URSA Mini 4.6k The Original™ Magenta Cast Issue

Hi Kyle. First four digits: 3169
I did another test and realised the last one was at f5.6 so this is at f8.

18-35 35mm f8

UM4.6K fw 4.2.jpg (930.77 KiB) Viewed 7602 times

I placed the white board in a position to get a more even illumination and turned the camera upside down in shot to test the evenness of the illumination.
There was absolutely no difference in the waveforms when rotating 180 degrees so the small variations in the shape of the curves are down to the sensor.
When I first received my Mini I tested it and got lentil shaped curves with a pronounced dip on the right hand side so I RMA'ed it.
BMD tech support said they recalibrated the sensor and there was a slight improvement but I couldn't see the improvement.
After updating to fw4.2 and doing black shading, I see a definite improvement to the point I am very happy with the sensor.
I have done 3 projects with the 4.6K that I'm still working on in post.
I absolutely love working with this camera. The images are often exquisite(when I get it right) and the latitude makes them very forgiving in post.
I had noticed that sometimes in shooting outdoor scenes with sky backgrounds, some shading appeared.
Now the shading on the right hand side is imperceptible and this is reflected in the waveforms.
Using this lens at these settings is an extreme stress test of this issue so other settings and lenses are not going to be a problem anyway.
For me, I have peace of mind.
Maybe someone else can do a more technical test.

Thx Paul!
What about magenta vignette?
My mini is gone RMA.

Best

Are you saying you have seen an improvement in the magenta vignetting with FW 4.2? I think you are, but I wanted to be sure.

Id love to see the DNG! Very exciting!

Hi Kyle,

Yes, any news on the magenta vignette especially with Sigma 18-35 discussed by Paul interested me.

Harold

Right on Harold! Me too! I was asking Paul

Hi guys. Yes I see a definite improvement in the sensor.
Not scientific proof but stress test of camera wiith the 18-35.
My camera did not have so much the vignette but bands of colour cast sometimes referred to as the Italian flag effect: http://www.l-camera-forum.com/topic/153464-towards-an-explanation-of-the-italian-flag-phenomenon/ green on the left, white in the middle and redish on the right.
Otherwise known as the asymmetrical magenta issue.

Hey,
i am also having a major improvement with the calibration.
I think it is so good, that i will start shooting with the camera now.
Attached are two pictures one with FW 4.0 and the other with FW 4.2
Sigma 18-35mm at 35mm f8 ISO 800

Okay, just about the whole world knows that no intelligent and thinking person would ever buy an URSA Mini 4.6K due to its sensor aberrations (slight exaggeration but you know what I mean) and given that bad news spreads like wildfire but good news is often lost, I wonder how long it will take the camera-buying public to catch on that this camera has been reborn? You just know at NAB 2017 someone is going to say they've never taken the Mini 4.6K seriously because everyone knows the sensor is flawed, right?


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Jonas, be sure and keep the camera on for several minutes (like say 10 minutes at least) before you do the Black Shading calibration.


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Hey Jonas, have you tried with a more homogeneously illuminated white wall?
or even better a backlit white cloth or a strong diffusion with a soft source like a kino behind?

This is good, a controlled before and after fw4.2 and Black Balance. With the same settings and illumination, we will get a more definitive test.

Hey,
i am also having a major improvement with the calibration.
I think it is so good, that i will start shooting with the camera now.
Attached are two pictures one with FW 4.0 and the other with FW 4.2
Sigma 18-35mm at 35mm f8 ISO 800

Correct me if I'm wrong, but the uneven color cast is still pretty strong in this test, correct? Improved. Different. But still present.

I realize this update is aimed at crosshatch, but I was getting the impression the color cast was improved to some degree as well.

Also, the 18-35 vignettes a bit on this sensor. At 35 it should be pretty dang clean though right? Could this be partially to blame for the poor edges/corners?

Sure it could be a factor. Sigma doesn't recommend using it on the 4.6K sensor at 4608x2592 open gate. The windows are all fine, but the corners using the full sensor are beyond the published image circle for the lens. 29.08mm sensor versus 28.4mm zoom lens.


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My test is graded dngs in Photoshop camera raw.
I pushed it to the limits with saturation and exposure to minus limits.
I also made a test with grey sky and tried to grade it to show off the magenta.
it is attached to this post, i also think it is pretty usable.

Hi Jonas,

Thx for posting. It looks good.
Can I ask you what lens and aperture you used?
Also, did you push saturation to max to show magenta?

Regards,

Harold

Okay, just about the whole world knows that no intelligent and thinking person would ever buy an URSA Mini 4.6K due to its sensor aberrations (slight exaggeration but you know what I mean) and given that bad news spreads like wildfire but good news is often lost, I wonder how long it will take the camera-buying public to catch on that this camera has been reborn? You just know at NAB 2017 someone is going to say they've never taken the Mini 4.6K seriously because everyone knows the sensor is flawed, right?


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Rick there is no telling how long it will take the buying public to catch on that the camera has been reborn. But I don't see this as a fundamental problem for the camera given that it must have some popularity, otherwise it would have been available for actual purchase long ago. Also BM is a camera company after all, and the cure for a camera with problems is a "new and improved" camera with problems. I look forward to it, NAB 2017!

In the meantime I am being blown away by what Sony is doing with their RX100V and a6500. Especially when you connect a VA4K to them.

Gene, was that a Freudian slip or your wry sense of humour:
"... the cure for a camera with problems is s 'new and improved' camera with problems?"


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Rick, It was both a sardonic and practical observation.