Gemini: ISO and REDCODE

[JT Thurlow]

Hello,

I'm starting a documentary project soon with the Gemini and am trying to pin down a strategy for ISO and REDCODE.

I will mainly shoot dawn/dusk/overcast exteriors (mainly landscapes, with things like light at golden hour hitting mountains) & interiors with available light (only exceptions: some interiors with candles).

I'm not a fan of grain, so would like the look to be as clean as possible. Looking at test footage, things are pretty much squeaky clean up to 400 (though sometimes visible noise creeps in around here). When going as low as 250 it looks like too much information is lost in the blacks. Any suggestions on choosing the most natural ISO for clean and realistically dynamic results for this camera would be greatly appreciated.

In regard to REDCODE, I'm not sure at what point lower compression rates will actually be noticeable over a range of shots. I will mainly be shooting at 24fps 4K, but sometimes 24fps 5K, and 60fps 4K. The film will likely have a small theatrical run, so it needs to look good on the big screen; I just don't want to spend the twice the amount on media if it will make no difference.

Thanks!

 

[Brian Timmons]

Hello,

I'm starting a documentary project soon with the Gemini and am trying to pin down a strategy for ISO and REDCODE.

I will mainly shoot dawn/dusk/overcast exteriors (mainly landscapes, with things like light at golden hour hitting mountains) & interiors with available light (only exceptions: some interiors with candles).

I'm not a fan of grain, so would like the look to be as clean as possible. Looking at test footage, things are pretty much squeaky clean up to 400 (though sometimes visible noise creeps in around here). When going as low as 250 it looks like too much information is lost in the blacks. Any suggestions on choosing the most natural ISO for clean and realistically dynamic results for this camera would be greatly appreciated.

In regard to REDCODE, I'm not sure at what point lower compression rates will actually be noticeable over a range of shots. I will mainly be shooting at 24fps 4K, but sometimes 24fps 5K, and 60fps 4K. The film will likely have a small theatrical run, so it needs to look good on the big screen; I just don't want to spend the twice the amount on media if it will make no difference.

Thanks!

Hey JT,
You seem to know the specifics of what you want to achieve and issues you want to avoid which in itself puts you ahead of others who didn’t think that through.
Your best step from there is to test, test, test.
Test based on the lenses you will be filming with in combination, with the resolutions, compression ratios, frame rates amd light levels you are likely to encounter,
Even if you can’t get to that specific location for the test try another location that can stand in as a rough proxy for where you will film.

What you observe based on those test (which includes projecting it big on a screen) will answer many uncertainties and make you an expert in how to approach filming the project based on the specific needs and goals you outlined,

Brian Timmons
BRITIM/MEDIA

 

[Nick Morrison]

For the cleanest image, shoot 5K.

For the most dynamic range, shoot 800 ISO. Remember there is no denoising in-cam, so you can always denoise a bit later.

And feel free to use lowlight mode, and shoot at 2000 ISO. That's also a real treat.

Enjoy

 

[Ignacio Aguilar]

I shot a feature film on the Ranger Gemini and was pleased with the results. If you want the cleanest image, shoot 5K as Nick says and test the optimum operating temperature and black shade for that. I found it was extremely important to be VERY precise about it, as noise could be non-visible or ugly depending on this settings, even more so than ISO and exposure. Also, I wouldn't go any lower than 3200 kelvin (5000-6000-7000k is fine) and if you want a bluer look I'd rather use blue lights or a mild 80D filter on the lens. The blue channel can introduce lots of noise if underexposed.

 

[Ignacio Aguilar]

As for REDCODE, I found that Low Light mode worked much better with a 2:1 compression, but for well exposed scenes in normal mode, 3:1 works fine. Then, again, testing everything if you're not familiar with the camera is the safest way.

 

[JT Thurlow]

Thanks very much for the suggestions.

I'm tempted keep things around 250 ISO, as visible noise often comes in at 400, generally becoming bothersome to my eye from 800 (depending on what's in the frame).

We shot my last feature years ago on a Scarlet-MX, pretty much all at 250 ISO (at the DP's behest). Then I read that the MX sensor technically overloads when you go below 320, so I'm not sure if this was a mistake (though it turned out fine). I'm not sure if the Gemini is the same?

 

[Ignacio Aguilar]

I shot both Dragon and MX at 250 ISO and found the results to be good, but you really have to be careful about ypur highlights of course, as the sensor will be very inclined towards the shadow areas. On my feature film with the Ranger Gemini I shot plenty at 250-320 ASA for night scenes -using quite a lot of night and stopping down for anamorphic- and the results were lovely. Very rich and clean images. But that's my humble opinion.

 

[Nick Morrison]

The only issue with shooting at such low ISO's is your bombarding the sensor with light, and anything that clips is gone. There's no headroom in the highlights. Your shadows are perfect, but at a cost. Not saying it's wrong, just saying to be mindful. On Dragon we used to shoot at low ISO's too, but we've found Gemini so forgiving we've shot at 800 without the same worries.

best of luck