Wednesday, February 04, 2009

A note on studio camera settings

I've noticed some confusion about what camera settings to use in the studio with strobes, even among photographers who are competent outdoor photographers. You can get decent results despite a certain amount of confusion so people can go on for a long time without really understanding this stuff. Maybe you'll get a bit more noise than normal, or a little more post production, but it takes no longer to set the settings correctly as it does to set them wrong so you might as well learn something. (Update: Somebody thought I might have been talking about them specifically in that last paragraph - I was actually talking about me. Remember, I came at this from bird photography. When I started selling prints I was able to go back to my very first outdoor nude shoot and sell prints but when I later started doing studio work, the first half dozen or so studio shoots, ugh, better forgotten. My apologies for causing anybody any angst about this, however unintentional, the goal with a lot of these technical posts is to write down the information I wish I'd known years ago or to answer something people ask me in email so next time I can just point them to the post and that's really all there is to it.)

Note here I'm talking about where all the lighting is coming from your strobes and you want to get rid of any effects from light in the room. If you're trying to mix ambient and strobes that's another article entirely.

Put the camera on manual mode.

Set the ISO to whatever setting gives the least noise. Leave it there unless you have a darn good reason. Note that on some cameras the lowest ISO is not the best. As an example, on a Canon 5D the ISO 50 setting is a bit of a kludge and ISO 100 is cleaner and has better dynamic range. That's why you have to specially enable it. It's for extreme situations, like you're shooting a waterfall and want to give the water time to move and your lens is physically incapable of stopping down any more. If you're in the studio shooting at ISO 50 on that camera it's most likely a mistake. If you're trying to make the camera less sensitive because of ambient light concerns you should be looking other settings first.

Set the time to the x-sync speed of your camera (look it up in your manual). The time doesn't affect the exposure of the strobes (because they're shorter than that anyway). You want it as high as possible so you'll cut out as much ambient light as possible. 1/200 or 1/250 is pretty common for a SLR. Some of my cameras have lenses with leaf shutters that will sync at 1/500. If you have a crappy trigger system you might need to back off on this a bit - you can tell just by taking a few shots. If your setting is too high you'll see a black bar on one side of the frame. The worse your sync problem, the bigger the bar will be. Unless your room is super bright you won't have major problems even at a lower speed, but if you find yourself wondering why your shadows are noisy or just not very shadowy you should be checking this setting first. If you're using 1/125 or even 1/60 because some instructor told you to, that's because they were choosing something that would work with the crappiest camera in the room. Look it up for your camera and stick with it.

Set the aperture to get whatever depth of field you want. If you're doing a fashion headshot and you might want something really narrow with just the eyes really sharp. I usually want the whole body sharp. Another concern might be how you do/don't want the background to be sharp. If you have no idea, set it to f/8, that's a reasonable setting for most things. It will probably leave the model pretty sharp but the background a bit less so. Then adjust according to taste.

Set the light power to match those settings. (If you're just setting some random flash setting and changing your camera to match, you're letting random chance set your depth of field. It's the wrong approach.) You would usually set your main light to read whatever aperture you set in the last step, and any fill lights with some ratio from that. If you have a flash meter it's easy - you just change the power until the meter reads the right thing. If you don't you'll need to keep taking shots and checking the histogram. Don't use the picture - it's not accurate enough to tell you much. Note that some setups really have two mains - doesn't matter - the point is get the camera where you want it and then make the lights conform.

The big exception is that you might want the light at one extreme or another as a backdoor way to control its flash duration. With some lights they actually have shorter duration at higher powers which is a little counter intuitive. So you might want to crank the power and just let the depth of field fall where it may. That's fine, as long as you know what you're getting. I'll do this sometimes with jumping models.

A secondary exception is that if your lights are underpowered or you're trying to improve recycle time you can bump up the ISO a notch or two. That's usually better than changing your depth of field, unless you really don't care.

So there you go. It's not hard, it will give you control over depth of field and remove any ambient from your shadows, and it will keep other photographers from looking at your settings and teasing you. ;-)

Update: I actually wrote the above a couple of days ago and used Blogger's scheduler feature to postpone it. I do that sometimes if I have two unrelated things I want to talk about so they don't appear on the same day. (I forgot that this would appear the same day as the new studio shots above, oops). And then invariably what happens is I read what I wrote and I've thought of something new, sigh. Anyway - another interesting case is when you have studio lights outdoors. It's kind of the worst situation where the ambient light can be very bright relative to your strobes. And basically all you can do is the same as the flash duration trick above - max out the power, hope you're around f/22 or even f/32 if your lens can handle it (if you have a really powerful light here's a case where dropping to ISO 50 would gain you something, but only if you're still out past f/22. If you change it before the light's maxed out it won't gain you anything since both the ambient and the strobe will drop by the same amount). Anyway, if you look at the set with Daniela that's what's happening. Note on the full body shot you can see the ground she's standing on, and I think in a few shots you can just make out some leaves in the background. Obviously that could just be fixed in post processing if you're totally trying to hide the background.

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