Ursa Mini 4.6 And Alexa side by side

So here’s an interesting one.

I had a chance while shooting some tests recently of the new Olympus firmware upgrade to the Olympus E-M5 Mark II to shoot some tests in a studio under controlled conditions.

I set up a 3200K balanced lighting setup and then also able to shoot the Ursa Mini 4.6K in RAW and then shot the same again with Arri RAW on an Alexa XT.

This was shot using Cooke S4’s and both cameras were exposed for ISO 800.

I designed this scenario to show some contrast and I’ve also added a brightness ramp on the back wall.  You can work out how many stops over and under from the Fc readings here.


Tungsten Set




I think the UM4.6K stacks up very well against an Alexa shooting RAW, but I’d love to hear if you think it does.

The only thing I’ve noticed now that I’ve had some time with these files is that there appears to be a small amount of IR contamination in the blacks around Maddy’s shirt and the fabric on the table on the UM4.6K.  This can be easily corrected but it’s unexpected.

I used a mitomo True ND6 here and these filters have been very reliable for me on other cameras.  I have to admit a lot of the other shooting I’ve been doing for Blackmagic I’ve been using the firecrest ND’s and haven’t seen this problem before.  It may well be that the TRUE NDs are letting in some IR that the UM4.6K is seeing, but I’d have to test further for that and haven’t had a chance to.

In any case please do enjoy these camera original files hosted by my friends at Digital Pigeon.  I’d love any feedback too if you’re finding the files fast to download or not.

Here are the Blackmagic shots.


And then the Arri Alexa RAW



Arri Alexa RAW open gate Cooke S4 32mm




Arri Alexa RAW open gate Cooke S4 75mm











About johnbrawley

Director Of Photography striving to create compelling images
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21 Responses to Ursa Mini 4.6 And Alexa side by side

  1. Hi, I’ve tried a couple of times to download and unzip the Ursa footage but it won’t unzip – no problem with the other footage though.

  2. Filip Vandoorne says:

    for the usra images : download a file at the time, then it will work
    Also update Resolve to version 12.3.2 !!!

  3. the default dng decoding in resolve is a bit harsh if you want to compare with, so go to Project settings, Camera RAW,
    popup CinemaDNG, set Decode Using on Project, on then Project Settings Colorspace on BMD and Gamma BMD Film

    • Togan Gokbakar says:

      I think Ursa 4.6K is a big leap for closing the gap between high end cinema cameras. In terms of latitude and color science,everyone can be fooled as it is an alexa. But I think there is a uncharted territory in sensor development, which is motion rendering and pixel ghosting(or any other motion based characteristics including shutter, scan direction etc) First it was resolution,then color, than latitude to develop but it should be some development in motion rendering issue also. URSA 4.6K creating perfect images as still pictures but with motion I immediatly feel this videoish, soap opera effect which is caused by the way of motion blur rendered,shutter and pixel ghosting ratios. I am not a scientist, I can’t tell exactly how it differs but it looks different than Alexa in motion, you can feel the same with Sony cameras also. Also it is very characteristic that even you can tell which camera is used with the shot. It looks gorgeous in terms of pixel peeping,but does not feel filmic. I guess,what arri achieved is to minimise this digital video motion effect to create cinematic moving images. What do you think about this issue?

  4. Paul Del Vecchio says:

    I see what you mean about the IR contamination. From this footage, straight out of the box, it seems the BM4.6k is a little more red and has a little more contrast than the Alexa. However, the red is probably the IR and if not, it’s easily “corrected” and also when I bring the shadows up to about +20 in the raw tab, that contrast into the blacks seems to match better… almost exactly.

    I think the Alexa has nice color and so does the 4.6k. There’s a difference for sure, and maybe I like the Alexa just a tab bit more (maybe 10%) out of the box, but then again, after small tweaks, the 4.6k looks AMAZING.

    One other thing I’m noticing is that it seems the Alexa renders colors a little bit nicer and on her downside, there’s more grey on her face in the BM4.6k. Maybe that’s just a positioning thing.

    In the end though, they both look sooooo damn good and only in a side by side comparison would you be able to ever tell the difference.

  5. Just wanted to post a big thank-you to you and Blackmagic Design for posting camera-original Uras Mini 4.6K RAW clips here and also on BMD’s site. Your footage looks beautiful of course! It’s helping me learn how to work with RAW files in Davinci Resolve 12.3.2. This is also the first time I’ve had an opportunity to work with Alexa RAW files. I’m looking forward to reading about what BMD announces at NAB in a few weeks (I won’t be there, regrets). Thanks again, and cheers!

  6. Alexa colors are sooooooo damn beautiful…its like from another planet.Thank you so much for the test.Alexa is being alexa as usual.

  7. Greg Greenhaw says:

    Thank You for this test. They are so close I would say the differences are insignificant. I head the Alexa has a built in softening filter is that true? Should you try a test with the ursa with one as well?

    • johnbrawley says:

      Alexa has an OLPF which reduces aliasing and moire. That’s a known fact. There is a rumour too that Arri use a “low con” filter as well but I’m not so sure that’s the case. I’ve heard this denied pretty strongly by someone senior at Arri and I tend to believe them.

  8. Ferenc Józsa says:

    Thank You for this test, it was very useful !

  9. Currently downloading…
    Thanks a lot John, I really appreciate!

  10. lukeplattestudio says:

    Thank you for your camera testing. Your shots are beautiful as always and I appreciate the time you put into sharing your thoughts with us! The 4.6K sensor on the Ursa Mini really is quite impressive against the Arri.


  11. Rody Oddos says:

    Hi John,

    Thanks for the time and trouble of doing these tests. They look terrific, and are vey useful for all of us who don’t have at hand an Ursa Mini 4.6k and an Alexa. Kudos also for the footage at the Beach House and all.

    I’ve downloaded the Alexa footage without trouble, but the Ursa Mini footage doesn’t download completely. It stops downloading half way through, even when downloading only one file at a time. [I’ve heard of a 4GB size limit on a .zip file, and could this be the reason???]

    Anyway, would it be too much to ask to post again the Ursa Mini 4.6k footage under the same form as you did for the Alexa? This way, at worst, we could download a few separate frames to see how the Raw looks.

    Thanks so much in advance, and keep on the great work.

  12. Pingback: A Video Comparing the URSA Mini 4.6K and the ARRI ALEXA

  13. Sherri Kauk says:


    “I’m not crazy!” rang in my head when I read your comment in Film and Digital Times (April 2016): “The Ursa Mini 4.6K intercut beautifully with the Alexa Mini and XT” because one year ago, I chose the Black Magic Pocket Camera over consumer DSLR’s for the B camera to my A camera Alexa Indie feature in India, LOEV. So, I agree – on a level. However, the Black Magic Production and Cinema cameras did not have the same feel and did not intercut seamlessly like the Pocket, at that time. Can you talk about different sensors Black Magic might use in their various cameras and specifically about the sensor in Ursa4.6K vs Pocket? Do you think color bits captured is giving the seamless intercut more so than other sensor features? For example, for LOEV, I gave up RAW and RESOLUTION, recording ProRes 1920X1080 to get more BITS.

    The FDTimes, when profiling the Alexa Mini and Ursa4.6K did not mention bits, however bits was the reason Storaro, ASC, chose the F65 for Allen’s CAFÉ SOCIETY.

    I am thrilled you’ve brought the visual similarities between Black Magic and Arri to the forefront of conversation. Let’s get in this!

    • johnbrawley says:

      Hello and thanks for taking the time to respond. Shooting RAW shouldn’t give you more BITS. RAW on a blackmagic gives you a 12bit LOG / 16 bit LIN image, where as the best of ProRes on the pocket can be is 10 Bit 1920. So for the best bit depth and colour fidelity, you should be shooting RAW. JB

  14. Nick says:

    Thank you for the files


  16. Daniel Daniel says:

    Where I can download files from URSA?
    The link is not working:(

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