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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 :)

True Crop Factor when shooting lower than 4k

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David Vollrath

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First post here ...

Can Jim or someone else from Red please tell me for sure if there is an increased crop factor when shooting at 3k, 1080p or 1k when compared to shooting 4k. Plenty of people on this forum are saying that this is the case, but I have scoured the web to find an answer from Red and can't find one. (maybe I'm not looking hard enough).

Also. I believe I read that there is autofocus ability with the Canon mount. Does this mean that there may be ways to create a remote follow focus for Canon glass similar to the non-existent Birger mount?
 
I would really like to hear the implications of the sensor crop from those that know. All I wanted was decent over crank but best you can get is 60 at 1080 - which would be fine other than the massive sensor crop issue. I've heard that at such a crop you decimate your low light gathering ability, so way more noise than say an fs100 not to mention what it does to the focal length and DOF at such a crop. Is all this true?
 
It's for this reason that I will probably not be buying a Scarlet. I like 4k. Don't really need it though. 99.9% of my stuff goes on the web. 2k is fine for me. Would love RAW and HDR, but being forced to shoot 4k kills my buzz. I guess I'll have to wait until I can bankroll an Epic. Scarlet seems like a great b cam for someone shooting with an Epic.

That said, I do appreciate Jim's drive to push the industry forward.
 
Yes, all the reduced resolution modes are cropped. That means less pixels, so also means higher fps and/or less compressed REDCODE.

Graeme
 
Jonesy Jones said:
It's for this reason that I will probably not be buying a Scarlet. I like 4k. Don't really need it though. 99.9% of my stuff goes on the web. 2k is fine for me. Would love RAW and HDR, but being forced to shoot 4k kills my buzz. I guess I'll have to wait until I can bankroll an Epic. Scarlet seems like a great b cam for someone shooting with an Epic.

That said, I do appreciate Jim's drive to push the industry forward.
Click to expand...

+1.
 
i'm pretty sure autofocus is already working, somebody can correct me if i'm wrong. if it's not, it will be...

as graeme knows better than i do, the lower resolution modes work by "windowing" the sensor. processing power and read/write speed of the media is the biggest factor. if there's less information to record (i.e. lines of resolution) the framerates can increase (or the compression ratio). this windowing of the sensor means that less lines are read, and thus uses an increasingly smaller portion of the sensor, which effectively increases the crop factor.

the best way to understand what you're going to get, rather than looking at numbers, is to take a 5k image from any source, and crop it down to 4k, 3k, 2k, 1k.
 
I think a lot of us were hoping for pixel binning that allowed for use of the whole sensor instead of cropping, albeit with limited frame rates for higher resolution.
 
graeme and the rest of the team can comment on the feasibility of that. i'm guessing if it was simple it would have been done, but maybe it's on the board.
 
I think a lot of us were hoping for pixel binning that allowed for use of the whole sensor instead of cropping, albeit with limited frame rates for higher resolution.
Click to expand...

For that, you most likely need the same horsepower that is in the EPIC, because the camera has to capture at the full resolution and frame rate. In addition, it has to perform resizing, which is an additional process.
 
PLS i'm interesting too.

How about AI Canon mount autofocus? one shoot or continuos in rec mode?
Can explain the different btw TI Canon mount and AI?
 
I have a feeling that many of us will be using EF lenses and probably wishing to shoot below 4k a fair amount of the time so as to take advantage of HDRx (at 24fps because, as I understand it, you cannot use HDRx at above 12fps in 4k or 15fps in 4k QHD) and/or faster frame rates. Given that, what I'd like to know is:

1) The Scarlet-X has a particular field of view with the Canon EF 24-70mm f/2.8L USM lens on it when it is set to 4k. If I set the camera to record at 2k (for example) is field of view on the lens the same or is it altered somehow? Does the zoom lens' range of potential fields of view become more akin to the Scarlet-X shooting at 4k with a 48-140mm? Is it changed in some other way?
2) I'd ask the same question when the camera is set to 3k with the same lens. Does the field of view of the lens become like shooting at 4k with a 32-93mm lens? Again, is my math funky?
 
attachment.php

http://www.reduser.net/forum/showthread.php?65973-Crop-Factor-Demystified
 
That is very helpful, but is that all that happens recording at those crops? The way many are talking is that In addition to turning your lens into a tele is that you loose half the light, meaning a much noisier image particularly in low light and you also have a much less shallower DOF?
 
So can anyone chime in on this? Like I said I get the crop factor as illustrated by the picture above but what about the other claims of poor low light, noise and DOF ? I spoke to someone yesterday that said in many scenarios where 60p is needed you would likely get a far better image from a $5k Sony FS100 than a $16k scarlet. This scares me to say the least...
 
Yes you need to log in to see the picture I think
 
http://www.reduser.net/forum/showthread.php?65973-Crop-Factor-Demystified

read through this thread guys...

the boxes are the area of the sensor being used to record, that's how it works. not sure where this stuff about low light, noise, and DOF are coming from. it's a really straightforward process, the camera just chooses to ignore parts of the sensor, that's it.

now, for a similar field of view (FOV), because you'll have to use a different lens, you will get depth of field differences - but that's pretty straightforward as well.
 
Graeme Nattress said:
Yes, all the reduced resolution modes are cropped. That means less pixels, so also means higher fps and/or less compressed REDCODE.

Graeme
Click to expand...
Hi Graeme,
is it possible to use EXTERNAL recorder like KiPROmini for 2k or LOWER Recording if Scarlet is set for 4K.?
 
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