Do you believe DXO's pronouncement on lenses and high megapixelcameras?

On 22/05/13 06:56, RichA wrote:
They said you need top-flight lenses for a 24mp APS camera or you will
not match the resolution the sensor is capable of. This is a first,
IMO, as I understood that any moderately decent lens stopped down
would exceed current camera sensor resolutions, at least in the
centre.
So, D7100, D5200, D3200 users...better set aside a few thousand $$$'s
for those FX lenses.

Back in the day I did some calculations on equivalence between film and
digital repro. I took the specs of my Olympus OM series 50mm f1.8 as a
basis for comparisons. For simplicity I supposed that lens performance
was equal across the entire field.

To match the performance of the lens I calculated that a 24x36mm sensor
would require 64 Megapixels.

An APS sensor is about half the area so say about 32 Megapixels.

That suggests to me that figures you quote are about right. In fact as
lens performance falls away off-axis then at the extremities a lot of
pixels in the sensor are wasted. Manufacturers might consider building
sensors with denser packing in the centre to capture maximum detail but
looser packing off-axis to save file storage space.


--
Bernard Peek

In article , Bernard Peek
wrote:

Back in the day I did some calculations on equivalence between film and
digital repro. I took the specs of my Olympus OM series 50mm f1.8 as a
basis for comparisons. For simplicity I supposed that lens performance
was equal across the entire field.

To match the performance of the lens I calculated that a 24x36mm sensor
would require 64 Megapixels.

how did you calculate this number?

because you don't need anywhere near that many pixels to match film.

On 23/05/13 19:10, nospam wrote:
In article , Bernard Peek
wrote:

Back in the day I did some calculations on equivalence between film and
digital repro. I took the specs of my Olympus OM series 50mm f1.8 as a
basis for comparisons. For simplicity I supposed that lens performance
was equal across the entire field.

To match the performance of the lens I calculated that a 24x36mm sensor
would require 64 Megapixels.

how did you calculate this number?

I used the lens resolution figures reported in a review.

--
Bernard Peek

In article , Bernard Peek
wrote:

Back in the day I did some calculations on equivalence between film and
digital repro. I took the specs of my Olympus OM series 50mm f1.8 as a
basis for comparisons. For simplicity I supposed that lens performance
was equal across the entire field.

To match the performance of the lens I calculated that a 24x36mm sensor
would require 64 Megapixels.

how did you calculate this number?

I used the lens resolution figures reported in a review.

and those numbers are?

and what about the resolution of the rest of the system? just because
the lens may be good doesn't mean film or digital is going to resolve
it perfectly.

and what about dynamic range, colour accuracy and other factors that go
into image quality?

Bernard Peek wrote:

Back in the day I did some calculations on equivalence between film and
digital repro. I took the specs of my Olympus OM series 50mm f1.8 as a
basis for comparisons. For simplicity I supposed that lens performance
was equal across the entire field.

At f/8 or at f/1.8?

To match the performance of the lens I calculated that a 24x36mm sensor
would require 64 Megapixels.

Which film would manage that sort of performance?

An APS sensor is about half the area so say about 32 Megapixels.

That suggests to me that figures you quote are about right. In fact as
lens performance falls away off-axis then at the extremities a lot of
pixels in the sensor are wasted. Manufacturers might consider building
sensors with denser packing in the centre to capture maximum detail but
looser packing off-axis to save file storage space.

They won't. They could simply scale down towards the corners
if they want to save storage space --- but JPEG already needs
less space with less detailed area, negating this "advantage".
(Even lossless RAW compression is somewhat sensitive to lower
detailed areas.)

Additionally a non-grid layout is vastly more complicated than
a grid layout, harder to handle in software, much harder to
handle as a sensor.

And (good) long tele lenses don't fall off much, IIRC, so
you'd need a different sensor for every group of lens ...

Basically: nice idea, but the drawbacks are *vastly*
overshadowing the small real advantages over what is common
today.

-Wolfgang