

Now this is a Japanese term and it literally translates into “blur” and quite often used to describe the aesthetic quality of the blur of the background. Now to create this you actually need a shallow depth-of-field But what does a shallow depth of field Actually mean.

Now the depth for field refers to how much but the actual scene from front to back is actually in focus, now obviously this is a shallow depth of field but how shallow I can actually demonstrate.

Now and if I put my hand to my face here you save it should be in focus now as I move it forward you should see it move out focused very rapidly until I’m almost at the camera lens and now it’s really out focus. Now if I do the same with this hand here and I move back you see again it moves rapidly out of Focus as I go back. Now the depth field in this actual shot it approximately 12 inches so its only that deep. So I can’t move much more than 6 inches front and 6 inches back before I become so out of focus but it’s not really a usable shot anymore. Now compare this to a deep depth of Field which I can show you now.

I have changed a couple settings on the camera and as you can see now we have a really deep depth of Field and whereas before it was around about 12 inches now you can say it’s huge. In fact it is so deep i shall demonstrate this by showing but we did before and start off with my hand here and before it was going out of focus about here now it’s in focus literally up to the actual camera.

Again I can do same this way but in fact I don’t need to move my hand, I can actually just walk all the way over here and I’m still in focus way back over here. So what actually controlling the actual Depth of field and how does it make it go from very short to actually very deep.

Well there are several factors in here firstly the position where you actually standing. When I’m standing close to the camera and in focus then the chances are that I will have more the background out focus. Now of obviously this is not the case because I’m still in the same position as I was before and you can see there is no background Blur.

Secondly the actual lens or the focal length of the lens will make a lot of difference as well. Now this is a wide angle lens or a fairly wide angle 35mm lens on this camera at the moment. That will naturally give a deeper depth of field with less background blur. Again as we can see I had at the background the deep background blur before with a shallow depth of field and now I’ve got a very deep background

Here and we’ve no blur, but I haven’t changed lens it always exactly the same lens. There are two other factors which we be come in to play and these are the size of the image sensor the camera uses and size of the aperture that the lens is set to.

Now one of the main determining factors in getting that really shallow depth of field is going to be the size of the image sensor in the camera. Basically you want to go for the camera which has got the largest image sensor to you can get your hands on and out of these really it’s going to be this one here this is a Sony A7s and this has a full-frame Sensor.

Other full-frame sensor cameras will include the Canon 5d, Canon 6D and also Nikon 600D so this sort of thing here will give you shallowest depth of field when combined with a very large aperture lens this is the one the sort of size camera the image sensor you need to go for. These are the most expensive as well and also the lenses are more expensive because they are physically bigger.

So the next size down from the is one like this this is a crop sensor camera with an APS-C size Sensor in here, this is a Canon 600D and also known as Rebel T3i and also The Rebel T4i, T5i. Now there are a whole range of cameras which use this size of image sensor.

This will not produce quite such a shallow depth of field for the same size aperture lens as this one but it still can do reasonably well. Then we come down to this one this is the Panasonic GH4, a 4k camera with 4k capabilities but this has got the Micro Four Thirds image sensor. This is actually only one-quarter of the sized of the Sony’s here you can get shallow depth of field with these but your going to have to use really wide aperture lenses, probably in the region about a f0.95 one to f1.2.

Now compare that to this to an Apple iPhone 5, this is used by a lot of people on YouTube and to shoot video and this has got probably the smallest sensor of any the main video cameras, its only 3.5mm by 4.5mm inside here.

See if you compare that to the Sony’s you can see how small it is and this the lens, the image sensor is slightly smaller behind here.

The thing is that a lot of compact cameras and other tablets have these sized image sensors in them, even the camera which I’m shooting on moment which is a Panasonic SD900 has only got an image sensor that’s is about twice the size so it’s not very big.

This is what you going to find that when you get into the video cameras be consumer video cameras, compact video cameras and mobile phones, smart tablets and that sort of thing. The image sensor size is very small and that is going to be a big big limiting factor to getting that shallow depth of field.

Now the second requirement to get in a really shallow depth-of-field Is actually going to be the lens and it’s going to be the lens that controls the depth of field and as to actually how shallow or deep it actually is.

These two lens here, this one here is the lens which I’ve been using on my Sony and it’s a 35mm f1.5 and you can see it’s quite a big lens, this here is a lens for the Panasonic GH4 this is the smallest image sensor camera.

This is a zoom lens it goes from 12mm to 35mm, this is fixed 35mm, this is an f2.8 lens this is an f1.5 now because this is a f2.8 this can’t produce the same sort of shallow depth of field that this lens can provide even if they were the same format you need to get really down to f1.5, f1.4, f1.2 to get really shallow depth-of-field.

If we have a look what’s going on in the back here you can see the aperture blades are closed up, now that’s f22 and this gives you the very deep depth of field. If we open it up we go to f8, f5.6 is now opening up and the depth of field would now becoming shallower. That is now f2.8 that’s where this lens stops and this keeps going and this will now go on to an f1.5 and that is as wide open this lens will go.

So as we saw with the cameras, we saw we had the size of the image sensor and also the aperture of the lens which when combined can create a very shallow depth of field but it’s really the aperture which is going to be the controlling factor because we can’t control the size of the image sensor, once you’ve got the camera that stays fixed so the only thing that’s going to be variable then really is going to be the aperture size of the lens and how wide open it can go, the more wide open the actual lens can be the shallower the depth of field can be but this also creates a few problems.

Now at the moment we’ve got really deep depth of field and I’ve got this lens set to f22 which is minimum setting, now on a lot of cameras this will be so dark you won’t see anything. So what we have to do this is to actually then crank up the ISO setting on here.

You could reduce the shutter speed down but obviously you can go so low and I’m keeping a constant 1/50th second throughout the whole this filming session so I’m not changing anything on the shutter speed so the only thing I can do here then is to actually control the actual light level sensitivity of the camera by the ISO level.

This camera which is Sony A7s which is a very low noise and also has a very high ISO capability is set to 10,000 ISO. A lot of people say well that’s really high ISO compared to some cameras and it is but basically allows me to get this really super deep depth of field with the same 35mm lens with the same light levels and it’s the light levels which are going to be the killer here. Because if you want to get the shallower depth for field to and reduce the aperture down, we’ve got to actually open up the aperture and if we open up the aperture to say f5.6 there, now instantly you see it’s got much too bright, it’s letting in too much light.

So first we can actually put on an ND filter, this is an ND4 filter that will knock down some of the light input but equally I’m going to have to reduce the ISO. If I move the ISO down, we’re coming down to around about 3200 on the ISO setting now to actually get at the light level down to what it was before.

Now I’ve got a bit of depth of field coming back, its still quite deep but you can see does blur it out a bit, not a lot but a bit it’s probably now probably around about 4 – 5 foot deep now or something like that the actual depth of field.

So if you really want that really shallow depth of field we’ve got to open the aperture right up which is going to let a lot more light now when we get to this stage you could actually reduce the actual light coming in by adjusting the shutter speed and speeding it up.

I don’t want to do that because really if you do that you end up with a high shutter speed you could end up at like 1/500, 1/1000 or even 1/2000 or even higher maybe and you end up then with a very hard jittery sort of to look and when you’re trying to get shallow depth of field you don’t want this hard jittery look because the two don’t really go together.

So we need to do is keep the ND filter on here and this is how i’m controlling the actual amount light. This ND4 filter is knocking down the light and as i have opened it up now we’ve got down to 3200 if we actually go down a bit more if we go down to f2.8 will see it opened up again I need to reduce the ISO again and we’ll go down and we need to be. Probably around about ISO 800 now so again it keeps the light level consistent but I’m actually again in focus now you can see the depth of field is becoming shallower. Their might so now if we go for super shallow depth-of-field we go down to f1.5, this opens up the lens even more lets more light in so you’ve got to knock the ISO down even more so we go down and on this setting to round about ISO 320 so now we have this really shallow depth of field on here.

You can see that I’m just moving the focus plane so it’s in focus over there and in moving the whole thing so it comes here and then back again and in back.

So this is what you’re actually doing with the aperture and focus, the focus is actually moving this small plane of focus backwards and forwards and the aperture is controlling how deep the actual amount of focus or the depth of field actually is from a very shallow which we’ve got at the moment to the very deep when we’ve got the actual aperture really compressed down and that’s what you need to do to actually get this shallow depth-of-field.

So what sort of cameras do you actually we need to look for you looking for really shallow depth of field, well I’m afraid it isn’t going to be one of these, a lot of people use these on Youtube and for filming around but the combination of the very small sensor size and the wide-angle small lens, short focal length lens really does nothing for shallow depth of field and that nice blurred out background.

You can get it if you look at something probably about a couple inches away and even then background is going to be still pretty much in focus is going to have a tiny amount a blur but not much but that’s about far as you going to go these things are not going to be any good if you want that shallow depth-of-field.

If we move up to video cameras like this this is going to be better it’s got a better lens on it which will certainly help but the small image size sensor in here still going to be a problem. There are some bigger image sensor camera’s around, there is the FDR AX100 from Sony which is a 4k camera and it has a 1 inch sensor in it, so that’s quite large now that will start to give you a reasonable sort of background blur but again the lens is not that shallow and it goes only down to f2.8 maximum, really if you want to get some super shallow depth of field you’ve got to go towards the DSLR’s with the big image sensors.

This is a Canon 600D this is a crop frame sensor now when it’s pared up with this, this is a Canon 50mm f1.4 you can get a really nice background blur but because it’s a crop frame sensor it means then that this 50mm lens actually works like an 85mm lens on my full-frame camera here so if you’re going to do and we going to want to do that really shallow depth for field work you really need to go for a full frame camera and a lens approximately about f2.8 or less.

I would go for something like a f1.5, f1.4, if you can afford to go down to f1.2 to f0.95 your going to spend thousands and thousands of pounds on the lens where as this lens was only like £350 ($500) and is going to do almost the same job.

Again depending upon the focal length for the lens this is 35mm, if it was a 50mm or a 85mm it will give me a nicer at shallower depth field for the same given sort of the size sensor but obviously i cant getting as close because it’s going to be more of a narrow focus.

This gives me a me a good compromise so I can get shallow depth of field and also getting most of the room scene I actually need.

So there we are if you want shallow depth-of-field you need to go with The biggest sensor size camera which is full frame and really an F 1.4 or thereabouts lens.

So I hope you enjoyed the video and you found it useful and it shed some new focus onto the subject.. bad puns, pad puns, anyway if you liked the video don’t forget to rate and subscribe and also leave any comments in the box below and also share this with anybody you think might find it useful also don’t forget hop on over to Video-Alchemy.com don’t forget that and visit, sign up our newsletter and see what we do over there as well.

Anyway my name’s Paul Shillito and this has been Video Alchemy production and until next time see ya later byeeeeeeeee

 

Comments 6

  1. Jossef

    Hi
    Im using a asp-c camera and i have the kit lense 18-55 f3.5-5.6 and recently i got the 50 f1.8 that give great bokeh but only half body. My problem is how to get bokeh without backing up more than 2.5 meter when shooting video, partly because my mic cable is only 2.5 m long.. Is there any idea? Thank you

  2. Janaj

    Hi Paul,
    Thanks for these ideas. Your discussion of the sensors explains a lot about shooting with a DSLR.
    Do you have any comments when shooting with a prosumer, with a fixed lens?
    I’m shooting with a Panasonic AG-AC90

    Also, how did you make your flashy transitions between scenes?

    Thanks,
    Janaj

    1. Post
      Author
      Paul Shillito

      Prosumer is fine but as you say the lenses are fixed so there is not much you can do to change the physical set up which will have the biggest effect. the Transitions are standard ones done in Adobe Premiere Pro

Leave a Reply

Your email address will not be published. Required fields are marked *