Flash range for daylight fill

<p>I would really appreciate help to calculate what range a 580exii would have in the following situation:</p>

<p>- Open area, group shot of 8 people, in the mid afternoon with sun at their backs (background around EV14). Not sure what their faces would be with sun behind them, EV12 maybe?<br>

- Crop sensor 60d with 70mm lens</p>

<p>Can it be done? Can I get far enough away to fit them in and still have the flash give me enough light? I'm not sure how to calculate all of it - see below.</p>

<p>GN at 105mm is 58(m). At 1/250th and f/8 that's 7.25m. At 1/500th and f5.6 with HSS its... what...?! I guess its better just to stop down instead of use HSS in this situation?</p>

<p>But that's assuming I need all the light from the flash when they're already lit by ambient as well. So if the group was at 7.25m, instead of full power would I need what? 1/2 or 1/4 power to bring up the group to something nice? If half power that would give me about 10m range?</p>

<p>Would it just be better to find a darker [shaded] background?</p>

<p>Any chance you could do some test shots ahead of time? That's one of the great benefits of digital, being able to test settings and see results immediately. If it were me, I'd just put the camera on P and leave the flash on auto and shoot.</p>

<p> </p>

<p>I agree with Bob - maybe put the meter on center or spot</p>

<p>Trial and error -- meter for the background and underexpose it, set flash output to +1 compensation, season to taste. In short, dial exposure comp down and flash comp up.</p>

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<p>Open area, group shot of 8 people, in the mid afternoon with sun at their backs (background around EV14). Not sure what their faces would be with sun behind them, EV12 maybe?</p>

 

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<p>I don't know how you can know this until the actual time of the shoot. However, if you are dealing with bright sun, no diffusion, your contrast ratio will be much higher than that. And no, a 580 isn't going to cut it at that point. A shoe mount flash is maybe 80w/s. To over power sunlight you need at least 600w/s. So I don't see how you could underexpose the background and then use a shoe mount to light the group unless the sun is really cooperating with you that day (let me know that works out ;) ). I would tend to agree that HSS isn't going to be your friend for this type of shot. At best, it is OK when you can get the flash much closer to your subject, but I am amazed at the amount of power you loose going into HSS. And again, that is dependent on what the ambient light is doing that day.</p>

 

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<p>Would it just be better to find a darker [shaded] background?</p>

 

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<p>Probably. Also keep in mind that if you can give yourself some height and shoot down, this can avoid the skys EV. Or use a longer lens (compressing the background) and find a "darker" background with your subjects in the light (assuming you can use your flash off camera).</p>

<p>It depends on what kind of picture you want to make. If you want the bright sunlit bits on people's backs to be fully detailed (may be important if photographing a bride with a veil on), full power from your 580EX II will not help you, since sunlight exposure is ISO 100, f11, 1/250th. If using a 70mm focal length on a cropped sensor lens for a full length group shot of 8 people, your subject distance will probably be more than the flash can accommodate at f11. The one thing you can do in this situation is move closer, use a wider focal length, like 35mm and wider, and you might have enough at 1/1 to fill (not full exposure) at a subject distance of about 12 feet.</p>

<p>If you are letting some of the sunlit bits blow a bit, things get better. Even with weddings, I let the sunlight go by up to a stop. Some people let it blow even more. Some of this depends on just what bits are sunlit. If pretty much backlit, you can blow quite a bit. The more the sun comes around toward faces, the less you can blow without it seeming to be a mistake.</p>

<p>Seems you already know how to figure the flash exposure, so figure it out. Test it. My question is--why are you using 70mm (112mm) for a group shot?</p>

You could use the flash units off shoe on stands or held by an assistant, thus getting close enough to balance the

backlight.

<p>HSS cuts the flash unit's range, particularly as the shutter speed rises, because much of the light reflected by the subject ends up hitting the shutter curtains. So it's useful over a short range, but otherwise, you're usually better off if you can find a way to keep the shutter speed low enough to use normal flash (which obviously will depend on things like how much ambient light there is, what ISO you choose, and any constraints on aperture based on your needs for DOF and background blur).</p>

 

<p>Sorry that I can't really help you out more with this, but others have contributed a fair bit of additional information so hopefully that's just about covered it.</p>

<p>Ben, I know of at least one wedding photographer who would set up "clothes horses" to do test shots with under different lighting conditions and whenever a new piece of equipment was purchased. He kept meticulous notes so that he could be reasonably sure of exposure, flash settings and distances. This was in the days of film, when there were no preview shots, save for polaroids, and no second chances.</p>

<p>One of these props amounted to nothing more than a portable coat rack with a hat on top, a suit jacket and pair of slacks on hangers dangling from it.</p>

<p>My suggestion would be to take a series of test shots on location or under similar conditions and make notations anytime you are working in unfamiliar territory (or equipment), this way when the day of your shoot arrives-it won't be as daunting an experience. Best of luck-</p>

<p>Randall</p>

<p>I am not going to go into the maths and the Guide Numbers – as mentioned Ben seems proficient in working out the theory to ratify these comments: but I shall just note a few in the “in the field” working parameters which I use.</p>

<p>Yes - at the Scene EV = 14 (light overcast sun) the EV on the shadow side of a back lit face will be about 2 to 2½ stops less, so EV ≈ 12.<br /><br /><br />Outdoors in Full Sun, Backlit - we have working distance about 12ft of “totally flexible” Flash Fill with a 580 (or 580 MkII).<br />We can push that out to about SD = 15ft with a bit of cloud cover and if we do not want total flexibility across the range of Flash Fill ratios - for example, if the Flash is just a touch up on the faces and most of the exposure is to be from the ambient.<br /><br />But as the ambient exposure becomes the more dominate exposure for the “In Shadow” faces – the background becomes more towards blown out. That might or might not be what you wnat. Especially the side, top or back light on the hair might blow out – Blonde hair can blow out easily - or as mentioned by Nadine the <em><strong>Detail</strong></em> of the Veil or Gown or Train which is illuminated by the Backlighting.</p>

<p>In your scenario, with a 70mm lens on a 60D at SD = 7.25 mtrs (24ft), we are framing a ¾ Shot.<br />I ask the same question as Nadine, why a 70mm lens?<br />To pull that shot, I would use a 35mm lens at SD = 12ft and have much more flexibility with the Flash Fill.<br />Actually, I would likely use my 24mm lens and shoot at SD = 12 ft, such that I had a Full Length Shot of the group of 8 and a wide flexibility within the Group’s Arrangement - and I don’t really like ¾ Shots anyway.<br />Alternatively, SD = 12ft, with an APS-C camera: a 50mm lens give an half shot for a group of 4 to 6 people.<br />(These are referencing Landscape Orientation).</p>

<p>WW</p>

<p>Why 70mm? Inexperience? :) I "know" I'm "meant" to use a "longer" focal length for group shots to get the proportions all right and though that would mean 70mm. I can easily go to 24 or 35mm...</p>

<p>I'm trying to figure out where to do group shots, and unfortunately haven't been able to have a look at the venue at the correct time of day (could only go earlier), and there are trees etc around. I wish I had the experience to know what the "best" way is... </p>

<p>Alternatives to above are to use shaded greenery as a background (which actually looks like it could be tricky to find), or let the group be lit by sunlight coming at about 30 degrees from their side. (Sun would be quite low in the sky about 15 degrees above the horizon at this time of day according to calculator - about 1 to 1.5 hours before sunset).</p>

<p>Still trying to figure out how to pose groups of up to 14. Don't want to do a straight line, but not sure that using chairs is getting too complicated for me just starting out. Just pack them in with some people partly behind others, some kids in front. Kind of like my own wedding photos by a pro... Or use some wide stairs - which are going to be sunlit by low sun coming in from a bit forward of sideways (about 30 degrees)...</p>

<p>A real wedding photographer would just know in about 2 seconds of looking at it. But I'm not! Nobody has rubbed it in yet, but please don't start... Having said that I've see pro shots from the same location with groups in mixed lighting (about 1/3 of the group in full and deeper shade than the rest of the group...)</p>

<p>The easiest re exposure is even shade or backlit shade (no dappled sun) because you don't have to compensate for big contrast between sun and the shaded parts of subjects. If you can't find that, because it can be difficult since the whole group has to fit in it, then backlit sun with fill flash on the shaded parts. This is where you pay attention to how much you are blowing the dress, veil, and blonde or white hair. Unfortunately, we can't make recommendations, not seeing your actual locations.</p>

<p>The worst--dappled sunlight or bright sun from overhead. Even sun used as key light is easier (all you have to do is use fill flash to raise the shadows up). The only thing is that people will squint. Hatchet lighting is not difficult, just ugly, as is bright sun from directly overhead. Dappled sunlight--you never get rid of the dappling. If you do, you've probably nuked the subjects with flash and the pictures will look like you took them at night.</p>

<p>Unfortunately, wedding photographers also deal with last minutes changes and requests/demands, such as the client telling you that you have to do the photos 'right here' or they won't do it--Grandma can't walk that far (to your chosen spot). Or other similar reasons why you have to think fast on your feet. So while planning is good, you need to be able to handle many different lighting situations--quickly.</p>

<p>Chairs can be easy to do if you a) have enough chairs and b) do the largest groups first so you aren't constantly bringing chairs in and out (or at least, just twice--once for each side of the family). I usually do the symmetrical thing--leave a space for the bride and groom dead center, with chairs fanning out in a V or U shape on each side of them. Women and older people sitting, husbands stand behind, parents and family members closest in. Kids in front, but if they are too tall, to the side. Standing rows turn shoulders inward to center, stacked tightly. No one directly behind the couple. Doing 14 people standing in a line is not fun and people are too small in the resulting image. You can do 'medium' stacking--which is more like 2 very tight rows, with spaces between people in the front row so you see the person standing just back of them.</p>

<p>Take a deep breath. 14 is NOT a lot of people.<br />You have the B&G in the middle and a nice area for them - and her train.<br />That leaves just two “sixes” ether side.<br />That's two rows of three tucked neatly shoulder behind shoulder.<br />If each of those two groups has one child - then that is two rows of Adults (three at back two in front) and child standing in front.<br />That is NOT a lot of landscape width real- estate in the frame – basically only a “row” - eight people wide.</p>

<p>All these combinations can fit with SD=12 ft for a Full Length Shot and using a 24mm (or 28mm) lens on an APS-C and not appear cramped or the Subjects appearing as sardines in a can.<br />It is all in the <strong><em>arrangement</em></strong> of the Subjects - and that doesn't mean "stiff starch" posing - there will be plenty of room to arrange them with a bit of air between them - but “arranged” none the less. You'll get half shots of that and smaller sub groups, at about FL = 35mm shooting at about 12ft</p>

<p>For insurance, if you want to - take a small step ladder and shoot from the first or second step - you will get more head and torso of each person, in shot.</p>

<p>WW<br /><br /></p>

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<p>Take a deep breath.</p>

 

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<p>I cracked up at that - good advice :) Thankyou, thinking of it as 2 "sixes" made it a lot easier conceptually.<br>

Nadine and William providing sage advice as usual. Randall - will be going outside at the right time today :)</p>

 

<p>go get 'em . . .</p>

<p>Another, lower-tech option that might work in some (but probably not all) such situations: can you use one or more reflectors to redirect some of the natural light onto the subjects' faces?</p>

<p>I did not read all valueable posts carefully, but possibly there is another way, if you have remote TTL (or even manual) flashes. Best if you have remote HHS or FP flashes. Set of Nikon CLS flashes working in remote automated FP mode would be perfect.</p>

<p>Use 2 of them on high standing light posts, and locate them closer to the group of people than your camera with longer lens. Proximity of flashes to subject works well even with the HHS or FP flahes that loose much power in this mode.</p>

<p>Since you locate flashes closer to the subject, you may get enough light power, even if in FP or HHS mode, and use any fast shutter speed synch to combat and/or concur the ambient sun lighting.</p>