URSA Mini 4.6k The Original™ Magenta Cast Issue

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Andreas Schwarz

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 5:36 pm

rick.lang wrote:But Frank as a beta tester may have the preproduction camera. Might not be conclusive about what is happening with the production cameras. It's also possible some production or beta are fine and some are not. People posting should specify if the camera is a preproduction or production camera if they know.

BMD really sent out so many cameras to beta testers, some of the testers who received their cameras later may even have production cameras. BMD knows.


Sent from my iPad using Tapatalk
...its like you said. i am sure all pre production cameras performed perfectly, maybe with a little bit more magenta all over the image - what is absolutely no problem. The sensor is fine...it may be a production (placement of the sensor) or hardware component issue...
Last edited by Andreas Schwarz on Thu Mar 31, 2016 6:21 pm, edited 1 time in total.
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Brandon Richardson

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 6:16 pm

Kristian Lam wrote:Hi guys,

We’re going through the posts and looking into this.

In the meantime, I would appreciate it if you contact our support office to provide more details, such as the type of lens used, aperture settings and if possible, provide DNGs shot without any lens attached. Please make sure that you don’t clip anything and have it white balanced.

You should also make sure to check the RAW DNG files in an application such Resolve or Photoshop. We’ve noticed that Preview in OS X generates a very weird over constrasty image.


So is this confirmation it is an issue or is it a characteristic of the sensor? Or further investigation is required? And we need to find a sensor that doesn't exhibit this with the parade or waveform to match. More less the waveform because that will show lighting continuity. I don'y want to RMA the camera just to get a worst sensor if there isnt an official fix. Currently my camera has a pretty uniform cast and doesnt vignette like a few others.
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Eric Ackman

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 6:22 pm

Thanks for the more precise tests Benton. The non-uniformity of the color cast is unfortunate, and in line with my experience as well. Rick, my camera is a regular production model. I'm sure the Blackmagic crew is on the case. 8-)

Edit - They are indeed on the case, just heard back from BM support confirming the issue is being investigated.
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John Brawley

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 7:50 pm

JeffreyWalther wrote:John, may I ask you which lens you did use for picture no. L1000574?

Jeff


The Leica 50mm F2 APO. You seem to have had the exact same reaction as Kholi when he saw that photo a while ago :-)

JB.
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John Brawley

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 7:55 pm

JoeyL wrote:
John Brawley wrote:My very expensive Leica M-E, long renowned for their image and IQ...


Marketing hype.



I beg to differ. They charge a lot no doubt. But I find I always return to shooting a rangefinder / m. And I've tried most of the alternatives.


JoeyL wrote:A flat sensor plane should not have a cast (unless introduced by lens optics). I fix color cast all the time example).


Google....

You can have sensor shading.

You can have Lens shading.

It's the downside of holding onto legacy mounts from the "film days" and not using telecentric lens design (like m4/3)

JB.
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Adam Langdon

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 8:03 pm

John Brawley wrote:
JeffreyWalther wrote:John, may I ask you which lens you did use for picture no. L1000574?

Jeff


The Leica 50mm F2 APO. You seem to have had the exact same reaction as Kholi when he saw that photo a while ago :-)

JB.


gah! the lighting on the shot looks soooooooo good. :o
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Steven Abrams

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 8:20 pm

Willem Timmersma wrote:It's something else then just a green or magenta cast.

It's difficult to correct because it's an uneven tint, you need to correct this with powerwindows.

Can you post a DNG from your camera with no lens against flat white like Benton shot? I saw you posted that it was still an issue doing that, but never saw your shot. Benton's looked totally fine, especially his first image that was just an overall white balance adjustment based on the edges.
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Kholi Hicks

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 8:35 pm

That Leica photo, though.

I started going back to JBs early 2.5K footage with the Leica's... Finally couldn't stand it any longer. Even seventy percent of this look in Summicron's would be amazing.

That 50 APO though, looks otherworldly.
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Andreas Schwarz

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 8:39 pm

Eric Ackman wrote:Thanks for the more precise tests Benton. The non-uniformity of the color cast is unfortunate, and in line with my experience as well. Rick, my camera is a regular production model. I'm sure the Blackmagic crew is on the case. 8-)

Edit - They are indeed on the case, just heard back from BM support confirming the issue is being investigated.
Good News!
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Willem Timmersma

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 8:45 pm

For what it is worth, checked some more beta footage, and downloaded some clips (from daniel peters his 4.6K for example, he also shot with the sigma 18-35mm). Those clips look clean, I couldn't really spot any of the issues I got. It's really night and day.
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Ivon Visalli

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 8:57 pm

Willem Timmersma wrote:For what it is worth, checked some more beta footage, and downloaded some clips (from daniel peters his 4.6K for example). Those clips look clean, I couldn't really spot any of the issues I got. It's really night and day.

I attended a lunch and learn with Noam Kroll at Filmtools in Burbank yesterday. Noam is a filmmaker and one of the beta testers for the 4.6K. He says he's been shooting with it for a few months now. He showed some of his posted footage along with some more recent stuff. I didn't see any of the magenta issue as we've seen here. He also made the statement that he's using the 4.6K as his A camera on paid work (his Dragon now becoming his B cam).

As Rick pointed out, there may be a difference in the units beta testers received and production units, but it would appear that not all cameras exhibit this issue to the extent that Willem and others have shown. I hope we can get a clearer understanding of the issue before too long.
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rick.lang

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Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 9:00 pm

Kholi Hicks wrote:That Leica photo, though.

I started going back to JBs early 2.5K footage with the Leica's... Finally couldn't stand it any longer. Even seventy percent of this look in Summicron's would be amazing.

That 50 APO though, looks otherworldly.


Agree, Kholi. That simple shot of the young woman under the fluorescents at night. I just love that shot. L1002378.

It's the last day of March. The next production run of the 50mm APO PL I preordered will be shipping in April. Would be nice to have an URSA Mini 4.6K PL to put it on! For me though, I'm going out on a limb and will buy that 50mm APO lens even if I don't have a camera to test it. And the 85mm, 25mm, and 32mm. But that's it. I'm not buying anymore until I have the PL camera. Okay, maybe a 16mm! All right, enough already, after the 135mm. Unless there's a 65mm/100mm macro. But no more until my camera ships... Oh, yea, almost forget the Fujinon, that too. I'm doomed.
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Willem Timmersma

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 9:16 pm

Steven Abrams wrote:
Willem Timmersma wrote:It's something else then just a green or magenta cast.

It's difficult to correct because it's an uneven tint, you need to correct this with powerwindows.

Can you post a DNG from your camera with no lens against flat white like Benton shot? I saw you posted that it was still an issue doing that, but never saw your shot. Benton's looked totally fine, especially his first image that was just an overall white balance adjustment based on the edges.


Need to check at my office, but here's a screenshot. white card, kino flo's 5600K, white balanced with the eye dropper in the middle of the frame with ACR.

withoutlens.jpg
withoutlens.jpg (865.84 KiB) Viewed 19579 times
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Benton Collins

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Re: URSA Mini 4.6k Serious Magenta Cast Issue

PostThu Mar 31, 2016 9:24 pm

Subrata Senn wrote:
jasonparker wrote:http://imgur.com/a/mZaE5

Posted in the other thread as well. I tested my new 4.6k MINI today and see no magenta cast anywhere.

Tested

RAW
prores
prores w/no lens


This is reassuring. I hope most people are getting sensors like this. And for others there should be RMA. Waiting to see Benton's tests.

Subrata, I posted a test in the other thread. I'm definitely seeing magenta cast in the corners.
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Brandon Richardson

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Re: URSA Mini 4.6k Serious Magenta Cast Issue

PostThu Mar 31, 2016 9:40 pm

Jason you cant clip the sensor so if there is no data then you clipped the sensor. Your test needs to be in between 20-80 ire
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Re: URSA Mini 4.6k Serious Magenta Cast Issue

PostThu Mar 31, 2016 9:56 pm

Brandon Richardson wrote:Jason you cant clip the sensor so if there is no data then you clipped the sensor. Your test needs to be in between 20-80 ire


Thanks, I'll try again and do the test right this time.
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Benton Collins

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 9:57 pm

I just used Capture One Pro 9 to create a LCC (Lens Cast Correction) file for the darker of my test frames. If we can get a similar tool for Resolve, short of fixing this in the firmware, this is the silver bullet! In fact, this may be better than a firmware fix as it addresses each lens and pattern it creates with a custom created filter mask. If Resolve does not have this feature, they really need it ASAP!
Attachments
Blackmagic URSA Mini_C1_LCC.jpg
Custom white balanced in center with LCC
Blackmagic URSA Mini_C1_LCC.jpg (648.53 KiB) Viewed 19535 times
Blackmagic URSA Mini_1_2016-03-30_2135_C0000_000014.jpg
Custom white balanced in center NO LCC
Blackmagic URSA Mini_1_2016-03-30_2135_C0000_000014.jpg (638.23 KiB) Viewed 19535 times
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Eric Ackman

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Re: Ursa Mini 4.6K - Another magenta thread

PostThu Mar 31, 2016 10:11 pm

So I got to thinking about my immediate shooting needs, and it dawned on me that I don't need the full 4.6k at the moment. Did a quick no lens/5600 WB test using Benton's ACR eyedropper method at windowed 4096x2160 and the center vs corner are looking very similar:

Center:

Image

Corner:

Image

DNG: http://bit.ly/25zdcgW
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 12:37 am

Hey Benton and Erick, thanks for testing and also good workarounds for now.

Nothing wrong with shooting the 4K crop, by the way. The Mini46 Sensor's larger than S35, and the 4K crop's actually larger than Ursa4k and Mini4K. Of course if you're getting vignetting then this is a workaround, they're on it and investigating.


Rick -- Did Andrew mention when we're going to see a wide SLR Magic APO variant? Or even a 35mm. haha

I'm going to give SLR lenses one last chance with Leica Rs now that I understand them a bit more. Maybe by the time I'm over it SLR Magic will have done the right thing and begun shipping a wide and tele.
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garrettgibbons

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 1:18 am

Here's my set of results: vignetting is clearly visible on the bare sensor.

Image

I filmed a few frames in each of the following scenarios:

1. No lens – bare sensor
Image

2. Lens in focus (Canon 24-70 f/2.8L @ 50mm)
Image

3. Lens defocused (Canon 24-70 f/2.8L @ 50mm)
Image

You can download my DNGs here: https://www.dropbox.com/sh/l4pzvpm8lyx9uap/AACzFYPujproW-bvAK79fin_a?dl=0

Is the vignette present? Absolutely. What do I think about it? I am in love with the image quality. A beautiful camera.

http://garrettgibbons.com
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Benton Collins

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 2:15 am

garrettgibbons wrote:Here's my set of results: vignetting is clearly visible on the bare sensor.

Image

I filmed a few frames in each of the following scenarios:

1. No lens – bare sensor
Image

2. Lens in focus (Canon 24-70 f/2.8L @ 50mm)
Image

3. Lens defocused (Canon 24-70 f/2.8L @ 50mm)
Image

You can download my DNGs here: https://www.dropbox.com/sh/l4pzvpm8lyx9uap/AACzFYPujproW-bvAK79fin_a?dl=0

Is the vignette present? Absolutely. What do I think about it? I am in love with the image quality. A beautiful camera.



Garrett, Thanks for posting your tests. Aside from the vignetting, you are getting much cleaner color than many others have posted. This now looks like a camera to camera issue. Black Magic please take note!
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 2:18 am

Sensor vignetting in the corners is pretty normal.

The colour change in the corners....not so much.

JB.
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Benton Collins

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 2:36 am

John Brawley wrote:Sensor vignetting in the corners is pretty normal.

The colour change in the corners....not so much.

JB.

I completely agree with you John! Any chance you could post your own evenly lit blank white surface using the same camera that you shot the promo on? I would be very surprised if you got magenta in the corners. I'd bet that camera behaves more like Garrett's examples, which color wise looked pretty even.
Attachments
lens defocused.jpg
Garrett's frame
lens defocused.jpg (609.75 KiB) Viewed 19350 times
Blackmagic URSA Mini_1_2016-03-30_2135_C0000_000014.jpg
Benton's frame
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rick.lang

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Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 3:39 am

Kholi Hicks wrote:... Rick -- Did Andrew mention when we're going to see a wide SLR Magic APO variant? Or even a 35mm. haha

I'm going to give SLR lenses one last chance with Leica Rs now that I understand them a bit more. Maybe by the time I'm over it SLR Magic will have done the right thing and begun shipping a wide and tele.


Kholi, this is what is shipping, planned or my estimate.

SLR Magic APO PL primes:
50mm T2.1, December 2015, shipping
25mm T2.1, 85mm T2.1 IBC 2016 (September), planned
32mm T2.1, December 2016, estimate
16/18/20mm T?, TBD 2017
135mm T?, TBC 2017
65/100mm macro T?--no plans at this time.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 4:14 am

Tested again shooting RAW with no lens.

my results:

Image

Image
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 4:34 am

jasonparker wrote:Tested again shooting RAW with no lens.

my results:

Image

Image

We have another winner! Congratulations to Jason and Garrett! Your sensors look great. Vignetting yes, but no dreaded cross color magenta / green.
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Andreas Schwarz

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 4:53 am

Benton Collins wrote:
jasonparker wrote:Tested again shooting RAW with no lens.

my results:

Image

Image

We have another winner! Congratulations to Jason and Garrett! Your sensors look great. Vignetting yes, but no dreaded cross color magenta / green.
...lucky guy...this is how it should look like...
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Re: URSA Mini 4.6k Serious Magenta Cast Issue

PostFri Apr 01, 2016 5:32 am

jasonparker wrote:Just trying to help. The images out of the camera look fine to me. The dropoff to the right is just the shading of the scene, I did not set up a perfectly lit environment - just a quick test. Some people here seem as if they want something to be wrong with the camera.

Hi Jason,
Can I interest you in a trade? My UM 4.6k for your UM 4.6k and I'll throw in a very nice Trusmt follow focus unit and a Sony Blu-Ray player that's barely been used.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 5:37 am

I originally did a very flawed test yesterday and jumped the gun thinking there was a magenta issue with my camera but decided to try again with a more controlled test.

Recorded a white piece of paper evenly lit with and without lens. Link to DNG below.

https://drive.google.com/folderview?id=0B7RgtsqUz67_c0UxLTZNelNuekE&usp=sharing

Lots of vignetting with the lens but that's probably normal since I shot at 35mm but the image without the lens looks fairly clean and even. Looks like the sigma is introducing some magenta to the image also. Will try another lens next time and see if the results are the same. Let me know what you guys think.

EDIT: Forgot to mention these were shot 4:1 raw at 4k, iso 800.
Attachments
Screen Shot 2016-04-01 at 1.30.59 AM.png
without lens
Screen Shot 2016-04-01 at 1.30.59 AM.png (698.37 KiB) Viewed 19244 times
Screen Shot 2016-04-01 at 1.30.46 AM.png
with lens (sigma 18-35)
Screen Shot 2016-04-01 at 1.30.46 AM.png (666.51 KiB) Viewed 19244 times
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Re: URSA Mini 4.6k Serious Magenta Cast Issue

PostFri Apr 01, 2016 5:47 am

Benton Collins wrote:
jasonparker wrote:Just trying to help. The images out of the camera look fine to me. The dropoff to the right is just the shading of the scene, I did not set up a perfectly lit environment - just a quick test. Some people here seem as if they want something to be wrong with the camera.

Hi Jason,
Can I interest you in a trade? My UM 4.6k for your UM 4.6k and I'll throw in a very nice Trusmt follow focus unit and a Sony Blu-Ray player that's barely been used.



Aww geeze. Bummer that BMD has put some people in this situation. I've gone through a couple of returned Mini 4k's and was lucky to find this 4.6k over at Markertek.com after waiting a few months on my Adorama order which I canceled. At this point I feel lucky to have the camera and without any problems. I'm happy to help in any other way, sorry!
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Re: URSA Mini 4.6k Serious Magenta Cast Issue

PostFri Apr 01, 2016 5:59 am

jasonparker wrote:
Benton Collins wrote:
jasonparker wrote:Just trying to help. The images out of the camera look fine to me. The dropoff to the right is just the shading of the scene, I did not set up a perfectly lit environment - just a quick test. Some people here seem as if they want something to be wrong with the camera.

Hi Jason,
Can I interest you in a trade? My UM 4.6k for your UM 4.6k and I'll throw in a very nice Trusmt follow focus unit and a Sony Blu-Ray player that's barely been used.



Aww geeze. Bummer that BMD has put some people in this situation. I've gone through a couple of returned Mini 4k's and was lucky to find this 4.6k over at Markertek.com after waiting a few months on my Adorama order which I canceled. At this point I feel lucky to have the camera and without any problems. I'm happy to help in any other way, sorry!

My offer was really more in jest being that it is April 1! You are very lucky indeed and I'm very grateful that you posted your tests, because they prove that some sensors are good and others much less. Personally, I don't think I'd take $1,000 to swap out the camera you have for something unknown, especially for the one I got! If you had said yes, I couldn't in good conscience go for it. Best of luck with your new giant killer! I'll be on the phone with BM tomorrow morning.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 8:27 am

Jack Liu wrote:I originally did a very flawed test yesterday and jumped the gun thinking there was a magenta issue with my camera but decided to try again with a more controlled test.

Recorded a white piece of paper evenly lit with and without lens. Link to DNG below.

https://drive.google.com/folderview?id=0B7RgtsqUz67_c0UxLTZNelNuekE&usp=sharing

Lots of vignetting with the lens but that's probably normal since I shot at 35mm but the image without the lens looks fairly clean and even. Looks like the sigma is introducing some magenta to the image also. Will try another lens next time and see if the results are the same. Let me know what you guys think.

EDIT: Forgot to mention these were shot 4:1 raw at 4k, iso 800.

I think yours looks very good! Congratulations!
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 8:42 am

John Brawley wrote:Yeah I think at this point BM need to say something. Let's wait and see.

It's honestly not something I've seen with my own shooting but it does seem to be present in some way for some.

JB.



Honestly John, I really admire everything you do for the community. But we've pointed this out on the bmcuser forum when first beta footages came out. And you made really clear that everything we said about it was complete nonsense, not sure why you've gone out of your way denying it was there in the first place. I'm not saying it's a problem, I absolutely love the image and have the cam on order. But it was definitely something worth pointing out in the beta stages of the camera.

Please do correct me if I'm wrong...
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:07 am

So I figured I would try the Raw 4K DCI work around and I think I stumbled upon the culprit. Somebody far smarter than me can tell me if this holds any validity or not. The other day I tested with a daylight balanced source. Today I used a regular household tungsten light fixture and low and behold NO magenta cast on the sensor. I did these test with no lens attached. Is it possible the daylight color spectrum is causing the cast? Compare to my first test its night and day difference

You can see the 4.6K had a small roll off, like I said I didnt bother to light it properly. Just a house hold light on a white paper from above. No residual magenta cast on the sensor at 4.6K Raw, 4K DCI RAW and 2K Raw was flat white.

Not to mention 4K DCI 4:1 Raw is only around 75Mb/s :o how awesome is that lol

White balance was achieved at 2800K -10 tint

MagTest24.6K.jpg
MagTest24.6K.jpg (126.87 KiB) Viewed 19192 times


MagTest.jpg
MagTest.jpg (123.64 KiB) Viewed 19192 times


MagTest2k.jpg
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Andrew Deme

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:20 am

Nice work Brandon, I imagine we are talking about the visible wavelengths on the left (Purple) which are kinda missing in a Tungsten light and therefore could be why you end up with a more balanced result ?


image.jpeg
image.jpeg (41.55 KiB) Viewed 19184 times


http://www.olympusmicro.com/primer/ligh ... intro.html
Last edited by Andrew Deme on Fri Apr 01, 2016 9:31 am, edited 1 time in total.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:30 am

Wander Andringa wrote: And you made really clear that everything we said about it was complete nonsense,.


I don't believe I ever actually said it was complete nonsense.

I might have said that I don't think it's a big problem. And I still think that.

I haven't seen it with my own BM cameras. But I also don't have cameras made on the assembly line and I know that my experience is not others experience either.

But many many other beta testers have cameras form the line. And there are many beta testers who don't post footage publicly. And a lot of that feedback is shared amongst the beta testers. And it wasn't really that much of an issue amongst the many that were beta testing.

So when I see people posting a shot as dusk that would naturally have magenta colour in it as evidence of a magenta problem then yeah, I'm going to ask if there really is a problem.

I posted an experiment with my own camera and I was somewhat surprised to see my stills camera does the same thing, if not worse. I invite you all to try it as well. Shoot a RAW still with no lens on.

But even as bad as my stills camera was, I'd never ever noticed it in the work I was doing with it over the last 18 months. I think that says something about the severity of this issue as well. Yeah you can make a fault show in the worst case scenario of a white wall with no lens. But does it make your shots unusable ?

There was a similar sensor issue when the pocket first started starting shipping. Sometimes there was an ORB in highlights or a kind of odd clipping. Next thing you know, people were posting shots of out of focus highlights as evidence of an ORB crisis.

I have a fair bit of skepticism when manufacturers tell me things like "hey it's got 15 stops" because I want to be able to prove that stuff to myself. I also have a healthy skepticism for problems posted by users that I can't see or document or repeat for myself. 9 out of 10 users with corrupt frames that start threads about how crap their camera is fro dropping frames, turn out to be bad docks or backing up and have nothing to do with the camera.

I think that this is the very first run of a brand new camera with a new sensor and they have some issues dialing things in. You know I read over on REDUSER that they have a 90% rejection rate on their new 8K sensors. It's really hard to make sensors (BM don't actually make them) and getting consistency from batch to batch and sensor to sensor is also really difficult. I don't want to preempt what BM are doing to address this, but if I had to guess, I'd say it's an issue of something like sensor to sensor consistency or calibration from the factory. I'm going to bet that it can be and will be reduced and anyone who thinks they have a problem sensor will be able to get it 'sorted"

I think that BM, as they have done with similar issues in the past, will happily address the issue via their service department. They've done it before and I'm sure they'll do it for this problem. They key is to be able to identify if you actually have a problem. So far we've already in this thread developed a good way of baselining each other's sensors. We can compare and see them in similar circumstances and therefore judge the severity of the issue. I think that's where a forum like this is super cool...

JB
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:33 am

Hello Brandon.

Spectral output of the light source you're using to illuminate the test chart (a white wall !) will definitely factor on what colours are reproduced or not.

Actual daylight will probably be best if posisble, but it's tricky when you don't have ND's. I suspect you could use higher shutter speeds to get around this and it shouldn't affect the results.

JB
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:38 am

A011C001_160401_R54N.mov.Still003.jpg
A011C001_160401_R54N.mov.Still003.jpg (311.79 KiB) Viewed 19165 times
And here's an Alexa XT frame from today.

Shot with actual daylight, 5600K WB 0 tint, no lens.

JB
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Willem Timmersma

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:48 am

This is interesting, going to test it one more time when I got time and see what happens. Just to be sure.

Some posted a clean sensor with the no lens test, but with lens a magenta uneven cast, lens shading right?

How come some beta footage with the same lenses like the sigma 18-35mm doesn't suffer from this issue within the same conditions.

I checked some footage from Daniel peters, shot with the 18-35mm, those look really clean. I'm just trying to wrap my head around this.

Btw if you don't see in your real life shoots, I really wouldn't bother and try to find it with those tests. :)
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:52 am

Willem Timmersma wrote:This is interesting, going to test it one more time when I got time and see what happens. Just to be sure.

Some posted a clean sensor with the no lens test, but with lens a magenta uneven cast, lens shading right?

How come some beta footage with the same lenses like the sigma 18-35mm doesn't suffer from this issue within the same conditions.

I checked some footage from Daniel peters, shot with the 18-35mm, those look really clean. I'm just trying to wrap my head around this.

Btw if you don't see in your real life shoots, I really wouldn't bother and try to find it with those tests. :)



Well, like sensors, lenses too are all unique. There are going to be some that show some faults more than others. Lens shading is variable even in the same lens (as well as other attributes). I think there's a system with some broadcast cameras where the serial number of the lens is recorded against the shading correction in the camera for this reason. Because they all perform differently.

jb
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 9:54 am

Under daylight conditions there is an even cast on my sensor its correctable. Under tungsten based on the wavelengths its clean like Johns Alexa shot. I may end up shooting 4k DCI 4:1 Raw exclusively just for the data rate alone. Moire shouldn't be an issue in 4k DCI nothing like the pocket/bmcc pre olpf?

And I'll try the white paper outside and crank the shutter down.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 10:06 am

John Brawley wrote:
A011C001_160401_R54N.mov.Still003.jpg
And here's an Alexa XT frame from today.

Shot with actual daylight, 5600K WB 0 tint, no lens.

JB


Barely 1.5% variance across any part of the frame....and instantly balanceable.

Pretty much perfect to be honest and for $70K am not suprised !
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 10:18 am

John Brawley wrote:
Willem Timmersma wrote:This is interesting, going to test it one more time when I got time and see what happens. Just to be sure.

Some posted a clean sensor with the no lens test, but with lens a magenta uneven cast, lens shading right?

How come some beta footage with the same lenses like the sigma 18-35mm doesn't suffer from this issue within the same conditions.

I checked some footage from Daniel peters, shot with the 18-35mm, those look really clean. I'm just trying to wrap my head around this.

Btw if you don't see in your real life shoots, I really wouldn't bother and try to find it with those tests. :)



Well, like sensors, lenses too are all unique. There are going to be some that show some faults more than others. Lens shading is variable even in the same lens (as well as other attributes). I think there's a system with some broadcast cameras where the serial number of the lens is recorded against the shading correction in the camera for this reason. Because they all perform differently.

jb


Fair enough, I know they are all unique. And some might preform just a tad better then other ones.

I'm trying to say, should we just deal with it then, knowing there are slightly better copy's and hope for the best when I decide to get another one as B cam for example?
Last edited by Willem Timmersma on Fri Apr 01, 2016 10:30 am, edited 1 time in total.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 10:21 am

John Brawley wrote:
Wander Andringa wrote: And you made really clear that everything we said about it was complete nonsense,.


I don't believe I ever actually said it was complete nonsense.

I might have said that I don't think it's a big problem. And I still think that.

I haven't seen it with my own BM cameras. But I also don't have cameras made on the assembly line and I know that my experience is not others experience either.

But many many other beta testers have cameras form the line. And there are many beta testers who don't post footage publicly. And a lot of that feedback is shared amongst the beta testers. And it wasn't really that much of an issue amongst the many that were beta testing.

So when I see people posting a shot as dusk that would naturally have magenta colour in it as evidence of a magenta problem then yeah, I'm going to ask if there really is a problem.

I posted an experiment with my own camera and I was somewhat surprised to see my stills camera does the same thing, if not worse. I invite you all to try it as well. Shoot a RAW still with no lens on.

But even as bad as my stills camera was, I'd never ever noticed it in the work I was doing with it over the last 18 months. I think that says something about the severity of this issue as well. Yeah you can make a fault show in the worst case scenario of a white wall with no lens. But does it make your shots unusable ?

There was a similar sensor issue when the pocket first started starting shipping. Sometimes there was an ORB in highlights or a kind of odd clipping. Next thing you know, people were posting shots of out of focus highlights as evidence of an ORB crisis.

I have a fair bit of skepticism when manufacturers tell me things like "hey it's got 15 stops" because I want to be able to prove that stuff to myself. I also have a healthy skepticism for problems posted by users that I can't see or document or repeat for myself. 9 out of 10 users with corrupt frames that start threads about how crap their camera is fro dropping frames, turn out to be bad docks or backing up and have nothing to do with the camera.

I think that this is the very first run of a brand new camera with a new sensor and they have some issues dialing things in. You know I read over on REDUSER that they have a 90% rejection rate on their new 8K sensors. It's really hard to make sensors (BM don't actually make them) and getting consistency from batch to batch and sensor to sensor is also really difficult. I don't want to preempt what BM are doing to address this, but if I had to guess, I'd say it's an issue of something like sensor to sensor consistency or calibration from the factory. I'm going to bet that it can be and will be reduced and anyone who thinks they have a problem sensor will be able to get it 'sorted"

I think that BM, as they have done with similar issues in the past, will happily address the issue via their service department. They've done it before and I'm sure they'll do it for this problem. They key is to be able to identify if you actually have a problem. So far we've already in this thread developed a good way of baselining each other's sensors. We can compare and see them in similar circumstances and therefore judge the severity of the issue. I think that's where a forum like this is super cool...

JB
....I agree that this forum is great, but I think all 4.6 K buyers should get the information about the possibility that they have purchased a not correct working camera (If there is an issue). This is what we see in other product sales (like cars), too. That may hurt a company badly, but if they really know an issue they have to do a recall for inspection...I am curious, how BMD will behave..
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 10:38 am

Quick'n'dirty RAW shot with good'ole 5Dmk2 aimed towards white wall outside sun-lit, no lens, "stopped down" via short shutter, auto-WB for the center.. looks a little magentary towards right/top and more greenish towards the left side of the frame. Not sure where the heavy vingetting in the bottom comes from :? might have to redo when more time..
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IMG_6948.jpg
IMG_6948.jpg (125.5 KiB) Viewed 19101 times
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 10:46 am

Andrew Deme wrote:
John Brawley wrote:
A011C001_160401_R54N.mov.Still003.jpg
And here's an Alexa XT frame from today.

Shot with actual daylight, 5600K WB 0 tint, no lens.

JB


Barely 1.5% variance across any part of the frame....and instantly balanceable.

Pretty much perfect to be honest and for $70K am not suprised !


But a little magenta don't you think ???

JB.
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 11:02 am

John Brawley wrote:
Andrew Deme wrote:
John Brawley wrote:
The attachment A011C001_160401_R54N.mov.Still003.jpg is no longer available
And here's an Alexa XT frame from today.

Shot with actual daylight, 5600K WB 0 tint, no lens.

JB


Barely 1.5% variance across any part of the frame....and instantly balanceable.

Pretty much perfect to be honest and for $70K am not surprised !


But a little magenta don't you think ???

JB.


Sort of....I measure the variance within each base color is within 1.5% anywhere in the frame and the variance between base colors is a max of 5% but of course it is the 'flat' 1.5% that makes this frame a breeze to grade. It's the edge to edge and corner to corner that blows me away, but like I said...it's a $70K Camera.

Just in case anyone is wondering, the 'overshoots' and 'dropoffs' are a result of where John obviously just cut the frame and left in borders that are not part of the original Alexa XT image and nothing to be worried about.

The first scope is from the original image and the second scope the result of a 10 sec fix.

alexaxtbefore.JPG
alexaxtbefore.JPG (68.35 KiB) Viewed 19084 times


alexaxtafter.JPG
alexaxtafter.JPG (69.63 KiB) Viewed 19084 times


This is the 'balanced' resulting image from the parade above, at 700 (10 bit waveform scale)....or damn close.

Like I said it was a 10 sec grade and now everything is within just over 1.5%, across the entire frame and across all colors.

alexaxtfixed.jpg
alexaxtfixed.jpg (408.71 KiB) Viewed 19068 times


I would be a tad careful pixel peeping the 4.6K as there is no end to the level of detail and can pretty quickly end up in discussions around Quantum Physics and the behavior of light waves versus photons.

My recommendation is to go shoot real life test footage, make it many and varied and if what you see you can't grade easily in Resolve then contact BMD....otherwise crack on and enjoy what is an amazing camera.

For your enjoyment :-
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 1:37 pm

Could the software version of the camera be involved here?

3.1 includes a Tint slider in the menu. My camera runs 3.0 and does not have that slider, and it will not update to 3.1. The Camera Setup utility thinks it is already "up to date."

I am interested to see what happens with these tests once BM figures out how to get this camera to update to 3.1
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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 2:41 pm

No issues on my side.

My test process:
ND gel on a window (to control exposure)
White paper stuck over the ND
Camera without lens pressed up against the white paper
Camera set to: RAW 3:1, Full Sensor, ISO800, 25P, 180º

Global exposure, white balance and tint adjustment in the RAW controls in Resolve.

Here is the 4.6K DNG:
https://dl.dropboxusercontent.com/u/646 ... r_Test.dng

Here is the DNG in Resolve with a global balance and tint adjustment. No magenta in the corners as the all fall off uniformly:
ursa46_sensor.jpg
ursa46_sensor.jpg (70.2 KiB) Viewed 18933 times


Here are the scopes in Resolve:
ursa46.jpg
ursa46.jpg (111.4 KiB) Viewed 18933 times


And just as another point of reference here are the scopes my Sony A7s under that same test conditions:
sony_a7s.jpg
sony_a7s.jpg (109.38 KiB) Viewed 18933 times

Even the Sony has fall off.
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Ivon Visalli

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Re: Ursa Mini 4.6K - Another magenta thread

PostFri Apr 01, 2016 2:51 pm

Thanks, Adam. Sounds like a very good test methodology.
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