Exchange Sony A7R IV with GFX 50S?

Started 2 months ago | Questions thread
Erik Kaffehr
Erik Kaffehr Veteran Member • Posts: 3,480
Once things are good enough....

Velocity of Sound wrote:

Erik Kaffehr wrote:

It is obvious that larger size has an advantage. But the 44x33 mm sensor is just 1.68 times the area of the the 24x36 mm sensor. Going from APS-C is 2.25X, a much larger step. The 1.68X size is equivalent to 2/3EV advantage.

I am a dual-system shooter with µ4/3 (Olympus) and Fuji's GFX system. The µ4/3 system (and the 4/3 system before it, which I was shooting with for about a decade prior to "upgrading" to the newer mount) were always trashed based on sensor size. It's a bit better these days but people talked about APS-C as being far superior to 4/3. Yet the size difference (based on a multiplier) between 4/3 and APS-C is about the same as the difference between "full frame" and "mini medium format." If there's a significant difference between 4/3 and APS-C then there must be a significant difference between "full frame" and medium format.

So it's been very interesting from my perspective to see the way that both systems are treated. µ4/3 is still trashed for its size and all of the downsides that people assume must come with it (many of which are overblown, in my opinion). I figured the GFX system would be universally exalted but it's not the case. Many "full frame" shooters claim they don't see a significant difference, and there's not a significant difference in sensor sizes. It comes across as a double standard. (Both 4/3 and GFX systems earn ire from APS-C and "full frame" shooters for having the 4:3 ratio.)

To me it indicates that the standards and views are not held universally. They are tweaked so that "full frame" is the preferred format by the photography community and many review sites. I don't find it fair or particularly intellectually honest. But then photography is an interesting mixture of art and science, and at the end of the day this is about business rather than pure science. There's little fairness in business, I suppose.


Once things are good enough, additional 'goodness' may matter little.

So, if 4/3 delivers the image quality needed, there may be little advantage in going to larger formats. But, it may also depend a little bit on user needs.

Lets look at some parameters:

1) Resolution, that is essentially the number of pixels the camera has. No camera ever can resolve more detail than the pixel resolution.

I normally print A2 (16"x23"). I would say 12 good MP are good enough for that. That said, I would suggest that having a bit more doesn't hurt, though.

2) Acutance, is essentially delivered by the lens. Having smaller pixels improves acutance. Having more pixels benefits acutance, too.

3) Signal Noise Ratio benefits a lot from a large sensor. But again, if the image is clean enough there may be little advantage to a larger sensor.

3) A larger sensor also allows for a higher DR. But DR essentially says how much darks can be pushed. In many situation DR simply doesn't matter. Also, there is nothing like highlight DR.

4) Limited DoF and maximal bokeh. Larger sensors need more stopping down for the same DoF or deliver larger bokeh balls at the same aperture.

Just as an example, once upon the time I was shooting some autumn trees. It was a bit dark and windy.

In that case I had an older 24 MP full frame DSLR and a 16 MP APS-C camera with live view. The APS-C camera had an electronic viewfinder.

I was shooting on a tripod, but I was concerned about wind caused motion on leaves and branches.

  • With the 24x36 mm camera I would use a 70-300/4.5-5.6 lens while with the APS-C the 24-70/2.8 was an option.
  • The APS-C camera had a newer sensor with possibly better performance at high ISO.
  • The APS-C camera had magnified live view, so I knew I could 'nail' focus. With the DSLR I wanted to stop down a bit more as I don't believe in AF being totally accurate.

In the end, I took a shot with each. Both were printed at 16"x23" and there was not a lot of difference, but in the end the APS-C image made it to the wall. Less wind caused motion...

Best regards


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Erik Kaffehr
Magic uses to disappear in controlled experiments…

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