Are our lenses good enough for high pixel count sensors ? December 2025

 

Canon EOS M6 Mk2 with Canon EF-M 32mm f1.4 lens.

The M6.2 uses the same 32.5Mpx sensor as the R7. The EF-M 32mm f1.4 lens used for this shot is one of the sharpest I have ever tested and possibly one of the few which might be able to come close to fully revealing the potential of the 32.5Mpx sensor. Unfortunately that lens which is no longer in production is very slow to focus on the M6.2,  has no stabiliser and is not compatible with the RF mount.

In the days of 35mm film photography a good lens would be able to resolve about 80 lines (technically line pairs) per millimeter.  This translates to about 2880 line pairs on the long side of the standard 24 x 36mm frame.

A standard HD TV flat screen has 1920 pixels on the long side of the panel. My old HD TV measures 1020mm on the long side giving us 1.9 pixels per mm.

For the purposes of this post I will assume that for a lens to resolve all the detail  which the sensor is able to represent,  it will need to have a resolution of one line pair per sensor pixel. That might not be technically entirely correct but should be close enough for the present exercise.

The Canon EOS D30, introduced in the year 2000, had  3 million pixels on an APSC sensor measuring 22.0 x 14.9 mm, giving us 2160 pixels on the long side of the sensor, equivalent to 98 pixels per mm, nominally requiring a lens resolution of 98 line pairs per millimeter.

The Canon EOD 40D put 10 megapixels, 3888 x 2592 pixels onto a sensor measuring 22.2 x 14.8 mm giving us 175 pixels per millimeter.

The EOS R10 has 6000 pixels on the long side giving us 270 pixels per millimeter.

The R7 with 6960 pixels on the long side has 314 pixels per milllimeter.

Some Fujifilm cameras already have 40 million pixels on APSC. If as rumored the R7 Mk 2 gets 40 million pixels it will have 348 pixels per millimeter.

By the way a full frame sensor with the same pixel pitch as the R7 would have 32.5 x 1.6 x 1.6 = 83 Mpx. No currently available full frame cameras have such a high pixel count. 

My current camera is a Canon EOS R7 with 32.5 Mpx on a 22.5 x 14.8mm APSC sensor. I devised a simple test to discover whether one of my sharpest lenses could resolve all the detail potentially available from this sensor.

I used the Canon RF 28mm f2.8 lens which although inexpensive and fitted with three large plastic moulded aspheric elements is actually one of the sharpest lenses in the RF catalogue.

My standard test chart measures 1200mm on the long side. I attach a millimeter rule to the chart, near the centre.  If I make the chart fill the frame we have 1200 lines on the long side of the frame. This has to be projected onto the sensor which measures 22.5 mm on the long side, giving us a required lens resolution of 53 lines (technically line pairs) per mm.

The RF 28mm f2.8 is easily able to achieve this.

Next I double the distance between the chart and the focal plane of the camera. Now the millimeter scale represents 2400 lines per long side of the chart and a required lens resolution of 106 lppmm. The RF 28mm f2.8 manages this easily.

Then I increase the camera distance to 3x that which fills the frame with the chart. The lines on the rule now represent 3600 lines per long side of the sensor requiring a resolution of 162 lppmm from the lens, which it can manage.

At a distance of 4 x the original we are asking the lens for 213 lppmm which it cannot manage. All the lines are mushed together into a blur.

So the on-sensor resolution of this lens tops out somewhere around 180 lppmm.

Now let us check out how much lens resolution our current model cameras require if all the spatial information which the sensor could deliver is actually able to be revealed.

The EOS 40D with 10 Mpx has 3888 pixels on the long side requiring a lens resolution of 175 lppmm, which our RF 28mm f2.8 lens could just about manage if we could somehow mount it on the 40D.

The EOS R10 has 6000 pixels on the long side of the frame, requiring a lens resolution of 6000 divided by 22.5 which is 270 lppmm.

The EOS R7 has 6960 pixels on the long side of the sensor requiring a lens resolution of 314 lppmm.

A 40 Mpx Canon APSC sensor would require a lens resolution of 348 lppmm.

We have a problem.

Either the anti-aliasing filter on these Canon sensors is substantially reducing the real world resolution of the sensor, or the lens lacks sufficient resolution, or both.

Which raises the question: why stack so many pixels onto the sensor ? Is it just marketing or is there a real advantage ?

There is a mis-match between the theoretical resolution of the lens-sensor system and the actual real-world resolution.

We have been seeing this in camera reviews for several years . For instance when the Fujifilm X100.6 arrived in 2023 with a 40 Mpx sensor, reviewers compared its image quality with that of the older X100.5 with a 26 Mpx sensor, and found no difference in ability to resolve fine details. In this case the lens appears to be unable to keep up with the sensor.

When I compare the R10 with the R7 as to ability to resolve fine subject details, I find at most a barely detectable difference even with the best available lenses.

If current and rumored high pixel count camera sensors are to reveal their full potential maybe we need a new line of ultra high resolution lenses, or perhaps a less resolution robbing alternative to anti-aliasing filters especially for APSC models with the highest pixel densities.