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Flash and meter exposure, Help! I had a bit of a dilemma this weekend. I moved up to MF. I bought a used RZ Pro II. Works great. But, I am totally new to this format. I almost want to sell it and just stick with my trusty 35mm that I know and love so well. But, I also want to branch out. So, I have been doing "studio" shots of friends, family, stuffed animals, and real animals (dogs) for free while I try my new camera out. On Sunday, I did an impromtu shoot with 2 friends. I had 2 Visatec 3200 stobes about 9 feet away (give or take) (this is the first time a used my RZ and my strobes together), one with a soft box (main at 1/4 power), and the other was bouncing light off a reflector for fill-in. Also was placed closer (maybe 7 feet) at 1/16 power. I have a Sekonic L-358 Flash Meter. Here's the problem... I was using a sync cord from the main strobe to get a reading on my meter. The problem is that no mater what shutter speed I would set on my meter, it would read f/8. So from about 1/15 to 1/1000 I shoot at f/8? It didn't make sense. So, I shoot one roll at 125, but turned up the strobe power. Of course, the meter read f/8 at 125. But, they were all overexposed. Then, I turned the power down, as cited above, and they were exposed perfectly, although the meter still read f/8 at 125, as well as every other speed at f/8, until I got below 1/15, then it would close down to f/11. Is this normal? Is there something more to this? Is this where the art of photography comes in? Or, was something wrong? I guess what has me second guessing myself, is I mostly shoot with available light. With available light, my meter works great and always provides the information I need such as the differing speeds and f/stops to use, and even averages them out for me (very useful) for a difficult subject. But, for the strobes, it just gave me the same answer everytime. I even turned off one of the strobes (the fill-in) and it didn't make a difference, although it made a big difference in the shots. I'd post them here for you folks to review, but I don't have 'em scanned yet. And, it's embarrasing to post overexposed shots. Thanks,
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Sorry! I forgot to mention that I was shooting with Fuji Provia 100 film. Jerry
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Flash is dependent on f-stop instead of shutter speed. So if you use a flash meter, and get a reading of f/8 with 1/30, you're still going to get a reading of f/8 even if you set it at 1/250. Now turning up the power should give a different f-stop reading. So I have to ask whether you were holding the meter in such a way that when you got a reading, you may have been blocking the fill light with your body, and only reading one light? Because depending on where you have your fill light, you can still get some from that light spill on to the areas lit by the main. Second is if you had the main light sync to the flash meter to test, was the fill light firing? An easy way to test your meter to make sure it's working properly is to use one light, and just take different readings by moving it closer but keep the power level the same.If you keep getting the same reading at different distances, than you have a problem with the flash meter.
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Thanks Gregory. I moved right up next to the bulb intermittently firing the main as I got closer, and I kept getting the same f/8. So, I may have a problem with my meter/flash. Since my meter works fine in other applications, I suspect something is wrong with the flash units, or the sync cord. I suspect I may have been blocking the fill light as I was taking readings. I noticed that later on in the shoot - duh! Maybe I understand the concept that the flash is not dependant upon the speed of the shutter, but rather the f/stop. But, then how do you determine shutter speed; shutter speed and aperature are totally dependent on eachother? I'm going to attempt an answer before you give me one...I bet it has to do with EV. So, if my meter says I should shoot at f/8, I can use any speed I want that corresponds to the f/8 EV along the Ev table. Is this correct??? My exposure meter also has an EV function. When using flash, should I just use that? Jerry
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
When you ask how do you determine shutter speed, I'm not sure if you're asking me why shutter speed dosen't really matter with flash or something else you're asking me. You have to set the shutter speed at or near the sync speed when using flash. Set it too high and the shutter and curtains in the camera start to close too soon in relation to when the flash goes off, and you get a dark line that didn't get exposed from the flash. You can set the sync too low, this will get exposure from ambient light. Depending on how bright the room lights are and things like that. If you meant coming up with the shutter speed with ambient light you can send me an email if you'd like. EV values are about how much light in ratios and not necessarily specific f-stops. Like if you set the meter on EV at a certain film speed. If you go outside at 12:00 noon, you'll have a higher EV than if you went back out at 6:00. And I've seen EV used to explain a good way of using fill for backlighted subjects. Because you can't know what film somebody is going to use, or even how bright it's going to be, some people use EV to explain a good way a taking a picture. For example. Somebody asks what should they do to get a good picture with the sun behind the subject. Because you don't know what film they are using, what time of day, cloudy or not, you can say that you have to use fill light so that the light on the face of the subject is 1&1/2 EV less than the sunlight, then exposed for the fill light. So as long as you use fill light that is 1&1/2 Ev less(or 1&1/2 stops less) than the sunlight, and then you expose for the fill, you'll get a nice looking picture. So if somebody shoots a back lit person with a reflector to add fill light, if the fill is 1Ev less than the sunlight, and you expose for the fill, it will look too dark. If the fill is 2EV less than sunlight and you expose for the fill, then then difference between the fill and the sunlight will make the sunlight look to bright, and it won't look natural. So because you can't know if somebody is going to shoot middle of the day when it's brightest, or evening, or film speed, Ev is used to explain how whatever the correct exposure is, if you have light in these ratios relative to each other, you'll get a nice looking picture. I guess an analogy would be like having things balanced on something. Regardless if you have 20lbs or 200lbs on one side of something, if you don't balance it on the other side, it's not going to work right. I hope I helped you. If not send me an email and I'll see if I can explain it better.
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The sync speed on my Mamiya is anywhere from 8 seconds to 1/400 of a second. So, I don't know where to set my shutter speed. How do I figure that out? On my Canons (EOS 1V's), the sync speed is 1/250, so that's easy, depending on what I'm doing. Jerry
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Sreedevi Kashi |
Jerry, did you plug a slave into your other strobe while metering? I just wanted to make sure- that's the first thing I thought of. But of course, both strobes went off when you were shooting, right? The Mamiya, like the Hasselblad uses a leaf shutter, so it doesn't have the same type of sync speed that your 35mm SLR would have- which has a sliding shutter. That's why you can sync at any speed. A leaf shutter opens as if a flower were blooming- I don't know how to describe it, but it can be pretty even on the picture, and doesn't show vignetting, where as a slide shutter, like what Gregory mentioned above, will slide open from side to side, so it's not getting evenly lit with the flash- which fires the second you click and just for that moment. But after you meter, you can look at your readings in either shutter mode or f mode, and as you change the shutter speed it's still going to change the aperture value- metering is for all cameras, regardless of what kind of shutter they have. It doesn't change as far as the meter is concerned. I would first decide what F/stop you want- I assume since it's in a studio and with people, you could go as slow as 1/60 as people can move. You said you were shooting at 1/125 of a second. It seems like Gregory was talking about a different set up than the one you described. He's describing a scenario in which your subject is backlit and you need to use fill flash on your subject. For that, if you were shooting 1/125, then you'd go out and take a meter reading of the background of the subject at 1/125. Whatever your f stop is on your background is what you're going to try to get your reading to be when you read the fill flash on your subject. So if the background is at F8, and you take a reading with the flash on your subject and it reads F16 at 1/125, then you'll want to turn down the power of the flash until it reads F8 on your subject. So you're taking a reading in two different places. And if you want to make the background to make it either lighter or darker, you'd change the shutter speed, but as long as you keep your Fstop the same, your subject, will be lit properly by the flash. For what you're talking about, it seems to me that both of your strobes were in front of your subject- one about 7 ft. away and one 9, right? Did you make sure the bulb was out on the meter, and that you meter close to your subjects? Also, which setting on the meter were you using? There are two flash settings- one for when you connect to the strobe, and one for if you're not connected to the strobe and you want it to take the reading when you set of the strobe yourself. So if it was on the wrong flash setting, then I could see it always saying the same thing. It could have just been reading the ambient light that way. Although using 100 speed film at 1/125, I doubt you'd get f8 inside, unless there were a lot of lights on. I don't know, but I thinking maybe you didn't attach a slave to your other strobe when metering, or you had it on Fstop priority in the flash mode, which is tricky, or you were in the wrong flash mode, which could be it, because in the other flash mode, you press the metering button, and it waits for you while you go set off the flash, then you can come back and see what your reading is. If it was set there, then probably what was happening was everytime you pressed the button, the flash would go off, because of the sync cord, but the meter may have been catching the tail end or not catching at all the flash. If you have questions let me know, because there are many techniques used with the flash, and they are dependent on both the shutter and aperture settings no matter which type of shutter your camera has. And your meter is just reading the light and giving you a value based on your fstop- or shutter speed- ISO, and the light itself. It would always be the same. If you get a reading and change your fstop, your shutter speed will change. If you move the light farther or closer, you meter reading will show differently depending on which priority mode it's in. People use drag shutter, which is exposing at a longer shutter speed than what you metered for (or what your camera is synced for if it only syncs at one speed). What this will do is, the flash goes off at the beginning of the picture, freezing your main subject. Things in the background will be shown in movement, however, or if the background is darker, it helps to lighten it up. Ok, good luck, and let me know if you have any more questions, or if you figured it out.
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Thanks Sreedevi. What you're saying is different than what Gregory is saying. So, I'll clarify. When I plug my sync cord into my meter, I only have one option, that option is to measure the aperture. I do not have the option of measuring shutter speed. This is what is frustrating. To answer your question, both units were firing. The main was attached to a sync cord, the other was firing as a slave. Everytime I fired the units, and they both would go off, I would get a reading of f/8. I think what Gregory described is probably correct. I need to use the sync speed of 1/400. Then, what should occur is at f/8, 1/400 of a second, I should thoretically get a perfectly exposed image. Now, if I want to pick up ambient light or do something a little different, I could use a slower shutter speed and open up the aperture...that's up to the creative process...but, I'm not there yet. I did take an ambient light reading too, and it was very low 1/15 at f/1.0. And, my meter was correctly telling me that all the light was coming from the flash. I checked the manual that came with my meter last night, and it verified what Gregory had said, when measuring flash, you only get the aperture reading, then you set your camera at it's sync speed. I believe the creative process allows my to mess with that, but as I said, I'm not there yet. I'm just working on getting a perfectly exposed image first. Once I have that down, then I'll move on to other things. Thanks for your input. If I seem to be missing something, please email me. Thanks
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