The Official Nikon D800 Thread

[TheAnimus]

You got the maths or anything behind that statement Manehead?

Surely it differs for APC-S vs 35mm, Surely cannon the max would be slightly less than Nikon?

[kalniel]

An average lens would only require around a 12MP sensor to resolve it adequately.

This statement doesn't make sense without reference to aperture size and sensor area.

The D800 has a 24x36mm sensor, and at f/4 will not be diffraction limited in green-yellow wavelengths until 118MP. That's a lot of room for lens flaws before saying the resolving would be limited to 12MP.

[Manehead]

Ok I admit I was flippant in quoting an actual MP figure. But the point I was trying to get across is that it has come to the point where the lens resolution is the limiting factor compared to the sensor resolution. For an APS-C camera, the optimal point is *roughly* around 12MP, after which the extra detail captured by higher resolution sensors starts to taper off exponentially. For FF obviously this will be proportionally higher, at around 18MP, but still no where near the 36MP of the D800. These are not exact numbers obviously, and will depend on the quality of the lens. But the idea is, using the same lens, the extra detail captured when going from a 6MP to 12MP sensor is much higher than going from a 12MP to 24MP sensor, and even less real detail is gained when upgrading to the 36MP of the D800.

[TheAnimus]

But that assumes a perfect sesnor, which doesn't exist.

With the D800 it can subsample to provide lower resolution images, which much less noise.

Basically it's not a marketing exercise

[kalniel]

Ok I admit I was flippant in quoting an actual MP figure. But the point I was trying to get across is that it has come to the point where the lens resolution is the limiting factor compared to the sensor resolution.

My point was you just can't generalise and say that. It's totally dependant on factors such as aperture size.

If you shoot relatively wide open you can resolve huge numbers. An APS-C sensor at f/2 is not diffraction limited until 209MP in green-yellow wavelengths. Of course, a lens is not going to approach that resolution, but you can imagine a good quality prime not being so underwhelming as to limit it down to 12MP.

On the otherhand, if you are shooting closed up to f/8, then you are going to start being diffraction limited on APS-C and only resolve around 13MP.

For FF, like the D800 then the equivalents are a whopping 471MP and 29MP respectively. And sure, it's harder to make bigger glass as good, but assuming you do get OK glass you are going to be able resolve more going from 12MP to 36MP in both cases.

But the idea is, using the same lens, the extra detail captured when going from a 6MP to 12MP sensor is much higher than going from a 12MP to 24MP sensor, and even less real detail is gained when upgrading to the 36MP of the D800.

This I would mostly agree with - it's diminishing returns in the improvements we might perceive.. but that's more a consequence of using a total area count like MP over X by Y resolution counts.

I think your general point that chasing MP at all costs is a bad thing is correct - especially for APS-C markets where this is most prevalent. But this is not the case here - this is a FF camera and the MP count is not at all ridiculous.

[Manehead]

I'm not talking about diffraction limiting caused by the aperture here... in fact I'm not even factoring in the extra blur caused by aperture diffraction.

I'm talking about the quality of the glass, and how the *maximum* resolution of the average lens is way below that of an average sensor, and it doesn't matter if you increase the sensor resolution by 10x or 100x, you will not get any extra detail unless you improve your glass.

You are correct in that the effect is more pronounced in high resolution APS-C sensors, but I think 36MP is getting close too being overkill for FF sensors too.

[kalniel]

Fair enough. We need more lens tests to see how much they are actually limiting things

[Bobster]

so D800 shot - resized

and 100% of the same image

head on over to my friend Rob Mitchell's blog to read more on how he gets on with it

[merdat]

Bob, can't find your mates blog is your link ok ?

[Bobster]

fixed link - thanks