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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Imax Epic

PaulClements

PaulClements

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It seems a shame that the 645 Epic isn't quite large enough to mimic Imax (56mm x 42mm 645 vs 70mm x 48.5mm Imax).

With the increased size of the sensor, and possible implications on skew, using a horizontal shutter, such as the Imax film cameras, might also make sense.

Is there much call amongst RedUsers for Red to adopt a large format based on movie cameras over medium format photography? I personally would prefer it as an option.

Of course the lack of usuable lenses is the biggest problem for users but it equally represents a new opportunity for Red to develop affordable lenses. And of course an Imax sized sensor could always be used with 645 lenses as originally intended anyway.

Paul
 
The EPIC 617 has a sensor size of 168x56. I'm sure it can have the ability to establish a 15-perf 70mm "IMAX" frame size. :)
 
9K is enough for film out to 15-perf IMAX.

or maybe IMAX will get their act together and make an 8K projector?
 
Most of the IMAX shots in the IMAX release of "The Dark Knight" were contact-printed o-neg, but the efx supervisors said in the Cinefex article that even though IMAX is a theoretical 15K, they did their highest-resolution digital efx shots at 8K, and when it mattered less, they did 5.6K.

15K though is a bit of an exaggeration -- the IMAX frame is 70.41mm wide, so is about 3X the width of Super-35 (24mm). If Super-35 should be scanned at 4K, this means that IMAX should be scanned at 12K. If Super-35 is more like 3K in actual resolution, then IMAX is more like 9K in actual resolution.

Which all points to 8K as being a good target for digital IMAX projection even though some would say if 2K DLP projection matches 35mm contact-print projection quality, then that would mean that IMAX is like 6K projection.

So let's say that if 9K RGB is the target resolution, you'd want something like a 12K RAW camera, and the digital projection should be 6K to 9K. But I'm sure that a 9K RAW camera would do a pretty good job for IMAX release, especially if IMAX projection ends up being more like 6K in measurable resolution.
 
Yeah, with a RAW camera, you'd really want like a 10K or 12K camera to finish at 8K. But in reality, the 9K RAW to 8K 15-perf film out would probably be okay, since you are also dealing with the limitatations of the acquisition and projection lenses anyway.

Even the 4K scans from Dark Knight's 35mm anamorphic looked pretty damn good on the IMAX screen, to my eyes.
 
Well if you figure the lines are reading down, from top to bottom, then the total read time would be less on the cropped area than the full sensor, right?
 
Makes sense to me.

But I've never fully understood how they work period. If it was just reading off for x time and then reading the next then shutter speed would also affect skew. But it doesn't... so... I'm not sure how I'm supposed to think about rolling shutter.

If it's just going down the line saying "start, start, start, start" then "Read and reset,Read and reset,Read and reset,Read and reset" then yeah I would expect there to be more rolling shutter artifacts on the bigger sensors.
 
David, thanks that post. Clears up what I've been wondering for a while.

One other thing I've been wondering about is how much different the FOV will be with 645 glass VS IMAX glass?
 
Ahh yes I see now, that makes sense. I guess its easier than I thought to figure that out.

Cool, and thanks again.
 
Tom said:
Yeah, with a RAW camera, you'd really want like a 10K or 12K camera to finish at 8K. But in reality, the 9K RAW to 8K 15-perf film out would probably be okay, since you are also dealing with the limitatations of the acquisition and projection lenses anyway.

Even the 4K scans from Dark Knight's 35mm anamorphic looked pretty damn good on the IMAX screen, to my eyes.
Click to expand...
Tom,

Don't forget the shape of the 645 sensor means you wouldn't get 9K when you go down to a 2.40:1. If using spherical lenses (And I don't believe their are anamorphic lenses for imax or medium format photography) then you will be using 56 x 23.3mm of the sensor, almost half the size of the 645 sensor.

As such you'd be lucky to get more than 5K out of the camera with a theoretical resolution of around 4K or less. This means the 645 wouldn't really be close to Imax resolution. Whilst I'd say you'd probably get away with it I just think I and many others would prefer to pay any extra for the ability to get over actual 6K at 2.40:1.

Red's Epic and Scarlet lineups seem to be aimed more toward the photographic market than the cinematic market at present. I'd like to see them focusing a little more on the latter. It's what they've made their name in so far and whilst they'll obviously make their money in the stills market having a high end footing in digital cinema is, for me, a must in order to promote their lower budget cameras to the stills market.

Paul
 
Gavin Greenwalt said:
Hmmm... is there going to be more skew on the larger sensors?

Can the sensor reset faster on a cropped REDOne currently?
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As Tom said.

The Epic and Scarlet are going to have faster read/write rates which will improve skew and other shutter artifacts but due to the large size of an Imax sized sensor any skew would be more noticable.

As such having a horizontal electronic shutter (Reading left to right) would make sense as it would practiacally eliminate skew if it was there (All you'd get is a slight horizontal squeeze or stretch on whip pans - Of course if you whip pan vertically you'd see any skew but how often do we do that?) . Furthermore it would mimic the way the Imax cameras feed the film through the gate, so it'd make sense to do it this way.

Paul
 
Hi Paul,

You're talking about a vertical crop, not a horizontal one - so you'd still get 9K, just with a wider ratio.

Also, native IMAX footage is not 2.40:1 - it's 1.44:1, which is pretty close to the 645 format's ratio of 1.33:1, so you're not loosing much resolution at all.

If you wanted to shoot 2:40:1 material on 65mm, you'd be frankly far better off with the 5-perf 65mm format which has a native ratio of 2.20:1 to start with, so giving very little wastage. Slightly less image area than an IMAX frame croppped to 2.40:1, but only by a very small amount for much less wasted film stock!

I personally don't see any major reason why the Epic 645 couldn't be used successfully for IMAX shooting, given that it's resolution is about right (if a tiny touch underpowered for a bayer system), it's physical sensor size is slightly smaller, but not by much, allowing the use of existing IMAX mounts and lenses, and it's native ratio is very close to that of IMAX - I'm also sure all these considerations were taken into account in it's design, and the fact that it's 645 as opposed to 15/70 in size is (I would guess) a slight concession toward still photographers whilst still aiming to keep IMAX-compatible digital work possible...

Cheers,
Dom.
 
Is there any sense in using 65mm lenses on the 645 (if Red made a mount for it of course - a maxi-PL mount I believe it's called)? I haven't heard any talk of such a thing yet. Arri/Zeiss make a set of these lenses for the 765 camera (30mm up to 350mm, not particularly fast though...T3.0 to T4.6). I'm not sure how much call there would be for this sort of thing and I'm sure these sets of lenses aren't exactly plentiful right now, but it might be good to know there was an existing, established lens rental option if the need ever arose?
 
I'm really interested to know what Jim is thinking about IMAX.
 
David Wyatt said:
Is there any sense in using 65mm lenses on the 645 (if Red made a mount for it of course - a maxi-PL mount I believe it's called)?
Click to expand...

Aperture sizes become somewhat smaller, proportionately so, with these "larger" lenses and the T-stop or transmission speeds also decrease. A lot of that has to do with the amount of light gathered in relation to the size of lens and the imaging area it has to cover.

65mm is just one potential application for the 645 and 617 Epic cameras. Aside from Arri's 65mm lens offerings (which are neither plentiful or cheap), there is also the Panavision option. So rental options do exist, but once again, neither are plentiful or cheap. I think a lot of early adopters of these cameras will be using existing medium format stills glass. The biggest issue I see there is if we want to shoot something similar to a 65mm frame size, but only have medium format lenses, we'll be shooting telephoto all the time as 65mm is a severe crop of the 645 image area. Then again, 4K is getting pretty easy to deal with. That 9K 645 frame isn't sounding all that bad and should have many of the same properties of an IMAX image as we're getting to be nearly as big and with resolution comparable to 8K scans.

I'm anxious to get my hands on the Epic 645. I envision that as my big workhorse brain and it will probably be the one brain I rent out and use for all my special needs. Other than that, for my every day use, I see the fixed lens Scarlet and Scarlet FF35 filling most of my needs. That Epic 617 is sure sexy too and I'd like to own it as well, but I think availability, timing, etc.. will determine that.
 
Dominic Jones said:
You're talking about a vertical crop, not a horizontal one - so you'd still get 9K, just with a wider ratio.
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You're right Dom, I was having something of a brain freeze writing fast as I had to catch my train this morning!
Dominic Jones said:
...a slight concession toward still photographers whilst still aiming to keep IMAX-compatible digital work possible...
Click to expand...
I'd prefer to see Red catering for both standards. An Imax sized sensor could still be used to shoot medium format photography. Perhaps this is a question of the size of the Epic housings though. If they need to design a whole new form factor to accomodate the sensor it might not be all that worthwhile.

Cheers
Paul
 
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