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03/23/2006 09:21:35 AM · #1 |
Lets say I am metering around the highlights and shadows of a subject and I have a 3 fstop range at 90 sec except for when I get to the darkest shadows. Then, I have to reduce my shutter speed in half to 30.
If my film, or digital has a 2 stop latitude for underexposure, would I count the shutter speed as another stop giving me a range of 4 stops on the scene or is the shutter speed difference between 90 and 60 actually more then 1 stop?
I know this is a complicated question and I am not exactly sure of how to word it.
Basically, I am trying to learn how to itergrate specific highlights and shadow areas of a scene so I lean how to acheive the best exposure. What I am running into is my lense has bottomed out the apature. I cant open up anymore so I have to then keep open the shutter longer to allow more light in.
Thank you!
JD |
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03/23/2006 09:42:48 AM · #2 |
| Can't help you with that, but another way around is to take two or even three different exposures of the subject, and combine them together in an editing program to get an even exposure. I don't think any camera or lens can properly expose all the highlights and shadows throughout a scene. |
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03/23/2006 09:49:56 AM · #3 |
Every time you cut the shutter speed in half, that's one stop. So starting from 1/90s, one stop greater exposure is 1/45s, then the next stop is 1/22s, etcetera.
To determine the dynamic range of a scene, spot meter on the brightest area and the darkest shadow, and calculate the difference. For instance:
Bright area: 1/400s @ f/4
Dark area: 1/20s @ f/4
The range is just over 4 stops. Keep dividing 1/400s by two, and after you've done this 4 times (4 stops) you end up with 1/25s. The 1/20 speed measured for the dark area is just under that, so a little more than 4 stops range.
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03/23/2006 11:10:52 AM · #4 |
You basically have five zones/five stops of useable range between pure black and pure white.
Zone 8 (and higher) = pure white
Zone 7 = "textured white", bright areas with trace detail.
Zone 6 = light, fully-detailed gray
Zone 5 = middle gray
Zone 4 = dark, fully detailed gray
Zone 3 = "textured shadows", dark areas with trace details
Zone 2 (and below) = pure black
The nominal "Zone System" divides all tones into ten zones, with Zone 10 being pure white and Zone 1 being pure black. You cannot represent the full 10 zones properly in a photographic print. You can get a little closer using transmitted (instead of reflected) light, such as with slides or other projected renditions. The computer screen, arguably, has more range than the print, being closer to a slide.
The useable range varies with the print media; glossy prints have 7 useable zones of range, arguably a bit more. Matte prints have less reflectance, and thus less range.
You need to adjust the contrast and tonal values of the image you are going to print/display to the demands of the media you will be using for the purpose. I use a differently-processed print file for glossy vs matte prints, for example.
In digital, especially working from RAW, you have a couple stops of latitude for extreme range in the imaged scene; you can overexpose by 1 or 2 stops and compress the tonalities by adjusting curves/levels/contast to constrain the image for viewing.
(Quick and dirty overview)
Robt.
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03/23/2006 11:17:06 AM · #5 |
Great explaination. Let me just add a twist. What if you needed to also change the f with the bright areas to say the next f up? Would that still be 5 stops range?
Originally posted by kirbic:
Every time you cut the shutter speed in half, that's one stop. So starting from 1/90s, one stop greater exposure is 1/45s, then the next stop is 1/22s, etcetera.
To determine the dynamic range of a scene, spot meter on the brightest area and the darkest shadow, and calculate the difference. For instance:
Bright area: 1/400s @ f/4
Dark area: 1/20s @ f/4
The range is just over 4 stops. Keep dividing 1/400s by two, and after you've done this 4 times (4 stops) you end up with 1/25s. The 1/20 speed measured for the dark area is just under that, so a little more than 4 stops range. |
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03/23/2006 11:22:18 AM · #6 |
Thanks Robt,
Thats answers my questions as far as how much latitude. Now, how do I count that latitiude in stops if I am using say f4@60sec for highlights but in order to expose my shadows I need to use f1.4@30sec? Would that be 3 fstops + 1 fstop in shutter speed totalling 4 stops?
Originally posted by Bear_Music:
You basically have five zones/five stops of useable range between pure black and pure white.
Zone 8 (and higher) = pure white
Zone 7 = "textured white", bright areas with trace detail.
Zone 6 = light, fully-detailed gray
Zone 5 = middle gray
Zone 4 = dark, fully detailed gray
Zone 3 = "textured shadows", dark areas with trace details
Zone 2 (and below) = pure black
The nominal "Zone System" divides all tones into ten zones, with Zone 10 being pure white and Zone 1 being pure black. You cannot represent the full 10 zones properly in a photographic print. You can get a little closer using transmitted (instead of reflected) light, such as with slides or other projected renditions. The computer screen, arguably, has more range than the print, being closer to a slide.
The useable range varies with the print media; glossy prints have 7 useable zones of range, arguably a bit more. Matte prints have less reflectance, and thus less range.
You need to adjust the contrast and tonal values of the image you are going to print/display to the demands of the media you will be using for the purpose. I use a differently-processed print file for glossy vs matte prints, for example.
In digital, especially working from RAW, you have a couple stops of latitude for extreme range in the imaged scene; you can overexpose by 1 or 2 stops and compress the tonalities by adjusting curves/levels/contast to constrain the image for viewing.
(Quick and dirty overview)
Robt. |
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03/23/2006 11:36:32 AM · #7 |
Originally posted by johnco:
Thanks Robt,
Thats answers my questions as far as how much latitude. Now, how do I count that latitiude in stops if I am using say f4@60sec for highlights but in order to expose my shadows I need to use f1.4@30sec? Would that be 3 fstops + 1 fstop in shutter speed totalling 4 stops? |
Here's how it works:
Look at your scene/setup and "visualize" how you want the final image to look. You have bright cloud areas you want on zone 6.5, say. You meter the clouds, the meter gives you a Zone 5 exposure for the clouds (that's what meters do, assume they are pointed at a middle gray and give you the exposure for that).
So you take the indicated exposure for the clouds and add a stop and a half to that. For example, they meter at f/16 at 1/250, so you'd set camera for f/16 at 1/90 to expose properly for the clouds.
Now you look at a largish area of trees in shadow on your image, and you want to render those at Zone 4, so you have full detail. You meter them and you get f/16 at 1/40 for a Zone 5 placement. Moving them to Zone 4 would give you an exposure of f/16 at 1/80. This scene, you conclude, has a normal tonal range and you shoot it at f/16 at 1/90 to "expose for the highlights".
If the dark area of the trees metered at f/16 at 1/20, you'd have a stop too much range; you'd need to compress the tonal range in post processing. Instead of shooting f/16 at 1/90, you'll try, say, f/16 at 1/60th or so, "overexposing" the clouds slightly and fully exposing the shadows, with the intention of controlling the contrast in post processing.
There's a limit to how far you can overexpose the highlights and still recover detail in the final image, but you will learn about this as you experiment carefully and constructively. Your basic rule in digital is to "expose to the right side of the histogram", i.e. opt for overexposure instead of underexposure, but that's a whole new "lesson", one Kirbic's better-equipped to explain than me.
Robt.
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03/23/2006 11:42:29 AM · #8 |
| Depending on how your scene is composed, you may also be able to use a low tech solution: a graduated Neutral Density filter - the most common example is a bright sky with shadowed foreground - an ND filter could possibly be positioned to compress the exposure down to something the camera could register. |
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03/23/2006 11:54:44 AM · #9 |
Originally posted by Johnco:
Thanks Robt,
Thats answers my questions as far as how much latitude. Now, how do I count that latitiude in stops if I am using say f4@60sec for highlights but in order to expose my shadows I need to use f1.4@30sec? Would that be 3 fstops + 1 fstop in shutter speed totalling 4 stops? |
Hey Johnco, I'm an ant next to these tech giants, but I think that one thing you might want to do is whether you are gathering information from your light meter or your camera, get at least one foot on the ground by choosing either your aperture (f) or your shutter speed to stay constant.
Most people keep their aperture as their constant value as this controls things like hyperfocus and DOF. Also, I have no idea if you mean actual 60 seconds or 1/60, but there's a pretty big difference. I'm trying to visualize what you might be shooting at 60 seconds, and that speaks of either astronomy or night-time landscapes, Neither of which are really well known for using f/1.4 or even f/4 for that matter.
f/4 at 1/60
f/1.4 at 1/30 = f/4 at 1/4
That's 4 stops of difference, so you should be fine with your D100.
Use aperture to control your scene and shutterspeed to control light (to start with).
Depending on what you want to expose for, you would probably want to shoot this at something like 1/40 or 1/30. You could experiment with a shot at 1/15 and see how you liked it.
Message edited by author 2006-03-23 11:56:24. |
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