Visual Sensor Format Comparisons

P

Proteus

Well-known member
formats-SMALL.png


I made this simple graphic to compare visually the size and the area of each format.
The external light grey outline is the full original 35mm still frame while the next shaded is a 16:9 vertically cropped version.
The cine formats that RED supports are all almost 16:9 but I decided to crop slightly the vertical dimensions, just a little bit, to make them exactly 16:9.

By comparing all formats in 16:9 (which probably will be the aspect ratio of choice), it’s easy to convert between their perceived focal lengths taking into account only the horizontal dimensions. For convenience, I list bellow each ratio of horizontal dimensions between the 35mm photo and the cine formats.
_________________________________________________
Case #1:
To calculate the increased (apparent) focal length of a known 35mm photo lens mounted on RED that can provide the same angle of view with another 35mm photo lens mounted on a 35mm still camera (in other words 35mm equivalent), just multiply its focal length with the ratio of the desired format.

For example a 14mm 35 photo lens intended for S35 (full frame) use, will be: 14 x 1.47541 = 20.6mm. This means that its angle of view will be equivalent to a 20.6mm lens on a 35mm still camera.

Case #2:
To calculate the equivalent focal length of another format lens that will provide the same angle of view as a known 35mm photo lens mounted on RED, just divide the focal length of the 35mm photo lens with the ratio of the desired format.

For example a 14mm 35 photo lens intended for S35 (full frame) use, will be: 14 / 1.47541 = 9.5mm. This means that the 14mm lens’ angle of view will be equivalent to a 9.5mm S35 lens.

Case #3:
To find out what focal length should have a 35mm still lens to match the angle of view of your cine lens, just multiply the focal length of your cine lens with the corresponding ratio.

Ratio____Format____

1.47541---S35 cine (full frame)
1.62162---35mm cine
3.24324---S16mm cine
3.46154---2/3” B4
_________________________________________________

Some statistics:

table.png


The 1080p output when using an expensive S16 cine lens of a resolving power (definition) of say 100, I estimate that it will be equal or worse than a good photo 35mm lens (or a S35) providing a resolving power of about 80 on S35 frame.

I think this is true because the definition that a single Bayer chip like RED can provide is about 70% of each format’s resolution. So the down-converted output from S35 frame will be limited mostly from the lens definition while the output from S16 frame will be limited mostly from the chips reduced "real" definition.
Now if you choose 2K instead of 1080 then the difference will be greater (about 30% instead of 20%).

This is why I hope that a good 35mm photo lens or a not so expensive S35 will provide most probably similar or better results in 2k or 1080 than an insanely expensive and heavier smaller format cine lens. Of course I speak only for image quality, not handling, although the 35mm photo will be definitely lighter and there are solutions for follow focus etc.
 
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A preview of the “Mysterium” sensor (almost)!

A preview of the “Mysterium” sensor (almost)!

sensor130k640.gif


This is a Bayer type sensor at almost the same dimensions as the RED‘s Mysterium.
The Mysterium’s capture area is 24.4 x 13.7mm while this sensor’s dimensions are about 24 x 16mm. It’s the Nikon DX format used in DSLR (still) cameras, although it seems that the actual size (internal darker area) is larger than the capture size (23.7 x 15.6) reported by Nikon.


EDIT:
WARNING: Soon after this post, I realized that if you stare at this alternating image for too long, you might fall asleep, or worse, ...hypnotized! Then, only the ...RED team can wake you up! :Drogar-BigGrin(DBG)

EDIT #2:
I corrected a typo, instead of writing 13.7 as the vertical dimension (which I referred correctly in my first post) I wrote here 17. Sorry if I gave wrong impressions.
 
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QUOTE:WARNING: Soon after this post, I realized that if you stare at this alternating image for too long, you might fall asleep, or worse, ...hypnotized! Then, only the RED team can wake you up! :Drogar-BigGrin(DBG)
NO NO PROTEUS THAT ONLY WORKS WITH THE RED SENSOR:Drogar-BigGrin(DBG)
 
it would be interesting (sorry my ignorance..) to have also the 35mm & S35 (with several windows right?) non-still comparision..

anyone?
 
Graeme Nattress said:
70% is a minimum extraction value for bayer. Usually you can get a fair bit more.

Graeme
Click to expand...
Graeme, what would be a good average estimation for RED demosaic, 80% of resolution maybe?
Filmmaker1977 said:
it would be interesting (sorry my ignorance..) to have also the 35mm & S35 (with several windows right?) non-still comparision..

anyone?
Click to expand...
Filmmaker1977, I’m not sure I understand what you mean, can you be more specific?
 
Awesome tables Proteus!

Especially from your description, for my own purposes of looking at buying one for filming smaller budget features at 1080p, it looks like a good 35mm still zoom lens with follow focus/matte box kit will give an image that is essentially limited not by the optics but by the 1080p capture, which is fine if that is my intended resolution (about the max usable with a high end editing PC without splashing out $1000s for hard drive arrays etc). Plus filming at 1080p will give up to 120fps variable which is more than ideal for speed ramps etc.

Truly the indie choice in my opinion, with the added bonus of moving to larger format captures if/when I get funding for a larger budget film!
 
A still photo zoom will not provide any wide angles for this format. Very restrictive.

I'm increasingly concerned about the many people who appear to be stretching their budgets to buy the camera body and have no funds left for lenses and accessories.
 
visceralpsyche said:
Especially from your description, for my own purposes of looking at buying one for filming smaller budget features at 1080p, it looks like a good 35mm still zoom lens with follow focus/matte box kit will give an image that is essentially limited not by the optics but by the 1080p capture, which is fine if that is my intended resolution (about the max usable with a high end editing PC without splashing out $1000s for hard drive arrays etc). Plus filming at 1080p will give up to 120fps variable which is more than ideal for speed ramps etc.

Truly the indie choice in my opinion, with the added bonus of moving to larger format captures if/when I get funding for a larger budget film!
Click to expand...

To avoid misunderstandings, I presume that with the 35mm still lens you capture at full frame (S35 4520x2540) and you down sample to 1080p either in post, or to 2k in-camera and then to 1080p in post (I wish it had 1080p down sampling in-camera too for the combination of max quality, economy and time saving for that format).

This is different than capturing with a S16mm lens. The output will be 2K native (no down sampling, no quality gain) so this quality difference will balance the lens quality difference, depending on the actual lens difference and the down sampling algorithm.

Now if you use the 35mm still in windowed mode, you can take advantage of 120fps but the lens will be converted to a longer focal length (equivalent) as you can see from the calculations (about 2.2 times longer than S35). Also in that case, the lens quality difference will be magnified -not fair for the 35mm still, but if the still lens is very good, it might not be noticeable.
 
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Greg Lowry said:
I'm increasingly concerned about the many people who appear to be stretching their budgets to buy the camera body and have no funds left for lenses and accessories.
Click to expand...

Greg, since there will be at least 2k down conversion in-camera things are not that bad. Still lenses can still be used in S35 (pun intended) :) with the penalty of a 35mm still equivalent focal length increase of 47.5% and the capture cost will be the minimum. Of course someone has to reserve money at least for such a lens.

EDIT: OK, the bandwidth and storage cost from capturing downconverted 2K might be a bit higher than the native RAW 2K output.
But the time cost might be lower...
 
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Proteus said:
Filmmaker1977, I’m not sure I understand what you mean, can you be more specific?
Click to expand...
if your graphic is 35mm still referred.. i was just asking for the comparision: 35mm used in motion picture vs S35 with the several windows.. can you add?.. Thx
 
Proteus said:
.....I made this simple graphic to compare visually the size and the area of each format.
The external light grey outline is the full original 35mm still frame while the next shaded is a 16:9 vertically cropped version.
The cine formats that RED supports are all almost 16:9 but I decided to crop slightly the vertical dimensions, just a little bit, to make them exactly 16:9.

By comparing all formats in 16:9 (which probably will be the aspect ratio of choice), it’s easy to convert between their perceived focal lengths taking into account only the horizontal dimensions. For convenience, I list bellow each ratio of horizontal dimensions between the 35mm photo and the cine formats.
_________________________________________________
Case #1:
To calculate the increased (apparent) focal length of a known 35mm photo lens mounted on RED that can provide the same angle of view with another 35mm photo lens mounted on a 35mm still camera (in other words 35mm equivalent), just multiply its focal length with the ratio of the desired format.

For example a 14mm 35 photo lens intended for S35 (full frame) use, will be: 14 x 1.47541 = 20.6mm. This means that its angle of view will be equivalent to a 20.6mm lens on a 35mm still camera.

Case #2:
To calculate the equivalent focal length of another format lens that will provide the same angle of view as a known 35mm photo lens mounted on RED, just divide the focal length of the 35mm photo lens with the ratio of the desired format.

For example a 14mm 35 photo lens intended for S35 (full frame) use, will be: 14 / 1.47541 = 9.5mm. This means that the 14mm lens’ angle of view will be equivalent to a 9.5mm S35 lens.

Case #3:
To find out what focal length should have a 35mm still lens to match the angle of view of your cine lens, just multiply the focal length of your cine lens with the corresponding ratio.

Ratio____Format____

1.47541---S35 cine (full frame)
1.62162---35mm cine
3.24324---S16mm cine
3.46154---2/3” B4
_________________________________________________

Some statistics:

table.png


The 1080p output when using an expensive S16 cine lens of a resolving power (definition) of say 100, I estimate that it will be equal or worse than a good photo 35mm lens (or a S35) providing a resolving power of about 80 on S35 frame.

I think this is true because the definition that a single Bayer chip like RED can provide is about 70% of each format’s resolution. So the down-converted output from S35 frame will be limited mostly from the lens definition while the output from S16 frame will be limited mostly from the chips reduced "real" definition.
Now if you choose 2K instead of 1080 then the difference will be greater (about 30% instead of 20%).

This is why I hope that a good 35mm photo lens or a not so expensive S35 will provide most probably similar or better results in 2k or 1080 than an insanely expensive and heavier smaller format cine lens. Of course I speak only for image quality, not handling, although the 35mm photo will be definitely lighter and there are solutions for follow focus etc.
Click to expand...
Thank you, this is a very great graphical description. S35mm and 35mm Cine describe here are also the dimensions of S35mm and 35mm cine's stock films that cameras from ARRI or Panavision uses, or just RED's version of S35mm?
 
Greg Lowry said:
A still photo zoom will not provide any wide angles for this format. Very restrictive.

I'm increasingly concerned about the many people who appear to be stretching their budgets to buy the camera body and have no funds left for lenses and accessories.
Click to expand...

I must admit that this is a big concern for me as well. However, I'm not sure if the difference between the 35mm still format and 35mm film format is actually great enough to prevent the effective use of 35mm still lenses on the RED camera.

I've updated Proteus' format comparison visual to include the D-SLR format (Canon EOS 20D, 350D, etc.). It's almost the same size as 35mm film format. In fact, if you crop a 20D image to 16x9, it will give almost exactly the same FOV (if the same lenses are used).

formats-dslr.png


I'm quite happy with my EOS 20D, even with it's 1.6x crop factor. Obviously, slightly wider angle lenses are required to get the same shots, but it's really not that bad. I think it could be workable.
 
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