The Sony FX6 is Full Frame – Sometimes!

Perhaps I’m splitting hairs here a little bit – and I still think the FX6 is an amazing camera. But the more I look at it’s different scan modes and recording mode the more I’ve realised that it’s only actually “Full Frame” in few certain settings. 

When the FX6 is set to UHD and operating from 1 to 60 fps then it’s full frame and the whole width of the sensor is used. Put a Full Frame lens on the camera and you get the same FoV as an FX9 or any other camera with a similar sized sensor.

But if you want to shoot 4K DCI then something strange happens. Switch the FX6 to 4K DCI and the sensor is cropped/windowed by 5% and instead of the field of view becoming 5% wider as happens on most cameras, it instead  becomes 5% narrower. In 4K DCI the FX6 is very slightly less than Full Frame. 

To shoot at more than 60fps the camera has to be in UHD. 60 fps and below it’s full frame but when you go above 60fps the image is cropped even more, this time by 10% so the FoV gets 10% narrower.

If you want to record UHD Raw at any frame rate the image is also cropped by 10% so UHD with raw out at 30fps results in a 10% narrower FoV than when you are not outputting raw. When you enable raw at 4K DCI raw it’s a 5% crop.

So while none of these crops are huge it is worth noting that the FX6 is actually a little less than full frame more often than not!

Just to put all this into some perspective the FX9’s Full Frame Crop 5K mode involves a 17% crop. The FX6 outputting UHD raw or recording UHD at more than 60fps is a 10% crop. That’s not a vast difference. In these modes the FX6 is closer to the FX9 5K mode than to Full Frame.

Why is this? Well the FX6’s sensor is 4.2K pixels across. In the “normal” UHD frame rates (up to 60fps) the full 4.2K is read and downscaled on the fly to 3840 x 2160 UHD.  When you shoot 4K DCI there is no downscale and instead the sensor is read out at 4K and the extra 0.2K of pixels at the edges of the frame are not used – 0.2K being 5% of 4.2K and thus you have a 5% crop and the FoV becomes 5% narrower in DCI 4K than in UHD.

When you shoot above 60 fps then the sensor is read directly at 3840 pixels rather than 4.2K to make the readout simpler and faster. So now we are reading 0.4K fewer pixels from the sides of the sensor which is 10% of the total pixels and we get a 10% narrower FoV above 60fps as a result.

As I said at the start, perhaps I’m splitting hairs. I certainly don’t think this detracts from the FX6 in any significant way. But if it’s a camera you are thinking of getting, you should be aware of this.

29 thoughts on “The Sony FX6 is Full Frame – Sometimes!”

  1. I like the FX9 as I often shoot UHD wide shots for theatre shows and ‘virtually zoom’ in post as the full resolution is there (much more than an FS7). Will the FX6 also be good at this?

    1. Perhaps not, a lot will depend on how good your focus is and how sharp the lens is. But the FX6 does also have clear image zoom.

  2. But, the FX6 does have a 30p, 4.2k raw output like the S-III? (That results in an unusual frame sized file….but at least it’s a full width sensor readout)

    Or, is this incorrect?

    1. Unfortunately No. From the FX6 website ” RAW video output is 4096 x 2160 or 3840 x 2160 data from the image sensor with a choice of 59.94 / 50 / 29.97 / 25 / 24 / 23.98 frame rates “

  3. Alister, in all the comparisons I’ve seen, the one I wonder about the most is how the images compare between the FX6 and the A7siii. Seems like the same sensor, so do the images look the same, or does putting the chip in a bigger box allow for more processing and a better image?

    1. In terms of image quality there is very little difference between the A7S III and FX6, the image processing is more or less the same, except you have more control over the noise reduction and detail correction in the FX6.

      But the FX6 uses the same S-Cinetone gamma and matrix as found in the FX9, the A7SIII has a different gamma/matrix which looks slightly different.

      In isolation I doubt most people would really spot the differences. But if you want to work alongside an FX9 (and I’m sure S-Cinetone will be implemented in other Sony pro video cameras going forwards) the the FX6 will be a better match.

    1. The RAW maximum resolution from the A7SIII is 4.2K, whereas for the FX6 it is 4K DCI. This is a decent advantage that A7SIII has over the FX6. The extra resolution is very helpful for stabilisation in post. Any thoughts on whether three FX6 might output 4.2K RAW with a future OS upgrade ?

      1. No idea.

        In reality I doubt anyone would actually be able to discern any difference between a 10% crop into 4K or 4.2K.

  4. Is there any difference between FX6 and A7s iii in extreme lowlight? In moonlight shooting at 102000 iso? Presumably shooting raw to an external recorder is the best option in this case?

    1. My FX6 is on pre-order so I will do a side by side with my S-III next month. Same sensor but the FX6 offers something that is REALLY important to me….noise reduction control. Noise reduction and the artifacts it brings is something can never be removed in post by anybody. Once it’s baked in, you are stuck with it forever. It’s like cooking with salt. You can add all you want to the food in the kitchen but if you make a mistake and add too much?….you can never take it back out.

      The S-III uses very harsh noise reduction processing in higher gain amounts. The FX6 “can” have much less NR processing and you can even turn it off completely if you want. This is it’s greatest “low light” option. Neat Video is FAR more surgical at removing noise then ANY in-camera and “crude” live noise reduction system.

      No, the FX6 with noise reduction turned off is not “raw”,…nope. But it is one step closer to raw.

      1. Thanks for this Cliff, so best option is to use FX6 not A7siii, turn off any in camera NR (or set it to low). Record RAW to shogun 7? Is it possible to record FX6 raw to ninja V with SDI adaptor (already have the ninja).

        1. Depends on what you are shooting and how you are going to work with it. If you turn off noise reduction,…yes, you will bring home the very most you can have to work with….but be ready to do all that work in post. It’s a commitment you need to know and understand when you are shooting in the field.

          1. Hi Cliff
            I presume recording RAW out of either FX6 or A7siii means no noise reduction will be done in camera?? So ideally record RAW (a7s or fx6- doesn’t matter if it’s RAW) if not RAW fx6 offers a lower noise reduction option. If not RAW then best to avoid VLog too. Shooting in available moonlight only so around 102000iso, no option for adding light…
            Luckily someone else is doing post, I’m just the cameraman, but they should have the time and skills to do it properly…

      1. But you can only shoot raw at the base ISO’s, you can’t add gain or change the ISO when shooting raw anyway.

  5. Thanks for this info on the cropping. How does the FX6 sensor compare to the FS7m2 sensor, in regards to wobble motion?

  6. Hey Alister

    Will my fujinon mk 18-55mm emount lens fit onto this camera?

    I converted the lens it to fit onto my F55. Will I be able to use this lens with this camera or will I have to sell?


Leave a Reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.