Why are my photos noisy - discussion

SrMi
April 2, 2023
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    Team
    April 17, 2023, 12:30 p.m.
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    They are. If you do a units analysis in SI units, both end up as having the unit lux second. That's usually a good indicator as to whether something is the same or not.

    No. Where is is a bit short is that it omits 'per unit area', but in an informal definition, not a problem. You can talk about an amount of rain, and what you mean is 'per unit area'.
    His definition is:

    So, film is a kind of 'sensor', so in terms of that is covers all photography. You could argue that it doesn't apply to electronic shutters, though there is no difference in effect, so that quibble would be rather pedantic.

    The owner of this site is The Photographer's Foundation Limited. It's hard for a company to hijack a thread. I think it should be quite plain to most people here just who it is hijacking the thread.

    The exposure that a photographer uses is central to the issue of noisy photos.

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    Members 3613 posts
    April 17, 2023, 12:30 p.m.
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    I'm not wrong because our definitions are the same 🙂

    * exposure - amount of light per unit area that struck the sensor while the shutter was open
    ** optimal exposure - the maximum exposure* within dof and motion blur requirements without clipping important highlights.
    *** under exposed - more exposure* could have been added with the DOF and blur constraints still being met without clipping important highlights.

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    Members 976 posts
    April 17, 2023, 12:34 p.m.
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    In a moment we will be discussing the difference between "the shutter was open" and "integration time" ;)

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    Members 3613 posts
    April 17, 2023, 12:35 p.m.
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    I have updated it to include 'per unit area'

    * exposure - amount of light per unit area that struck the sensor while the shutter was open
    ** optimal exposure - the maximum exposure* within dof and motion blur requirements without clipping important highlights.
    *** under exposed - more exposure* could have been added with the DOF and blur constraints still being met without clipping important highlights.

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    Members 2292 posts
    April 17, 2023, 12:47 p.m.
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    come on Porky your letting the team down 💪💪

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    Members 260 posts
    April 17, 2023, 12:47 p.m.
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    some cameras do not have "shutters" ( neither have their lenses )

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    Members 878 posts
    April 17, 2023, 12:51 p.m.
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    Well, I did not mention integration on purpose but it is integration...

    BTW, there should be "per unit area" there.

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    Members 260 posts
    April 17, 2023, 12:52 p.m.
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    sometimes more exposure ( while optimal from S/N standpoint ) is not going well with a particular raw converter ... yes theoretically things on software side are supposed to be designed to allow relevant sliders to be dialed back w/o any ill effects - but it is not always the case...

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    Team
    April 17, 2023, 12:57 p.m.
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    And you're going to do your damndest to make sure that it does.

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    Members 976 posts
    April 17, 2023, 12:58 p.m.
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    Yes and yes.

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    Members 128 posts
    April 17, 2023, 12:59 p.m.
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    Even I have my limits.

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    Members 509 posts
    April 18, 2023, 4:36 p.m.
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    I don't find them as useful as I expected with my camera. They trigger too soon even on the highest tolerance level and they obscure the view including peaking if I try and go a little past their arrival. Works better with my Lumix G9.

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    Members 132 posts
    April 18, 2023, 4:42 p.m.
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    Have you confirmed (with a RAW histogram) that their “arrival” is indeed pre-clipping?

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    Members 509 posts
    April 18, 2023, 4:50 p.m.
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    So, we have hundreds of posts about exposure and ISO already across various threads. Thanks for the discussion so far (although it appears to be a subject that could be discussed forever).

    I think it has improved my understanding.

    But how to pull this together as an exposure strategy? I'm going to propose the following for me. Will this lead to disaster?

    1. Shoot raw
    2. Set camera to base ISO
    3. Within constraints of available light, desired aperture and shutter speed, attempt to expose to the right while avoiding clipping of crucial highlights
    4. If there is insufficient light, give priority to setting desired shutter speed and aperture even if this leads to underexposure.
    5. Do not increase ISO
    6. Correct tones in post and apply whatever noise reduction needed to control noise resulting from this strategy.

    Justification of this approach (for me)

    1. All my cameras use modern Sony sensors
    2. No need to bother raising ISO or using auto-iso because boosting ISO only helps reduce read noise, not shot noise
    3. Read noise is a minor component of overall noise in modern cameras, boosting ISO to reduce read noise may make a small theoretical difference but the improvement will likely be lost in the wash.

    Keeps it nice and simple.

    Comments (pragmatic rather than theoretical)?

    Thanks

    Dave

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    Members 360 posts
    April 18, 2023, 4:55 p.m.
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    I do not believe those sensors are fully invariant, and so raising ISO speed still gives you more image quality compared to raising image brightness in post.

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    Members 1737 posts
    April 18, 2023, 5:01 p.m.
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    You will have slightly better shadow noise at the ISO point where the conversion gain increases than just below that point. There is little improvement in input referred read noise above that point.

    Most raw converters and most color profiles have difficulty with more than a five-stop push, and the finder will be pretty dark by then, too.

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    Members 1737 posts
    April 18, 2023, 5:04 p.m.
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    Right, through some of the ISO range.

    gfx 100s input reffered rn.png

    The GFX 100S shares its pixel architecture with the Sony a7RIV and a7RV.

    gfx 100s input reffered rn.png

    PNG, 86.9 KB, uploaded by JimKasson on April 18, 2023.

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    Members 509 posts
    April 18, 2023, 5:07 p.m.
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    (Counting on my fingers) 5 stop push is equivalent to ISO 3200? Very unusual for me to shoot that high. So Ok to using this strategy to, say, ISO 1600, then boost ISO for those emergency situations? I'm not bothered by optimising perfectly, if it's a stop more noise than when optimised, I'm fine with that, primarily interested in keeping it so simple I can remember it in the field.

    My current strategy is auto-iso.

    My previous strategy was base ISO only, resulting in lots of shots ruined by camera shake. Then one day I awoke and realised that noise is better than blur.