did you ever measure the dynamic range of the MF systems compared to the DSLRs
No. I can
measure it only if I get suitable raw files (I measure the raw channels). A raw image is suitable, if it contains spots, which are
1. smooth (not textured surface),
2. unicolored, though any color,
3. uniformly lit; this is the most difficult issue; for example curved surfaces are inherently not suitable,
4. dark, but very dark, three-four stops underexposed. There is no point to measure the noise on well-lit surfaces.
Though I received quite a few raw files from a dozen different MFDBs, those are not suitable for measurement.
What I found out was that when I shot ISO50 on the 5D and I suppose also on the MKII is that I sacrifised about a stop or so in DR
The 5D does not have any ISO 50. If you select ISO 50, the metering doubles the suggested exposure, but the shot will be made @ ISO 100. Of course this cause unexpected clipping, thereby reducing the dynamic range.
When I shot in California with the Leaf and 5D next to each other on ISO100 the Leaf clearly showed more detail in the shadows and in the sky which on the 5D was almost always blown out in the clouds
This is too vague; an analysis can be done only based on raw images.
Also when I drop the ISO on the Leaf I cannot see a difference in DR from ISO50-200 on ISO400 and ISO25 I have the FEELING that I lose about half a stop but I could be wrong, I never tested it but your post triggered my interest
Based solemnly on the sensor dimension in pixels (5344x4008), the Aptus 22 has the same sensor as the Sinar e54. If this is so, then I can say with certainty, that ISO 50 to ISO 400 are equal; the selection of the ISO creates only a remark in the metadata.
The set of raw files I received did not contain ISO 25, so I can't say anything to that. It is not impossible, that ISO 25 is different from the others. For example the P30Plus has real ISO 100 and 200, but 400, 800 and 1600 are the same as ISO 100; they induce pushing in the raw conversion.
In order to verify this, I need raw files with a full set of ISOs: the same scenery, same illumination, from tripod. Either all shots with the very same exposure, or decreasing exposure according to their ISOs.