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I am filming video with my Canon Rebel T3i (my lens is 18-55mm, the starter kit one) and would like a big DOF for my footage. My problem is that I have to pick between having a big DOF and my frame being lit poorly (dark) OR a small DOF and my frame being lit well (bright). My goal is to have the frame be big DOF while being lit well.

I am not an expert so I did some research and learned that the ISO, F-Stop, and Shutter Speed affects my situation. I am filming at 24fps which means my shutter speed has to be double that (50). I cannot increase my shutter speed to bring in more light. Since I want a big DOF, my F-Stop value is high (ex. >12) which darkens the frame. I have increased my ISO to 3200 but it already looks grainy so I do not want to increase it more, in fact I want to lower my ISO but it will be almost pitch black.

Can anyone provide me with some solutions? Is there a better lens I can purchase to overcome this problem? Would the most obvious solution to be just buy more studio lights?

Thanks!

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5 Answers 5

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There are three variables you can change on the camera to modify the exposure. Unfortunately in your case, you can't lower the shutter speed, you can't use a wider aperture and you're already unhappy with the grain so you don't want to raise the ISO any further. A new lens won't help you as you still need to keep the aperture narrow for your DoF requirements.

Therefore you have two options:

  • Get more light onto the scene
  • Get a sensor with better low-light performance. The T3i is certainly not class leading in this regard, so you could certainly do better. Note that moving to full frame isn't an obvious a win here as is it in other cases, as you'd again need to stop down to keep your DoF - but something like the Sony A7S, which is class-leading in its low-light performance would still help.
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  • \$\begingroup\$ Canon T3i which OP mentions is the Canon 600D in Europe. The 1300D which you mention is the T6 in America. \$\endgroup\$
    – crunch
    Commented Jan 18, 2017 at 10:19
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    \$\begingroup\$ Good point, corrected, thanks - doesn't change the conclusions though :-) \$\endgroup\$
    – Philip Kendall ♦
    Commented Jan 18, 2017 at 10:27
  • \$\begingroup\$ We like to make a big deal about the differences from one camera to the next. But in the overall scheme of things there's not that big a gap between current DSLRs. Even with an A7S (or even a broadcast quality dedicated video camera) the OP is still likely to not be satisfied until more light is added to the scene. There's a reason why broadcast studios which use cameras and lenses worth hundreds of thousands of dollars still use intense lighting. \$\endgroup\$
    – Michael C
    Commented Jan 18, 2017 at 22:40
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Would the most obvious solution to be just buy more studio lights?

Yes. A better lens will do you no good because to allow more light in would require a wider aperture which will reduce your depth of field.

The only way to brighten the scene without either:

  1. Lengthening the shutter time
  2. Opening the aperture and reducing depth of field

or

  1. Raising the ISO

is to increase the amount of light illuminating the scene.

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Is there a better lens I can purchase to overcome this problem?

There are three ways of overcoming that problem:

  1. use fisheye/ultrawide objectives, they will let you use smaller F and still have many things in focus. This will obviously affect your footage so you need to decide whether it is optimal for you or not. Your options are Tokina 11-16/2,8, Samyang 10mm/2,8 and some more.
  2. another way is getting different camera
  3. use MagicLantern to record raw cropped video with full readout

There are two reasons to get a different camera with a smaller sensor: 1) cameras with smaller sensors perform significantly better when big DOF is required 2) there are many cameras made recently which feature full sensor readout - that is they are not trashing 2/3 of captured information like your Canon does, this means a whole stop+ of light is wasted

Your options are Panasonic GH2, Panasonic GX85, Sony RX100 III. Other cameras with small sensor and full sensor readout are available but they are pricier. There are also dedicated video cameras with full sensor readout like BMCC but I am not informed about them.

MagicLantern will let you record video without skipping lines, this will crop your video and you will be able to use wider objective with smaller F like Samyang 10/2,8. I do not know how how much advantage it will give but I am sure that there will be some.

My answer got completely video-related.

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If the options above about getting new camera/lighting/lens etc are not within immediate budget, a method to try is this.

DOF is also affected by how close you are to the subject you are focused on. So with all other factors the same, if you focus on something further away the general rule is a deeper DOF.

This of course can affect the composition of your film etc, but if your lens is zoom, then you can zoom in from further away to retain the composition and this might allow you to open the aperture to let more light in.

Its worth experimenting with and your manual should have a chart showing DOF for each f/stop and focus distance which should allow you to try and find the best to allow you to do what you need.

Andy

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A wider angle lens would allow more light to reach the sensor in a given situation and would give a deeper Depth of field.

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  • \$\begingroup\$ No, a wider angle lens would give a shallower depth of field. That's why koko777 is using f/12 in the first place. \$\endgroup\$
    – Philip Kendall ♦
    Commented Jan 18, 2017 at 9:25

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