Under exposed was better in bright sun w/shadow @ ISO 50

Jay25Jay25 Registered Users Posts: 70 Big grins
edited October 30, 2010 in Technique
Pictures kept on getting washed out @ ISO 50 in the bright sun. I underexposed and shot was way better, Canon 5D MKII, 28-70 2.8L F9 125 @ISO 50. Had to underexpose three stops down:scratch


5d1.jpg
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Comments

  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 5, 2010
    Interesting, Jay, that you said you had to under expose three stops for this image.

    From the exif data encoded in your image of the rooster, I find - ISO 50, f9.0 1/125th sec as you said.

    I KNOW from the [url="http://www.dgrin.com/showthread.php?t=30235
    "]sunny 16 rule[/url] that for an ISO of 50, a normal subject in direct sunlight, like your rooster, would be correctly exposed at 1/50th sec at f16, or 1/100 sec at f11, or 1/200th at f8. Your exposure of 1/125th at f9, is maybe a 1/2 stop MORE exposure than that rec'd by sunny 16. Not under exposed at all, but just a tad over exposed.

    I would re-check your metering. Camera's meters are real sensitive to the red channel - Try looking at your histogram in three channel Red, Green, Blue display.

    The sunny 16 rule has been used for the correct exposure of film for over 70 years, and is remarkably accurate if used correctly. Sunny 16 says the correct exposure for a sunlit subject at ISO 50 is 1/200th at f8. If you doubt me, check your meter reading on a 18% grey card in sunlight. Betcha a beer, I am right.thumb.gif
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • Jay25Jay25 Registered Users Posts: 70 Big grins
    edited March 6, 2010
    Thanks for the tip. However alot of the photos I see here look 3D, post card HIGH Quality work. Im using a Canon, however I dont know if people are using a special website. Or maybe I need to dump all this Canon stuff and move to a Nikonne_nau.gif
    Im freaking hell a confused now?
  • ziggy53ziggy53 Super Moderators Posts: 24,127 moderator
    edited March 6, 2010
    Jay25 wrote:
    Thanks for the tip. However alot of the photos I see here look 3D, post card HIGH Quality work. Im using a Canon, however I dont know if people are using a special website. Or maybe I need to dump all this Canon stuff and move to a Nikonne_nau.gif
    Im freaking hell a confused now?

    A Nikon camera, or any other brand for that matter, is not the solution to high-quality photography.

    The best images start with a clear understanding of all of the concepts of photography. Until you gain control over lighting and dynamic range, you can use any brand camera and get the same results. Until you understand what apertures are appropriate, and for what reason they are appropriate, you will keep guessing.

    Practice with exposure until you understand how to gain control of the subject's illumination. Using a flash in HSS/FP mode will help you to control over ambient light with shorter shutter speeds and then use the flash to provide primary exposure for the subject. HSS/FP mode will also allow the use of large apertures to help separate the subject from the background.

    Adding a neutral density (ND) filter is another way to allow larger apertures in strong daylight.

    You have demonstrated that you understand part of the exposure relationship. Now just extend your knowledge to the rest of the puzzle of advanced photography. thumb.gif
    ziggy53
    Moderator of the Cameras and Accessories forums
  • craig_dcraig_d Registered Users Posts: 911 Major grins
    edited March 6, 2010
    Jay25 wrote:
    Thanks for the tip. However alot of the photos I see here look 3D, post card HIGH Quality work. Im using a Canon, however I dont know if people are using a special website. Or maybe I need to dump all this Canon stuff and move to a Nikonne_nau.gif

    No, you just need to stop using ISO 50. The "expanded" ISO levels are just being faked in software anyway. ISO 50 is basically just ISO 100 overexposed by one stop. I suppose if you have the camera make JPEGs for you (which I have never done with the 5D2), it probably compensates, but for RAW shooting the expanded modes are a waste. You're better off just shooting RAW ISO 100 (or 6400 on the other end) and adjusting the exposure in your RAW workflow.

    Nikon makes nice cameras too, of course, but my potential interest is shot down by the fact that only their $8000 primo pro camera, the D3x, offers more than 12 MP. A D700 with, say, 18 MP would be strong competition for the 5D2.
    http://craigd.smugmug.com

    Got bored with digital and went back to film.
  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 6, 2010
    Jay,

    One of the embarassing things you learn when you have a very good camera, is that your pictures rarely get any better than before, unless you really were limited by your present camera, and for most pictures most of us take, the camera is just a black box to hold some film, The limits are our own understanding and knowledge. Ziggy is giving you some good advice. The 5D Mkii will make excellent pictures. I use a 5DMk ii also.

    Correct exposure, lighting, posing, seeing are really the key aspects.

    As for brands, I shoot Canon, but I could be just as happy, maybe even happier if I switched to Nikon. But I own lots of very fine Canon glass, a little Panasonic glass, some Olympus and some Zeiss glass, that I can use on my Canon bodies, so I will make do with what I have, and let others struggle along with their Nikonsmwink.gif
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • ziggy53ziggy53 Super Moderators Posts: 24,127 moderator
    edited March 6, 2010
    pathfinder wrote:
    ... Zippy is giving you some good advice. The 5D Mkii will make excellent pictures. I use a 5DMk ii also.

    Correct exposure, lighting, posing, seeing are really the key aspects.

    ...

    Well said. Now who is this "Zippy" character? ne_nau.gifrolleyes1.gif
    ziggy53
    Moderator of the Cameras and Accessories forums
  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 6, 2010
    Duh!!

    Slaps his forehead with the palm of his hand!!

    Sorry Ziggy.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • Jay25Jay25 Registered Users Posts: 70 Big grins
    edited March 7, 2010
    pathfinder wrote:
    Jay,

    One of the embarassing things you learn when you have a very good camera, is that your pictures rarely get any better than before, unless you really were limited by your present camera, and for most pictures most of us take, the camera is just a black box to hold some film, The limits are our own understanding and knowledge. Ziggy is giving you some good advice. The 5D Mkii will make excellent pictures. I use a 5DMk ii also.

    Correct exposure, lighting, posing, seeing are really the key aspects.

    As for brands, I shoot Canon, but I could be just as happy, maybe even happier if I switched to Nikon. But I own lots of very fine Canon glass, a little Panasonic glass, some Olympus and some Zeiss glass, that I can use on my Canon bodies, so I will make do with what I have, and let others struggle along with their Nikonsmwink.gif

    Im going to have to take some vacation from work. Reason for that is that I have not being paying too much attention to the small stuff, like correct exposure and lighting. I may not be even using the correct ISO for the situation. In another post one of the guys here stated that Smug mug is another reason why alot of the photos on this site have that 3D look. One more thing alot of guys here god knows how long they have being doing this.

    Alot of the work here by other members is beautiful. The photos have a beautiful 3 dimensional look, clarity and sharpness. I love detail and clarity. Alot of the work here has that and then some. I will take it one day at a time, open me a smug mug account. Maybe that will help so I can post up some pictures and let the guys critique some my work. Their tips can help me achieve the goals that they have!!!
  • ivarivar Registered Users Posts: 8,395 Major grins
    edited March 7, 2010
    pathfinder wrote:
    Interesting, Jay, that you said you had to under expose three stops for this image.
    I think it's underexposed by 2/3 of a stop according to the EXIF data. I can see this image being a result from that.
  • Art ScottArt Scott Registered Users Posts: 8,959 Major grins
    edited March 7, 2010
    Jay25 wrote:
    Im going to have to take some vacation from work. Reason for that is that I have not being paying too much attention to the small stuff, like correct exposure and lighting. I may not be even using the correct ISO for the situation. In another post one of the guys here stated that Smug mug is another reason why alot of the photos on this site have that 3D look. One more thing alot of guys here god knows how long they have being doing this.

    Alot of the work here by other members is beautiful. The photos have a beautiful 3 dimensional look, clarity and sharpness. I love detail and clarity. Alot of the work here has that and then some. I will take it one day at a time, open me a smug mug account. Maybe that will help so I can post up some pictures and let the guys critique some my work. Their tips can help me achieve the goals that they have!!!

    Another thing no one has mentioned IS that maybe these 3D looking photos you keep refering to are HDR's (High Dynamic Range photos) .....these ALMOST ALWAYS LOOK 3 D and are the end product of a series of shutter speed bracketed shots taken and stacked to gether and ran thru special software (Photomatix or one of the other HDR softwares) for processing.............

    Another thing to look at is this tutorial on POP,,,,,,,MAKE YOUR IMAGE POP ...................................

    GOOD LUCK
    "Genuine Fractals was, is and will always be the best solution for enlarging digital photos." ....Vincent Versace ... ... COPYRIGHT YOUR WORK ONLINE ... ... My Website

  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 7, 2010
    ivar wrote:
    I think it's underexposed by 2/3 of a stop according to the EXIF data. I can see this image being a result from that.

    What are you basing the correct exposure on, Ivar?
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • ivarivar Registered Users Posts: 8,395 Major grins
    edited March 7, 2010
    pathfinder wrote:
    What are you basing the correct exposure on, Ivar?
    Experience, I guess? The histogram shows a graph I would expect to see (give or take) on a 5d2 for this scene, based on 2/3 under exposure.
  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 7, 2010
    I interpreted this scene as sunlit, not hazy bright - the shadow by the rooster's foot is not perfectly sharp, so if the sun was diffused by clouds, the correct exposure by sunny 16 would be a ~ 1stop more exposure.

    This is the histogram from Photoshop you are referring to? The image file is in Adobe RGB also
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • Scott_QuierScott_Quier Registered Users Posts: 6,524 Major grins
    edited March 8, 2010
    Jay25 wrote:
    Im going to have to take some vacation from work. Reason for that is that I have not being paying too much attention to the small stuff, like correct exposure and lighting. I may not be even using the correct ISO for the situation. In another post one of the guys here stated that Smug mug is another reason why alot of the photos on this site have that 3D look. One more thing alot of guys here god knows how long they have being doing this.

    Alot of the work here by other members is beautiful. The photos have a beautiful 3 dimensional look, clarity and sharpness. I love detail and clarity. Alot of the work here has that and then some. I will take it one day at a time, open me a smug mug account. Maybe that will help so I can post up some pictures and let the guys critique some my work. Their tips can help me achieve the goals that they have!!!
    Your post brings to my mind a couple or three thoughts. I hope they help...
    • "... using the correct ISO for the situation ...." - The "correct ISO" is a product or, if you prefer, a function of the scene, and the selected aperture and shutter speed. These last two are, usually, selected for artistic reasons. For example, if you are:
      • Shooting a landscape scene a smaller aperture is usually going to be the driving exposure parameter and shutter speed not so much and ISO is not even a factor at all (lower is going to be the plan for the day here) as one would stongly consider shooting such with the camera mounted on a tripod.
      • Shooting kids racing around the back yard (or any other high-action shot), your concern would be shutter speed. You select your desired shutter speed and an aperture that increases your depth of field (DOF) enough that a slight focus error will not be noticable and then your ISO to get the exposure values (see your histogram) you need.
      • Portraits ... OK, one could argue that aperture and ISO are your primary considerations. Aperture to get the DOF, or lack thereof, needed for the desired effect and ISO to keep the digital noise to a minimum. Shutter speed will be whatever is needed to reduce/eliminate ambient light from your image.

      The point is there is no one "correct ISO" for any given situation. The photographer must evaluate the photographic challenge before him/her and select the three elements of exposure (shutter speed, ISO, aperture), in combination with the possibility of adding light, that will produce the effect/image he/she is looking to create.

    • Clarity and sharpness - As much as I love my SmugMug account, I have to say that I have some really trash images there. Whatever clarity/sharpness you see in any SmugMug hosted image is more result of the skill of the photographer in capturing the image and then in processing the image. Changing hosting sites, like changing camera bodies, will, in all likelihood, not produce the quantum improvement in your images you seem to be looking for. There is one cavet to this statement I feel I should make .... there are some photo hosting sites that do a huge amount of image compression during the ingest process. Image compression, without exception, does damage to a photo. How much damage is done is a function, at least in part, of the amount of compression being done and the software technology being used. Some sites do better than others in both regards and, IMHO, SmugMug seems to do better than most others.
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 8, 2010
    Sunny, soft shadow = +1 stop

    so

    original image EXIF ISO 50, f9.0 1/125th sec should have been ISO 50 f11 1/60sec

    so, this looks like slight overexposure to me, given that f9 is closer to f8 than it is to f11.

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 8, 2010
    • The point is there is no one "correct ISO" for any given situation
    Scott, there is a line of thought about ISO which is, as I understand it, that a moderately high ISO is better with plenty of light. So in daylight, a higher ISO, and commensurably higher aperture and shutter, gives superior results, and in low light as low an ISO as possible, with commensurably lower aperture and shutter, gives superior results.

    The OP's image might have done better with a much higher ISO.

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • ziggy53ziggy53 Super Moderators Posts: 24,127 moderator
    edited March 8, 2010
    NeilL wrote:
    [/LIST]Scott, there is a line of thought about ISO which is, as I understand it, that a moderately high ISO is better with plenty of light. So in daylight, a higher ISO, and commensurably higher aperture and shutter, gives superior results, and in low light as low an ISO as possible, with commensurably lower aperture and shutter, gives superior results.

    The OP's image might have done better with a much higher ISO.

    Neil

    What are the presumed advantages of using high(er)-ISO in good light?
    ziggy53
    Moderator of the Cameras and Accessories forums
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 8, 2010
    ziggy53 wrote:
    What are the presumed advantages of using high(er)-ISO in good light?

    Higher signal to noise, resulting in better detail and dynamic range! :hide

    I believe it!!! But... not to be used indiscriminately. I think in the case of the OP's image it would have produced something he would have found closer to what he wanted.

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 8, 2010
    Edited my post #16 to correct the incorrect use of "stops". ;)

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • craig_dcraig_d Registered Users Posts: 911 Major grins
    edited March 8, 2010
    NeilL wrote:
    Higher signal to noise, resulting in better detail and dynamic range! :hide

    I don't see any technological reason why ISO 400 should have better dynamic range than ISO 100, nor do I recall reading any technical camera reviews that show this to be the case. Do you know of any?

    DPReview's measurements with the 5D2 show pretty consistent dynamic range for all hardware ISO modes except 6400 (which, not surprisingly, is a little worse than the others), and somewhat degraded dynamic range in the "expanded" modes.
    http://craigd.smugmug.com

    Got bored with digital and went back to film.
  • ziggy53ziggy53 Super Moderators Posts: 24,127 moderator
    edited March 8, 2010
    NeilL wrote:
    Higher signal to noise, resulting in better detail and dynamic range! :hide

    I believe it!!! But... not to be used indiscriminately...

    Higher ISOs always return higher random sensor noise, resulting in lower signal to noise ratios. Higher ISOs always return lower dynamic range.

    The detail in higher ISOs is partially obscured by the random noise, so there is less detail at higher ISOs too.

    DXOMark has a very nice documentation of both signal to noise and dynamic range as relates to ISO in the Canon 5D MKII:

    http://www.dxomark.com/index.php/eng/Image-Quality-Database/Canon/EOS-5D-Mark-II

    It is sometimes appropriate to use higher ISOs in good light to satisfy a need for both maximum DOF, using a small aperture setting, and maximum shutter speed, to reduce camera shake, camera related slap and to reduce subject motion. I don't think that this rooster image is a demonstration of that need, especially as relates to the DOF.

    In the case of the OP and the original image I believe that a larger aperture would have allowed better separation of the subject from the background, so a faster shutter speed and larger aperture setting would be my recommendation for this particular situation.
    ziggy53
    Moderator of the Cameras and Accessories forums
  • QarikQarik Registered Users Posts: 4,959 Major grins
    edited March 8, 2010
    from my understanding..the base iso of the camera is going to give you the highest dynamic range. As you increase iso you start to lose dynamic range though with modern FF cameras, the loss in dynmic range is not really noticable in most shots until you get to north of 1600 or so.
    D700, D600
    14-24 24-70 70-200mm (vr2)
    85 and 50 1.4
    45 PC and sb910 x2
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  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 9, 2010
    Yes, Qarik, Ziggy and Craig, I'm sure you are all right!

    However, in my experience, which is very little, correct exposure is the basic factor in image quality. Noise will occur, especially in mid to low tones at any ISO whatsoever if the exposure is not spot on, so compromising detail and dynamic range, laboratory tests notwithstanding. Base or low ISO is not a guarantee against noise. Higher ISOs increase the visibility of noise because the 'sensitivity' (output) of the sensor is increased overall, so if noise is present it will be more apparent. The trick is to find the ISO which produces optimum exposure, because then a negligible amount of noise is in the image, and the boosting of its visibility with a higher ISO can be offset, depending on the camera's ability, but not at the highest ISOs a camera is capable of. So it is a tradeoff. Higher ISO in good light can be an aid to getting the best exposure, which can mean that detail and dynamic range can be optimised, and the increased visibility of the very restricted noise is, on balance, a price worth paying.

    While the laboratory tests on ISO and noise are informative, they don't always speak to real world shooting. Lab test tables have their place in our thinking, but they are not always directly applicable to our practice. Anything which helps get us optimum exposure is of more value in real life.

    I think, too, that there are advantages to image quality of using higher aperture and shutter speed in good light, not only in sharpness but also in resolution. Using a higher ISO can allow us these benefits, if they fit the style (DOF etc) that we want for the image.

    "So beware when setting ISO levels with a digital camera. Wonderful though the concept of changeable ISO speeds undoubtedly is, a measure of practical use to establish the best settings to use is always advisable. Unlike with film use, a higher/faster ISO setting may in some circumstances actually turn out to produce a superior image quality to a lower/slower one. The best ISO varying with each and every camera and the particular conditions under which it is used." http://www.digicaminfo.btinternet.co.uk/isosettings.htm

    I still think that an ISO of 200 would have helped the OP's image, so I'd have liked to see it shot at ISO 200 f5.6 and 1/500sec or higher. A real world test like this has its own value, whatever the lab tables say.

    But what would have helped the OP most would have been a lightmeter! Exact exposure is the holy grail!

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • craig_dcraig_d Registered Users Posts: 911 Major grins
    edited March 9, 2010
    Well, I'm sure we all agree that if you need fast exposure to freeze motion, and you need a narrow aperture to obtain sufficient depth of field, then even in pretty good light it may be necessary to boost the ISO level to get proper exposure. If that's all you meant, then I don't think you made yourself clear earlier. The impression I got from your previous comments was that you think a higher ISO might have better dynamic range than a lower ISO, which does not make sense to me. In fact, you specifically said that even in good light, a higher ISO level could lead to "higher signal to noise, resulting in better detail and dynamic range". The impression this gave is that if 1/100 sec. f/4 ISO 200 was a proper exposure, then 1/100 sec. f/5.6 ISO 400 (which would also be proper) might somehow give better dynamic range, which to the best of my knowledge is not true on any camera.

    Nobody is arguing that it is best to always shoot at the lowest ISO level available even if that results in underexposure. Anyone who understands basic digital photography techniques knows that aperture, shutter speed, and ISO level have to be balanced for correct exposure in any given situation.
    http://craigd.smugmug.com

    Got bored with digital and went back to film.
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 9, 2010
    craig_d wrote:
    Well, I'm sure we all agree that if you need fast exposure to freeze motion, and you need a narrow aperture to obtain sufficient depth of field, then even in pretty good light it may be necessary to boost the ISO level to get proper exposure. If that's all you meant, then I don't think you made yourself clear earlier. The impression I got from your previous comments was that you think a higher ISO might have better dynamic range than a lower ISO, which does not make sense to me. In fact, you specifically said that even in good light, a higher ISO level could lead to "higher signal to noise, resulting in better detail and dynamic range". The impression this gave is that if 1/100 sec. f/4 ISO 200 was a proper exposure, then 1/100 sec. f/5.6 ISO 400 (which would also be proper) might somehow give better dynamic range, which to the best of my knowledge is not true on any camera.

    Nobody is arguing that it is best to always shoot at the lowest ISO level available even if that results in underexposure. Anyone who understands basic digital photography techniques knows that aperture, shutter speed, and ISO level have to be balanced for correct exposure in any given situation.

    Where did you get that last set of numbers above? If you mean to assert that I said there were no limits to the ISO used, that high ISOs were always better, and the highest ISO best of all, you are not being honest.

    The actual image characteristics cannot be 100% predicted from rules of thumb, or even laws of physics. We are dealing with technology, not with theory, and not with a laboratory situation controlled to the nth degree. We should try things in real world shooting and see the results. I don't argue against anything that you say. I said so.

    I know that the figures we have for the behaviour of things like sensors are approximations, affected by the sensitivity of our measuring instruments and how tightly the independent variables are controlled.

    It is not possible for us to describe with precision each and every set of conditions of exposure in which a sensor will be at optimum operation. As you know, analog is smooth but digital is stepwise. The complexity of the smooth non-linear analog inputs to the sensor are crudely transformed into the stepwise outputs of the sensor, processor and software. This creates "shoulders" in which the predictabilty of response is reduced. Changing one variable, such as ISO, might tip the balance this way or that in a comparatively unpredictable way. Put together a lot of variables, all acting non-linearly on the sensor, and you end up with an approximate prediction only of the sensor-procesor's reaction to a change of settings.

    My point, again, is quite clear, as is the quote in my last post. In the real world, guided by what science tells us, we can try things and see what gives us the best results.

    Now if you like to say that it is impossible that the OP's image could have had better resolution and dynamic range, shot with the settings I suggested (not the ones of yours you have in your post which you attribute to me), then on what authority do you do so? You yourself said above that "aperture, shutter speed, and ISO level have to be balanced for correct exposure". Balance is hardly consistent with your throwing out the idea that a higher ISO might benefit resolution and dynamic range. Finding that balance is precisely what I am talking about. How do you propose we go about finding that balance with your "nobody is arguing", rules?

    Underexposure or overexposure are both no-nos for best resolution and dynamic range. Lowest ISO does not guarantee best resolution and dynamic range. Sometimes a higher ISO might do better. There is no exact truth. The best guidance we have in real world shooting is lightmeter readings. Then it's up to the skills of the photographer, and the human judgement factor is very significant.

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • craig_dcraig_d Registered Users Posts: 911 Major grins
    edited March 9, 2010
    1) if you want to have a civil discussion, accusations of dishonesty are counter-productive.

    2) I did not attribute my example exposure values to you. They are an example to illustrate that I understood us to be talking about raising ISO while keeping the overall level of exposure the same, rather than raising ISO to correct what would otherwise be underexposure.

    3) Any analog signal has some level of noise. Amplifying the signal unavoidably amplifies the noise as well. Therefore you want the cleanest, highest-amplitude signal (within the limits of what the system can handle without clipping) that you can get. In a digital camera, this means an exposure that is correct at the lowest hardware-supported ISO level, since ISO level in a digital camera (aside from "expanded" ISO modes) is typically implemented by adjusting the gain on one or more analog amplifiers.

    4) It makes no sense to me to worry about the level of error in 12-bit or 14-bit quantization of an analog signal, considering that the digitized data will be demosaiced, reduced to eight bits per channel, and probably subjected to lossy compression. The effects of any one of those things will completely drown out any quantization error at the ADC stage. Basically, the RAW data is oversampled, so any error in the least-significant bit or two is completely insignificant.

    5) Even if it were true that digitization of a signal already made noisier by greater analog amplification (i.e. higher ISO level) might somehow, some small percentage of the time, produce a better image than using an initially stronger signal requiring less amplification, I don't see how this could possibly be predicted in the field for any given shot. To say that it might be possible is still not to say that it's probable or predictable, and if it is neither probable nor predictable then the "possibility" is useless.
    http://craigd.smugmug.com

    Got bored with digital and went back to film.
  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 9, 2010
    Lets keep the discussion about the posters original question and not wander afield into personal recriminations, which are non-helpful, and derail the the thread and interested readers.

    Rarely is a great image, defined entirely, by whether it was shot at ISO 100 or ISO 200 or ISO 400, or even higher. I even add noise now and again to images.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 9, 2010
    craig_d wrote:
    1) if you want to have a civil discussion, accusations of dishonesty are counter-productive.

    2) I did not attribute my example exposure values to you. They are an example to illustrate that I understood us to be talking about raising ISO while keeping the overall level of exposure the same, rather than raising ISO to correct what would otherwise be underexposure.

    3) Any analog signal has some level of noise. Amplifying the signal unavoidably amplifies the noise as well. Therefore you want the cleanest, highest-amplitude signal (within the limits of what the system can handle without clipping) that you can get. In a digital camera, this means an exposure that is correct at the lowest hardware-supported ISO level, since ISO level in a digital camera (aside from "expanded" ISO modes) is typically implemented by adjusting the gain on one or more analog amplifiers.

    4) It makes no sense to me to worry about the level of error in 12-bit or 14-bit quantization of an analog signal, considering that the digitized data will be demosaiced, reduced to eight bits per channel, and probably subjected to lossy compression. The effects of any one of those things will completely drown out any quantization error at the ADC stage. Basically, the RAW data is oversampled, so any error in the least-significant bit or two is completely insignificant.

    5) Even if it were true that digitization of a signal already made noisier by greater analog amplification (i.e. higher ISO level) might somehow, some small percentage of the time, produce a better image than using an initially stronger signal requiring less amplification, I don't see how this could possibly be predicted in the field for any given shot. To say that it might be possible is still not to say that it's probable or predictable, and if it is neither probable nor predictable then the "possibility" is useless.

    Perhaps some other viewers might be interested in how you would translate what you say here into real world shooting technique. That's my primary interest, and that's why I brought up the "higher ISO is more useful in good light than in bad" school of thought (I didn't invent it) in relation to Scott's post.

    What you describe above should be presented as statistical probability. That's what it is. It is not an exact description of the actual behaviour of this technology. People might not realise that from the way you write.

    I think what you wrote above doesn't change what I said in plain language: that the theory and science is a guide, but within a certain "bandwidth" of settings, you don't know what the result will be until you try. This very uncertainty (it is not possible fully and exhaustively to describe all possible events within that bandwidth, and in every set of gear in every situation) creates the possibility that unorthodox changes in settings within that bandwidth will result in image improvement. That is the practical implication, is it not?

    In any case, you appear not to be saying it is impossible, under the right conditions, to improve resolution and dynamic range by raising ISO. I have said, as you do, there will be a price to pay in amplified noise, but a perfect exposure will already have minimised the generation of noise, and the small amplification of noise at conservative ISO settings is a price worth paying for improvement in other image characteristics should they be achieved.

    I would not however put the emphasis, as you seem to do, on ISO, but more generally on perfect exposure. I keep repeating that setting the ideal ISO for the hardware (and software?) is not going to guarantee the maximum resolution and dynamic range. I suggest, singling out ISO in that fashion is a non sequitur.

    You don't seem to have shown categorically that raising the ISO, under the conditions I described, will not improve resolution and dynamic range.

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited March 9, 2010
    deal.gif
    I said lets keep the discussion about the original post, and abandon the discussion of noise vs ISO. Further comments in this vein will be deleted without further warning......

    If you wish to debate without name calling, in a new thread, that is ok. This thread will be limited to discussions of exposure and roosters, pleasethumb.gif

    I am not taking sides, here, but discussion will remain on topic or disappear.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited March 9, 2010
    pathfinder wrote:
    deal.gif
    I said lets keep the discussion about the original post, and abandon the discussion of noise vs ISO. Further comments in this vein will be deleted without further warning......

    If you wish to debate without name calling, in a new thread, that is ok. This thread will be limited to discussions of exposure and roosters, pleasethumb.gif

    I am not taking sides, here, but discussion will remain on topic or disappear.

    I'm perfectly willing to oblige, of course, Jim. I am just left wondering, since your reply to the OP, the first reply, was about ISO settings, among other things. I am just continuing to work through the issue that you yourself raised, of the implications of exposure settings, including a higher ISO, for this particular image.

    Scott also raised the role of ISO in relation to this particular image, and I responded to that.

    I must say that I have kept on topic as you and Scott developed it.

    Apply the gag if you feel something is to be gained by doing so, you have that prerogative, but I don't think you are accurate in describing my posts as being off topic.

    Neil
    "Snow. Ice. Slow!" "Half-winter. Half-moon. Half-asleep!"

    http://www.behance.net/brosepix
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