Controlling DoF with available light

Lets say you are shooting the ceremony with no flash allowed, and you are using focal lengths between 50 and 100mm (+ crop factor). Shooting wide open seems like the first choice so you can keep the ISO down in the available light, but you will probably not have enough DoF for the bride and groom. What aperture, approximately (I know different situations call for different measures) would you use in this situation? f/4? f/5.6? f/8?

The wedding I am shooting next month has a bride that is obsessed with bokeh, so I know I'll be shooting at f/2.8 and below a lot, but of course during situations like the ceremony I don't think she'd be too happy with bokeh if it included her husband's face!

Your DOF will depend on aperture, focal length, and subject (focus) distance .. there are many online DOF caculators to help you there.

Hard to answer your question as a 100mm lens focussed at 5 meters at F4 will have a different DOF (and bokeh) than the same 100mm lens with the same aperture focused at 2 meters. The former would be more of a full shot where the latter would be more of a head shot.

So much depends on what you're shooting and how far away you are from what you're shooting. The answer will be different every time.
Mike

I do understand how DoF works. I guess with so many variables my question is indeed very hard to answer.

As with anything, it's a tradeoff. You have to decide on a case by case basis what you want to do... It ends up being a compromise between bumping the ISO, shooting wider (with the option to drop), and stopping down. I love shooting available light, and rarely find it to be a problem.

This is one of these things that I have tried to build up a "feel for" by fiddling with the online DOF calculators (you can also buy DOF charts, DEPSSI) and its probably something that an experienced pro just knows from years of experience that at certain distances and focal lengths he needs a certain aperture to get the DOF he wants.

You could always use the DOF preview button as your setting the shot up of course, although I always think its quite hard to see exactly what your getting with that but again if you use it a lot when practicing it can help you build up a feel for what you need for certain shots.

Thanks for the input guys. I'm going to be honest and say I've almost never used the DoF preview button, just because I always forget its there. I know it can be tricky to use but it might be helpful in the right situation.

If they are in the same plane you can get away with f/2 like this:

In a church where there is no flash allowed I usually need ISO 3200 but STILL a very wide aperture. I am trying to not go wider than 2.8 but sometimes even need 1.8.

I make sure I focus on the important.. the couple. If you need the light, you need the light so not much else you can do.

I shot at 1.2 on my 85 at the last wedding for a lot of shots and the pictures were totally usable (don't have it to show at the moment) -- just make sure that they are in the same plain and you are far back, as the closer you get the shallower your depth of field will be. And it can be nice to have just the bride or groom in focus for some shots, especially if you are off to the side and your getting the back of someone's head anyway. It will put more emphasis on your subject, especially if he/she is crying or something!

motogeno wrote in post #3036440
And it can be nice to have just the bride or groom in focus for some shots, especially if you are off to the side and your getting the back of someone's head anyway. It will put more emphasis on your subject, especially if he/she is crying or something!

For sure! But what I don't want, at least in most shots, is only one of them in focus and the other one just a bit fuzzy & soft.

Digitalwave wrote in post #3036461
For sure! But what I don't want, at least in most shots, is only one of them in focus and the other one just a bit fuzzy & soft.

Just make sure that you can get the shot to look like you meant it. You either get them in a similar plane so they'll both be in focus OR shoot from the side and take advantage of the narrow DoF by concentrating on an expression on 1 face. There's not a magic formula, you will have to use some judgement.