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01/21/2011 03:57:49 PM · #1 |
About to do a photoshoot in a few hours (free, but i still want it to be good).
How do you get the correct exposure on manual without a light meter...just by looking at the histogram?
My setup is a B800 with a large octabox 35 degrees camera left, a B800 shot through an umbrella to camera right 45 degrees behind subject, and a strobe camera right 45 degrees pointing at the ceiling with an index card taped to the back of it to bounce some fill flash in and help fill the overall scene.
When I did a test shoot a week ago I was basing exposure off looking at the LCD on the camera, but when I got home, the exposure looked much different on the computer than they did on the camera (actual exposure was darker than the LCD was telling me).
When I did some test shots just a few minutes ago it seems brighter, but the histogram is spiking toward the highlight end. Is that normal? But the spike is not all the way to the right side, it's about 3/4 way to the right and then not much information is shown after the spike. Doesn't that mean I'm losing detail somewhere?
I can't read histograms!! |
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01/21/2011 04:14:52 PM · #2 |
| Im sorry your having difficulty... but unfortunately i am not one to give advice when it comes to this... hopefully someone will see this in time so the problem can be solved... :( |
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01/21/2011 04:26:00 PM · #3 |
If you are shooting in RAW, I would think judging it via the LCD would be close enough to work from. A RAW file should have about 2 stops of image data in either direction from what is visible in the preview.
On your histogram, you are looking to make sure that neither the shadow areas (the left end) nor the highlight (the right end) are clipped off, which looks on the histogram like a cut off mountain peak. In a photo is a blown highlight or too dark shadow. Your 7D should also have a function for image review where it can blink any blown highlights or clipped shadows when viewing it.
Message edited by author 2011-01-21 16:26:32.
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01/21/2011 04:54:31 PM · #4 |
This doesn't really answer your question, but it might help you understand histograms ;)
//www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml
It helped me understand them, anyway. At the very least, this will act as a bump for your SOS ;)
- Justin |
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01/21/2011 05:24:18 PM · #5 |
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01/21/2011 05:45:18 PM · #6 |
the histogram is your friend in this situation--trusting the lcd image to judge exposure is a recipe for disaster. The LCD display brightness is adjustable for viewing conditions, and is not calibrated.
The histogram is a simple vertical bar graph chart of the number of pixels in the image that are at a certain luminance level, increasing brightness from left to right. There is no right or wrong histogram, standard way they should look, because it depends on your subject: If you are taking a picture of a penguin against a dark background, you will have a lot more pixels in the dark range, and only a few in the light range.
In general, though, you don't want a huge bulking or a big spike in the graph at either end. At the left end, this would mean there will be pure black (no information) pixels in your image file, and on the right side this would suggest blown highlights. If you have to go off one end or the other, it is better to "fall off the right" as you are losing Some information/data, rather than getting no data at the low end. If you are shooting RAW, some recovery from the high end can be done in post.
Even if you don't normally shoot RAW, in this circumstance you might want to set for RAW + JPEG just to have some back up.
Also, if the 7D has this feature (I suspect it does) it is worth looking at the Separate RGB histograms--zoom the image into the face/foreheads and be sure the red histogram is not falling off the right side: this ensures you don't have hot spot highlights on the skin, which can be harder to fix in post.
If you have a gray card, or a black/gray/white combo card, shoot a fairly tight (nearly full frame) image of it/them in the actual lighting. Check the histogram: you should have a spike very near or slightly to the right of middle of the graph for the gray, near the right edge for the white, and near but not off the left side for the black. You can then adjust the lighting or your camera exposure to shift it as might be needed. If you need the exposure settings to be the same, then change your lighting, for example.
But you are quite correct: if you just look at the mini image on the screen to judge exposure, you can fool yourself, be in for a surprise later. do a bit of googling on camera histograms. Once you know it, it is a very useful tool and easy to use. |
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01/22/2011 02:33:34 AM · #7 |
Originally posted by kleski:
Fixed your link |
Thanks, I just became a member today and forgot I can actually post hyperlinks now!
- Justin |
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