Sekonic L-358 q. about flash mode

I've skimmed the manual a few times. Just got the L-358 meter in the other day and have been playing around with it a bit today.

When metering for flash in cordless flash mode, it appears that I can only use the meter in shutter priority. Am I correct? Why is this? I understand that the sync speed is 1/200 or slower with my camera.

Thanks

It's for just that reason. So that you can set sync speed, because it's different for different cameras. If it were aperture priority, it might set a sync speed faster than your camera will allow.

See?

You will find that it doesn't really matter what shutter speed you choose when metering studio flash lighting. That's because the duration of the flash is MUCH faster than any usable shutter speed. Thus, the shutter speed really has no effect on the flash lighting exposure.

The only thing that CAN happen if you use shutter speeds that are too slow is that ambient lighting can start to have an effect on the image in addition to the flash lighting.

Thanks for the replies. One more question.

I notice there is a percentage that shows up during flash mode. This is the percentage of the total light that is coming from the strobes, correct? So flash% + ambient % =100%, right?

How is this number useful to me?

Are there any tricks that can be used when mixing ambient lighting and strobe lighting? Should I take an ambient reading, then a strobe reading to come up with a proper exposure?

Thanks!

I can't imagine much of any ambient lighting having any effect on your exposure. The strobe is extremely bright, and will overpower most any ambient. Just make sure you're near your sync speed so that it will have the least effect.

Because aperture controls the flash exposure and shutter speed controls the ambient exposure. If you are wanting ambient light in your photo, you must meter the ambient light first and then set the flash power to achieve the amount of over/underexposure of the background you desire.

Hmmm...I will have to do some testing on this tonight. I still don't have my mind wrapped around this concept.

lhoney2 wrote in post #2852693
Hmmm...I will have to do some testing on this tonight. I still don't have my mind wrapped around this concept.

Do you have any studio flash equipment, Lonnie?

You will not be able to experiment with this sort of thing using a Speedlite connected to your camera unless you put both the Speedlite and the camera into fully manual mode.

Yes, I have two 100 w/s strobes, operating as optical slaves. I use the camera on manual, and set my Sigma 500 DG ST on Lo (1/16th power) to trip the slaves. Also have a few 250W photofloods. I don't have a PC cord adapter for my Rebel XT yet, but I will probably end up picking one up and some cheap radio slaves at some point. Hadn't really thought too much about how complex the lighting could be using ambient and strobe lighting simultaneously, but it makes sense.

I should note, the strobes are somewhat directional, using umbrellas.

Since we are dealing with two exposures, flash and ambient, that are on top of eachother...what happens when something is hit by flash in the first 1/700th of a second or so? It's exposed by the flash. What happens when that same object continues to be exposed for another 1/30 sec? Does is become more exposed, or is the first exposure unable to become more exposed because of the relatively dim ambient light? This kind of reminds me of when I would paint a tree with a flashlight on a long exposure.

Does anyone use the % indicator on the flashmeter?

Apologize in advace if my thoughts are unclear.

Thanks!

I could think of a scenario that the % indicator of the flashmeter comes into play. Keep in mind that all the numbers are made up in my head in thie example.

We are shooting a model, afternoon daylight and in the shade. After metering and frew test shots, we have a good exposure with 1/100, f8 on the camera, and 1/4 power on the flash for fill, and the L358 shows the flash contributed 50% of the overall exposure.

On the next shot, we want the same aperture for DOF but a more dramatic look by using more fill light. So we increase the shutter speed to 1/200 and underexpose the background, then we adjust the flash power ouput till we have f8 on the meter, in this case, lets say we end up with flash at 1/2 power and meter % says 75%.

Couple days later we return to the same location with a different model, and need the same dramatic look. But now it's 2 hours later into the afternoon and ambient light is different. So the shutter speed and flash output need to be adjusted accordingly, but the 75% from the flash is a good reference point.

Lotto -
Reading your post made me realize that when dealing with flash, you cannot use your camera creatively like you can with ambient light. I'm so used to being in situations where the light can't be changed, so I use shutter speed/aperture to adjust exposure.

With flash, especially if you want to maintain creative control over DOF, you HAVE to either change the output of your strobes, move them, or diffuse them.

Might seem simple to some, but it took me some time. Thanks for the input.

The % display is very significant and important in creative control. I use it all the time, and its important when shooting where you are using flash, but also where you want some available lighting to be used in the exposure. Lotto and lhoney2 touched on it briefly.

The shutter speed is significant even with flash. Once you have all your lighting down pat in your next studio shoot, adjust the shutter speed to 2 seconds, and watch what happens to your image. The modeling lights will also be recorded and vary your exposure significantly, and probably overexpose your whole image. It can also change your color temperature and give you odd color shifts.

Where this really comes into creative play, in one example, is shooting in the city at night. You set your flash at say f5.6 (or whatever) to get the exposure you want on the subject by the flash. Then also set your shutter speed at your cameras sync speed, lets say 1/250. The image will show a mostly black background, while your subject is exposed properly by your flash. Many people stop here, getting a properly exposed subject, but a lackluster background.

To add more creativity to your image, instead adjust the shutter speed to a slower value to let in more amibient light which exposes the background more. Keep adjusting this slower and slower until you get the look you want, or you start to see image blur. At some point you will have the foreground flash adjusted properly with the f-stop, and the background ambient light adjusted properly with the shutter speed. The results are sooooo much better with this balanced lighting, than with a very dark background void of any details.

The % display tells you how much of the exposure is based on the flash. If its 100%, then all the exposure is coming from the flash, and anything not hit directly by the flash will be black. If its at 50% for example, you are getting half of your exposure from the flash, and the other half from some sort of available light.

Here is a good example to help illustrate this;

HTTP response: NOT FOUND | MIME changed to 'image/gif' | Redirected to error image by FLICKR

HTTP response: NOT FOUND | MIME changed to 'image/gif' | Redirected to error image by FLICKR

Great post and example shot Stephen, I appreciate the time. You answered my question about what happens to the flash portion of the exposure once you lengthen the shutter speed. Your photo illustrates the concept brilliantly. The subject is sharp and well exposed while you still get a good exposure on the train, and even get to show motion. Awesome.

I noticed you picked a number off the top of your head, 1/30. I guess you could do what bluebomber suggested, take a meter reading at the track (before the train comes) for your shutter speed, then take a flash reading on the subject.

COOL. And what a pro looking shot that is.

I picked 1/30 based on my memory of what I thought that image might have been taken at, and an educated guess based the typical lighting I encounter in the subway. But yes, you are right you could meter the flash, then meter the background as well to get your proper background exposure.

To save time I usually set the aperture I want and use ETTL on the flash, then I just change the shutter speed until the in-camera exposure meter gives me about 1 stop underexposed (usually where I like to place the ambient vs a 0ev exposure). Takes about 15 seconds, and a lot less running around metering, changing modes on the meter, etc. If I use manual mode on the flash, I just dial it in with a couple test exposures.

If I am doing more complex lighting setups, then I'll use the L-358 and make good use of the % flash display.