Geoff, I've extracted a still and you'll find it at https://www.dropbox.com/s/rgkmb4iiqeprebd/zeis%2028%20flat_1.21.1.jpg

This is quite unfair to the camera in the sense and in any realistic lighting and grading the effect isn't there. Even in this shot it was difficult to grade to retain the effect in jpg. Ignoring all the normal lens flare, the effect I'm referring to is the horizontal fan of light. It's effect is rather similar to the VariCon adjustable contrast filter (if you are old enough to have been involved in film) -- the Varicon added photons to the low lights while not affecting the highlights.

Hmm, I would guess that most of that effect would be caused by the lens itself. It would be hard to see the image sensor causing that, I can't think of a mechanism within the sensor that could cause it.

Mind you, that sort of effect was much sought-after in the past, so maybe you could can it and sell it. I used to experiment with making various effects filters in past times, and it looks like the effect you got with a light coating of dulling spray over a glass sheet in the matt box.

Yes, I am old enough to remember film, I began in the television industry in 1963, so having a 50th. this year. In fact, we may very well know some of the same people.

Geoff

Looks like a lens effect, but not affected by changing the lens or zooming/focussing. Certainly additional artefacts from iris leaves and internal reflections. Anyway I've passed the camera to John Barry for the new calibration and should be able (in a week) to comment on how that changes the effect (if at all).
Talking of desired effects, "lens whacking" is popular in some quarters, but it doesn't do anything for me (handhold the lens in the mount and displace it to let in stray light).

Geoff,
to answer your original question:

In my own tests I was able to replicate what I'd seen elsewhere on the web. I shone a single white LED towards the lens with the iris open. What I got was pretty much what I'd expect, a clipped white circle.
I then moved a hard edged object so that it progressively occluded the LED. The white orb of the LED was not affect and it looked like a bite had been taken out of the object.
There's a similar example of this somewhere on the web where the sun is behind a woman's nose and it looks like the Sun has taken a bite out of the nose.

Since our camera has been recalibrated I cannot reproduce this effect. Sure the LED flairs past the object occluding it, this is to be expected as you've said either because of the lens or some crosstalk in the sensor.

Like you I have no explanation for what was causing the original problem.

Bob.

Bob,

I really do not know what the sensor used in the BMPCC is, but whatever type, it is, it most likely has a variant on the Bayer filter over the top of the sensor, and I have heard of that type of filter exhibiting a 'spill' onto adjacent cells under very strong illumination.

Perhaps that is what we are seeing, in which case the solution would be to stop the iris down and increase gain. But I have a feeling that there would be an un-avoidable, and undesirable, change in the picture if that happened suddenly in a scene.

Geoff

Geoff,
Yes, as it's only a single chip it must be one of the Bayer Pattern variants. Certainly spill can be problem especially with sensors that use micro lenses when lenses that have a low angle of incidence. That doesn't explain what we're seeing here. It's almost like some Quantum Mechanics paradox :)

Bob.

It will be interesting to see what the result is when Serena gets her camera back.
Geoff

Serena,
I was just wondering if this was correct or a typo:

"Then I render the whole thing as a single clip (ProRes 422 10b) and take that back into Vegas "

I can't render out of Resolve to Prores becasue I'm on a PC. I was just wondering if you meant DNX, cineform, or you found some kind of work around.

Thanks,
keith

Keith,
You should be able to render to ProRes out of Resolve (on a PC). The workflow I used isn't ideal but it was one I got to work. It assumed that I was satisfied with the edit and wouldn't wish to revise the cut (works best if you are the director). Obviously I had ProRes clips from the camera so it made sense to stay with that codec. I could have rendered out to cineform and taken that back into Vegas.

Thanks Serena, I give it another try. I was just looking for another pro-res converter option then something like cinac.

Did you attempt to render to ProRes from Resolve and it failed? Of course you can use other codecs if you prefer.

Correct, out of Resolve. It's really just to have a way to render to prores when it's advantagious for delivery (i.e. some whinny Apply guy who won't accept anything else). I normally use DNX and cineform. I guess I need to research a bit if it's not working for me. thx.

Ah, what I output from Resolve was actually uncompressed quicktime YUV 10bit 4:2:2 . From another thread I've learned that you need an Apple to render ProRes. Another brick in my dislike of Apple policies (and therefore their stuff).

HD Cinematics AW Pro is free and will render Prores on a PC (no bloat ware comes with it either)

Theoretical Question: why do WE have to conform to Apple's limited file type? Can't THEY open a hundred different file types like we can?
What a limited world that must be.