Effects of shooting Scarlet at 2K

[Noel R.]

Why would I like to shoot Scarlet at 2K? For Slow mo shots. I'm Curious about the image quality of 2k because of the crop factor. If my final output is 1080P will it still hold up?

My concerns:

1) DOF - How will the smaller crop factor affect DOF? Will I be able to get shallow DOF at 2K?
2) Low Light - Since larger sensors = better low light capabilities, will the cropped 2K greatly diminish that?
3) Smaller Spaces - Because in essence I will be zoomed in, will shooting in smaller rooms be feasible? What kind of EF lens would one recommend in this situation?
4) Noise - Will noise be very noticeable at a final output of 1080P?
5) Sharpness - Because of debayering I understand that the true output will be less than 1920 x 1080. Will sharpness still look better than say a 5D which I understand isn't true 1080P either?

And yes I know that if I want higher frame rates I should just get an EPIC, but for clients that only need or want a 1080P output will the Scarlet still have great image quality if I shoot 2K?

 

[Brad Crawford]

if you need to go really wide the Tokina 11 - 16 f2.8 is your best answer. Otherwise a solid zoom lens that gets to 16 or 17mm will also be a solid lens at 2k I would imagine. I imagine my 35mm f1.4 prime will be a great lens at 2k especially for low-light.

 

[Peter N]

You might need to post-sharpen a bit. But using a great algorithm the finished material will look better than the in-camera sharpened 5D image.

 

[Terry VerHaar]

DOF: It will be commensurate with the dimensions of the smaller "window" of the sensor - lots of specific posts around with that info
Low light (#2) - cropping the sensor should have no effect; same amount of light falling on each photo site.
Smaller spaces - yes, lenses will be more "telephoto" so you'll have to go wider and there'll be a limit (as there always is)
Noise - there should be no more noise than shooting any other way... why would there be?
Sharpness - i don't think this holds, either. Sharpness will be the same. Again, it's a window of the full sensor.

In general, the performance of the camera at 2K is like shooting at 4K and then cropping in post. The unknown here is how higher frame rates effect the image quality. That probably has more to do with compression than with the sensor window itself. If you just want 2K, then obviously you might shoot at 4K and down sample for highest quality. If you are looking for the high frame rates, you are in a bit of uncharted territory as this is new to Scarlet and, again, is most likely a compression issue to be tested.

 

[Noel R.]

I've been thinking about the Tokina 11-16 f2.8. Would really like to see if I can get shallow DOF at 2K with this. Right now I have it's competitor the Canon 10-22mm which doesn't have much shallow DOF at all because of the slow speed.

 

[Zhibo Lai]

Why would I like to shoot Scarlet at 2K? For Slow mo shots. I'm Curious about the image quality of 2k because of the crop factor. If my final output is 1080P will it still hold up?

My concerns:

1) DOF - How will the smaller crop factor affect DOF? Will I be able to get shallow DOF at 2K?
2) Low Light - Since larger sensors = better low light capabilities, will the cropped 2K greatly diminish that?
3) Smaller Spaces - Because in essence I will be zoomed in, will shooting in smaller rooms be feasible? What kind of EF lens would one recommend in this situation?
4) Noise - Will noise be very noticeable at a final output of 1080P?
5) Sharpness - Because of debayering I understand that the true output will be less than 1920 x 1080. Will sharpness still look better than say a 5D which I understand isn't true 1080P either?

And yes I know that if I want higher frame rates I should just get an EPIC, but for clients that only need or want a 1080P output will the Scarlet still have great image quality if I shoot 2K?

Noel, see link http://www.reduser.net/forum/showthread.php?66210-Scarlet-X-Data-Sheet for sensor crop comparisons.
1. 2K is at aprox S16 sensor size, which was the scarlet-fixed sensor. Your DOF difference is around 2.5 stops for equivalent field of view. Shallow DOF is a subjective term, it all depends on what you're looking for.
2. 2K crop shouldn't affect light sensitivity, since the size of the sensor pixels aren't changing, just the amount of them being used. Someone can correct me if I'm wrong.
3. see link above
4. Noise shouldn't be an issue if you shoot it right.
5. All cameras resolve less resolution than they capture. 5Ds are closer to 720, Scarlet will resolve less than 2K, but still far sharper than your 5D.

Shot 3K to get a pristine 2K resolve. I'll be staying in 3K for many shoots and only go to 4K for high end features.

 

[Noel R.]

Thank you, I appreciate the response, very infromative.

 

[Jonas Klittmark]

4. You will have more noise than if you shot at 4K and downsampled to 1080p. There are lots of threads about this but if I remember correctly you essentially cut the noise in half by downsampling from 4K to 2K. So by capturing in 2K directly and not having the luxury of downsampling, you should see twice the noise.

5. The bigger concern for me would be sharpness. Like others here are saying, you will definitely not resolve the full 2K by capturing at 2K. Whether it's good enough for 1080p or not, I don't know. It would be very interesting to find out the actual resolving power of Scarlet's 2K. Does anyone know?

 

[Noel R.]

4. You will have more noise than if you shot at 4K and downsampled to 1080p. There are lots of threads about this but if I remember correctly you essentially cut the noise in half by downsampling from 4K to 2K. So by capturing in 2K directly and not having the luxury of downsampling, you should see twice the noise.

5. The bigger concern for me would be sharpness. Like others here are saying, you will definitely not resolve the full 2K by capturing at 2K. Whether it's good enough for 1080p or not, I don't know. It would be very interesting to find out the actual resolving power of Scarlet's 2K. Does anyone know?

I plan on shooting no less than 3K even with a 1080P output. I will only shoot 2K if I need the higher frame rates. I believe Jim said somewhere that you could use a ballpark figure of 80%. So 80% of a 2K image will be less than true 1080P but should still be better than a 5D which I feel I will be happy with.

 

[Keith Putnam]

1) DOF - How will the smaller crop factor affect DOF? Will I be able to get shallow DOF at 2K?

Cropping the sensor does not affect your depth of field. If you're using 35mm format lenses your depth of field will be the same no matter how much or little of the image you select with your crop. If you use 16mm format lenses to cover your 2K crop instead of 35mm format lenses, then you will see the greater DOF that 16mm format lenses have, because DOF is related to the size of the image circle projected by the lens and not the size of the sensor itself.

Imagine a photograph, like a physical photograph. If you cut away the outer 50% of the photo so you have a new photo that is half as large as the original, the DOF of the print does not change. If your 35mm format lens is casting an image circle large enough to cover a Super 35-sized sensor, merely selecting the middle 50% of that image circle doesn't change the DOF.

 

[David Rasberry]

Cropping the sensor does not affect your depth of field. If you're using 35mm format lenses your depth of field will be the same no matter how much or little of the image you select with your crop. If you use 16mm format lenses to cover your 2K crop instead of 35mm format lenses, then you will see the greater DOF that 16mm format lenses have, because DOF is related to the size of the image circle projected by the lens and not the size of the sensor itself.

Imagine a photograph, like a physical photograph. If you cut away the outer 50% of the photo so you have a new photo that is half as large as the original, the DOF of the print does not change. If your 35mm format lens is casting an image circle large enough to cover a Super 35-sized sensor, merely selecting the middle 50% of that image circle doesn't change the DOF.

DOF is strictly a product of lens focal length/image magnification and aperture. You get greater depth of field with shorter focal lengths which you have to use to match field of view for the smaller format. There is no more noise for a given exposure but what noise is visible will be coarser due to the increased magnification. If you use the 80% figure for optical resolution, probably close to right, Scarlet should resolve around 800 lines vertical for 2k 1080p, about as good as 1080p gets from just about any camera. Timur's chart test of his F3 indicated about 800 lines vertical resolution too. 5D is about half that, around 500 lines clean. Most 1080p HD cameras fall somewhere in the 600-800 line range.