RED vs. SI 2K

[Rudi Herbert]

Sorry for the sensationalist tittle to the thread, I just wanted to make sure that those who can contribute don't miss it.

With all the discussions lately about the dynamic range/lattitude of the RED and the disparity of results among owners, some claiming the Mysterium is to blame for the poor results, while others, namely (and significantly) Jim and RED team, explaining that the post management of the files is the most important aspect, I wanted to see if any members of the forum have similar experience with the SI 2K. Why the SI 2K? Because it is, as far as we know, the ONLY other camera out there that has an almost identical workflow to RED, with the sensor feeding an uncompressed image to a processor that spits out a proprietary wavelet compressed image, retaining the flexibility of RAW but having to compromise something to become manageably small. While the Viper and the Dalsa send out uncompressed images, they are not really RAW, so even if the SI 2K is only a 2K camera, it is still pretty much a match to RED in concept, approach and technology.

So, of all those out there that have worked with the SI, what have you noticed in terms of DR and lattitude? Is the handling of highlights and shadows similar to RED's? Does the camera tend to clip more, less, as much as RED? How is the noise handling? Anyone? I do not wish to evoke another competitive comparison between RED and another camera, I think that in many ways both cameras belong in different categories, even though the RED is cheaper while being the "more professional" of the two. But with such similar image processing pathways, would we not learn something if we could analyze the SI, both on its own and against the RED?

Please be constructive, informed, informative and respectful, or don't bother with this post at all.

 

[Jason Ing]

Constructively phrased, thoughtful post. Looking forward to likewise responses.

 

[Steve Sherrick]

Well, this is taken from the SI2K frequently asked questions section. It gives a little insight into how the sensor reacts, so you can compare that to RED on paper. But to really compare the cameras, you'd have to establish some real world tests and see exactly how each camera captures images.

The CMOS sensor in the SI-2K is approximately "daylight" balanced for 5600K (give or take a couple hundred degress Kelvin). This is because the sensor is more sensitive to red (specifically infra-red), than it is to blue light. So for a given scene, by exposing the sensor to more blue light and less red light, the response of the blue channel will be evened out with the response of the red channel.

For instance, in order to achieve native "white-balance", one would want the color-temp of the light exposed to the sensor to produce an equal response in both the red, green, and blue channels. If one exposes a very warm source to the sensor, the red response will be very high, and the blue response will be very low as the sensor is more sensitive to red light . . . and the resulting picture of course will not be white-balanced unless digital gains are applied to the blue-channel. As one moves the light source from a warmer to cooler spectrum, the blue light being exposed to the sensor is increased, creating an associated greater amount of blue response compared to red response for that give light-source. After a certain threshold, the red response will be the same as the blue response, and a "native" white-balance point will be acheived that does not require a digital gain in any of the channels to create an even response in the three color channels. That being said, because the sensor is more sensitive to red light, a higher ISO for the sensor will be acheived in tungsten light. Of course, along with the higher native ISO under tungsten, the blue channel, because it will have a lower response, will need to be gained-up in order to match the response of the red and green channels for proper white-balance. As a result, the blue channel will be noisier.

While daylight is the native white-balance of the sensor (and will give a cleaner blue channel), because the sensor is being exposed to a color temperature that it is not the most sensitive to, the ISO will be lower (daylight does not have as much red light which the sensor has a higher response to). The SI-2K has an approximately 1/2 f-stop loss in sensitivity going from tungsten to daylight. Based on the native ISO of the SI-2K being 250 for tungsten, that means an approximate ISO of 160 for daylight balanced light-sources.

When shooting green-screen or blue-screen footage, in order to prevent higher digital gains (that in-turn produce higher noise) in the blue and green channels in order to match the response of the red channel, it is suggested to shoot with daylight balanced light-sources. Also daylight balanced light-sources will extend the "useable" dynamic range of the image around 1/3 to 1/2 f-stop (because the red-channel will not clip first).

Shooting with color-balancing filters in front of the camera lens will also achieve the same effect when under tungsten lighting, but doing so will also interfere with digital white-balance in-post. Color-balancing filters basically "bake-in" the white-balance setting, defeating the purpose of the white-balance metadata that is saved in each recorded file in order to be further processed or adjusted in post.

Why does the perceived sensitivity of the SI-2K change with different white-balance settings?

The sensitivity of the SI-2K differs because the white-balance is accomplised through a digital, not analog gain on the RAW data. This means that the sensor's RAW data is being adjusted digitally for the optimum white-balance, rather than before the A/D converter. This gives us the flexibility to adjust the white-balance in post because the RAW data itself from the camera does not have a non-reverseable white-balance "baked" into the image. The applied digital gains though will affect the perceived luminance sensitivity of the camera due to the fact that luminance is a weighted sum of red, green, and blue, so as the different channels are gained up and down to achieve an optimum white-balance, there will be a different luminance value for a given desired middle grey subject. The SI-2K is most sensitive to red light, so the perceived sensitivity of a middle grey subject will be higher under tungsten lighting than daylight. The important thing to note is that since the white-balance is metadata, the actual exposure ISO of the RAW data is the same no matter what the white-balance setting, but it's in the conversion to a luminance value based on a given white-balance that one will see the actual exposure ISO values fluctuate for a grey reference. For example, if one were to shoot a given subject, and then evaluate a middle grey card in that subject, they will find as they digitally adjust the white-balance through a range of kelvin, because of the weighting on the rgb->luma conversion, the exposure on that grey card will fluctuate slightly (approximately 1/3 to 1/2 of a f-stop) with different white-balance settings.

 

[M Most]

SWhile the Viper and the Dalsa send out uncompressed images, they are not really RAW...

In Dalsa's case, yes, they are RAW. That's not usually what the end user deals with, because very few end users have systems capable of dealing with uncompressed 4K, but what comes out of the camera is indeed uncompressed Raw data. It is debayered and converted (usually by either Dalsa or by the user via either a Codex or S.two system) to RGB for later post production, but that is mostly because Dalsa's workflow is based on uncompressed material. Whether that is good, bad, or neither is a separate issue.

 

[Mitch Gross]

Actually, Dalsa's material is "mathematically lossless compressed," which in my book is as good as uncompressed. Phantom footage is truly uncompressed RAW.

 

[m.treurniet]

Viper RAW

Viper RAW

The Viper has in Filmstream mode definitely a RAW output. The only thing it does is that the 12bit RAW data from the sensor are mapped to a 10 bit logarithmic (filmstream logarithmic, NOT cineon logarithmic and the same as REDlog) stream that is recorded onto the SRW1 or sTWO or Codex machines.

 

[AntiMutant]

I have the SI-2K, the SI-2K Mini, and a Red One. We got our Red while I was renting my SI-2K to a feature so I haven't had a chance to play with it yet. I just want people to know that I'm not biased towards one camera or the other. The problem is, however, that I'm not very technical, so I'm not sure how much I can add to this thread. Maybe in a month or so once I've done some real world comparisons.

I will say that everyone that sees the SI-2K footage is amazed by the latitude. Not compared to the Red, but compared to whatever they were expecting from a digital camera. Silicon Imaging claims 10+ stops, and in a test with a DP we found this to true. However, at a certain camera rental company, not known for being supportive of cameras that they don't rent themselves, they insisted that the latitude was just over 9 stops. I'm assuming that there is some difference in what is considered "usable" latitude??

The SI handles low light fairly well. It doesn't do anything strange, just the expected gradual increase in noise as the light falls to unacceptable levels.

I'm very happy with the SI-2Ks, and I hope to find the Red comparable. I've been following this latest "issue" with a little concern, but it seems that one has to wait for the dust from the fan boys and "naysayers" to settle before the facts can sift through.

In the near future I hope to do some side by side shooting ... but I don't know if I'd want to post the results here! I think both cameras have their strengths and are amazing tools, especially considering the price. Could it be possible that the SI-2K actually has more latitude than the Red, while the Red has higher resolution? Or would this be blasphemy? :mellow:

EDIT: I guess for the sake of complete honesty I will admit that I find I'm a little biased towards the SI-2K. Not for purely technical reasons, but because I find some of the hype surrounding the Red nauseating (not from the company, but from some others in the community) and I find the lack of hype for the SI-2K a bit sad. I tend to root for the underdog. Just being honest. h34r:

 

[Edgar Pitts]

AntiMutant,

I would really love to see your unbiased side-by-side tests. I have been following both the Red and SI cameras for over a year now. I am a Producer for an independent production company (http://www.jetrefilm.com) that will be shooting a multi-Red camera feature in September.

SI really shot themselves in the foot because even though they had working cameras, they could not get the main SI-2K unit ready or the mini in any quantities. They could have gained lots of market share due to Red's delivery delay.

Top this off with the fact that they raised the prices and dropped the PS 35mm adapter. Bad move in my book, but I don’t think that they are owned by a billionaire, who can eat a lot of upfront costs, either.

I really like SI and love the idea of getting Cineform RAW straight from the camera. There is definitely room for both SI and Red.

Please do your tests - I would love to see how Red and SI footage cut together because the mini can get shots that Red can not sometimes.

Thanks!

Edgar

 

[M Most]

Top this off with the fact that they raised the prices

It would be almost impossible to not raise prices on devices that are assembled in and imported from Europe (the SI2K is assembled in Germany) when the dollar has lost almost half its value vs the Euro.

 

[AntiMutant]

Yeah, the price increase is a bit of a disappointment, but I fail to see the point in a 35mm adapter. You get a ridiculously shallow DOF whenever you want it. We found a 35mm lens (in super 16) to give us almost too shallow DOF for our tastes for most coverage, and at 120mm well, it was that much less.

I must be missing something about the nature of 35mm DOF because I keep asking myself why one would want even less. Is it because you can get that shallow DOF at wider angles of view? Off topic, I guess.

What I hope to do is a comparison between the 2 cameras with the help of some friends, one of whom is co-owner of the Red and is overjoyed with it.

 

[Edgar Pitts]

Like I said, I am a fan of SI. I think that Jason R. is extremely knowledgeable and a class act.

The 35mm adapter was important due to its price point (6k less the pro PS) and the ability to use lenses at their proper focal length.

The falling dollar is definitely behind the price increase, but that is the difference with partnering with a foreign company and building something (having the resources) yourself.

I look forward to your comparison. Please post your results here. Thanks.

 

[Illya Friedman]

Actually, Dalsa's material is "mathematically lossless compressed," which in my book is as good as uncompressed. Phantom footage is truly uncompressed RAW.

???

The DALSA cameras send out 100% uncompressed, RAW, 4K, DPX files. You can't get more RAW or uncompressed.

Both the CODEX and the S.Two will capture these DPX files in their native RAW and uncompressed format.

Mitch, where I think you may have gotten confused is that last year DALSA has announced building a "FLASHMAG" flash recording device that would have the OPTION to record uncompressed or a 2:1 "mathematically lossless compression" which of course means that you could always decompress the images and be uncompressed.

The Flashmag isn't available yet, so the 2:1 isn't either. Unless the good people at S.Two and Codex choose to add it as a option, you can't record that way with a DALSA camera.

I.

Illya Friedman
DALSA
Digital Cinema Division
www.dalsa.com/dc

 

[Mitch Gross]

Illya,

Sorry for my mistake. I first heard the term "mathematically lossless compression" from Dalsa and thought it was implemented in the Origin. My apologies.

 

[Rudi Herbert]

Well, apologies, I was also under the impression that the Dalsa sends out some sort of not RAW file, but then, there's so little I know about that camera, except that it makes exceptional images and that is very bulky and available only as a rental item...

Going back to the SI 2K, I've seen all the clips posted on their website, not a great selection by the way, but whatever is there I've seen, and at least to my eyes the images show a nice dynamic range, I don't know if it's more than the RED's, but there are very few blown out highlights, something which can be attributable to those users knowing their kit or craft better, or maybe the camera is more forgiving that the RED. I don't know, it was my intention to gain a better understanding of that workflow by starting this thread, but so far, we don't have much. Thanks to anti mutant BTW.

 

[M Most]

The falling dollar is definitely behind the price increase, but that is the difference with partnering with a foreign company and building something (having the resources) yourself.

Just to keep everything in perspective:

The Red is assembled in Singapore, and although the company has never really talked about it, I would suspect most of the components are foreign sourced as well. However, I do understand your point, and it is certainly true that the industrial design as well as the optics on the SI are done by a German company, where the core design of Red is done by the company itself.

 

[AntiMutant]

I have some SI-2K footage and stills from the last shoot I was on that I can post. However, I'm sensitive to the fact that this is a Red forum, so I don't want to do that until I can post some images from both. Hopefully this week I'll get the time to do that ... hopefully I won't forget about this thread!

 

[RobRoySyd]

We now have a full SI-2K body and OLED viewfinder. It's off at a conference so I can't play with it until next week.
It has the same build quality as a cine camera, no screws into alloy. Lens mounts are the real deal and changing mounts is as easy and quick as changing lenses and there's been a very wide choice of mounts available for a long time.
I'll leave comparisons of image quality to others.
Perhaps worth mentioning that neither camera can output 1080p. The RAW workflow with the SI-2K is more mature however it is still RAW and that can leads me to say that both cameras have a lot in common and a steep learning curve.
Competition is always a good thing however I think the real competition between these two fine cameras is minor compared to that between both these cameras and the rest of the field. Having a choice of two such similar cameras should make it easier for both to gain wider acceptance when we have both pushing the RAW workflow into wider acceptance.

 

[chocblu]

I think the real difference between the two camera's(and one of the reasons i would go SI-2k rather than red *ducks*) is the workflow.

From what i know, the cineform/looks that the SI-2K gives is streets ahead of the red workflow. Just the ability to adjust LUTS however you want, without baking them in, and changing then at any point in the post-production run is fantastic.

As far as i know, the Red footage just isnt that flexible, and needs extended rendering time, and you have to "bake in" these colour changes.

If this isnt the case then please flame this reply into the gutter so that i can choose the better camera.

But frankly that is the thing that tipped me. The workflow with footage pure and simple.

On Paper the Red is a better camera as far as i can see. But the workflow is sooo much better on the SI-2k...now if only cineform could be intergrated on FCP as well as it is on PPro..its getting there

 

[Paris Remillard]

Maybe Geoff Boyle can chime in since he used both Reds and SI-2Ks for The Dark Country. I can't imagine a better comparison than a full feature length production and post.

 

[Rudi Herbert]

RobRoy and Antimutant,

It would be VERY useful for all of us here to see some comparisons between both cameras, shooting the same scene with both cameras so that we can see differences and similarities. This would be illuminating in more ways than one. For example, the F-23 seems to have more dynamic range than the RED, yet it is only a 1080p camera, which would seem to indicate that those gains are related to image management and not resolution. Given that the SI workflow is more structured and tied up to a color correction app, Speedgrade, perhaps that camera allows for an easier, more predictable way to extract the full potential out of the sensor, while RED makes this more difficult to many users. Please, do these tests and let us know, ALL current and future RED owners would benefit from them.

Thanks,