Canon 5D, 5D2, 7D vs Pentax K5 noise and DR comparision

Started Nov 30, 2010 | Discussions
photogerald Senior Member • Posts: 1,798
Re: Wow

Dave Luttmann wrote:

It seems that a lot of the benefits of fullframe just evaporated with this camera. Huge DR, low noise, in body IS. Pentax seems the one to beat. I find the 16mp enough for me....but it's the huge DR that is great. Lesser chance of blown highlights....more natural look.

Actually, "poor" DR at base ISO has been a complaint of 5DII owners over on the Canon forums. As unlikely as it may seem, the K-5 and D7000 have indeed gotten their attention.

photogerald Senior Member • Posts: 1,798
Re: Canon 5D, 5D2, 7D vs Pentax K5 noise and DR comparision

Thanks for putting the time (substantial, I'd imagine) into this very thorough analysis. Your results are consistent with those from DXOMark and Gordon, and also correlate with the real-world examples that have been posted by JohnBee and others.

Reading posts like this one is the next best thing to actually having a K-5 to play with.

Philip Goh Regular Member • Posts: 447
Re: Canon 5D, 5D2, 7D vs Pentax K5 noise and DR comparision

DR is measured from 0EV (sensor saturation). The plots don't reach that limit simply because I didn't care to have samples so close to saturation, since they are irrelevant. The only important thing to precisely know is where each sensor saturates and make that point the reference for 0EV.

These are the sat points I used for the test:

CAMERA ISO100/80 ISO1600
-------------------------------------------
5D: 3692 3692
5D2: 15758 15763
7D: 13582 15299
K5: 16383 16383

I'm sorry but I still do not understand this.

If the saturation points you've used in the test are different, does that make the test invalid? Additionally, my understanding would be that the saturation point corresponds to the point where highlight clipping occurs. Surely you'd want this point to be the same for all cameras?

What does the length of the SNR curve mean? I interpreted that as having a wider dynamic range. Is that incorrect?

OP _GUI_ Regular Member • Posts: 386
Re: Canon 5D, 5D2, 7D vs Pentax K5 noise and DR comparision

Philip Goh wrote:

These are the sat points I used for the test:

CAMERA ISO100/80 ISO1600
-------------------------------------------
5D: 3692 3692
5D2: 15758 15763
7D: 13582 15299
K5: 16383 16383

I'm sorry but I still do not understand this.

If the saturation points you've used in the test are different, does that make the test invalid? Additionally, my understanding would be that the saturation point corresponds to the point where highlight clipping occurs. Surely you'd want this point to be the same for all cameras?

What does the length of the SNR curve mean? I interpreted that as having a wider dynamic range. Is that incorrect?

The saturation point is an inherent parameter of each camera sensor. It's the RAW value in which clipped highlights are encoded in each camera.

I calculate and adjust this sat point to correspond with the 0EV reference of the plots.

The length of the curve means nothing; there is curve at those EV values for which I measured RAW data to plot the curves.

Regards

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solarider Veteran Member • Posts: 4,863
Re: Canon 5D, 5D2, 7D vs Pentax K5 noise and DR comparision

Actually it's an unreal ISO 70 according to DXO Mark - which is even more useful in my book.

photogerald wrote:

SOB1 wrote:

the ISO 80 of the Pentax is not real ISO 80.

The "real" or native ISO of the K-5 may not be quite as low as 80, but it has been shown to be less than ISO100 (therefore there is some IQ benefit to shooting at ISO80).

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