DOF and Cropping take 2

Started Feb 11, 2014 | Discussions thread
awaldram Forum Pro • Posts: 13,147
Re: U R Slippery II

Ian Stuart Forsyth wrote:

awaldram wrote:

In your La La world the first image should be over 2 stops under exposed as F2.8 on the Q is f16 on aps-C !

You just proved why it shouldn't be under exposed with your answer here kind of

Yep but thats obvious iso 100 = iso 100 on any format , f2.8 = f.28 , 1/180 = 1/180 format is irrelevant there a constant.

Hence my bewilderment about your claims to the contrary.

So irrelevant of sensor efficiency or size (light density) a camera will have the same exposure solution for the same ISO set.

the Q at F/2.8 1/80 iso 800 needs more gain as it has captured 13 times less total light than K3 at F/2.8 1/80 iso 800 because of the sensor size difference

Not sure what you trying to say. the Q will produce more noise at iso 800 than the k3 because it requires more internal gain to match sensitivity but both will have the same light sensitivity at iso800.

We can reduce the AP on the K3 to F/10 raise the iso 3000 and then it would gather around the same total light as the Q F/2.8 1/80 iso 800

Why would you do this.?

Or another way to look at it the Q iso 800 = k3 iso 3000

No chance ISo is a standard its calibrated and set on every camera ever made , without it photography would not exist as it does today. Every camera would require custom algorithms for every exposure

Q iso800 = k3 iso 800 = 645d iso80 = glass plate camera iso800 = hubble telescope iso800.

As the image I posted proved setting the same aperture , the same shutter and the same iso results in the same exposure across formats.

Not sure what your showing maybe that the k3 noise at 3200 is similar to Q7 @800?

I could only find the Q7 to compare to the K3

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Pentax K-x Pentax Q Olympus PEN E-PM2 Pentax Q7 Pentax K-3 +17 more
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