Won't larger formats give you more light?

[Shakedown St.]

I am having a heated debate with a few photographers right now.

I made the claim that a larger the sensor will allow a larger lens that can take in more light, and thus allowing you to take a brighter image.

Their response was that full frame or medium format cameras are not "brighter" than crop sensors, and maybe because I am using the wrong terminology.

I was always under the impression that photographers got into full frame DSLR's for their lowlight capability, that you can't get out of a crop sensor.

Who is correct? I was told it is all relative.

 

[Big Mike]

More light...but also a larger area to cover.

The main reason that lager sensors tend to be better, is that their pixels (photosites) are more spread out....they have a lower 'dot pitch'. This would mean that they are better at allowing heat to dissipate, which means that they end up with less distortion, which means that they show less digital noise, which means they can comfortably use higher ISO levels. So it's not that a larger sensor collects more light, it's that it is better able to deal with higher ISO, which makes it better for low light shooting.

Or alternatively, a larger sensor with the same pitch as a smaller sensor, would simply give you more pixels in the image.

 

[astroNikon]

To add to that ..
think of this.
I can use a FF lens on a Crop sensor camera.
But it doesn't help at all in relation to "light" as the sensor's physical dimension is less than a FF sensor. The larger image just goes to waste as the crop sensor only uses a smaller area inside the larger image.

So the lens "element size" to allow more light in has nothing to do with it.

Then as mentioned above, briefly, FF sensors have larger sensor pixels (for a 24mp FF vs 24mp Crop), which thus are more sensitive to light due to their larger size.

 

[tirediron]

To expand a little on Mike's point: In general the larger the format, the larger (physically) each photo receptor. A larger photo receptor is able to work with lower light levels (higher ISO) and thus, in general could in fact make a brighter image at a given light level (within limits of course) than a smaller one. So, is your contention correct? Well.. kind of, sort of, depending on circumstances. Maybe.

 

[petrochemist]

So, is your contention correct? Well.. kind of, sort of, depending on circumstances. Maybe.

No it's not.
The rest of your post was certainly 100% correct, but you don't get brighter images with larger formats.
Big Mike's post covered things nicely it's photons per unit area that matters which is purely a matter of subject brightness & aperture (well more precisely T stop).

Larger pixels can give that effect but there is also other effects that can give some degree of the reverse - lenses for large formats are more difficult to make at fast apertures.
This isn't too much of an effect for digital (though I don't remember any f/0.95 FF lenses and they are certainly several in MFT), with 4x5 lenses apertures as low as f/2.8 are super rare, yet my DSLR collection has many primes of under f/2 (and these are quite high quality yet relatively cheap).

 

[480sparky]

If larger formats made for more light, all hand-held meters would need to have the format your shooting dialed into it I'm order to provide a correct exposure.

Or you'd have to convert the meter reading manually to the format you're shooting with.

However, you don't have to do this. If my Gossen or Sekonic meters say, for instance, a given scene is 1/250, f/8 at ISO 400, then I can shoot it with those settings whether I'm using a smart phone or 20x24.

 

[Designer]

I made the claim that a larger the sensor will allow a larger lens that can take in more light, and thus allowing you to take a brighter image.

Incorrect. The ability of a lens to transmit light is governed by;

1) Its maximum aperture relative to its focal length. (the f-stop) and

2) Its materials (glass and coatings) that affect the "brightness" or "amount of light" that is transmitted.

A small DLSR lens that is f/2.8 for instance will transmit the same "amount" of light "brightness) as a huge medium format lens with the same maximum aperture of f/2.8. (Assuming the same kind of glass.)

The "brighter image" is a different quality that is essentially not related to the lens, but rather to the sensor and the processor.

As explained above, larger photosites can contribute to a "brighter image", or give acceptable results while working in low light conditions.

Clear now?

 

[Ysarex]

I am having a heated debate with a few photographers right now.

I made the claim that a larger the sensor will allow a larger lens that can take in more light, and thus allowing you to take a brighter image.

Their response was that full frame or medium format cameras are not "brighter" than crop sensors, and maybe because I am using the wrong terminology.

I was always under the impression that photographers got into full frame DSLR's for their lowlight capability, that you can't get out of a crop sensor.

Who is correct? I was told it is all relative.

As a general rule larger sensors deliver less noisy images than smaller sensors in low light conditions. Why is complicated. Start here: Noise, Dynamic Range and Bit Depth in Digital SLRs

Joe

 

[KmH]

With larger sensors pixels are larger which improves the signal-to-noise ratio which allows use of more signal gain (higher ISO).
Larger pixels also give more resolution.

 

[480sparky]

I think the confusion may come from looking at the physical size of lens apertures across the various formats.

Yes, a large format f/4 aperture is physically larger than f/4 on a DSLR lens. But remember that the numbers you are comparing the two are both fractions, the f being another number. .... the focal length of the lens.

 

[Ysarex]

With larger sensors pixels are larger which improves the signal-to-noise ratio which allows use of more signal gain (higher ISO).
Larger pixels also give more resolution.

From the article I linked above:

"Bottom line: Among the important measures of image quality are signal-to-noise ratio of the capture process, and resolution. It was shown that for fixed sensor format, the light collection efficiency per unit area is essentially independent of pixel size, over a huge range of pixel sizes from 2 microns to over 8 microns, and is therefore independent of the number of megapixels. Noise performance per unit area was seen to be only weakly dependent on pixel size. The S/N ratio per unit area is much the same over a wide range of pixel sizes. There is an advantage to big pixels in low light (high ISO) applications, where read noise is an important detractor from image quality, and big pixels currently have lower read noise than aggregations of small pixels of equal area. For low ISO applications, the situation is reversed in current implementations -- if anything, smaller pixels perform somewhat better in terms of S/N ratio (while offering more resolution). A further exploration of these issues can be found on the supplemental page. Rather than having strong dependence on the pixel size, the noise performance instead depends quite strongly on sensor size -- bigger sensors yield higher quality images, by capturing more signal (photons)."

Joe