 Sobia Chishti |
Studio Shoots Without a Flash Meter? I seem to misplaced (or, worse, lost) my flash meter and am having a very important studio shoot coming up. I can't buy a new one at this moment. I own a Canon 10D and have done studio shoots without using my flashmeter. Well, now when I want to be more accurate, I don't have it in hand. Do you have any solution or tips of how to get an accurate exposure especially to get the light ratios like 1:2 without a flash meter?? If I want to use f/8 or 11, how can I be sure to set the strobe strength? Thanks!
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Debby A. Tabb |
Well, thank goodness you're shooting digital! You can test and see if the results are what you are looking for. If you have a laptop, you can also shoot into that for a bigger capture screen - to help with your immediate viewing.
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Sobia Chishti |
Hi Debby. Thanks for responding again. Would you please explain how can I shoot into a laptop for a bigger capture screen?
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Alan N. Marcus |
Hi Sibua, No flash meter? Like a ship at sea without a compass! All is not lost! Place”main” as desired to yield the best lighting for subject type. Suggest high and off to the side. More to the side for round face – more forward for thin face. Placement is art not science. Measure main to subject distance using either inches or centimeters. Use only one of these unit of measure, no swapping. Place second light “fill” close to an imaginary line drawn between camera and subject at lens height. With fill off and main operational, shoot a series of test shots. The objective is to set camera aperture for a pleasing skin tone. Portraiture is generally best served if the aperture is set to achieve a shallow depth-of-field. Generally this will be somewhere around f/5.6. Thus I advise starting with the lens set to f/5.6. Make an exposure and evaluate for over or under exposure. If the strobe has a power adjustment, use power setting to achieve an exposure that yields a pleasing skin tone. If strobe has no power adjustments, then subject to lamp distance is altered to achieve desired exposure level. If first test shot is over exposed – move the lamp further from subject. Revised distance is achieved by multiplying preliminary lamp to subject distance by 1.4. This factor reduces the light energy at the subject plane by half (1/f stop). Shoot and evaluate, if still over exposed continue again using the 1.4 multiplier. Repeat moving main further away until a correct skin tone is achieved. Once the correct exposure of the main is achieved, turn on the fill. Its intensity is set subordinate to the main by 1 /f stop 9 (achieves 3:1 ratio). This can be accomplished in two ways. A. Set fill power adjustment to next lowest setting based on setting used for the main. B. Set fill to same power setting as main but place further back using the 1.4 multiplying factor. This 1 f/stop subornation yields a 3:1 ratio. For more dramatic lighting try 5:1 this is 2 f/stops subordinate to main. 5:1 is achieved by setting the fill further back by a multiplying factor of 2. Very theatrical is 9:1 achieved by setting the fill back by a multiplying factor of 2.8 which is 3 f/stops subordinate to the main. The 2:1 ratio you stated you desired is achieved only if the fill and main are set so the light energy at the subject plane. This is a flat lighting devoid of depth perception and generally not suitable in portraiture whereby we attempt to replicate a 3 dimensional object in a 2 dimensional media. 2:1 is bet suited for copy work of 2 dimension subjects (flat copy) and some product shots. While many lighting ratios are mathematically reachable, the only ones obtainable using full f/stop increments are 2:1 – 3:1 – 5:1 – 9:1. Greater than 9:1 is analogous to a no fill set-up. Alan Marcus
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Alan N. Marcus |
Corrections for typo Once the correct exposure of the main is achieved, turn on the fill. Its intensity is set subordinate to the main by 1 /f stop (achieves 3:1 ratio). The 2:1 ratio you stated you desired is achieved only if the fill and main are set to arrive at the same light energy at the subject plane. Alan Marcus
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Sobia Chishti |
Thanks Alan Marcus for a detailed answer. I'll have to reread to remember it all and do practice. I have two strobes. One alien bee 640ws and other 320ws and these do have dial down feature. I don't know how to convert these watt difference in f/stop #. I mean is 320ws, one stop lower than 640ws if run at full strength and dialing down both one step down will keep the same ratio?
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Linda Buchanan |
Sobia, I have just recently started to shoot with my laptop tethered to the camera. I have a Canon 350D but I think it would work about the same way with yours. I downloaded the instruction manual for Canon Capture from their website. Everything you need should be with your camera, you run from the utilities program. Mine came with a with a white cord, there is a USB connection on one end for the computer and a funny looking little connector on the other end for the camera. I am at work so I don't have all the steps with me. If you can't get this figured out email me and I will email you the information, I believe the instruction manual I downloaded includes your camera. Good luck, it is really a big help to be able to do this.
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Sobia Chishti |
Thanks Linda for such a useful information. I've tried to find Canon Capture download on Canon site. For 10D, they are show download for only Mac users not for Windows. Whenever you find time, could you send a link from where you've downloaded this instruction manual?? Another question is instructional manual enough to install since i've Fileviewer Utility 1.3 on my laptop ?
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Linda Buchanan |
Sobia, click on the "contact us" link at Canon's website and send them an email telling them what you are wanting to do. They respond very quickly. That is how I found my download information. I will check my laptop at home for the link.
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Alan N. Marcus |
Hi again Sobia, No meter! Mathematically we can compute a table to convert watt seconds to f/numbers but this is mind-numbing. The best procedure will be trial and error. Again start at f/5.6 and experiment using different main to subject distances until a correct skin tone is achieved. The employment of the second fill lamp increases the light so we need to stop down a tad but not very much. Again, without meter, trial and error is the only way and easy with digital. Your strobes may come with a table of guide numbers. Look at the manual. Published guide numbers are based on the ISO setting of the camera. If the guide number is known we divide this value by lamp to subject distance. Say the guide number for a camera functioning at 100 ISO is 40. If the main lamp is positioned 5 feet from the subject we divide 40 by 5 = 8. Thus our first trial exposure will be a camera setting of f/8. Why is this 3:1 and why do we want 3:1? If the main is high and off to the side it delivers 640 watts to the face of the subject, most of the face receives this light however, shadow are cast in the dimples (hollows) and in areas shadowed by the nose i.e. the main does not illuminate shadowed areas. Shadowed areas will not properly record as detail in the shadows is lost. Thus the one light set-up delivers a picture that is too contrasry unless we take countermeasures. We use a fill lamp place to illuminate from the camera’s prospective i.e near the lens, to fill shadows. Light from the fill commingles with light from the main. Now the frontal areas of the face receive light from both the main delivering 640 watts the fill delivering 320 watts thus the frontal areas of the face receive 640 + 320 = 960 watts. Not all of the face receives the 960 watts. The shadows did not receive any light from the main thus they only receive 320 watts from the fill. Thus the light on the face is 960 in frontal areas and 320 in the shadows or stated another way the ratio is 960:320. Now this is the lighting ratio. Saying 960:320 is awkward so we divide both sides by a common denominator (320) and the ratio reduces to 3:1. The 3:1 ratio is know as the bread and butter ratio as this is the one that sells best as it is most flattering. Masculine subjects are sometimes better served by a 5:1 ratio. 9:1 is dynamic as it is contrasy. Alan Marcus
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Sobia Chishti |
Alan, thanks again for doing all the math. Your information will certainly help me especially how to find the starting f/stop with the guide number of lamp. You also made it very clear how shooting my two strobes at full strength will give me a 3:1 ratio. Thanks again for your help.
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