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
PhotoTeach2 Forum Pro • Posts: 15,805
Re: Back to the original point:

YangMills wrote:

PhotoTeach2 wrote:

YangMills wrote:

PhotoTeach2 wrote:

FingerPainter wrote:

PhotoTeach2 wrote:

YangMills wrote:

PhotoTeach2 wrote:

Great Bustard wrote:

PhotoTeach2 wrote:

FingerPainter wrote:

Bob A L wrote:

But the op's question was not about noise. It was about different sensors in low light.

When OP said "Does this mean the 1" would do better in low light?" what do you think he meant the 1" would be better at, if it wasn't noise performance and DR?

The first thing I (personally) think about is what SS I need to use, (preferably w/out increasing ISO).

Again, the only reason a higher ISO setting is undesirable is because when you use a higher ISO setting, it means you are using a lower exposure than the camera is capable of absorbing. However, that lower exposure may be a necessary evil to accommodate the constraints of DOF and/or motion blur.

Exactly why I prefer to not increase ISO.

But it is not the higher ISO setting, per se, that results in the more noisy photo -- it is the fact that you are choosing (or letting the camera choose) f-numbers and/or exposure times that result in less light getting to the sensor.

I only think about noise if I indeed have to raise ISO, (w/ also reduced DR).

Sure, 'cause at base ISO, you are doing the best your camera can do, with regards to noise, for a "properly exposed" photo.

I see f/1.8 as 2-stops faster SS than f/3.5, (w/out increasing ISO w/ noise & DR concerns).

You see incorrectly, since the same exposure time can be used at f/1.8 as at f/3.5. It's just that f/3.5 will result in less light reaching the sensor as f/1.8 for a given camera, scene, and exposure time, and thus a more noisy photo.

And thus I would NOT want to do that.

But the more narrow aperture may be a necessary evil to get the DOF/sharpness you want.

However, if we are comparing f/1.8 on 1" to f/3.5 on APS-C, then, for the same scene and exposure time, f/1.8 on 1" has only a 1/3 stop noise advantage over f/3.5 on APS-C, with a concomitant more shallow DOF (trivial difference on both counts).

But if I am also changing sensor sizes, I realize I will have an inherently lower noise as a offsetting factor, (if noise has indeed become noticeably-objectionable on the smaller-sensor).

There is not "inherently lower noise". The noise for *all* systems is the same for the same DOF and exposure time, assuming equally efficient sensors. For example, FF has no noise advantage over a smartphone for the same DOF and exposure time.

The noise advantage of larger formats comes from either using a more shallow DOF for a given exposure time, or a longer exposure time for a given DOF, or any combination in between. And, as a side, situations where the more shallow DOF is "enough" or the longer exposure time is "short enough" are extremely common -- thus the advantage of larger sensor systems as a whole (aside from size, weight, and price, of course!).

So w/ (possible) noise as a factor, the overall advantage drops to only about 1/3-stop.

The overall noise advantage was 1/3 of a stop right from the start, since f/1.8 on 1" puts 1/3 of a stop more light on the sensor as f/3.5 on APS-C for the same scene and exposure time.

But how many times do I have to say that "noise" is NOT a concern until it becomes noticeably-objectionable.

So from a "PRACTICAL" standpoint, I see a 2-stop (SS) advantage, (until noise becomes a factor).

No. Why do you insist on making objectively false statements? There is no such 2 stop advantage. What is the advantage that you are claiming?

The advantage is an f/1.8 lens is "faster" ... because you can use (2-stops) "faster" SS (than f/3.5).

You can use whatever shutter speed you want, regardless of the max aperture of the lens. Using an f/3.5 lens doesn't prevent you from using a shutter speed as fast as you use with a f/1.8 lens.

It extends my options and flexibity.

All things being equal ... i will select f/1.8 over f/3.5 lens every day.

But all things are not equal so far as the topic of this thread goes. Of course f/1.8 gives you about 2 stops advantage over f/3.5 for the same size sensor. But an f/1.8 on a 1” sensor gives you only 1/3 stop options and flexibility advantage over an f/3.5 on an APSC sensor. And this is the point you keep making objectively wrong statements about.

If "noise" is NOT A FACTOR (until noticeably-objectionable), then my main advantage is (only) the 2-stops "SS" advantage, (because it is a "faster" lens).

There is NO 2 stop advantage. Nothing stops you using the same SS in both situations. Nothing. You will get identical results within 1/3 of a stop: image lightness, DoF, motion blur and noise.

If there "no" advantage, then why not continue from f/3.5 to f/128 and continue to raise ISO ???

It is exactly the same context.

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