Moving to Full Frame

Morning all,

I have a question that I'm struggling to find an answer for from good ol' Mr Google.
(I went looking for a Newbie section, so if I missed it - Mod's, feel free to move )

So...
I realise aperture has two main affects on photography. The amount of light let in (as part of the Aperture/ISO/Shutter triangle), and also DoF.
Now, the DoF bit of FF vs APSC I get, but... what effect does a FF sensor have of the amount of light let in?
EG: If we were to take two similar cameras (Say, D800 and a D7100). Both at ISO 200 and 1/250sec shutter. And set them both at (for arguments sake) f3.5
Ignoring DoF for a sec; would there be any difference in exposure?
I'm trying to understand if the larger surface area of the senor allows for more light to be 'soaked up' or anything similar?

Sorry for the long and probably dumb question; but its something I havent been able to get my head around - so figured I'd just ask

- Lurch

Lurch - based on the test that I have made comparing the D7000 and D700 / D800, the FX in general has a one stop difference. Meaning if you shoot a subject at ISO 3200 on a D7000 DX, the D800 can get the same or similar exposure at ISO 1600 when you use the same settings (shutter speed, aperture and lens).

Ahh - nice. Exactly what I was after.
So (roughly speaking) a FF is one stop "lighter" than an APSC. Cool.
EDIT: It just makes a difference in lens choice regarding what I'm used to

Yeh, but the sensor is better in the D800. So you are going to have a lot more flexibility in exposure balancing in post. There are probably several more ways the D800 sensor is going to best the 7000. You may not be, but I would not use that one parameter as a proxy for the difference in the sensors. These cameras are in a whole different league. JD

Question.
The local retailer (Teds) has the D800 listed as 4ps and the D800e as 6fps.
I though it was the same of both (eg, 6fps is only available when a) the grip was on and b) you slim down to DX mode)?

Very interesting question. I would have to believe that, all things being equal, there should be no difference. In other words if the FX and DX sensors are identical other than the size then I would expect there to be no difference in how they would expose the same image. Now, given that there are no two cameras that exhibit this, then all things are never equal and any difference you see on a D800 over a D7000/7100 probably owes as much to the sensor technology than it does to sensor size (i.e. a D800 shooting the same image in FX and DX mode should expose the same),

Both D800 and D800e shoot 4fps in FX mode and 5 in DX mode, 6 in DX plus grip.

It isn't just how big the sensor is but actually how large each pixel is and its sensitivity to light, whether it has a microlens, etc.. Think of it as the number of photons hitting the surface per unit area of pixel. Larger pixels collect more light so they tend to be more sensitive and have better low light performance (less noise). Larger sensors tend to have larger pixels. I believe the D800 pixels are, for example, larger than those of the D7100 because the D7100 has higher pixel density for its chip size. Size of the sensor along with size of the pixel determines pixel density per unit area. Higher density means each pixel collects less light assuming overall area stays the same.

Edit:

Pixel pitch for respective cameras:

D7100 3.91 um
D800 4.8 um
D600 5.96 um
D4 7.4 um

D4 has the largest pixel size in the group which partly explains its excellent low light performance, irrespective of sensor size.

BackdoorHippie said:

Very interesting question. I would have to believe that, all things being equal, there should be no difference. In other words if the FX and DX sensors are identical other than the size then I would expect there to be no difference in how they would expose the same image.

Click to expand...

This is my thinking as well... Exposure is a result of intensity and duration, yes? So why would two sensors, exposed to the same intensity of light for the same duration, expose differently?

If there are differences between the two exposures, and assuming all things being equal BUT the sensors, then I would have to assume there is something else about the sensors, other than their respective sizes, that accounts for the difference in exposure.



Edit: Never mind... Just read crycocyon's post.

Durrr... Pixel size. That's what i get for posting while still working on my first cup of coffee this morning.