Shutter speed - portraits

[mjcombe]

I've been shooting portraits against a hilite at 80th/s and I've noticed that on the odd one where a child is maybe not sitting 100% still that some have come out a little soft.
Using 5D MK II with an apeture of 7.1, should I be upping the shutter speed and would I need to adjust apeture or ISO to compensate?

Many thanks,

Michael

 

[chphotos]

Try to get to 1/125. You'll probably need to up the ISO or up the flash a little.

 

[Garry Edwards]

Shutter speed is almost irrelevant when shooting in the studio because it's the very brief flash that freezes the action (not the shutter speed), so setting the shutter speed anywhere between say 1/60th and the maximum that your camera will work at is going to give you a good result.

The only exception to this is if you have VERY high levels of ambient light - say sunlight streaming through a window - and you can test for this simply by setting up for flash and then taking a shot without the flash. If your digital camera monitor is dark then the ambient light isn't causing a problem.

In the absence of an example photo I'm just playing guessing games here, but my guess is that you have the lights in the Hi-lite set far too high and that this is causing flare, which you are mistaking for softness.

 

[mjcombe]

Thanks. I'm not sure it's flare as there are two children in the shot - one sitting down (older child - still, nice and sharp) and the other a toddler standing up which is the one that's a bit soft as she was wobbling a little bit. Looks fine on a small image but on a larger size it's a little more noticeable.

There was a little bit of ambient light coming from the window but next time I shoot I will have the hilite with it's back to the window, blocking out most of the light.

 

[elphesadente]

Are they the same distance away from the camera? Is this a dof issue?

I thought you had to have a faster shutter speed of say 1/60th otherwise you get the black line (shutter) across the photos?

 

[Garry Edwards]

Are they the same distance away from the camera? Is this a dof issue?

I thought you had to have a faster shutter speed of say 1/60th otherwise you get the black line (shutter) across the photos?

The black line (caused by the shutter not being fully open) occurs when the shutter speed is too high. The fastest shutter speed that will work has nothing whatever to do with the flash, it is mainly to do with the camera - a cropped frame camera will generally work with a faster shutter speed than a full frame camera simply because the shutter is smaller on a cropped frame camera, but a radio trigger that has a delay in the system will reduce the max speed that can be used.

It's worth remembering that the fastest speed that the camera manufacturer says will work may not work with studio flash - they are talking about hotshoe flashes that they make themselves - and it's also worth remembering that the shutter doesn't need to be set to its fastest speed anyway (unless there is a lot of ambient light present).

 

[mjcombe]

Are they the same distance away from the camera? Is this a dof issue?

I thought you had to have a faster shutter speed of say 1/60th otherwise you get the black line (shutter) across the photos?

Actually, this could be the issue - the toddler was a foot closer to the camera than the other child. Never thought about this at the time.

I will have to make sure that in future they are side by side or closer together.

 

[HoppyUK]

I'm thinking maybe DoF too - it's sometimes less than you think and f/7.1 isn't that high on a 5D2.

I can get clean images with my 5D2 at 1/160sec with studio flash and a radio trigger but 1/125 will be totally safe. For kids moving about, obviously reduce the ambient and switch off the modelling lights in the Hilight.

 

[mjcombe]

I'm thinking maybe DoF too - it's sometimes less than you think and f/7.1 isn't that high on a 5D2.

I can get clean images with my 5D2 at 1/160sec with studio flash and a radio trigger but 1/125 will be totally safe. For kids moving about, obviously reduce the ambient and switch off the modelling lights in the Hilight.

Thanks mate