Sensor size and light gathering capability

[woeilee]

Two different size sensors (518.94mmsq vs 328.56mmsq) with pixels of the size, e.g. both 5.7µm, obviously the former will have higher pixel count
Taking that every other things are the same, will the larger sensor allow a brighter exposure.

I am curious if APS-H sensor will use a faster shutter speed than APS-C sensor camera to produce the same exposure, given that ISO and Aperture are the same.

 

[Override2Zion]

Two different size sensors (518.94mmsq vs 328.56mmsq) with pixels of the size, e.g. both 5.7µm, obviously the former will have higher pixel count
Taking that every other things are the same, will the larger sensor allow a brighter exposure.

I am curious if APS-H sensor will use a faster shutter speed than APS-C sensor camera to produce the same exposure, given that ISO and Aperture are the same.

That is not true, if that is true, it will defeat the entire point of metering. Sensor size will allow a larger area to be exposed through the lens but not more light. Since each photosite on the sensor works independently to "collect" light, having a larger sensor will only mean you can
1) have more space between photosites (larger gap = less interference = less noise)
2) pack more photosites onto the sensor (more photosites = capable of more pixels after interpolation)
3) more space to arrange additional photosites to extend dynamic range (like the Fuji S5Pro)

 

[ExplorerZ]

1) have more space between photosites (larger gap = less interference = less noise)

i tot larger gap between photosites = smaller photosites = more noise due to the surface area being smaller? :dunno:

 

[Override2Zion]

i tot larger gap between photosites = smaller photosites = more noise due to the surface area being smaller? :dunno:

Larger gap simply means the photosites are spaced further apart, the photosites can still be larger in size.

Small sensor, small gap, small photosites, same megapixel
o o o o
o o o o
o o o o

Large sensor, bigger gap, bigger photosites, same megapixel
O O O O
O O O O
O O O O

Bigger photosite = More light can enter = Better Signal-Noise Ratio
Larger gap between photosite = Less heat & interference = Less noise = Better Signal-Noise Ratio

Either way, we achieve IQ improvement. Hope this explains better.

 

[ExplorerZ]

eh since TS is talking about same density sensor, doesn't the larger gap means smaller photosite? either way, one will decrease the surface of the other? :bsmilie:

 

[Override2Zion]

TS gave a scenario of 2 sensors of different size with same photo site sizes, there can be 2 variables left
1) Assuming, photo sites are pack at the same density (no of photo sites per square unit), you will achieve more pixel count, no improvement in IQ
2) Assuming you drop the photo site density but increase the distance between each site, you will achieve better noise control and possibly increase in pixel count

Either way, in neither scenarios will allow you to capture a MUCH brighter image on the same shutter, ISO, aperture settings.

 

[Override2Zion]

eh since TS is talking about same density sensor, doesn't the larger gap means smaller photosite? either way, one will decrease the surface of the other? :bsmilie:

If you read closely on TS assumptions, there was no mention of density
"with pixels of the size, e.g. both 5.7µm, obviously the former will have higher pixel count ". My interpretation here is that higher pixel count does not equal to same pixel density. No hostility intended bro, just to clarify my interpretations.

 

[Rashkae]

Two different size sensors (518.94mmsq vs 328.56mmsq) with pixels of the size, e.g. both 5.7µm, obviously the former will have higher pixel count
Taking that every other things are the same, will the larger sensor allow a brighter exposure.

I am curious if APS-H sensor will use a faster shutter speed than APS-C sensor camera to produce the same exposure, given that ISO and Aperture are the same.

Short answer: Nope.

Long answer: You may get higher ISO capabilities, and the difference in perspective when using the same lens on a APS-H vs. APS-C.

But other than that, no change in the metering. Light is still light.

 

[woeilee]

Larger gap simply means the photosites are spaced further apart, the photosites can still be larger in size.

Bigger photosite = More light can enter = Better Signal-Noise Ratio
Larger gap between photosite = Less heat & interference = Less noise = Better Signal-Noise Ratio

Either way, we achieve IQ improvement. Hope this explains better.

Thanks for this explanation.

TS gave a scenario of 2 sensors of different size with same photo site sizes, there can be 2 variables left
1) Assuming, photo sites are pack at the same density (no of photo sites per square unit), you will achieve more pixel count, no improvement in IQ
2) Assuming you drop the photo site density but increase the distance between each site, you will achieve better noise control and possibly increase in pixel count

Either way, in neither scenarios will allow you to capture a MUCH brighter image on the same shutter, ISO, aperture settings.

Many thanks Override2Zion, I am actually thinking of (1).

If you read closely on TS assumptions, there was no mention of density
"with pixels of the size, e.g. both 5.7µm, obviously the former will have higher pixel count ". My interpretation here is that higher pixel count does not equal to same pixel density. No hostility intended bro, just to clarify my interpretations.

Actually I am looking at same pixel density of 2 different size sensors. If each individual is collection a unit of light, same pixel density in larger sensor means more total pixel available to collect more unit of light?

Short answer: Nope.

Long answer: You may get higher ISO capabilities, and the difference in perspective when using the same lens on a APS-H vs. APS-C.

But other than that, no change in the metering. Light is still light.

Thanks Rashkae.

 

[Anthony Lee]

According to DXO, lenses with wide aperture like f1.2 may cause light fall-off. This is another interesting aspect that shows the complexity of DSLR sensors and their ability to capture light through lenses.

http://www.dxomark.com/index.php/en/Our-publications/DxOMark-Insights/F-stop-blues