Gemini is basically full frame! A comparison with the new Sony FX9...

[Evin Grant]

I'm doing some testing for a feature coming next month and the director really wanted to see how the new Sony FX9 stacked up to the Gemini we are planning on shooting.
The answer is pretty good, but it's not there yet...



There is a UHD Prores LT file downloadable from Vimeo if you want to scrutinize or try other LUTs on the LOG portions.

I like doing comparisons in moving cars because they offer a wide range of lighting, contrast and color changes as well as gives you a good sense of the motion rendering.

The Sony keeps up with the Gemini pretty well in color and DR but there are some real issue at the sensor level like this color aliasing on high contrast edges...

This is NOT CA as you can see there is no hit of this on the Gemini still.

Another interesting observation is that the Gemini recording area in 5K is only 10% smaller than the "Full Frame" of the FX9 in UHD, I don't think this even equates to one standard lens size or even a 1/2 stop of equivalent DOF. You can see that a 2 shot from the hostess tray is doable with a 40mm on either camera.

The 10bit 422 XAVC-I codec is doing Ok but you can definitely see where it falls apart in high color contrast situations like the crop below from a different shoot (check out the blocking at the edge of the blue)...


Overall I'm very impressed with the FX9, especially the AF, and in it's intended role as a replacement for the FS7 in low to mid range documentary and ENG roles but it still needs some work before I'd be willing to put it on set for a narrative piece. This really makes me excited for how the Komodo will shake out now, especially when it come to sensitivity and AF tracking.

[Phil Holland]

Evin, I have never enjoyed looking at your nostril more :)

Kidding. But yes. Sony needs to evaluate a few things regarding higher gamut tuning on the Venice and FX9. It's a rad camera with lots of cool tech, especially that audio stuff too, but I wouldn't shoot a feature on it personally.

[Evin Grant]

Evin, I have never enjoyed looking at your nostril more :)

I trimmed my nose hairs just for you!

[Karim D. Ghantous]

It goes to show just how good RED sensors are. I do expect better from Sony, though. That sort of colour aliasing is something I'd expect to see from an older DSLR, not a brand new cinema camera.

[M Harvey]

Thanks for this. I was more impressed with the Sony than I'd expected to be-- especially since you're shooting the Gemini at 4:1 and 2:1 compression ratios. Makes me wonder what the Sony could do if a more robust codec were available; I gather we'll get a raw workflow at some point, but in-camera recording of X-OCN could be pretty compelling.

[Patrick Tresch]

This is NOT CA as you can see there is no hit of this on the Gemini still.

This is a debayer issue. I bet it dissapear if recorded in RAW and debayered in post at full res.

[Nick Morrison]

Evin this is a fascinating thread, that I don't think people appreciate.

You are 100% correct about Gemini almost being the same size as FX9...when shooting HD

It's all about the sensor HEIGHT.

So FX9 is only 18.9mm tall. Not 24mm tall like Venice. Why does that matter? Well though that's great for anamorphic, what that means is when it shoots HD it's only 33mm wide (as opposed to 36mm wide on Venice).

OK remember that.

Lets get to Gemini.

When you shoot 5KHD Gemini is 28mm wide. That's a clean 5K. And it's 28.8mm x 16.2mm.

But there's a cheat that Phil just confirmed for me!!

If you shoot 5K FULL FRAME (ie the full sensor), and then crop later in post (using HD guides on set). You can get an HD extraction that is 30.7mm wide (and taking advantage...wait for it...of Gemini's 18mm tall sensor).

So in reality Gemini can shoot somewhere close to 5.1K or 5.2K HD. That's 30.7mm x 17.25mm, which is certainly much closer to FX9's 33.4mm x 18.8mm.

Like scary close.

NICE CATCH EVIN!!!!

This is something Helium and Dragon can't do because their sensors are 16mm tall.

[Phil Holland]

Heh. I've been asked this once or twice or three times even before the latest crop of bodies.

For or less if you explore a 5K 16x9 extraction from the full Gemini 1.7:1 frame versus the Sony FX9 in 6K UHD mode you're looking at a HFOV crop factor or 1.09X.

In 6K UHD FX9 image you are seeing a 16x9 sensor 33.43mm wide.

A 5K 1.7:1 16x9 extraction from the full Gemini 5K sensor is 30.72 wide.

A bit different than the Canon C500 MK II as it's a wider sensor than the FX9.

[Hrvoje Simic]

If you shoot 5K FULL FRAME (ie the full sensor), and then crop later in post (using HD guides on set). You can get an HD extraction that is 30.7mm wide (and taking advantage...wait for it...of Gemini's 18mm tall sensor).

So in reality Gemini can shoot somewhere close to 5.1K or 5.2K HD. That's 30.7mm x 17.25mm, which is certainly much closer to FX9's 33.4mm x 18.8mm.

Like scary close.

You mean...if you shoot "open gate" on 30.7mm wide sensor you get very close to cropped 35.7 mm sensor ?

: )

There is no 5.1K delivery and there is this thing with scaling any numbers and why you don't wanna do that.


I don't understand the thread title, btw.
30.7 mm is "basically FF" which is 36 ?

[Nick Morrison]

You mean...if you shoot "open gate" on 30.7mm wide sensor you get very close to cropped 35.7 mm sensor ?

: )

There is no 5.1K delivery and there is this thing with scaling any numbers and why you don't wanna do that.


I don't understand the thread title, btw.
30.7 mm is "basically FF" which is 36 ?

You're not reading what I wrote.

Yes the FX9 is a full frame 36mm wide sensor. But it's only 18.9mm tall.

Gemini is almost 31mm wide, and 18mm tall.

That slight variance in height means when they shoot HD aspect ratio, they end up being quite similar when Gemini shoots "open gate/full sensor".

GEMINI OPEN GATE cropped to HD: 30.7mm x 17.2mm
FX9 6KHD: 33.4mm x 18.8mm.

That's an 8% difference, a far cry from the 15% you'd expect.