Alexa 35 vs Mini LF

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  • #169876

      Hey there Roger and friends!

      Roger, this question is meant for you, but would love others opinions as well.

      Im prepping for a commercial shoot and the producers said this during a previs meeting,

      “Hopefully we can rent the Alexa 35, we won’t need to light outside with all of that dynamic range”

      I twitched. Don’t get me wrong, I’m excited to get my hands on one and take it for a test drive but it struck me that some people are too obsessed with the tech specs that they don’t really care for the look and feel. I’m sure the new camera will be beautiful and open the door for some new shots with the expanded DR, but I really love the LF.

      Maybe it’s because I have shot super35 most of career, that the LF just has a different feel about it. I’m just curious if the feel and look of the larger sensor would ever be a more important factor in choosing a camera than say the extended DR of the new camera. Every camera has its uses and their pros and cons. But hearing all this talk about the new color and dynamic range making the other cameras obsolete seems silly to me.
      Do you see yourself ever preferring the look and feel of a mini LF over the improved Dr of the new camera?


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    • #170041
      Roger Deakins

        I am not sure why the 35 would be that much more advantageous than the LF. Lighting is lighting. But, sad to say, many of the number crunchers see no difference between having enough light and creating the right light.


          It won’t make other cameras ‘obsolete’

          Going away from the ‘new colour’ and ‘new logarithmic container’. Which, by all means, is just a different way of storing value.

          Any tristimulus observer – any camera with three channels can resolve ANY colour. Yes, this does mean that a Canon T3I rebel and ALEXA Mini LF Super 35 Pro Colour 65 can determine the same amount of colours.

          The balance is the initial spectral sensitivity of the sensor concerning the XYZ Space / LMS cone function gamut or, as an alternative, the camera’s Wide Gamut’ space.

          However, as they’ve changed the size of their photodiodes and, therefore, the spectral sensitivity of each camera – while possible to be remapped to the initial AWG3 (note ARRI’s 65-point LUT that will re-map the colour near perfectly), a 3×3 Matrix (internal OETF) will not as with all 3×3 matrix’s they’re error-prone as they are inherently over determined as we’re trying to match any arbitrary spectral light.

          They rebranded it as ‘new and exciting.’ rather than ‘sh*t we can’t match our old gamut anymore’.

          So, what is remarkable about the Alexa 35 is the apparent SNR of -100db and, with that inherently, more camera latitude DR in which they needed to create an extended logarithmic container to store the additional values (that’s it).

          This is a marvel in internal camera circuitry – and I am, for one, looking forward to taking it apart. However, that doesn’t inherently make other cameras obsolete. Unless you were clipping signal left, right and centre and constantly struggling to gain exposure – there is not much difference.


          Gabriel Devereux - Engineer


            I should emphasise –

            The Alexa 35 has some crazy internal circuitry on an analogue sensor level.

            They’ve gone against their previous statements –  by creating a physically smaller photodiode with greater latitude and higher sensitivity. It isn’t inherently a good thing but is just an update on circuitry on their ALEV chipset.

            If they used the same circuitry on a larger photosite they would achieve even greater sensitivity – however, to do so and stick to the 4k mandate an LF-sized optical block would be required.

            I should note, when I talk about circuitry I’m not talking about some magic source, its generally quite simple physics – it’s more just actually fabricating the silicon.

            All CMOS cameras have a photodiode (charge as the electrons absorb the Magna of energy from photons) a reset switch (the shutter) that shorts the diode every assigned interval, a power source follower – an amplifier/gate that the charge generated by the photodiode dictates the amount of VDD (voltage) that passes through the MOSFET transistor in which there is a capacitor for ‘global shutter’ cameras and a column-line readout switch.

            Now, that’s all reasonably simplistic until you have made it 2.2micrometers wide and tall, and mitigate SNR while dealing with unimaginably small amounts of voltage.


            Gabriel Devereux - Engineer


              LF. Lighting is lighting. But, sad to say, many of the number crunchers see no difference between having enough light and creating the right light.


              you think you ll use the Alexa 35 in the future or are you gonna stick to Mini LF ?

              Roger Deakins

                That would be a question! Project dependent.


                  I’ve never shot with the Alexa LF. But I did shoot video with the Canon 5D mkII, also a full frame sensor. With low light I often found that the full frame sensor offered too little depth of field. The background would blur completely and isolate the person too much. You loose the sense of background completely, that’s not how our eyes see things.

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