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Of Shutter Speed and Flash Photography
This seems so obvious that I wouldn't mention it . . . except that it has come up four times now, including twice with people who make their living doing photography. When shooting with studio strobes, the exposure has nothing to do with the shutter speed! OK, I know that's a bit of an overstatement. The shutter speed has to be slow enough to sync with the studio flashes, and the ambient light has to be small with respect to the exposure from the flashes. "Nothing to do with" isn't quite accurate. But for practical purposes, it's close. Four times recently I have had photographers in the studio tell me that if their exposure is off when shooting studio shots with strobes, all they have to do is change the shutter speed to fix it. Happened again this last weekend, when a working pro told me, with a straight face, that if I were to go from 1/200th of a second to 1/100th, my exposure would go up one stop. And we were shooting with his Profoto flashes. No. It doesn't work that way. Really. Shutter speed is one of the ways you can use to control exposure when shooting with ambient light or continuous light sources. Not for flash. Doesn't work the same. Again, I apologize for all the very many of you who are scratching their heads and wondering why this even needs to be said, but urge those of you who are scratching your heads wondering why it doesn't work to actually try it and see what happens. Edit: This thread is not about ambient light, shooting outdoors, shooting in a studio with big windows, or any other situation in which continuous light sources are a substantial part of total exposure, whether deliberately or not. Yes, we all know ambient light can be mixed with flash. If someone feels the need to tell us still more about how to do that, please start another thread. It is off topic for this one, since it just dilutes the message to where it will not be understood by those who need to receive it. Oct 18 08 11:22 am Link Been one of those weeks, TX? Oct 18 08 11:27 am Link Yeah, You want to shoot within 1/100 or 1/200 that's it for strobes. The industry average is 1/125 Oct 18 08 11:27 am Link I remember learning this lesson. I was in a studio lighting with strobes workshop many years ago with experienced pros. When it was my turn to shoot I asked what shutter speed they there using because all we had talked about was F-Stops. They all laughed or smiled. The instructor was gracious enough demonstrate the concept to me rather than publicly flog me. Oct 18 08 11:28 am Link HAHAHAHAHAHA! That's a good one! But, I think I can top it. One time, I saw a photographer send her assistant across the street to the shady side a block away with a hand held reflector. Oct 18 08 11:33 am Link Try this one. Ask the guy what his sync speed is for a leaf shutter. ;-) Oct 18 08 11:34 am Link It might be well noted that shutter speeds do have a significant effect outside, when using strobes, in order to control the ambient light. Frequently, you can "cheat" the sync speed a little. So you see, no generalization is worth a damn! lol Oct 18 08 11:36 am Link As in "All generalizations are false"? Oct 18 08 11:44 am Link Art Schotz wrote: TXPhotog wrote: Sigh. Oct 18 08 11:44 am Link Art Schotz wrote: TXPhotog wrote: TXPhotog wrote: lol. Try not to get too frustrated. There are those of us that are paying attention and learning from this. Oct 18 08 11:55 am Link While your statement is generally true, there are a few exceptions. Any decent wedding photographer knows that "dragging the shutter" (setting the shutter speed to, say, 1/60) will allow some ambient light to warm/fill the frame in addition to the 'pop' you get from the strobe. When I shoot a model standing in front of water, such as a pool or a pond at the golden hour (sunset), I frequently will bounce the flash into a gold reflector to get the bright 'pop' of strobe light on the model, but I want to the water to burn more into the frame ... so I will intentionally slow the shutter speed down (1/60 or 1/30) to get the rich colors off the sunset reflections on the water. Also, when shooting at night, sometimes I will shoot time lapse with a strobe flash during the exposure. This works great, for instance, when you want to catch a trail of taillights on a curvy road, followed by a 'pop' from the flash to illuminate the entire car at the end of the trailing taillight stream. I occasionally also shoot at midnight on the beach ... using the full moon with a 4-6 second exposure (makes the sky light up and the water look awesome). During the open shutter, I will fire a strobe by hand to illuminate a model standing in frame. All of these examples use ambient light in concert with artificial (strobe) light ... and therefore shutter speed DOES matter. But when your strobe is brighter than your ambient light, and the strobed subject fills the frame, then your point is completely correct ... shutter speeds are irrelevant as long as you are within sync speed range. Oct 18 08 12:11 pm Link RichBruton wrote: TXPhotog wrote: Sigh. Oct 18 08 12:17 pm Link Yeah, it's definitely one of those weeks for you, Roger. I'd send over doughnuts if I knew a bakery that would deliver to you. Oct 18 08 12:23 pm Link TXPhotog wrote: All very nice replies, but wouldn't "studio" be one of the key words here? Oct 18 08 12:24 pm Link M W Photography wrote: That is the intent, although those determined to find "exceptions" will point out that "studio" lights can be used outdoors, or in the studio in conjunction with ambient light . . . all of which misses the point. Oct 18 08 12:30 pm Link I've had similar discussions with "professional" photographers who will swear blind that it is the focal length of the lens which affects perspective, and not one's point of view. It's fun up to a point, but I normally eventually reach the stage where I just shake my head and walk away. Oct 18 08 12:36 pm Link RickMartin wrote: I'm wondering if there could not be a "misconceptions about photography" thread in here somewhere . . . . Oct 18 08 12:38 pm Link cassios co wrote: Not with leaf shutter film cams it's not..nor with Nikon strobes and Nikon cams..probably equally false with Canon's too. And then there are all thso e P&S cams that defy the sync generalization too. Oct 18 08 12:42 pm Link R Michael Walker wrote: The important point being: know what your particular equipment's sync speed is, and don't shoot at shutter speeds above it. If you shoot at shutter speeds at or below the sync speed, the exposure from the flash won't change. Oct 18 08 12:47 pm Link TXPhotog wrote: it does work that way to a degree. if you are dealing with ambient light, changing your shutter sped like that will increase your ambient by a stop. Oct 18 08 12:48 pm Link And so it goes... just because someone can afford triple digit or quad digit prices for a camera body doesn't mean that their IQ exceeds double digits. Then again, I can probably bring them to the point of a mental seizure by pulling out one of my SBs, putting it in CLS mode, and then shooting at 1/2000 of a second! Oct 18 08 12:48 pm Link TXPhotog wrote: it might.....i have noticed an issue with not being able to achieve max sync speed, because of using a radio slave...in theory, it makes no sense to me, but in reality the radio slave it making sync slower. strange! Oct 18 08 12:49 pm Link Ethereal Pixels wrote: i could do that with a profoto or broncolor strobe. Oct 18 08 12:52 pm Link Its frustrating isn't it? Its amazing how persistent ignorance can be.. I've almost pulled my hair out over similar discussions on the inverse square law. Oct 18 08 12:52 pm Link Seattle Photo wrote: No, actually, it won't, unless the contribution to total exposure from the flash is very small. Please go back and read ALL of the original post. Seattle Photo wrote: See above. There are a VERY SMALL number of equipment cases - a trivially small number, for this purpose - where there is a relationship between shots at max sync speed and exposure, but even for those, it is NOT TRUE that shutter speed can be used to control exposure, yielding a one stop difference in exposure for a one-stop change in shutter speed. Oct 18 08 12:52 pm Link J. Stakeman wrote: Me too. Until on a discussion here I was shown to be wrong in my own understanding of it. I had always assumed that since the "point source" assumption was violated when using soft boxes, the inverse square law would not work in the studio. A nice person pointed out that it still does work (give or take a little margin for error), I tested it, and he was right. Oct 18 08 12:54 pm Link TXPhotog wrote: Seattle Photo wrote: No, actually, it won't, unless the contribution to total exposure from the flash is very small. Please go back and read ALL of the original post. um, yes it will. Oct 18 08 12:56 pm Link Hmmm... I might get to the point of pulling out hair because of the "photog" who thinks that image perspective is dictated by the lens focal length! Fortunately, I've got better sense than to do that since I'm happy with my full head of hair and don't want to lose it. Oct 18 08 12:57 pm Link Hi budddy. Got a match? Wooden prefered. Safety tip. Boxed. Now. lol bt Oct 18 08 12:57 pm Link Seattle Photo wrote: With what camera? Oct 18 08 12:58 pm Link you are right but not fully ... try drooping it to 10 sec exposure .. bet you your pic will look different from 1/200 hehe it doesn't play a role (big role) with the stobes but you still have ambent light all around you Oct 18 08 12:58 pm Link TXPhotog wrote: with none .. all strobes sync at 1/250 max Oct 18 08 12:58 pm Link TXPhotog wrote: sure it does. it's just that the front of your softbox is the source of the light now for that equation and the light head is the origin Oct 18 08 12:58 pm Link GSP - Envy wrote: So you have missed the several comments, including the one in the OP, about ambient light? Oct 18 08 12:59 pm Link GSP - Envy wrote: either you are joking or just ignorant Oct 18 08 01:00 pm Link GSP - Envy wrote: Wrong. Sync speed is a function of the camera, not the strobe, and there are many cameras with sync speeds higher than 1/250th. Oct 18 08 01:01 pm Link TXPhotog wrote: i jumped the gun Oct 18 08 01:02 pm Link Seattle Photo wrote: TXPhotog wrote: Seattle Photo wrote: Of course it "will affect" ambient exposure. What it will NOT do is make a one stop change in exposure based on changing the shutter speed one stop, unless the contribution to the exposure from the flash is very small. Oct 18 08 01:03 pm Link Seattle Photo wrote: i should have said "on my camera" Oct 18 08 01:03 pm Link TXPhotog wrote: Not everyone reads the whole thread on MM. Oct 18 08 01:05 pm Link |