Can the ISO be lowered?

[casey warren]

When determing a sensors ISO, is it possible to just set it at the desired number you want or is it native/built into the sensor and therefore unchangeable?

For example, I know RED's sensor is rated at 320, but is it possible that a firmware upgrade could lower it to 100?

looking at many of the shots from the Salt Flat shoot, they had to stack a ton of ND's infront of the lens. I know that when I crank on the ND's on my HVX, the results lead to imagery that loses color intensity and also contrast leading to the images becoming slightly muddy and not as rich as they were w/o the ND.

I Know that the RED footage from that shoot looks amazing, even with the ND's but could there be a simpler solution of just upgrading the firmware so that ISO 100 could be accessed?

[Shawn Nelson]

No, I talked to Jim in person about this. They have no plans to allow any changes in sensor sensitivity. On Red, the ISO you change is simply META data that changes how your monitor displays the data.

Changing the ISO to 100 is no different than shooting in 320 then pulling it to 100 in post.

[casey warren]

I see, that makes more sense.

Then the question is, why 320? and why not 100 or even 50. Is this something to do with how they developed the sensors optimal signal/noise ratio?

I know when I shoot with higher ISO's on my DSLR, I tend to get really really grainless and smooth imagery from ISO 100 and then when I shoot in 320 it introduces a lot more grain and also less color saturation.

Im not saying thats RED's 320 is exacly like the 320 on the 5D or Mrk 2, but, in terms of comparing the two, how close are they?

[Kevin Halverson]

In the case of a DSLR, changing the ISO does effect the analog gain before the quantizer so it will have an effect on the S/N ratio. In the case of the RED ONE, it only effects the meta data and has no effect at all on the actual image being recorded. Rating the camera at 320 is really just that, a rating. In the end all you have to do is protect your highlites and pick an illumination level that gives you a noise character you can accept.

[casey warren]

I see, wow, then the RED ONE method rocks! because one big complaint I have about DSLR's is that when you get past 400 ISO, your image is very unstable if you want to push the exposure in post.

I find that I am always running into this really deep reddish noise in the blacks. The highlights hold fine, but its all in the darker parts of the image where it becomes really apparent.

[Chris Nuzzaco]

Does Red plan on releasing a lower ISO sensor?

[MarcusX]

Does Red plan on releasing a lower ISO sensor?

Why would they make a worse sensor? Am I missing something?

[Kevin Halverson]

It wouldn't necessarily be a "worse" sensor if it were less sensitive as it might have even better noise performance. However, it would be less applicable for most cinema and ENG/EFP applications. If RED decides to get into the machine vision field then its possible, but I wouldn't count on that being a direction that they are looking to head.

[fightordie]

It wouldn't necessarily be a "worse" sensor if it were less sensitive as it might have even better noise performance. However, it would be less applicable for most cinema and ENG/EFP applications. If RED decides to get into the machine vision field then its possible, but I wouldn't count on that being a direction that they are looking to head.

ND's are your solution.

[Kevin Halverson]

While its very obvious that NDs will lower the apparent sensitivity, they don't address the original question as to why an actual lower sensitivity might be desirable. Just as in film, lower speed is usually the byproduct of finer grain characteristics, a higher photo receptor count (in the same area) would likely yield lower natural sensitivity.

[Leo Ticheli]

Are there provisions for selectable gain settings, such as plus and minus db?

Good shooting and best regards,

Leo

[Kevin Halverson]

Are there provisions for selectable gain settings, such as plus and minus db?

Good shooting and best regards,

Leo

No, not currently. The analog gain is factory fixed and not accessible to via the UI.

[jbeale]

It's better not to stack ND filters, the more surfaces in the optical path, the more flare and veiling glare I'd expect. It's tricky because the most common ND filters only go up to ND 1.2. However Kodak makes 4x4" and 6x6" ND gel filters including ND 3.0 (10 stops) and ND 4.0 (13.3 stops). For example http://www.bhphotovideo.com/c/product/28040-REG/Kodak_1497825_4x4_100mm_96_Neutral.html

[David Mullen ASC]

There is no reason for an ND filter to do anything but cut light -- it shouldn't affect color saturation or contrast, unless it is dirty... or you are stacking too many filters together, or you have a flare because of light hitting the mattebox.

I honestly can't figure out why so many people here have this hang-up about using ND filters -- they are the most commonly-used filter in the film industry (and inside ENG camcorders.) I would just get used to the idea that they are as necessary as a battery or a tripod or a lens itself.

Now (just seeing the other posts about shooting in the desert) I can see an argument for a lower ISO setting capability so that the degree of ND doesn't have to be as extreme, but remember that at 50 ASA in direct sunlight, at 24 fps with a shutter speed of 1/48, you are slightly over an f/16... so even then, you'd probably want some ND or a Pola. I think those filters are inevitable when shooting in sunlight.

The average ENG camcorder is also around 320 ASA and often the filter wheel has a 2-stop, 4-stop, and 6-stop ND option. But it's internal, which probably helps reduce any chance of glare/flare.

[David Battistella]

It's better not to stack ND filters, the more surfaces in the optical path, the more flare and veiling glare I'd expect. It's tricky because the most common ND filters only go up to ND 1.2. However Kodak makes 4x4" and 6x6" ND gel filters including ND 3.0 (10 stops) and ND 4.0 (13.3 stops). For example http://www.bhphotovideo.com/c/product/28040-REG/Kodak_1497825_4x4_100mm_96_Neutral.html

I am pretty sure you would want to put GLASS in front of the very expensive GLASS you have attached to your red.

David

[David Battistella]

I honestly can't figure out why so many people here have this hang-up about using ND filters -- they are the most commonly-used filter in the film industry (and inside ENG camcorders.) I would just get used to the idea that they are as necessary as a battery or a tripod or a lens itself.

...

The average ENG camcorder is also around 320 ASA and often the filter wheel has a 2-stop, 4-stop, and 6-stop ND option. But it's internal, which probably helps reduce any chance of glare/flare.


David,

I agree. I think that the current ENG setup is designed around and ease of use philosophy. Most news camera do not have Matte Boxes attached. They have a wide ranging zoom and shooting is designed to be an "it's all built in" proposition. I equate it to a fast food mentality.

There is a generation of videographers that have worked in this easy to use configuration. I think that many have not really experienced a film style shooting set-up and they feel speed is everything, "Hey man, the producer wants the shot". Flip a few switches and everyone is good to go. They don't want to reach for an, ND or a pola, etc.

This is what I love about RED. It may bring many back to thinking about craft and making considered decisions about lens and filter choices, lighting and shooting conditions/times. A RED will in some ways force the operator out of the "point and shoot" mentality and clearly it is becoming obvious that it is a more serious tool than an ENG camera.

David



PS: Thanks for posting into this site and sharing your experiences always a pleasure to read your posts.