Review Olympus OMD E-M1II Sensor

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I have now different E-M1II as I've returned the first one because it was in combo with bad 12-40 f/2.8 (new one is good). That allowed me to do basic measurements for the second copy.
I found that differences are minimal. Differences are at max 0.05 EV in DR and 0.2 dB in SNR.
But I did now measurements for the high resolution mode (HR mode).

Here is table which shows results for read noise, gain and full well capacity for the second E-M1II (I didn't measured ISO500, 640, 1000 and 1250 for normal mode) and comparison with high res mode.
High res mode works here as "synthetic sensor" with given parameters.

View attachment 862710

Next is the graph for dynamic range (DR). It's the graph from the first post but with added results for HR mode.

View attachment 862711

The last graph is for signal-to-noise ratio (SNR) and again it's the graph from the first post but with added HR mode.

View attachment 862712

Measurements for the HR mode show modest improvement (~0.7EV) of DR where best results are now at ISO100 and ISO320 (~13EV) and not ISO250 as for the normal shots.

More interesting is almost 5 dB improvement of SNR. That's really significant improvement and it means that daylight images should be at least comparable to those from Sony A7III or Canon 1DXIII.

Another interesting finding (for RAW shooters) is that optimal ISO for night hi-res photography is ISO1000 as it combines lower read noise with better highlight protection than maximum ISO1600.
Super helpful information. Looking forward to trying HR mode in ISO 100 during the day and ISO 1000 at night. Thank you!!!
 

Machi

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One more practical test comparing highlight protection for three Olympus cameras - E-PM2, E-M10II and E-M1II at base ISO (=ISO200).

In theory best highlight protection is at base ISO and it's given by (practical) full well capacity (FWC) of sensor.
From my previous measurements I obtained FWC:
~23 000 electrons for E-PM2,
~24 000 electrons for E-M10II and
~30 000 electrons for E-M1II.

Those results should be visible in practice and E-M1II should be the best.
For practical test I chose Moon at clear night as stable source of light and all cameras used the same Konica Hexanon 80-200mm f/3.5 lens at 200mm and f/8 with exposure time 1/20s and ISO200.

Here is animated gif showing differences between cameras.
Interestingly even small difference between E-PM2 and E-M10II is visible.
(Image from E-PM2 is slightly blurred due to shutter shock)

HComp.gif
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doady

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E-M1 II image is darker everywhere, not just in the highlights. No doubt the DR is higher, but perhaps it is also exaggerated a bit by some Olympus tricks. For example, base ISO is actually ISO 250, everything shifted 1/3 stop or something. See more here: https://www.dpreview.com/forums/thread/4108345

Very early on I found that E-M1 II photos are slightly too dark, so even from the very beginning I set exposure compensation to +0.3EV by default. I thought maybe E-M1 II metering is more careful, or maybe it's something else, it has always puzzled me. Maybe I will have to do direct comparison with my old C-7070 one day.
 

Machi

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E-M1 II image is darker everywhere, not just in the highlights. No doubt the DR is higher, but perhaps it is also exaggerated a bit by some Olympus tricks.
E-M1II must be darker. If older cameras gives with clipped highlights raw output 4095 (max at 12 bit), then E-M1II must give lower number to show something at 12 bit, therefore image looks darker.

For example, base ISO is actually ISO 250, everything shifted 1/3 stop or something. See more here: https://www.dpreview.com/forums/thread/4108345
Base ISO for E-M1II is 200. I've already demostrated it by my measurements in this thread.
E-M1II has at ISO250 lower readout noise and that leads to slightly better DR but that doesn't mean that it's base ISO of camera and Bill Claff (from photonstophotos) never claimed it. Again look at my measurements in this thread.
At base ISO camera uses most of available full well capacity of sensor photosites.
In practice that means best highlight protection for the equal exposure.
Here is another practical example which compares highlight protection at different low ISO settings with same amount of incident light (all exposures 1/2 sec at f/1.8).

As one can see, results again correspond to measurements:
ISO200 has best highlight protection, ISO64 is extended ISO200 which means the same results.
ISO100 is extended ISO320.
ISO250 has worse highlight protection than ISO200, therefore it's not base ISO.

Hcomp2.gif
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pdk42

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E-M1II must be darker. If older cameras gives with clipped highlights raw output 4095 (max at 12 bit), then E-M1II must give lower number to show something at 12 bit, therefore image looks darker.


Base ISO for E-M1II is 200. I've already demostrated it by my measurements in this thread.
E-M1II has at ISO250 lower readout noise and that leads to slightly better DR but that doesn't mean that it's base ISO of camera and Bill Claff (from photonstophotos) never claimed it. Again look at my measurements in this thread.
At base ISO camera uses most of available full well capacity of sensor photosites.
In practice that means best highlight protection for the equal exposure.
Here is another practical example which compares highlight protection at different low ISO settings with same amount of incident light (all exposures 1/2 sec at f/1.8).

As one can see, results again correspond to measurements:
ISO200 has best highlight protection, ISO64 is extended ISO200 which means the same results.
ISO100 is extended ISO320.
ISO250 has worse highlight protection than ISO200, therefore it's not base ISO.

View attachment 885320
I somehow missed this thread back when it was active. Great posts and great info. Quick question on this last one…. You say “ISO200 has best highlight protection, ISO64 is extended ISO200 which means the same results“. But if 64 is an ETTR on 200, presumably we’d expect worse highlight protection? What am I missing?
 

Machi

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I somehow missed this thread back when it was active. Great posts and great info. Quick question on this last one…. You say “ISO200 has best highlight protection, ISO64 is extended ISO200 which means the same results“. But if 64 is an ETTR on 200, presumably we’d expect worse highlight protection? What am I missing?
ISO64 works as ETTR but my point was that with the same amount of detected light, results will be practically the same (that's why my examples were all taken at the same "physical" exposure 1/2sec and f/1.8).
I wanted to simply demonstrate why ISO200 is the base ISO of E-M1II.
In practice camera will of course automatically choose overexposured values for ISO64 and results will be with worse highlight protection (but better shadows).
 

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