balance

nantnee

nantnee

Well-known member
How you balance Aperture and Shutter speed?

For instance:

In the same scene, you have both shallow and deep DOF. Now, how do you keep the same look with the two different shots set at different Apertures?
 
anybody. Changing the aperture changes the amount of light getting through the lens corret? So then the shutter speed needs to be change to compensate, right?
 
I actually do it the other way around. I set the shutter I desire for the scene and then adjust the aperature accordingly. Not saying that's the correct way or anything, just the way I do it.
 
I tend to consider my DOF goals for a shot as part of the set up process. It's a factor that I nearly always keep in mind. After a while, this process got to be more intuitive and less empirical. So I don't have any hard and fast rules. As you said, I just eyeball it.
 
The most noticable difference between two shots is going to be the shutter speed not aperture. There is nothing wrong with having a deeper depth of a field for a side shot and shollower DOF for a medium or CU.

That being said, if you want to keep your image totally consistent between a wide and medium make sure your aperture is the same. I would imagine that the XH camera don't have a constant f stop so if your iris is wide open at 1.6 and you zoom in, your lens will be forced to stop down to 2.8 lets say. This will result in different DOF. The only solution is to shoot your wide shot at 2.8 as well and then you can zoom through without changing your apeture.

Keep in mind that you are going to notice the shallow DOF more when you zoom into your medium shot because it exsentuated your DOF but technically your DOF is just as deep/shallow as it was when you were wide. If you want ot match it up more visually, you can allow the camera to stop down the lens when you go in for your medium shot. Theres no right way its all based on how you want the shot to look.

What I would avoid doing, is having differnt apertures at the same focal length, aside from the DOF noticibly changing, your out of focus highlights can change shapes based on your aperture which can be distracting.
 
A wide lens simply pulls out and lets you see a wider angle of view, decreasing the size of out of focus objects.

When you zoom into telephoto, you arent neccesarily changing the DOF, (some will argue with me on that) but you are simply magnifying the background and forground objects that are out of focus, narrowing your range of acceptable focus.

And then from there you can adjust your iris and see the changes in DOF

Try this:

Shoot something with foreground and background objects, reasonably seperated to assist you with shallow DOF

focus on the foreground object, and open up your iris ALL the way. Record.

Now iris down three stops and turn up your gain to get a ballpark estimate of the same level of exposure you had before. Record

Now look at both images, the 2nd image with the smaller aperature contained more in focus, because of the iris ring changing the angle at which the light refracts, causing the rays to converge within the depth of focus, and ultimately appear as smaller circles of confusion
 
Thanks for the responses, all of which helped. But, I think im still hazy on this.

Ill use a comparison.

The show "The Office." They use deep and shallow dof throughout the show. The look, how bright objects are, stays consistant.

So I guess where im getting lost at is - when I stop down the apt. without changing shutter speed, less light is let in, decreasing the brightness of the shot. So in order to compensate for the loss of light, the shutter speed needs to be turned down to let more light in.

How do you make two different shots with the same setup, with different apt. and different shutter speeds consistant with the look?

You all probably already answered it and im just reading it wrong.


thanks again.
 
Not sure i'm following you man.


DOF isnt ONLY a result of aperature changes.

It's also different focal lengths as well


Usually, I just maintain a constant aperature.
 
You see, the Office is shot on 2/3 inch cams, which use more powerful longer telephoto lenses to achieve the same field of view.

They get shollower depth of field my default. Just by using 2/3 inch cams they get 16mm film DOF basically

they dont need to play around with their aperatures

the longer the lens, the more the out of focus background, or foreground, is magnified
 
Along similar lines, I have a studio interview scenario coming up with my A-1. The framing will be from above the subject's head to around his waist. Using the stock attached lens, is there a preferred aperature I should be aiming for? I want to make sure that if the subject moves, I don't lose focus on him. I will have everything on manual control. Thanks.
 
Thanks for the answers Dan.

I understand what you're saying, but I think we might be talking about different things.

Ill try and clarify.

Having a smaller apt. size lets less light in making the pictuer darker... Correct?
Having a lower shutter speed lets more light in... Correct?

So,

At the same focal length, lets say I'm shooting at a 5.0 f/stop at 1/120th shutter speed.

Now, in the same position, nothings change, I shoot at 1.8 f/stop at 1/120 shutter speed.

There should be a difference in picture brightness and dof would have a slight change, so how do you balance the two differences so that they look like they have the same brightness and so on.

thanks again for the help.
 
Why adjust the aperture in the first place, if you really need to have a shallower DOF, then add more light to the scene and then adjust the aperture. I don't know of any way to keep it exactly consistent, but what I do is just pick a mark on the exposure monitor and try to match that mark in each shot. It has worked for me!
 
ok.. so I suppose everyone eyes it. I was just wondering if there was a method, or a way of measuring the two.
 
nantnee said:
Thanks for the answers Dan.

I understand what you're saying, but I think we might be talking about different things.

Ill try and clarify.

Having a smaller apt. size lets less light in making the pictuer darker... Correct?
Having a lower shutter speed lets more light in... Correct?

So,

At the same focal length, lets say I'm shooting at a 5.0 f/stop at 1/120th shutter speed.

Now, in the same position, nothings change, I shoot at 1.8 f/stop at 1/120 shutter speed.

There should be a difference in picture brightness and dof would have a slight change, so how do you balance the two differences so that they look like they have the same brightness and so on.

thanks again for the help.
Click to expand...

When would this situation ever occur and why would you have to change your aperture in that fashion?

I suppose your answer to that would make sense of what you're trying to achieve. If you want the brightness to stay the same, shoot in a controlled enviornment. If you want the same look as the office, realize first they are shooting with different cameras and lenses as Dan has pointed out. Then go research 35mm adapters. :)

I'm still not so sure what you're end goal is. If it's the look of "the office" you want or the technical aspect of it is what you're trying to grasp.
 
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