Controlling DOF while using flash

[LeeSC]

Let me preface this by saying I am flash (choose one!-handicapped, challenged, retarded).

I have typically shot in P mode with a little EC where needed. However, I was taking some shots of my children last night and noted an issue. P mode sets an auto 1/60 f/4 on my 24-105. Since my son was sitting closer to the camera than my daughter (12-16 inches), I could only get one or the other in focus due to thin DOF.

What is the easiest way to get a smaller aperture and increase DOF?

Thanks,
Lee

[Curtis N]

P mode with flash, indoors, will typically get you 1/60 with a wide-open aperture, so the exposure settings you got are exactly what I would expect.

Use manual mode.

Select the aperture you need for the DOF you want. Select shutter speed and ISO to get your desired ambient exposure.

[LeeSC]

Thank you Curtis. That was the direction I was leaning towards but wanted to defer to some of you as you have much more experience with flash!

[Jim M]

P mode with flash, indoors, will typically get you 1/60 with a wide-open aperture
No, not really. P gives you 1/60 at f/4 unless the lens is even slower than f/4. If your lenses are slow lenses with no more than an f/4 aperture, then you would get the wide open aperture, but if your lenses are faster than that, say f/1.8, you will still get f/4 in P mode with flash. The other exception is if there is too much ambient light for f/4. Regardless, as Curtis pointed out, setting the camera on manual is the way to go.

[Curtis N]

if your lenses are faster than that, say f/1.8, you will still get f/4 in P mode with flash.I just tried it with a 2.8 lens and a 1.4 lens on my 20D and got f/2.8 in both cases.

So I guess I was wrong. But so were you. ;)

[LeeSC]

I have been playing around too.

OK here is my issue. As I stated before, I used P which gave me 1/60 f/4. With the shallow DOF fully lighting the background really wasn't an issue. 1/60 is a decent handheld shutter speed with IS.

But, when I try to move to M I am getting very long SS (1/4ish). I understand that the light meter is trying to properly expose the backgound. Is there any work around for this or am I really missing something?

[ccp900]

you can try underexposing the ambient by 2 stops via the SS. Should raise your shutter speed by 2 stops and still let you catch some ambient lighting. The flash should take care of the foreground anyways.

so in this case lets say you were at f5.6 and 1/4 with the needle at 0 (full manual). You can then move to f5.6 f/15.

you can also put your camera on AV, set it to f5.6 and then use the wheel to EC -2. Same banana.

Oh and make sure your CFn in the camera allows you to move the settings when youre using flash. Theres a CFn there that sets your shutter speed to a static number when flash is activated.

[goatee]

Hi, when you shoot in full manual, only use what the camera tells you as a guide as to how the ambient light will affect the shot - then when the shot is underexposed, the flash will provide the rest of the light you need.

E.g. if you are shooting at an event with coloured lights, if you don't care about ambient light, but want to pick up some of the colours, shoot at around f/7.1 or f/8, which will limit how far the flash will light, and then up the ISO and slow the shutter speed to pick up more ambient light- e.g. ISO 400 and around 1/60s. However, if you do want the background to be lit as well, but don't want a narrower depth of field, crank up the ISO, and possibly slow the shutter speed as well.

I have been playing around too.

OK here is my issue. As I stated before, I used P which gave me 1/60 f/4. With the shallow DOF fully lighting the background really wasn't an issue. 1/60 is a decent handheld shutter speed with IS.

But, when I try to move to M I am getting very long SS (1/4ish). I understand that the light meter is trying to properly expose the backgound. Is there any work around for this or am I really missing something?