Thoughts regarding S35 vs. FF35 sensor size

[Häakon]

Most people who own a FF35 will be using PL-mount glass on it in a windowed super 35mm mode.

I've been wanting to say something about this for awhile, but haven't had the brainpower to articulate it until tonight. Maybe someone else has some thoughts on this as well.

I remember when I bought my first full-frame dSLR (a 5D) and was comparing the images to my previous dSLR (a 1.6x crop XTi), and the ever pervasive discussion about "zoom factor" came up when comparing the two. That is, with the same glass on both cameras, a 50mm lens on the 5D "becomes" an 80mm lens on the XTi, because you're covering a smaller sensor area and you're really only using part of the glass on the cheaper camera. So while some people have declared that you actually get "longer zoom length" on a cropped camera, we all know that isn't to be true - you're really just seeing part of the picture. I demonstrated that one could just as easily take a center crop of the 5D image to match the size of the XTi's frame, and you'd end up with the same FOV. Again, most of us understand this concept, especially after having shot with the RED ONE's "windowed" modes. Here's where the kicker comes in, though.

The 5D's sensor is 12.8MP while the XTi is 10MP. So while the XTi is a 1.6 "crop" camera, it doesn't have 1.6x less total resolution. Thus, the 5D's photosites are larger (a good thing), but when you take that center slice out of the 5D image to match the frame size of the XTi (and get an equivalent FOV), you actually end up with an image that has less resolution than the "inferior" camera. And when looking at comparative images, it's actually quite a noticeable difference. Now normally this isn't an issue, because you do have lenses that cover the entire full frame and thus you don't waste anything - you get the benefits of both added resolution as well as the larger pixels (better noise performance, more DR, etc.).

However, if you're planning on just using good ol' PL-mount lenses on the FF Epic (specifically ones that only cover the S35 frame), you are making that sacrifice and throwing away quite a good bit of the sensor. And since the jump in resolution between the two cameras isn't very much (5K vs. 6K), one would have to assume that the pixels are indeed quite a bit larger on the FF Epic (I believe they posted specific pixel size information during the November announcement but removed it from the updated Dec. 3 rollout). As a result, you're going to take a decent hit in resolution when shooting this way. To put it another way, you'll likely have more pixels (and in turn higher detail rendition) when shooting with a PL lens on the S35 Epic than the FF35 model.

Of course the monkey wrench in the equation is that the sensors are not the same, and the "Monstro" sensor is supposedly one generation better in terms of latitude and noise and all of that fun stuff. So it doesn't make the comparison apples to apples, because we're dealing with more than just a loss of resolution here.

I do put this out, however, because it seems like with no response to all of the requests for a S35 Monstro camera from RED (it really does appear that this is the best solution more and more every day), many users are thinking of jumping up to the FF version, putting a PL mount on it, and calling it a day. Admittedly, there are still many unknown variables here - not the least of which is the fact that we have no samples of image quality from either of these cameras - but it's just food for thought for those who may be considering this route. That 5K S35 Epic X may just be the best choice yet.

 

[paul engstrom]

I think you're thinking correctly Haakon--which makes me think an individual's commitment to glass will greatly affect what brain they go for. I suspect a lot of people will stay with s35 sensors (Epic and R1 and Scarlet) to take best advantage of cinema lenses.

That said, I think RED's moves are brilliant--whole new markets (full frame and 645) for geared, non-breathing/ramping cinema lenses, which RED will be at the forefront in delivering.

p

 

[Bruce Allen]

I totally agree. Except that I don't need >2K real resolution (3K Bayer?). I would gladly swap resolution for more sensitivity, more dynamic range and less noise than the Red One.

*IF* I were to buy a camera (I'll wait to see what happens with rental prices - may continue to rent), I'll wait until the FF35 comes out and see if Monstro is a big improvement over Mysterium X.

If it is... great, I'll get a Scarlet FF35 (and get additional benefit of Anamorphic lenses plus using my fast Nikon lenses for ultra-low light stuff where I want the benefits of the larger sensor size). Otherwise I'll pick up a used Scarlet S35.

But you're right - the 5K S35 may be the best choice yet. We won't know until the FF35 comes out and we can compare the two.

Bruce Allen
www.boacinema.com

 

[Häakon]

That said, I think RED's moves are brilliant--whole new markets (full frame and 645) for geared, non-breathing/ramping cinema lenses, which RED will be at the forefront in delivering.

I agree completely - and I've given RED many kudos for the willingness to break that barrier. The problem is that without the necessary glass, the larger sensor advantages are relatively moot. Issues with using lenses designed for still cameras are well-documented, and so far all of RED's announced FF offerings are all moderately slow zoom lenses.

In some deranged way, part of me is actually happy that there is no S35 Monstro camera as it encourages users to get into FF cinema - even if they don't intend to use the full sensor. And eventually someone will say hey, this is silly, we need to develop true FF cinema glass to take advantage of such these great, larger imagers. But how long will that take? What will the market be? The glass is so key here. And I don't even think it's really that all these production houses have a ton of PL glass lying around and they want to be able to keep using it, it's that there really isn't a viable alternative right now. Those PL mount primes from RED still haven't seen the light of day, and those are designed for the "old" sensors!

Bruce is right that for 1080 work, the resolution hit one would take by shooting with the FF35 RED will probably not make that big a difference... but the problem is that if it offsets some of the advantages of the Monstro chip it may not worth spending the extra cash to get there. The other problem is that we really don't know how long it will take to arrive as it is... we're already looking at "Winter '09" for the Monstro cams and we all know targets are, well let's just say, subject to change.

Perhaps I'm just being picky, but I definitely notice a difference in the output between 3K and 4K from the RED ONE even when they are properly scaled down, and for most of my work - which ends up finishing in 1080p - 2K is just not a valid format option. I'd like to keep that resolution up as high as possible (all other things being equal), and this is just an observation that when shooting S35 you may get more bang for your buck when going Mysterium-X.

Time will tell, of course... I just don't want to wait. :bleh:

 

[Emmanuel Cambier]

If it is... great, I'll get a Scarlet FF35 (and get additional benefit of Anamorphic lenses plus using my fast Nikon lenses for ultra-low light stuff where I want the benefits of the larger sensor size). Otherwise I'll pick up a used Scarlet S35.
Bruce Allen
www.boacinema.com

Hi Bruce,
The problem I see with the FF35 Scarlet is that it may not support on the fly desqueezed monitoring of the anamorphic signal.
At least that's what I read from the new brochure.

Häakon,
You do raise a good point, we may need to pickup a certain type of PL glass to work with FF35 monstro sensors.
Either Anamorphic Pl lenses, or spherical ones that cover most of the sensor.

Emmanuel

 

[paul engstrom]

These sorts of thoughts are making me think I'll probably stick with the R1 for awhile, quite possibly with the upgraded sensor.

I'm extremely interested in native iso of upcoming sensors. slower glass is not nearly such a big deal with the faster sensor...

Question: are there any down sides to a faster sensor? Is it a bad thing to be a bit fast for sunshine (ie. using more NDs and IR cut?)? Because the positives seem so big to me--keeping that lighting bill under control is always such a challenge.

p



By the way, Bruce, I got the chance to visit/shoot in South Africa. Wow, what a place!

p

 

[Alexander Nikishin]

The FF35 Scarlet models benefits are for serious photographers in the Scarlet model and added DR across the two.

Added thought, even if someone did utilize the entire 1.5 sensor with a FF lens, how would you project that format?

 

[Esteban Sosnitsky]

The solution for this matter would be IMHO a S35 monstro.
You could use your wonderful all timer lenses on a new updated sensor with nice DR and less noise. Why use it only in the FF35 where you are windowing the standard? Am I missing something? Why do you think there is no S35 monstro?

 

[Alexander Nikishin]

Am I missing something? Why do you think there is no S35 monstro?

I think the missing link here is a larger pixel density sensor in a 2:1 size thus giving you a higher DR sensor such as the FF35 Monstro.

When you go up in resolution with the FF/645/617 sensors you're getting a larger pixel density allowing for more sensitivity/DR.

The smaller, more dense S35 sensors are high res. with smaller pixels allowing for less DR.

Correct me if I'm wrong anyone.

 

[Gunleik Groven]

OR... The S35 monstro would have Lower REZ higher DR...

We'll see how the R1/Monstro upgrade puzzle comes out. Is the R1 at all capable of handling the higher bitrate with current boards?

 

[Alexander Nikishin]

I'm extremely interested in native iso of upcoming sensors. slower glass is not nearly such a big deal with the faster sensor...

Well the other main advantage to fast glass (T1.3) is an esthetic one and one that can save you if you have to cheat a location or have a horrible production designer, a very shallow DOF.

 

[Esteban Sosnitsky]

When you go up in resolution with the FF/645/617 sensors you're getting a larger pixel density allowing for more sensitivity/DR.

The smaller, more dense S35 sensors are high res. with smaller pixels allowing for less DR.

What confuses me is that when using Cine lenses the area covered by the image of the lens is not large enough to cover the FF35 sensor. (my guess) So when using the Monstro with a Cine lens, windowed, you would be using the same amount of sensor as if you were using a full S35 sensor size. Only that with the monstro you would have more DR and less noise, over the same area. In other words, you wouldnt be getting more res from one sensor or another, just better quaility in terms of noise and DR... Its like the R1 has a 4.5 sensor to produce a 4K image, how much bigger can the sensor be in order to obtain the best DR and noise acceptance with the lens we own?

 

[Alexander Nikishin]

Esteban, in theory the Monstro sensor should have resolution that is less or equal to that of the Mysterium X due to the larger pixels found on the Monstro sensors.

In other words, even though you are shooting in 6K mode with a Monstro sensor, it's pixels are larger and less dense than the Mysterium X's in 5K mode. They may well effectively level out in resolution yet the Monstro will have (According to specs) 2 more stops of DR, something that I am dying for.

To add: I'm not quite sure how the FF sensors will handle the crop factor? Maybe they'll allow for a windowed sensor mode thus allowing for accurate FOV on S35 lenses.

 

[Alexander Nikishin]

Esteban, to further answer your question, the only thing that would change when shooting with S35 glass on the FF35 sensor would be your FOV due to the crop factor, not resolution.

 

[Gunleik Groven]

You would have a different (lesser) rez @ the same cropfactor...

 

[Alexander Nikishin]

I have a question hopefully someone can answer, David Mullen maybe? =)

What would the crop factor of say a 25mm anamorphic lens be on an Epic 645 56x42mm sensor?

 

[Harry Clark]

I think, Haakon, your analysis is spot on.
One thing to keep in mind is that modern lenses such as S4s and Master Primes will project a circle that is quite a bit larger than the S35 frame.
Now the image all the way out on the edge of that circle is pretty distorted, but there may in fact be a useable area larger than the S35 frame before the distortion is to egregious. And those lenses are meant to cover a 4x3 image, so the 16x9 image that many of us would opt for even with these larger sensors may enjoy a significantly larger area (witness the use of regular 16mm primes and zooms in 2K; they don't cover a 4x3 area of the same width, but they do cover a Red One's 16x9 sensor)
So where to crop a FF Epic or Scarlet may be a question that deserves some investigation. There may in fact be a sweet spot that is larger than S35 (but not the full frame) and that, because of the larger area, preserves much of the resolution and DR improvements that the FF cameras have to offer.
There also may be some solution involving high-quality lens extenders, such as a 1.4X. These may have to be designed from the ground up, but it would be in the interest of Zeiss, Cooke, and Angeniuex to find a solution that allows the current cine lenses to work with these new cameras.
Unknown until we all get to play with the cameras, I suppose.
But the Red Team could offer some instructive insight as to what to expect as they develop these cameras.
Cheers,
Harry

 

[Mark K.]

Assuming that a person can afford the additional $3,000 required for the jump from S35 Scarlet to FF35 Scarlet, the question to ask yourself is: resolution or dynamic range?

Going by the specs that Red have mentioned so far (and assuming the use of PL-mount glass and S35mm-sized recording format on each camera), your options are either: 5K resolution and 11 stops of DR, or 4K resolution (the s35mm crop of the FF35 sensor) and 13 stops of DR.

For me personally that's a no-brainer. I can't envision any scenario in which I would be likely to have a delivery format higher than a 2K film-out, which means that 4K is plenty of resolution in that regard, and the higher DR of the Monstro sensor would be a bigger boon.

For people expecting to finish in higher delivery formats, I imagine the higher resolution of the S35 sensor could prove more useful.

 

[David Mullen ASC]

I have a question hopefully someone can answer, David Mullen maybe? =)

What would the crop factor of say a 25mm anamorphic lens be on an Epic 645 56x42mm sensor?

Since 56mm x42mm is 1.33 : 1, and the 2X anamorphic format uses a 1.20 : 1 area to create a 2.40 : 1 image when unsqueezed, there would be very little cropping, basically down from 2.66 : 1 to 2.40 : 1...

... but the problem is that modern 2X anamorphic lenses aren't designed to cover an area as large as 56mm x 42mm. The dimensions of the 4-perf 35mm anamorphic camera aperture are 22mm x 18.59mm.

 

[Chris Kenny]

It's worth noting that Red sells a lot of cameras by the standards of the market. The 3000+ Red Ones out there probably represent a substantial fraction of all the modern 35mm-format PL-mount sync sound cameras in the world. If, over the next couple of years, Red sells several thousand FF35 motion picture cameras, there's probably going to be a fair bit of interest in building lenses which cover that format.