P6K Sigma 18-35 Showing as F1.7 Solved

Seems this post is incorrect. See Denny’s comment below.

In one of my previous posts, I asked the users of this forum why my Sigma 18-35 F1.8 and 50-100 F1.8 where showing as being able to go down to F1.7 and even write that fact into the metadata. Well I emailed BMD support and they have given me the answer as to why this is able to occur. The following is copyied and pasted from their emailed replay.

"I checked with the developers for additional information about the behavior you're running into with your lenses.

From what I've been informed, Sigma’s rating of f1.8 is slightly on the conservative side; the lens actually opens up to f1.7. As such, what you're seeing is expected behavior on the Pocket Cinema Camera 6K."

So turns out its not a bug. How cool is that?! I had never heard of these two lenses being able to be effectively software modded to be able to use a wider aperture. I guess the next step is to figure out how much softer 1.7 is compared to 1.8. Anyway, I hope this information is useful.

No, what BMD state’s is, the Sigma f/1.8 setting on the lens is actually closer to f/1.7 as measured, so the camera sets the actual f/stop. Sigma listed the lens as f/1.8, because the math is probably between the two, but closer to f/1.7, so Sigma lists it as f/1.8, to error on the side of caution. This is interesting in that most of the time, manufacturers will opt for the better specification.

Focal length specifications are also similarly listed, and are rounded up/down from actual lens focal length. Very few 35mm to 50mm lenses, for example are actually 35mm or 50mm, but can vary from one to three millimeters. The actual focal length and iris pupil opening measurement is used to determine the f/stop.
Cheers

I've seen no evidence that nominal focal length designations can vary that much on a fixed focal length lens esp wide angle ones where even a 1mm difference can make a significant difference in the FOV.

Those numbers seem a bit high to me.
But it is known, for example, that the 25mm C/Y by Zeiss is actually more like 26mm (which is quite visible).
OTOH, one of my 21mm is wider than the others, more like 20.

OK, not splitting hairs, and my example may have been a bit off, (changed my post). But I have seen various 35-50mm lenses that were off by several millimeters from what they were listed as, which was to illustrate manufacturers listed specifications are not always exactly as listed, which was my point.
Cheers

Does the push to autofocus work with the 6k and the sigma lense?

Alex.

Does the push to autofocus work with the 6k and the sigma lense?

Alex.

Yes.