Originally posted by romay And yes, for a bigger sensor, the total amount of light gathered is higher, which equals more information in the final image. Assuming identical framing and pixel density, the bigger sensor will always be sharper. Assuming equal framing and same pixel count, the larger sensor will always exhibit better S/N ratio.
If an only if, you accept narrower DoF. If you equal the DoF, between APS-c and FF (and I assume other systems) you have to stop the FF down 1 stop to match DoF, which means you have to raise ISO to maintain shutter speed. Meaning the same amount of light is used to create each image, twice the light on half the sensor.
Based on the D750 and K-3 and a lw/ph close to 3000, the advantage to the FF is about 100 lw/ph, about .03 percent, I guarantee you, you can't see the difference.
This is seeming to be a really hard concept for folks to wrap their heads around. I guess it's just repeated so often, people assume there's some truth to it.
People have to realize equivalence describes how systems are the same. People trying to use it to make one system better at something than another system are wasting their time, unless you're talking about narrow DoF, like ƒ1.4. That setting produces the narrowest DoF, of any system available on only FF that's what you're going for. Everywhere else where you are talking about format advantages, you're giving up something to get something. That's because "equivalence" is not about "how do systems differ, and how is one better than the other", it's about "How are these systems equivalent." Why is that such a hard concept to understand? To try and use it to say one format is better than the other is a perversion of the term.
Quote: A person really doesn't need to have an understanding of circles of confusion to make incredible photographs.
There is not knowledge necessary to take incredible photographs beside where the shutter release is. But somewhere along the way you learn things to increase your control, and your odds of taking aa great photograph. Accidents do happen. The question is, can you repeat them.
You could construct a series of dictums like
"longer lens = shallower depth of field."
wider aperture means more diffuse out of focus areas
smaller aperture means more DOF.
higher ISO means less noise
There are all kinds of simple explanations that will do, until someone asks "why?" Could you achieve photographic proficiency without ever asking why? You could perhaps, is it a testable theory? Someone should put them together in a field guide with a thorough index.
The school I went to suggested I wouldn't be a proficient photographer if I didn't spend a semester studying lens design, but honestly, how do we know how much we need to know? I can't think of a single time I really needed to know anything about lens design, until this forum came along, and it's mostly used to converse with know it alls making rampant assumptions. But I may have used it a few times. It certainly didn't hurt me. Because of it the first thing I look at in a lens is "how many elements ", and try and understand the trade offs between the IQ , the handling of CA and out of focus areas, weight, and number of elements. I'm guessing you can buy a lens without doing that, but are you getting a lens that is suited to the purpose you are buying it for? You see this all the time on the forum, you see the guys who understand lens design talking to another , one has has bought a Sigma 18-35 ƒ1.8 and the other has bought the DA 20-40, because they understand enough about the design of the lenses and how they apply to the real world to make that decision. it's not that one is smart and one is stupid, it's that they both got what they wanted. They are both smart. But they bought two different lenses. It's an understanding of lens design that makes that possible.