Justin Hodson

Justin Hodson

Greetings...recently I purchased a Sony Nex VG20 with the SEL18200 lens and I'm having a little bit of trouble achieving shallow DoF so I decided to see if maybe some experts on the forum would be willing to give me some advice. Although I can achieve shallow DoF if I stand very close to a small object and film, once I actually try to film a human being from the waist up, It just doesnt work...To further clarify I will post this video youtube.com/watch?v=r1mJY-2xhdk ....what I want to achieve is exactly what happens in this video from 0:17 to 0:26. I know this was shot on a very nice lens but is it at all possible to even come close to achieving this waist up shallow DoF with my SEL18200? If not, can anyone recommend a lens for under $500 that could come close to achieving something similar? And finally, if it is impossible to achieve this on a budget of $500, should I consider selling my SEL18200 to get an SAL8514Z? Any help would be much appreciated.

Dave Baker

Dave Baker

The wider the maximum aperture the better for shallow DoF, so your f3.5 lens will not achieve the same as, say, an f1.8 of the same focal length. Focal length plays a part, the longer the focal length, the shallower the perceived DoF, so you shoud be able to reach a compromise.
Try it, shoot something like a tree in a field or a lamp post on a street at 200mm at maximum aperture, then move in and shoot it again at different zoom settings down to 18mm, keeping the image size and aperture the same (f6.3). You will see how the DoF changes.
You should be able to achieve the sort of effect you want with the knowledge you gain from this test.

Justin Hodson

Justin Hodson

Thanks for your response Dave. I tried shooting a tree and a few other things outside and I was definitely able to get the shallow DoF that I wanted, however, it required me to stand quite a distance from the subject and zoom in. This will be fine for outdoors, but for filming inside where there is limited space this method doesnt appear to work so well. I know that the subject should be as far away from a wall as possible (which I've tried) but I still cant quite get that shallow DoF that I need from the waist up when I'm indoors. Would an f/1.8 or f/1.4 lens solve the indoor problem or am I just missing something?

Dave Baker

Dave Baker

Shooting indoors does change things a bit, restricting the focal length you can use. It is a case of shorter focal length and wider aperture. If you can't achieve the effect you want with what you have, you have no real alternative but to get a wider aperture lens.
Yes, an f1.4 should be slightly shallower than an f1.8, but more expensive. Do plenty or research before you buy. If you can bear to dispense with full auto exposure and focus when you want this effect, consider a vintage lens and adaptor, there is a lot of good glass out there much cheaper than new.

Justin Hodson

Justin Hodson

I've been trying to do some research on focal length but I'm not exactly sure what to go with here...I know I want an f1.4 or f1.8 lens, but what is a good focal length to get a shallow depth of field from the waist up on a person while shooting indoors? 35mm? 50mm? 85mm?

Dave Baker

Dave Baker

It depends on the size of the smallest room you want to shoot in and the distance you can get from the subject.
It also depends on whether the focal lengths you are quoting are true 35mm or 35mm equivalents, because if they are true 35mm you need to know the crop factor of your sensor. Using the Canon APS-C sensor as an example, its crop factor ("telephoto effect") is 1.6, so fitting a 50mm full frame lens gives effectively 80mm (50mm x 1.6).
80mm-ish on a 35mm camera is reckoned to be a good portrait lens, assuming the room is big enough.

Justin Hodson

Justin Hodson

Thanks again for your responses. Just trying to get all the info I can so I don't end up buying the wrong lens. My crop factor is 1.5, the smallest room would be about 14ft x 12 ft (imagine the size of an average fast food restroom with no stalls), the average distance to the subject would be 6 or 7 feet, and the camera is a Sony Nex VG20. Given what I'm trying to achieve (waist up, shallow DoF) do you think a 50mm f1.4 would be best?

This conversation is missing your voice. Please join Vimeo or log in.