Why smaller sensors beat full-frame sensors for wildlife photography

Discussion in 'Beyond the Basics' started by freixas, Jun 11, 2019 at 10:05 AM.

  1. RVT1K

    RVT1K No longer a newbie, moving up!

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    There is an inherent level of noise in any electronic system, its called the noise floor.
    Smaller signals will be closer to this noise floor and have a lower signal/noise ration because of this. Any amplification stage also adds noise.

    So a small signal is noisier and boosting it makes it worse.


     
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  2. freixas

    freixas TPF Noob!

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    You might benefit from reading this article I found: The effect of pixel size on noise. It includes some real world comparisons. The author shows his calculations of the effects of both upstream and downstream noise with respect to pixel size. There is also some interesting debate in the comments section there.
     
  3. RVT1K

    RVT1K No longer a newbie, moving up!

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    Noise in an electrical system is noise weather it be in the circuitry of a camera, a radio, a piece of test equipment, or what ever. Smaller signals are closer to the noise floor of any device.

    And maybe its just the way the author chose his words but in my world all noise is random and will not "cancel each other out completely" when combined.

    But I also think a lot of this is a situation where just because you can measure something doesn't mean you can tell the difference.

    We encounter this with the equipment my company makes. We can and regularly do make measurement where we can see "a problem" that has zero effect on what the customer is doing.
     
  4. Ysarex

    Ysarex Been spending a lot of time on here!

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    I think this disagreement is effectively solved with this sentence; "The FORMAT SIZE is what matters in the argument, But as I said before, the format size is irrelevant if the photographer knows what they are doing."

    The format size is what matters and it is irrelevant.

    Joe
     
  5. freixas

    freixas TPF Noob!

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    Actually, I agree. I would welcome real-word comparisons. The link I gave includes some. Sadly, the article dates from 2015--I'd like to see a comparison from some more recent cameras.

    Keep in mind that my post is regarding wildlife photography (although, honestly, the wildlife I am thinking of is birds). So if I have a thrush 100 feet away and am shooting with a 400mm lens, what I want to know is if I would be better off shooting with a camera with a smaller pixel pitch. I want to know two things: 1) better off without scaling the image and 2) better off if the larger image is scaled to match the smaller.

    My post title is a misleading except in the sense that smaller sensors tend to have smaller pixel pitches (not always, of course).
     
    Last edited: Jun 12, 2019 at 10:41 AM
  6. freixas

    freixas TPF Noob!

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    Hi, Joe,

    I have no idea if I agree or disagree with you. What I would say instead is "The format size does not matter and is (therefore) irrelevant." When I have a shot of a bird that only fills 3mm x 3mm of a sensor's surface, every pixel outside this zone is irrelevant. I don't care if the sensor size is 3mm x 3mm or 8" x 10".

    However, my disagreement with Soocom1 was whether this 3mm x 3mm image of a bird is different when it falls on a small sensor vs. a large sensor. The answer is no: the image is exactly the same as it is entirely determined by the lens and the position (not size) of the sensor. As long as the shape and position of a sensor is the same within this 3mm x 3mm area, the projection/distortion is exactly the same regardless of the size or shape of the rest of the sensor. I am assuming that all sensors, regardless of size, are located the same distance from a lens.
     
  7. Ysarex

    Ysarex Been spending a lot of time on here!

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    I was just noting the problem with logical contradiction there.

    I'm not entirely sure what he's saying. I understand how objects in a photo are skewed (shape distorted) toward the edges of the frame relative to the center and I'm aware of this problem occurring with all camera formats i.e. it's a camera problem we've all lived with since day one. So I'm not sure what he's saying about that problem relative to working between different formats. I do find it odd to bring it up at all in this context because the problem diminishes with increasing lens focal length and of all the various sub disciplines in photo those most likely to use the longest of all focal lengths are wildlife photographers who in that context have every other possible thing to worry more about than that.

    Joe
     
  8. freixas

    freixas TPF Noob!

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    Thanks for the clarification.

    Again, my point is that it really doesn't matter if I stick a wide-angle lens or a telephoto on a camera. The focal length comment is a red herring. If an image fits on an APS-C sensor, then this same image will fit on a full-frame sensor with exactly the same projection and distortion. Let's say that there's a certain amount of light drop-off near the edges of the APS-C sensor. The same image won't be near the edge of the full-frame sensor, but it will be identical, with the same exact light drop-off in the same places.

    One way to picture this would be to imagine that we took the full-frame sensor and applied tape (ick!) to cover up the portions of the sensor larger than the APS-C size. The APS-C sensor and the exposed portion of the FF sensor occupy exactly the same space and shape. The lens neither knows nor cares what it is projecting onto (remember, we use the same lens in both cases). Unless you believe in magic, the image formed on either sensor will be exactly the same.
     
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  9. Derrel

    Derrel Mr. Rain Cloud

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    I want to see actual cameras compared, with real lenses, comparing Canons with Canons, Nikons with Nikons, Pentaxes with Pentaxes. Be aware that a six-inch mis-focus drops a 50 MP camera down to 4 to 6 MP of "resolution". AF system capability in sometimes overlooked...read the reviews of the latest FF Pentax K1 Mark II... it has slow AF for action work.

    Theory is fine, but in-field resolving power is affected by more than just "sensor size".
     
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  10. freixas

    freixas TPF Noob!

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    Those who think equipment doesn't matter aren't wildlife photographers. And key among the hardware features wildlife photographers look is fast, accurate auto-focus. On my old Canon 70D, I was unable to auto-focus when I used my 1.4x extender with my 400mm lens (it's not one of the pricey lenses). I found my bird photos improved when I took off the extender and got my auto-focus back, despite the reduction in magnification. Small and sharp beats big and fuzzy. One of the key advantages of my upgrade to an 80D is that the 80D will auto-focus with the same lens and extender.

    I, too, would love to see a good comparison, but how would one set it up? Unless you are DP Review or have friends with complementary equipment, it seems like it would be difficult. You need somewhat equivalent cameras and you definitely need to use the same exact lens.
     
  11. Derrel

    Derrel Mr. Rain Cloud

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    Exactly... all this theorizing doesn't take into account important issues like AF capability and speed, and real-world issues. Who remembers the Canon 1Ds-III focusing issue of circa 2010? The camera that consistently had trouble focusing?

    As I have read from MANY sources, the Nikon F5 has "uncannily accurate and fast" autofocusing..and the more-or-less same AF setup in the Nikon D500 has an extraordinarily good AF reputation. And as I understand, the D850 has really fantastic AF... but the same was not true of the D800 or D810.

    Speaking of better performance..who has seen the D810 compared to the D500 at ISO levels of 3200 and 6400 and 12800?? The ISO can be a BIG factor in many situations, and especially when one needs fast shutter speeds...in MANY action situations, one need 1/800 to 1/1250 second, maybe even higher in some situations.
     
  12. JBPhotog

    JBPhotog No longer a newbie, moving up!

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    One ingredient not included in this argument is budget. Pro wildlife shooters own fast long glass so a DX body with its limitations is not as attractive as say an FX body sporting a 600mm f4 or 800mm f5.6. ;)
     

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