Is RED really 320 ASA and 4K?

[Marco Graziaplena]

I hope this is not make anyone upset

- As I understood, RED has got a CMOS sensor rated by default at 320 ASA. CMOS is a linear sensor. So if I open a .r3d file properly exposed at 320 ASA in RA and use COLOR RGB as color space and LINEAR LIGHT as gamma, I should have what the sensor effectivly recorded: a shot 2 stops under exposed.
So here's what I'm wondering about: REDone is a 80 asa sensor native camera, but with the right gamma applied it can be rated until 320?

- The second point of this thread is: RED is often compared with film because as assumed by many, film is 4K. You can have a look at that
http://www.arri.de/camera/tutorials/4k_systems_theory_basics_for_motion_picture_imaging.html
The thing is that film has 3 layers of emulsion while RED has a Color Filter Array, so each pixel record just one color. In terms of overall resolution may be correct that RED is 4K, but the real resolution in terms of color is one third: more or less 1,3K

Thanks all of you for posting your suggestions

 

[Mazen Hashem]

yes i agree with you that you can't compare Film with RED or Sony F35
Film 3 layer of emulsion
Sony F35 3 CCD that will make it 4.4.4
RED is CEMOS one ship each color pixel fill the empty spaces

but at the and for independent filmmakers this is the only choice 4K camera interchangeable Lens , Large sensor perfect for 35mm primes
you don't need a player or recorder it's all built in, ready for editing ,
and affordable price .

this is what make me love redone

RED SPEAKS MY LANGUAGE

 

[Fredrik Harreschou]

I hope this is not make anyone upset

- As I understood, RED has got a CMOS sensor rated by default at 320 ASA. CMOS is a linear sensor. So if I open a .r3d file properly exposed at 320 ASA in RA and use COLOR RGB as color space and LINEAR LIGHT as gamma, I should have what the sensor effectivly recorded: a shot 2 stops under exposed.
So here's what I'm wondering about: REDone is a 80 asa sensor native camera, but with the right gamma applied it can be rated until 320?

- The second point of this thread is: RED is often compared with film because as assumed by many, film is 4K. You can have a look at that
http://www.arri.de/camera/tutorials/4k_systems_theory_basics_for_motion_picture_imaging.html
The thing is that film has 3 layers of emulsion while RED has a Color Filter Array, so each pixel record just one color. In terms of overall resolution may be correct that RED is 4K, but the real resolution in terms of color is one third: more or less 1,3K

Thanks all of you for posting your suggestions

:Yawn:

here we go again...

 

[Marco Graziaplena]

I completely agree with you
anyone has a clue about the linear light question? I'm really interested in that

 

[sander kamp]

The RED is very comparable to DLSR's and the specifications are given in the same way. So think of it as a 8MP 320 ISO DLSR and the pictures you get are more or less the same as you would get from a Canon or Nikon digital still camera - except that you get 24-30 of them per second.

If you rate the camera's ISO at 80 ISO to expose for the mid-gray's your highlights will be all blown out. If you rate the camera at 320 ISO and apply a gamma curve the image will look more normal to our eyes.

You can think of it any way you want, but it is the results that count and if you set the ISO to 320 on the camera and use the on-board exposure meters to expose you get the best image.

 

[Marco Graziaplena]

I thought D5 and DSRL were 100asa native actually... but I'm not sure.
I tried exposing 320 with redlog gamma, and exposing 80 with linear light gamma, and the result I think is little bettere in the second case

 

[J. Bernard Vallon]

DSLRs all have different native ISOs depending on the sensor and its individual noise levels. Most modern DSLRs are natively around 500-640 ish.

Remember, linear light gamma isn't how your eye perceives light, your should be looking at your footage with a steeper gamma curve when correcting it. If your shooting so your footage looks correct when viewed linearly, when its corrected it'll look way to bright.

80 ASA is almost certainly going to blow your highlights clean our of the water.

 

[Graeme Nattress]

I hope this is not make anyone upset

- As I understood, RED has got a CMOS sensor rated by default at 320 ASA. CMOS is a linear sensor. So if I open a .r3d file properly exposed at 320 ASA in RA and use COLOR RGB as color space and LINEAR LIGHT as gamma, I should have what the sensor effectivly recorded: a shot 2 stops under exposed.
So here's what I'm wondering about: REDone is a 80 asa sensor native camera, but with the right gamma applied it can be rated until 320?

- The second point of this thread is: RED is often compared with film because as assumed by many, film is 4K. You can have a look at that
http://www.arri.de/camera/tutorials/4k_systems_theory_basics_for_motion_picture_imaging.html
The thing is that film has 3 layers of emulsion while RED has a Color Filter Array, so each pixel record just one color. In terms of overall resolution may be correct that RED is 4K, but the real resolution in terms of color is one third: more or less 1,3K

Thanks all of you for posting your suggestions

Your understanding of how the REDOne works is not complete - let me help fill in the gaps:

First, resolution. To find the resolution of a system, we measure it. See the chart I shot here: http://www.cinematography.net/natress-red-res.html which measures resolution of the REDOne. It shows it to be at least 3.2k, probably more, but at a low contrast, and very low overall aliasing. A very good result. You can just see detail out to 4k, but it's at a very low level, not least because we apply no automatic sharpening to the image, which incidentally would help lead to the dreaded video look.

Chroma resolution is never less than 2k, but can be greater depending on the exact colour, although, in practical terms, the colour looks to be the same detail as the luma.

Second, ISO: It's a guide for how you should expose the image. The exposure of an image is related to the dynamic range of the image, so that the higher the ISO, the more highlight protection is offered, and the lower the ISO, the less highlight protection is offered. Say you think RED is 80 - expose that way with a light meter on the mid-tones and you'll get really clipped highlights. Expose at 320 and your highlights will be protected. Go outside on a really sunny day and expose at 500, and you'll see all the sky without it clipping (probably).

Linear light is very useful for compositing and extracting absolute light levels, but it's not too useful for viewing things.

Exposure usually works best on the ETTR rule, expose to the right.

Graeme

 

[Daniel Browning]

DSLRs all have different native ISOs depending on the sensor and its individual noise levels. Most modern DSLRs are natively around 500-640 ish.

For further clarification, allow me to add that all ISO ratings ("native" or otherwise) are completely arbitrary. Some manufacturers rate the ISO so there is 2.5 stops of highlight headroom, such as in the D200. That places middle gray at 18%. Other manufacturers/models place middle gray at 13% (3 stops headroom). Still others are rated for 3.5 or 4 stops of highlight headroom.

ISO: It's a guide for how you should expose the image. [...] Exposure usually works best on the ETTR rule, expose to the right.

Seconded.

 

[Marco Graziaplena]

I m startint to figure it out
thanks anyone for the kinds answers