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Author Topic: Nikon D800 - seems harder to justify Medium Format  (Read 48391 times)

BJL

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Re: Nikon D800: resolution (lp/ph) vs 22MP sensors
« Reply #120 on: May 08, 2012, 03:17:07 pm »

The question is not only about resolution but also MTF, and than we would need add sharpening to the equation.
Yes, I was rather loosely using "resolution" as shorthand to cover things like "MTF as a given lp/mm, or a given lp/ph".
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We also need to keep in mind that we may have different croppings. A square image on the D800 would be 24 MP.
And more relevant, a crop to 4:3 shape would be 32x24mm and 32MP.

Another thought: the D800E pixel size is not that much smaller than in the 80MP backs:
- The 80MP sensor is 10328 x 7760 over 53.7x40.4mm, so 5.2 micron pixel spacing, or 192 pixel per mm, so with Nyquist limit 96 lp/mm.
- The D800(E) sensor is 7,360 x 4,912 over 35.9x24mm, so 4.9 micron pixel spacing, or 205 pixel per mm, so with Nyquist limit 102 lp/mm.
So with the overall trend (based on fundamental optical factors like spherical aberration) being that good lenses for smaller formats have better resolution in the sense of higher MTF at equal lp/mm (larger formats win at equal line pairs per picture height, by having more picture height) the fact that MF lens systems are keeping up with 80MP backs suggests that 35mm lens systems should likewise be able to keep up with the D800(E) sensor.

Also, as I have mentioned before, fine grained black and white films like TMAX 100 still out-resolve any of these sensors, and I have never heard either 35mm or MF users commenting that the resolution of such films is useless because lenses are inadequate, so why should this be the case with sensors? Especially when one allows that Bayer demosaicing reduces the resolution somewhat, so lenses with good MTF up to about 80lp/mm should be able to keep up with these sensor just fine.

(TMAX 100 has MTF of 70% or better out to about 100lp/mm, at or beyond the Nyquist limit of any of these sensors, and has MTF of 50% or better out to 125lp/mm, the Nyquist limit for the 24MP "APS-C" Sony/Nikon sensors. We are still "not there yet" in terms of DSLR sensors out-resolving all film.)
« Last Edit: May 08, 2012, 03:19:22 pm by BJL »
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ErikKaffehr

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Re: Nikon D800: resolution (lp/ph) vs 22MP sensors
« Reply #121 on: May 08, 2012, 03:28:32 pm »

Hi,

That is pretty much what I have seen. Both Velvia 6x7 and Ektar 100 6x7 outresolve 24MP Sony Alpha 900 on high contrast detail, but the Sony image is much smoother and outresolves 6x7 film on low contrast detail.

http://echophoto.dnsalias.net/ekr/images/PublishedTests/Alph900vsAnalogue2/EktarVSA900_Forsmark_3200.jpg

Best regards
Erik

(TMAX 100 has MTF of 70% or better out to about 100lp/mm, at or beyond the Nyquist limit of any of these sensors, and has MTF of 50% or better out to 125lp/mm, the Nyquist limit for the 24MP "APS-C" Sony/Nikon sensors. We are still "not there yet" in terms of DSLR sensors out-resolving all film.)
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Erik Kaffehr
 

torger

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Re: Nikon D800: resolution (lp/ph) vs 22MP sensors
« Reply #122 on: May 11, 2012, 10:38:29 am »

Also, as I have mentioned before, fine grained black and white films like TMAX 100 still out-resolve any of these sensors, and I have never heard either 35mm or MF users commenting that the resolution of such films is useless because lenses are inadequate, so why should this be the case with sensors?

It is a question of current pricing. In the MF world a high pixel count is extremely expensive, so you don't really want to pay for more pixels than your lenses can resolve, then you just could buy a cheaper back instead. For DSLRs a high MP count don't really cost more for the customer, and in that case it can indeed be nice to extract all resolution the lenses can deliver.
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BJL

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In the MF world a high pixel count is extremely expensive, so you don't really want to pay for more pixels than your lenses can resolve ...
The dominant factor in MF sensor production cost is sensor size, not pixel count. High pixel counts are correlated with high price, but mainly through being correlated with larger sensor sizes. When it comes to retail prices, the higher MP count MF options are largely more expensive due to larger sensor size (like the same 6 micron pixels in 40MP 44x33mm, 48MP 48x36mm, and 60MP 54x40mm). There is also a natural market value premium for the higher resolution options and newer sensor models (80MP vs 60MP, newer 48MP vs older generation 22MP sensors at 48x36mm, etc.)  I do not see much or any evidence that increasing the pixel count at the same sensor size causes a significant increase in the _production cost_ of a MF back, anymore than it does for smaller formats. As an extremely well-known example with smaller formats, the 36MP Nikon D800 costs no more than any previous Nikon model in 36x24mm format, and $500 less that the 22MP Canon 5D MkIII.

And any decent MF lens can resolve well enough that an increase in sensor resolution (smaller pixels, more l/mm) will give an increase in image resolution. This gain does not stop simply because one is in the regime where both lens and sensor contribute to the overall resolution limits. MF is not at the stage where any MF sensor has "more pixels than your lenses can resolve". A more relevant issue seems to be "more pixels than the viewers of the image can resolve": plenty of MF users say that about 40MP is enough for all their practical/comercial purposes, and a good number go as low as 22MP on their resolution needs.

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