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Scarlet 2/3" vs. RED One 2K DOF

Andrew Rieger

Andrew Rieger

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Technically, the sensor size of 2/3" Scarlet is very close (slightly smaller) to the crop size of the RED in 2K mode. This should result in almost identical DOF characteristics correct? Thus, 2K RED One videos should give us a good idea about what to expect in terms of depth of field, right?
 
Hi Andrew, sensor size does not effect depth of field so the RED One in 2k mode will have the exact same DoF as the 2/3" Scarlet.

The size you view the footage at and distance you sit from the screen does have a small effect on DoF, though, as I'm sure someone will point out hehe.

Here are some 2/3" TIFFs I shot in 2k mode on the RED one at f2.2 on the 16mm Angenieux 17.5-70mm F2.2 lens: http://www.reduser.net/forum/showthr...796#post505796
 
Justin O'Neill said:
Hi Andrew, sensor size does not effect depth of field so the RED One in 2k mode will have the exact same DoF as the 2/3" Scarlet.
Click to expand...

Sensor size absolutely affects your depth of field. The smaller the sensor, the deeper the DoF, all other things being equal (specifically iris). Your DoF will be slightly deeper on a 2/3" sensor than with RED 2k, but the results should be almost indistinguishable. Check out RED's mysterium sensor comparison here http://www.red.com/images/pages/cameras/technology/formats.jpg

Justin O'Neill said:
The size you view the footage at and distance you sit from the screen does have a small effect on DoF, though, as I'm sure someone will point out hehe.
Click to expand...

This is completely untrue. Depth of field is a product of sensor or film size, and f/T stop of your lens. Viewing an image on a monitor does not change its depth of field.
 
Hi David, this has been argued to great length on reduser before: http://www.reduser.net/forum/showthread.php?t=35105

Personally I don't think taking viewing size into account when considering DoF is very important but as you will see some on reduser do.
 
David Kruta said:
Sensor size absolutely affects your depth of field. The smaller the sensor, the deeper the DoF, all other things being equal (specifically iris).
Click to expand...

I think I see what you are saying. If "all other things being equal" includes field of view then you have to change focal lengths. Changing focal lengths and keeping the f-stop the same will mean a change in DoF. It's not the sensor size per se that affects the DoF, but the need to change focal length in order to keep the same field of view.
 
Justin O'Neill said:
I think I see what you are saying. If "all other things being equal" includes field of view then you have to change focal lengths. Changing focal lengths and keeping the f-stop the same will mean a change in DoF. It's not the sensor size per se that affects the DoF, but the need to change focal length in order to keep the same field of view.
Click to expand...

If you are comparing a larger sensor to a smaller sensor, for example Red 4k vs Red 2k, then you will be dealing with crop factor. A 50mm at 4k will act like a (roughly) 80mm at 2k. Thus you will have to adjust your focal length to keep the same field of view. Your DoF will change drastically regardless.

One clarification - at the same stop and sensor size, different focal lengths will have different DoF. A 100mm lens will have a much shallower DoF over a 85mm, 50mm, 10mm. Etc etc.

Edit: in addition, if you change focal length to match field of view when changing between sensor sizes, the smaller sensor will always have a deeper depth of field. An equal field of view on a camera like the hvx200 or ex1 will always have more depth of field over the equivalent at red 4k or 35mm film.
 
The funny thing is that the only factor is CoC.

But to explain this we have a myriad of other factors that affect this :).

CoC that is affected by the how enlarged the blur is (or how sensitive to it the medium is), that is affected by aperture, that is exagerated or not based on the focal length that is chosen based on FoV needs, that is different for every other sensor size.

So ultimately, sensor size and focal lenghts get the blame. :P
 
I'm unfamiliar with the term CoC. Would you mind explaining?
 
I just figured that since the sensor sizes of the 2/3" scarlet and the crop of the RED 2K were very close, videos shot in 2k mode would give us a good idea of what to expect from the Scarlet 2/3" in terms of depth of field.
 
Andrew Rieger said:
I just figured that since the sensor sizes of the 2/3" scarlet and the crop of the RED 2K were very close, videos shot in 2k mode would give us a good idea of what to expect from the Scarlet 2/3" in terms of depth of field.
Click to expand...

Correct, it should be very similar. If you had them side by side, you would have trouble picking out the differences.
 
DoF is, technicaly, only affected by aperture and the distance of the subject to the focal plane.

In the real world, DoF is affected INDIRECTLY by sensor size, which equates to needing longer lenses to achieve an appropriate field of view, which then exaggerates percievable DoF.

David, CoC is short for Circle of Confusion. You can read more on this subject here - http://en.wikipedia.org/wiki/Circle_of_confusion

I think people who argue that the only thing that affects DoF is aperture are making things unneccesarily complicated for people who are unsure. Technically, it is right, but in actual practice these things all severely affect DoF no matter if it's indirect such as needing longer lenses to achieve the same FoV/magnification.
 
The clarification here should be that using a lens that equals 50mm (at s35) on the 2/3 Scarlet will produce the same DOF as a s35 camera would produce at 50mm.
So, yes, the DOF is the same.
 
Christoffer Glans said:
The clarification here should be that using a lens that equals 50mm (at s35) on the 2/3 Scarlet will produce the same DOF as a s35 camera would produce at 50mm.
So, yes, the DOF is the same.
Click to expand...

That's not true... you'd use a 20mm lens on a 2/3" camera to get the same FOV as a 50mm on a Super-35, and at the same f-stop and distance, you'd end up with more depth of field on the 20mm.
 
Christoffer Glans said:
The clarification here should be that using a lens that equals 50mm (at s35) on the 2/3 Scarlet will produce the same DOF as a s35 camera would produce at 50mm.
So, yes, the DOF is the same.
Click to expand...

Using a 20mm lens (equating to 50mm relative to S35) on a Scarlet would mean a deeper DOF at the same aperture. If you were to open up the iris by 2.5 stops on the 20mm (on the 2/3" sensor) over the 50mm on the S35 you would have comparable DoF.

This is exactly why smaller sized sensors have more percievable DoF. You have to use wider lenses to get useful FoV's. Shorter lenses have a deeper DoF when compared with longer lenses at the same aperture.

Edit: Correct me if I'm wrong David.
 
David Mullen ASC said:
That's not true... you'd use a 20mm lens on a 2/3" camera to get the same FOV as a 50mm on a Super-35, and at the same f-stop and distance, you'd end up with more depth of field on the 20mm.
Click to expand...

Oh, sorry, you're correct. My head is not with me today.
What I was meant to say was that using a wider 35mm lens on a 2/3 camera produces around the same DOF and FOV as a lens at the same focal range on a 35mm camera set to 2K sensor crop.

So, the dof should be around the same between a 2/3 scarlet at 20mm and a s35 Red One at 20mm set to 2K. Both having about the same FOV
 
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