So a f/1.8 on a 1" sensor would still gather more light than a f/3.5 on an APS-C?

Started Sep 18, 2022 | Questions thread
Great Bustard Forum Pro • Posts: 45,947
Re: Perspective.

alfn wrote:

Great Bustard wrote:

alfn wrote:

Great Bustard wrote:

Bob A L wrote:

Right, it's like

One size does not fit all, when it comes to sensor sizes for photos.

I think that's a given that no one has debated. What was being discussed is how f/1.8 on 1" relates to f/3.5 on APS-C. And the answer is that f/1.8 on 1" projects 1/3 of a stop more light on the sensor as f/3.5 on APS-C for the same scene and exposure time, which results in a very slightly less noisy photo (with very slightly less DOF), assuming similar sensor tech. Thus, f/1.8 on 1" is 1/3 of a stop "faster" than f/3.5 on APS-C, in terms of why we care about the f-number.

However, there may be other important differences between the photos (e.g. resolution, distortion, color, etc.) which matter as much, and likely much more, than the differences in noise and/or DOF, not to mention the elephant in the room, which are the differences in size, weight, price, and operation between the cameras.

So why bang on at such length about the trivial difference in this instance?

No one was "bang[ing] on at such length about the trivial difference" -- people were banging on at such length that the difference between f/1.8 on 1" and f/3.5 on APS-C is trivial. If you'll look above, my entry into this subthread was countering the claim:

So I suggest the most practical answer is that the f/1.8 [on 1"] has a (near) 2-stop advantage over f/3.5 [on APS-C].

That's it.

Why not just say there are many more important factors to consider?

I did:

You may suggest [that "the most practical answer is that the f/1.8 [on 1"] has a (near) 2-stop advantage over f/3.5 [on APS-C]", but your suggestion would have no photographic relevance. In fact, the 1/3 stop difference in light gathering and DOF between f/1.8 in front of the 1" sensor and f/3.5 in front of the APS-C sensor is, for lack a better word, trivial. Basically any other difference between the cameras *dwarfs* the difference in aperture.

But then Bob replied:

I don't understand.

Indeed, even in my posts that you just replied to, I restated that the other difference matter far more:

However, there may be other important differences between the photos (e.g. resolution, distortion, color, etc.) which matter as much, and likely much more, than the differences in noise and/or DOF, not to mention the elephant in the room, which are the differences in size, weight, price, and operation between the cameras.

And yet, you still said what you said. So, it doesn't seem to be a matter of "Why not just say there are many more important factors to consider?"; rather, it seems to be more of a matter of saying it, and the person reading and understanding that it was, indeed, stated, and more than a little clearly with more than a little emphasis.

The obsession with noise (and so-called total light) that pervades these forums is absurd. One should at least try to keep things in perspective.

It seems more than a little apparent that those who understand the situation are the ones who are keeping things in perspective, whereas those who don't understand, aren't.

That's what I like to see: concise and to the point without any obfuscation or personal slights.

Absolutely!  Although, and I'm sure you agree, it can get exhausting when you say something, and people either outright ignore it or say you said something completely different.  I'm sure I can find an example if I try hard enough, but, well...

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