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07/08/2005 05:42:31 PM · #1 |
Just stumbled across this info. Very interesting stuff here.
Not sure if this has been mentioned before, but this is the first time I heard of it.
(quoted from article)
"Within the first F/Stop, which contains the Brightest Tones 2048 levels available
Within the second F/Stop, which contains Bright Tones 1024 levels available
Within the third F/Stop, which contains the Mid-Tones 512 levels available
Within the fourth F/Stop, which contains Dark Tones 256 levels available
Within the fifth F/Stop, which contains the Darkest Tones 128 levels available
If you don't use the right-hand fifth of the histogram for recording some of your image you are wasting fully half of the available encoding levels of your camera, and it would give you a major advantage to bias your exposures so that the histogram is snugged up to the right, but not to the point that the highlights are blown. "
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07/08/2005 05:53:00 PM · #2 |
Yep, same information in Bruce Fraser's book, recommended to me by fellow DPCers a few months ago.
Very helpful stuff to know and helps one think about what to expose for.
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07/08/2005 05:57:36 PM · #3 |
This is at least as important for those who shoot JPEG, because:
- In JPEG mode, you have less data to start with (8 bits, as opposed to 10 to 12 bits in RAW)
- JPEG shooters with some experience seem to have a tendency to shy away from the right side of the histogram to avoid blowing one channel, or blowing small highlights.
In fact, it's usually much better to lose a few small highlights, or one channel in a small area, than it is to underexpose. The exception to this is when the subject is highly saturated in one channel, and blowing that channel would have a drastic impact on the photo. This happens often with flowers, or brightly-painted objects, particularly reds, oranges, and yellows.
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07/08/2005 06:04:00 PM · #4 |
Originally posted by Sonda:
"Within the first F/Stop, which contains the Brightest Tones 2048 levels available
Within the second F/Stop, which contains Bright Tones 1024 levels available
Within the third F/Stop, which contains the Mid-Tones 512 levels available
Within the fourth F/Stop, which contains Dark Tones 256 levels available
Within the fifth F/Stop, which contains the Darkest Tones 128 levels available
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Are these numbers the same on other cameras? My guess is no. Does anyone know what they are for D70?
Nick
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07/08/2005 06:05:59 PM · #5 |
Originally posted by Nikolai1024:
Are these numbers the same on other cameras? My guess is no. Does anyone know what they are for D70?
Nick |
Because the CCD or CMOS sensor responds to light in a linear manner, yes, they are the same for all cameras.
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07/08/2005 06:12:40 PM · #6 |
Does this mean that even if you are trying to capture a very dark image, with all the detail in the shadows, that you're better off exposing to the right and then dragging everything back down to the left in PS later?
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07/08/2005 06:14:22 PM · #7 |
Originally posted by kirbic:
Because the CCD or CMOS sensor responds to light in a linear manner, yes, they are the same for all cameras. |
Surely it depends on dynamic range?
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07/08/2005 06:16:21 PM · #8 |
Originally posted by PaulMdx:
Originally posted by kirbic:
Because the CCD or CMOS sensor responds to light in a linear manner, yes, they are the same for all cameras. |
Surely it depends on dynamic range? |
Yes, but the relationship between the number of levels remains the same. The actual numbers may change, but not their ratios, which is the crucial part.
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07/08/2005 06:18:51 PM · #9 |
Originally posted by Nikolai1024:
Are these numbers the same on other cameras? My guess is no. Does anyone know what they are for D70?
Nick |
Actually it's not quite the same for the D70, unfortunately. The D70 only has about 9.5 bits of resolution instead of 12 bits, because of the lossy compressed NEF format the D70 uses. |
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07/08/2005 06:21:14 PM · #10 |
Originally posted by bod:
Does this mean that even if you are trying to capture a very dark image, with all the detail in the shadows, that you're better off exposing to the right and then dragging everything back down to the left in PS later? |
ABSOLUTELY! If feasible, expose to the right for everything you shoot. Of course, for very dark subjects, you may not have the liberty to do so, fully, within the constraints of reasonable exposure time.
This is one thing that is very different with digital vs. film. With film, you always wanted to get as close to your "vision" of the final result as possible in camera. In this one case at least, digital is different. Expose to the right where you can, and you will be amazed at the reduction in noise that you can achieve in dark areas.
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07/08/2005 06:24:14 PM · #11 |
Originally posted by kirbic:
Originally posted by bod:
Does this mean that even if you are trying to capture a very dark image, with all the detail in the shadows, that you're better off exposing to the right and then dragging everything back down to the left in PS later? |
ABSOLUTELY! If feasible, expose to the right for everything you shoot. Of course, for very dark subjects, you may not have the liberty to do so, fully, within the constraints of reasonable exposure time.
This is one thing that is very different with digital vs. film. With film, you always wanted to get as close to your "vision" of the final result as possible in camera. In this one case at least, digital is different. Expose to the right where you can, and you will be amazed at the reduction in noise that you can achieve in dark areas. |
You just have to be aware that the histogram on the camera is only of the GREEN channel. So if you have a picture of the sky, or of a red flower, it can look like you can increase exposure and push the histogram to the right, but in reality, the red or blue channel is totally blown away and ruined. Only a few high-end pro cameras have actual RGB histograms. |
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07/08/2005 06:26:57 PM · #12 |
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07/08/2005 06:27:45 PM · #13 |
Originally posted by skylen:
Originally posted by kirbic:
Originally posted by bod:
Does this mean that even if you are trying to capture a very dark image, with all the detail in the shadows, that you're better off exposing to the right and then dragging everything back down to the left in PS later? |
ABSOLUTELY! If feasible, expose to the right for everything you shoot. Of course, for very dark subjects, you may not have the liberty to do so, fully, within the constraints of reasonable exposure time.
This is one thing that is very different with digital vs. film. With film, you always wanted to get as close to your "vision" of the final result as possible in camera. In this one case at least, digital is different. Expose to the right where you can, and you will be amazed at the reduction in noise that you can achieve in dark areas. |
You just have to be aware that the histogram on the camera is only of the GREEN channel. So if you have a picture of the sky, or of a red flower, it can look like you can increase exposure and push the histogram to the right, but in reality, the red or blue channel is totally blown away and ruined. Only a few high-end pro cameras have actual RGB histograms. |
Actually, I believe most histograms are luminosity hisstograms, which are weighted averages of the three channels. They are green-heavy, though.
My best advice is to shoot RAW, in which case the histogram shows where clipping will occur in JPEG, but you've got additional dynamic range in each channel beyond that.
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07/08/2005 06:33:52 PM · #14 |
Originally posted by kirbic:
Originally posted by bod:
Does this mean that even if you are trying to capture a very dark image, with all the detail in the shadows, that you're better off exposing to the right and then dragging everything back down to the left in PS later? |
ABSOLUTELY! If feasible, expose to the right for everything you shoot. Of course, for very dark subjects, you may not have the liberty to do so, fully, within the constraints of reasonable exposure time.
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This is kind of like a wakeup to me. I always try to make the shot as I see it, I didn't really realize this until now... :p
Been trying ways to minimize posterization and noise in shadow areas, thats how I found it.
But the reason I thought RAW is because you can tweak the exposure more wout loss in a RAW format than jpeg.
I wasn't sure this was feasible in jpeg as well.. very cool.
Thank you for sharing Guys. |
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07/08/2005 06:45:52 PM · #15 |
Originally posted by kirbic:
Actually, I believe most histograms are luminosity hisstograms, which are weighted averages of the three channels. They are green-heavy, though. |
Given that there are twice the number of green sensors to red and blue it makes sense that the histogram gives them that same ratio more of weight I think? I read too that human eyesight is much, much more senstive to green than anything else hence this arrangement of sensors.
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07/08/2005 06:51:16 PM · #16 |
Originally posted by Kavey:
Originally posted by kirbic:
Actually, I believe most histograms are luminosity hisstograms, which are weighted averages of the three channels. They are green-heavy, though. |
Given that there are twice the number of green sensors to red and blue it makes sense that the histogram gives them that same ratio more of weight I think? I read too that human eyesight is much, much more senstive to green than anything else hence this arrangement of sensors. |
Here's a nice little overview of the theory behind luminosity-based histograms. Green represents 59%, red 30% and blue 11%. The take-away is that a blown red or blue channel will not make the luminance histogram appear "blown" if the green channel is not near saturation in those same areas.
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07/08/2005 06:53:32 PM · #17 |
| Damn. Learn something new everyday. I wonder if this isn't good information for a color/luminosity thoery tutorial, with concrete Photoshop/Camera-LCD captures to illustrate. |
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07/08/2005 06:57:41 PM · #18 |
Originally posted by bledford:
Damn. Learn something new everyday. I wonder if this isn't good information for a color/luminosity thoery tutorial, with concrete Photoshop/Camera-LCD captures to illustrate. |
This thread could be a good basis for a tutorial. I can certainly think of some fun examples.
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07/08/2005 07:19:48 PM · #19 |
Originally posted by kirbic:
Originally posted by bledford:
Damn. Learn something new everyday. I wonder if this isn't good information for a color/luminosity thoery tutorial, with concrete Photoshop/Camera-LCD captures to illustrate. |
This thread could be a good basis for a tutorial. I can certainly think of some fun examples. |
hehe.. sounds like a great idea.
I am not quite qualified to make a tutorial on this subject, but if Kirbic, Kavey or someone who knows a little more were up to it, I would love to see one. |
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07/08/2005 07:22:24 PM · #20 |
| A good post. Also, exposing as describes reduces noise. |
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07/08/2005 08:36:04 PM · #21 |
As much as I would hate to argue with all those numbers and supposed facts....it is all based on somenone else's REVERSE engineered software of Nikons product. He does finally point out hat something may have been missed, but declares it unlikely.
For what it is worth I could care less. I get the control I look for in the RAW format, and am able to make up for rushed exposures if I need.
I read that L-L article over a year ago and did some testing. You definitley lose alot of noise in the shadow areas when you expose to the right, especially on dark, lowlight photos. May not look that great in camera, but when you make a few other adustments...you are surprised.
I have been doing this when shooting portraits especially. One customer wanted to see some at the time...so I showed her...she thought they were all messed up...until I put it in ACR and went to my preset dropdown for that light. POW! Almost spot on. She loved it...and was amazed about it.
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07/08/2005 09:05:12 PM · #22 |
| So does exposing to the right usually mean an exposure compensation setting of +0.3 or +0.7? Would that be about right for people without histograms on their cams or for those who don't have the time to review the histogram? |
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07/08/2005 09:27:36 PM · #23 |
I am so confused with all this RAW stufff, but really want to learn, i am still trying to learn apeature and speed, can anyone advise me on a good website that starts from scratch with shooting with RAW?...
thanks in advance
kel
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07/08/2005 10:15:56 PM · #24 |
Originally posted by Olyuzi:
So does exposing to the right usually mean an exposure compensation setting of +0.3 or +0.7? Would that be about right for people without histograms on their cams or for those who don't have the time to review the histogram? |
There's no set exposure compensation that always works... exposure compensation will always vary based on shooting conditions. Exposing to the right implies strict attention to the histogram. Think of it as pushing your vehicle near redline, you need to watch that tach more carefully to ensure you don't blow something ;-)
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07/08/2005 10:21:07 PM · #25 |
Originally posted by roadrunner:
I am so confused with all this RAW stufff, but really want to learn, i am still trying to learn apeature and speed, can anyone advise me on a good website that starts from scratch with shooting with RAW?...
thanks in advance
kel |
me too... |
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