Larger sensor just a luxury?

[EchoingWhisper]

Density of light does change. A larger f/stop will bring higher density of light, even if the total amount of light is the same.

You just added a variable that should be a constant between your comparisons. The only variable here should be the sensor size.

It's not a variable, just that sensor size affects the density of light given that the same total amount of light falls on the sensor. On the larger sensor, the light is refracted to fill a larger frame, thus the light is less dense.

 

[2WheelPhoto]

Larger sensors are a con, waste of money and time, there's no reason to use one at all. If you don't beleive me just do a forum search of some other threads you'll see

 

[Josh66]

Density of light does change. A larger f/stop will bring higher density of light, even if the total amount of light is the same.

You just added a variable that should be a constant between your comparisons. The only variable here should be the sensor size.

It's not a variable, just that sensor size affects the density of light given that the same total amount of light falls on the sensor. On the larger sensor, the light is refracted to fill a larger frame, thus the light is less dense.

So ... Are you saying that f/8, 1/125 will give a different exposure on full frame than it will on crop, with both cameras side-by-side, in the same light and the same lens?

edit
And same ISO, obviously...



(If that is what you are saying (which is what it sounds like to me) - you are wrong.)

 

[EchoingWhisper]

If there is a full frame lens that could refracts all of its its light to cover only the DX frame, then it'll be a fair comparison.

 

[Josh66]

If there is a full frame lens that could refracts all of its its light to cover only the DX frame, then it'll be a fair comparison.

There isn't, so it's not.

 

[EchoingWhisper]

You just added a variable that should be a constant between your comparisons. The only variable here should be the sensor size.

It's not a variable, just that sensor size affects the density of light given that the same total amount of light falls on the sensor. On the larger sensor, the light is refracted to fill a larger frame, thus the light is less dense.

So ... Are you saying that f/8, 1/125 will give a different exposure on full frame than it will on crop, with both cameras side-by-side, in the same light and the same lens?

edit
And same ISO, obviously...



(If that is what you are saying (which is what it sounds like to me) - you are wrong.)

No, that's not what I mean. A f/8, 1/125 and at the same ISO will give the same exposure for FX and DX, because their pixel pitch is the same. If both FX and DX have the same amount of pixels, DX would have about 1 time smaller pixels. So, at base ISO for both sensors with the same design, without amplification, DX's base ISO would be 1 stop less, the exposure for both would be different. Even at the same amount of amplification, DX's ISO would always be about 1 stop less.

This makes FX has higher low light capabilities - at the same f/stop. But that is not true, cause' FX's lenses would always be larger than DX's lenses at the same f/stop, which means FX basically gets more light because their lens. If both DX and FX's lens were at the same size, both DX and FX would get the same amount of light and their low light capabilities would be the same. A DX's effective f/stop is one stop less compared to FX. It's the lens that controls the low light ability, not the sensor. Do you realise why compact cameras are such bad low light performers? Cause' their lenses are small.

 

[Josh66]

It's not a variable, just that sensor size affects the density of light given that the same total amount of light falls on the sensor. On the larger sensor, the light is refracted to fill a larger frame, thus the light is less dense.

So ... Are you saying that f/8, 1/125 will give a different exposure on full frame than it will on crop, with both cameras side-by-side, in the same light and the same lens?

edit
And same ISO, obviously...



(If that is what you are saying (which is what it sounds like to me) - you are wrong.)

No, that's not what I mean. A f/8, 1/125 and at the same ISO will give the same exposure for FX and DX, because their pixel pitch is the same. If both FX and DX have the same amount of pixels, DX would have about 1 time smaller pixels. So, at base ISO for both sensors with the same design, without amplification, DX's base ISO would be 1 stop less, the exposure for both would be different. Even at the same amount of amplification, DX's ISO would always be about 1 stop less.

This makes FX has higher low light capabilities - at the same f/stop. But that is not true, cause' FX's lenses would always be larger than DX's lenses at the same f/stop, which means FX basically gets more light because their lens. If both DX and FX's lens were at the same size, both DX and FX would get the same amount of light and their low light capabilities would be the same. A DX's effective f/stop is one stop less compared to FX. It's the lens that controls the low light ability, not the sensor. Do you realise why compact cameras are such bad low light performers? Cause' their lenses are small.

So where does the 'light density' get factored in, and why does my light meter not have a button to adjust sensor size and/or light density?


And, even more puzzling, why does it give me correct exposures, even without knowing what size sensor I have?

 

[murlis]

large sensor, Sigma DP2

small sensor, Sony Cybershot

Need I say any more.

 

[EchoingWhisper]

large sensor, Sigma DP2

small sensor, Sony Cybershot

Need I say any more.

That has nothing to do with this thread, and these are JPEGs, they're not released at the same year, by the same manufacturers, so you can't really compare them. READ THIS: The Real Megapixel Myth

 

[Dao]

OP, just want to clear one fact.

DX lens and FX lens are basically the same as far as light correcting goes.

i.e. A DX 50mm lens vs a FX 50mm lens with same camera mount (Assuming they exist)

The only difference is the size of the image circle. Let's say AreaD (for DX) and AreaF(for FX) (AreaF > AreaD)
If all conditions are the same except the recording medium is different. The light intensity in a particular spot on AreaD is the same as AreaF.


For some reason, I think OP maybe thinking FX lens and DX lens has the same image circle.

 

[Josh66]

For some reason, I think OP maybe thinking FX lens and DX lens has the same image circle.

I think he is expecting the DX image circle to start out the size of the FX circle, but then get shrinked down (and 'intensified') before it gets to the sensor.

Similar to the way you would focus the light through a magnifying glass to burn something. When it's diffused (large image circle), it can't burn anything. When it's focused (small image circle), it'll burn ants all day long. In both cases there is the same amount of light coming through the glass, only the area it is focused on is changing. I think he is expecting the same thing to be happening inside the camera.

 

[Dao]

For some reason, I think OP maybe thinking FX lens and DX lens has the same image circle.

I think he is expecting the DX image circle to start out the size of the FX circle, but then get shrinked down (and 'intensified') before it gets to the sensor.

Similar to the way you would focus the light through a magnifying glass to burn something. When it's diffused (large image circle), it can't burn anything. When it's focused (small image circle), it'll burn ants all day long. In both cases there is the same amount of light coming through the glass, only the area it is focused on is changing. I think he is expecting the same thing to be happening inside the camera.

I think he believe they both have the same image circle at the focal plane. But the FX lens are larger, it collect more light and the image that cast on the recording medium is brighter. (Kind of based on the same magnifing glass example you mentioned)

 

[EchoingWhisper]

For some reason, I think OP maybe thinking FX lens and DX lens has the same image circle.

I think he is expecting the DX image circle to start out the size of the FX circle, but then get shrinked down (and 'intensified') before it gets to the sensor.

Similar to the way you would focus the light through a magnifying glass to burn something. When it's diffused (large image circle), it can't burn anything. When it's focused (small image circle), it'll burn ants all day long. In both cases there is the same amount of light coming through the glass, only the area it is focused on is changing. I think he is expecting the same thing to be happening inside the camera.

Oh thanks, now you understand what I'm talking about. So am I right?

 

[EchoingWhisper]

For some reason, I think OP maybe thinking FX lens and DX lens has the same image circle.

I think he is expecting the DX image circle to start out the size of the FX circle, but then get shrinked down (and 'intensified') before it gets to the sensor.

Similar to the way you would focus the light through a magnifying glass to burn something. When it's diffused (large image circle), it can't burn anything. When it's focused (small image circle), it'll burn ants all day long. In both cases there is the same amount of light coming through the glass, only the area it is focused on is changing. I think he is expecting the same thing to be happening inside the camera.

I think he believe they both have the same image circle at the focal plane. But the FX lens are larger, it collect more light and the image that cast on the recording medium is brighter. (Kind of based on the same magnifing glass example you mentioned)

Oh thanks, so there's a way to explain what I'm trying to say. What I'm trying to say is that at the same f stop, both lens don't actually get the same total amount light, but only the same density of light. Which means a larger sensor would always collect more light at the same f stop. If both lens started out with the same amount of light, the DX one would be 1 f stop higher.

 

[Dao]

Let's just make it simple. Shooting a evenly lit white wall.


Total amount of light collected
FX > DX because of larger area.

Expousre:
Same.

Please keep in mind that expousre has nothing to do with the size of the overall area. At a partcular spot, they receive the same amount of light. i.e. The 1mm x 1mm center of the center of DX or FX receives the same amount of light when all other conditions are the same.