Issues with shutter or flash kit when shooting studio shots?

I was wondering if someone could offer their advice. I'm kinda new to studio photography but I've been having an issue that has really been perplexing me.

When in studio I've been shooting ecomm shots of a model (using a 4 flash set-up). My issue is that sometimes when I take a shot it's properly exposed, and sometimes it looks a step or more down. My lights and model don;t move at all so I'm pretty sure that's not the issue. Does that preclude that the issue is my shutter? It's only at about 1/3 of what the shutter is rated for...
The camera is also 4+ yrs old, but I have had it cleaned a few times.

Any suggestions on what I should do?

What are your camera settings. You need to be on manual, shutter set at 1/200th, ISO at 200 and aperture set at what you meter for. If using a 4 light setup than i'm assuming you have no ambient contribution to the image so shutter wouldn't matter at all. What kind of lights do you have. Not saying you do but cheap lights will give you these results.

I'm wondering if one of the flash units is not firing every time? If a pro, the model may notice.

chriszac said:

When in studio I've been shooting ecomm shots of a model (using a 4 flash set-up). My issue is that sometimes when I take a shot it's properly exposed, and sometimes it looks a step or more down. My lights and model don;t move at all so I'm pretty sure that's not the issue. Does that preclude that the issue is my shutter? It's only at about 1/3 of what the shutter is rated for...
The camera is also 4+ yrs old, but I have had it cleaned a few times.

Any suggestions on what I should do?

Click to expand...

I assume your camera is in Manual mode, and aperture is not changing.

Turn OFF Auto ISO. The manual lights cannot adapt to ISO changes. You should see that in your Exif.

It is not the shutter, flash exposure is independent of shutter speed (the flash is faster than the shutter).

If you are shooting too fast, before the flashes can recycle to Ready, that would be a problem.

One flash not triggering could be a problem, but you should see that lighting change.

It is most probably a flash cycling problem, especially if the power pack is old.

You may also be a victim of light flicker if you are using flood fill lights. Unless the lights are led or have high frequency chokes, the shutter may be firing just when their intensity is lowest.