crop duster plane

Discussion in 'Photography Beginners' Forum' started by stevet1, Aug 15, 2019.

  1. Dacaur

    Dacaur TPF Noob!

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    You say iso has nothing to do with exposure.
    Ok. Set your iso to 100, go outside on a sunny day, and take a picture.
    Now go inside, turn off lights and close the drapes. and adjust your shutter speed and aperature to anything you like, and take a picture. (No cheating with a flash or tripod)t Is the exposure the same? No? Now adjust iso, and suddenly you can get a picture with the same exposure as the first one.

    Just because digital iso doesn't do it the same way as it did with film, doesn't mean it suddenly somehow doesn't affect exposure anymore. It still does the same thing. 200 iso film is twice as sensitive to light as 100iso film. A digital camera sensor set to iso 200 iso is twice as sensitive to light as a sensor set to 100 iso. A
    jet airliner accelerates by burning gas fuel resulting in expanding gasses pressing directly on the front of the combustion chamber, an electric car accelerates using electricity and magnetism. In both cases, it's still acceleration and accomplishes the same thing, just in different ways.


     
  2. Designer

    Designer Been spending a lot of time on here!

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    In case you would like to learn more, there are other discussions about digital ISO available on the internet. Just because digital camera manufacturers equate digital ISO to film ISO doesn't make it so. They did that originally to help sell digital cameras to film users who were used to the ISO (or ASA) rating as an indication of how much your image would be affected by the ISO setting.

    When you see your image, you are seeing the result of sensor data combined with the camera firmware which creates a viewable image, either on the LCD or on your computer. When you add ISO, you are informing the firmware to make the image brighter, but that still doesn't change the fact that the ISO value is applied gain. Your sensor does not suddenly become more or less sensitive to light. And if gain is applied, to what is it being applied? Obviously the captured data. Post-capture data is data that has already been captured, meaning the ISO setting had nothing to do with the exposure. Your sensor cannot change its sensitivity (without being physically rebuilt into a different sensor).

    Also; just a friendly suggestion; leave the analogy-making to someone else.
     
  3. RVT1K

    RVT1K No longer a newbie, moving up!

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    Word games to obfuscate the situation in an attempt to sound more intelligent than anyone else here.
     
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  4. smoke665

    smoke665 TPF Supporters Supporting Member

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    Rather then digress into an argument about what exactly digital ISO is, how about this gleaned from Nikon - "What is ISO Sensitivity" - "Photography is built on the three pillars of exposure: shutter speed, aperture and sensitivity. Shutter and aperture are controls for adjusting how much light comes into the camera. How much light is needed is determined by the sensitivity of the medium used. That was as true for glass plates as it is for film and now digital sensors. Over the years that sensitivity has been expressed in various ways, most recently as ASA and now ISO." What Is ISO Sensitivity? | Understanding ISO from Nikon One of the better descriptions I've seen to bridge the gap between film and digital, while still understanding the importance of ISO in calculating an exposure.
     
    Last edited: Aug 21, 2019
  5. zulu42

    zulu42 Been spending a lot of time on here!

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    Lots of smart people confuse exposure with image brightness. An easy mistake to make, but the terminology is important. I'll modify your example:
    set ISO to 100, take a picture. Set ISO to 200 - only change the ISO- and take the same picture.
    Is the exposure different?
    No.
    Is the image brightness different?
    Yes.
     
  6. Derrel

    Derrel Mr. Rain Cloud

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    Steve, when you refer to aperture as either "too high or too low" that is a very risky way to describe wide aperture settings such as F2.8,or small narrow apertures such as F16.

    Because aperture is a fractional value relative to the focal length of the lens, numeric values such as 16 and 22 are very small apertures, and low numbers such as 1.4 and 2 and 2.8 represent what are called wide apertures.

    Traditionally many people referred to a wide aperture or a small aperture, but in the modern era with a tremendous influx of people who are self taught there is a tremendous tendency to refer to aperture number value as either "high" or "low",which is a poor way of handling the terminology as it has traditionally been used for well over 150 years. It is if you're asking if you're driving100 miles per hour " Am I driving my car too wide or too narrow?" Referring to aperture as too high or too low is just not the way to ask if your aperture was too wide or to narrow, since it has a lot of potential confusion.

    My guess is that both your aperture and your ISO setting were not correct: with a shutter speed of 1/3400 of a second and an ISO value of 100, my instinct is to say that your ISO value was far too low.
     
    Last edited: Aug 21, 2019
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  7. zulu42

    zulu42 Been spending a lot of time on here!

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    We all have different ways of wrapping our heads around the process. For me: viewing ISO as a separate and subsequent process after the exposure is made helped my photographs - most notably with noise management and highlight preservation.
     
  8. stevet1

    stevet1 TPF Noob!

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    Derrel,

    Thank you, and yes, I don't think I needed a shutter speed of 3,400. I don't think the shutter was open long enough to let enough light in.
    Without knowing the aperture setting, I suspect it was too high - maybe at 16 or 22. I should have dropped it to 5.6 or 11 maybe.
    I think an ISO of 100 was too low - maybe I should have set it from 200 to 400.

    Steve Thomas
     
  9. Derrel

    Derrel Mr. Rain Cloud

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    When shooting in JPEG mode, the ISO does form part of the practical "exposure triangle"...when shooting in raw mode with an ISO invariant sensor, an exposure that appears basically black or almost black on the back of the camera can typically be recovered in post processing software.

    We have had this discussion here multiple times over the years. For the first 15 or so years of digital photography, an under-exposed or overexposed image that had been shot in JPEG mode gave the photographer very few options for correcting any exposure mistakes that had been made in camera;beginning a few years ago with ISO invariant sensors,things changed markedly.

    And here we are today; with some people claiming that ISO has no bearing on exposure given to the sensor in-Camera. I feel that saying that ISO has no bearing on exposure is somewhat disingenuous. For people who shoot in JPG capture Mode, the setting of the ISO in relation to the f-stop and shutter speed used still represents that third side of the exposure triangle, and to claim that ISO has absolutely no bearing on exposure is only describing part of the story.
     
    Last edited: Aug 21, 2019
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  10. Derrel

    Derrel Mr. Rain Cloud

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    When referring to aperture, we are referring to the size of the hole that lets light into the lens. Because of this it is best to use the traditional terminology, by saying that my aperture was "too small" Or "too narrow "... such as when having used an f-stop such as f/16 or f/22.... had your picture turned out over exposed you would say, "my aperture was too wide " or "my aperture was too big."

    Over the past decade or so there has been a tremendous influx of new writers on blogs, And among these new writers it has become common to describe aperture as the numeric value, in direct opposition to the 150 or so years of talking about and aperture having been "too wide"or "too narrow an aperture" or "too big" or "too small".

    The use of the terms "too low"or "too high" is not the way to communicate clearly and efficiently in regard to aperture. We are talking about the size of the hole, and not the numeric value of the f-stop in question.

    This is not me being pedantic, but rather explaining a situation that will serve you very well to understand clearly and permanently.
     
    Last edited: Aug 22, 2019
  11. Dacaur

    Dacaur TPF Noob!

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    All right, if that's the case, then you should be able to take an image taken in a fairly dark area, like , say, a basement room with the curtains closed (or mostly closed if they are blackout curtains. Set your camera to ISO 12800, using F3.5 and 1/30-1/60 second shutter speed, take a picture, it's probably going to be dark, and that's fine, actually if it's not, then take it again with a faster shutter soeed, then change the iso to 100, use the same aperature and shutter speed, take another picture. Now, according to you, simply by adjusting the brightness in your photo editing program, you should be able to adjust the iso 100 picture and make both pictures look identical... In theory sure, but you can't. Oh, you might get it close, depending on lighting, but identical? Nope. Give it a try. Like, actually do it, and see what happens. Lots of people shoot in jpeg only, and since you don't make the distinction, give it a try in jpeg too. Spoiler, the results aren't nearly as good as the imperfect results you got with raw.

    Question. Do you shoot everything in your cameras native iso then just adjust brightness in post? Because if not, if you ever adjust iso in your camera, you are a hypocrite telling people something doesn't exist then using it yourself.
     
  12. Tim Tucker 2

    Tim Tucker 2 No longer a newbie, moving up!

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    Was it actually dusting crops at the time?

    ;);););)
     

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