bclaff

Yes, ISO ratings are real; particularly if they are determined using the SOS rather than the REI method. Sensor sensitivity also doesn't change with the exception of dual conversion gain sensors in ...

Untrue. Read the post by Sharlin. It is much closer.

Corrected diagram. I had the lens reversed ! Note it's a coincidence that one focal length in front of the front plane is at the front of the lens.

Yeah, looks like I got the lens reversed !!!

Good work ! You got it :-) For fun I marked up a lens diagram with figures for closest focus: The lens elements are probably shown at infinity. FWIW, you can measure/confirm the infinity focal ...

The chart that applies to mkdarmroom is this : As nixda notes there's only about a 0.4 stop difference which might very well not be noticeable.

Two magnification measurements at two extensions like 0 and 10mm is sufficient at a minimum. Several measurements and a linear fit is best.

I rarely handle the cameras I test. I depend on contributors from around the world to collaborate with me in gathering the appropriate raw files. My goal is to test as many camera models as I can. ...

Let's try this ... Your OM-D E-M10 has a sensor that's 17.3mm wide; right? Let's assume you're using a lens focused at closest focus (Minimum Focus Distance (MFD)). If the object you photograph ...

The quick answer is that I don't use the WhiteLevel and use the 16383 regardless. This makes some cameras appear as if they have more highlight headroom than they really have. Most cameras have ...

0.11x at 500mm MFD 0.11x at 200mm MFD 0.17x at 200mm MFD (42mm) FWIW, as expected those figures are pretty close to the specs (indicated above).

You realize that doesn't quite "pencil out". 10mm extension at 30mm focal length would be an additional 0.33x magnification. 1.25x + 0.33x is 1.58x; well short of 2x. If you knew the magnification ...

OK. I just assumed you had actually done a measurement to "check" your setup. About 25mm extension with a 2x TC certainly sounds reasonable.  :-)

It's probably more sensible to compare the DxOMark Sports score using stops. 2862 is 0.29 stops higher than 2340; about 1/3 stop. FWIW, PhotonsToPhotos uses a different criteria for Low Light ISO. ...

You may not be aware that I also have DxOMark Derived data at PhotonsToPhotos such as this : Don't miss the sort-able table under the interactive chart as well as the additional information you get ...

As you say, it's "trivial" to measure magnification by photographing anything of known size at closest focus (also known as Minimum Focus Distance (MFD)). Magnification is the (size of the portion ...

Yeah. This is very hard to quantify because size, shape, placement, etc. changes the effect dramatically. So whether this is a limiting factor in practice probably has a lot to do with the scene ...

Not every 50mm lens has the same Minimum Focus Distance (MFD) or magnification. My question is whether the setup you listed actually goes to 1:1.

It wasn't my intention to act as the terminology police :-) I know you know your stuff but I do think that's DSNU. You may envision simulating something more complex, but here's my mental model. Ov ...

Interesting ... but I'm all set :-)