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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Misunderstood/Misled on Depth of Field?

There should be a 2.5-stop DOF difference between 2/3" and S35. There's about a 1.5-stop difference between S35 and FF35, so that's a 4-stop difference between 2/3" and FF35.

Not sure if that calculator is properly correcting for CoC differences. Also, it doesn't define "35mm". As a general rule, you'd pick a CoC that was twice as critical for a format that was half as large, but a lot of these calculators don't seem to be making the CoC figure much more critical for the smaller formats, so they are giving you much higher DOF figures because of the focal length differences.

For example, if you didn't make any CoC change in a calculation, going to half the focal length (let's say from a 50mm to a 25mm lens) at the same distance gives you 4-stops more DOF, but if you are going to a format that is half the size (so that the FOV of the 25mm lens on the smaller format is the same as the 50mm on the larger format) and the CoC is now twice as critical, that 4-stop DOF difference between the two focal lengths becomes 2-stops. So as a rough rule, the magnification factor is also the DOF difference in general terms.
 
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Lee Saxon said:
Found http://www.tawbaware.com/maxlyons/calc.htm which lets you enter CoC values directly and I got :

Fixed Scarlet @ 26.4mm f/2.4 @ 60in = 4.5in DoF = FF35 @ 105mm f/10 @ 60in

Less crazy than the other calculator but still makes the Fixed useless. Gotta have interchangeable and some fast primes!
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That doesn't make any sense. I've shot plenty of 2/3" material in the f/2.8 range and the depth of field is fine.

This is a medium close-up shot at f/2.8 on a 2/3" camera (F900) from a movie I did called "The Quiet":
quiet3.jpg


Does that look too deep-focus to you???

On what planet is an f/2.4 on a 2/3" camera "useless"???

Have you shot with a 105mm lens on a FF35 camera at f/10 focused at 60 inches? That's not particularly deep-focus either.

Look, the reality is simple: shooting on a 2/3" camera is like shooting on a 35mm movie camera where you tend to shoot at f/4.0-5.6 rather than f/2.8. That's it! Typical exterior shooting on 35mm movies is often even more stopped-down than that. And once you start focusing close to the camera, the depth of field drops off quickly even at f/4.0-5.6.
 
Hmm, I hadn't tried it, actually. I shot some self-portraits at different focal lengths at what would be the fastest aperture if i was shooting on Scarlet Fixed. Definitely a lot better than I imagined.

The thing I don't like with the smaller sensors and shorter focal lengths, I'm realizing, isn't DoF, it's background separation. DoF on my subject was shallow enough but the background was too in focus.

Your image there looks great but I'm guessing that background was pretty far away.

I was certainly wrong about the fixed being useless, but there's no doubt in my mind a Cinema and some fast primes will fit my tastes vastly better. Nothing wrong with that, right?
 
Lee, I think you're seeing it properly. Ive shot a couple features on my 2/3 inch camera (Viper) at f/2.8 and f/2.0 and trust me, the Dof was plenty shallow. Most of the shots I was was hoping for more light so I could get a little MORE Dof, not less.

If you normally shoot s35 at f/4.0, 5.6 then just shoot the 2/3" camera at f/2.8, 2.0 and the Dof will be similar.
 
Lee Saxon said:
I was certainly wrong about the fixed being useless, but there's no doubt in my mind a Cinema and some fast primes will fit my tastes vastly better. Nothing wrong with that, right?
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No, not at all. Personally I'm glad the one RED camera I can afford to buy has a relatively deep depth of field (and high frame rate capability, compared to the Epic-S). If I could have infinite depth of field at 120fps all the time, I would!
 
I could get shallow depth of field with my 1/3" JVC so I'm not too worried about the 2/3", though there is area's where it will be better over S35, low to no light deep depth of field will be hard to accomplish on s35 same as shallow depth of filed and lots of light will be harder to achieve on the 2/3". S35 is the standard but I can't afford it or handling that much data at this point so it's moot issue for me as I can't afford reds higher offerings.

I remember a time when I wished I could afford the FF line, when I dreamed only of the s35 models and I couldn't understand the fixed at all... and then I grew up I learned a little about the industry and the tools available to me and I fell in love with the idea of a sort of golf bag of camera's each one for different shots, we have selection I can't find any fault in that.

have a good one.
 
I think David Mullen has covered all this quite eloquently but from the standpoint of "just a regular guy" (as compared to a big time Hollywood DP) my own experience with the RED ONE at f/2.8 (and sometimes wider) has me biting at the bit to get my Scarlet Fixed at f/2.4. For a whole lot of the stuff I shoot on the RED ONE (indie film stuff) we often have to shoot in less than perfect lighting conditions and, when we have a little less light than we want, we get VERY shallow DOF and staying in focus can be a bear. Of course, we can fool with ISO and work with the lighting and dynamically pulling focus, but what I am saying is that the Scarlet Fixed at f/2.4, having the DOF of the RED ONE at f/5.6 or so, will work just great for these conditions. Many Hollywood films have "managed" with footage shot with 2/3" sensor (again, look at what David posted).

Personally, if you want to own, and can't afford to own several high end cameras, I think the Scarlet Fixed represents a real "sweet spot" for digital cinema cameras. :thumbup:
 
Lee Saxon said:
Found http://www.tawbaware.com/maxlyons/calc.htm which lets you enter CoC values directly and I got :

Fixed Scarlet @ 26.4mm f/2.4 @ 60in = 4.5in DoF = FF35 @ 105mm f/10 @ 60in

Less crazy than the other calculator but still makes the Fixed useless. Gotta have interchangeable and some fast primes!
Click to expand...

One observation here that I didn't notice come up already. Look at the focal lengths you are comparing. 26.4mm vs. 105mm. You have much deeper DOF at the wider focal length, even with all other factors being equal.

This is actually what causes DOF to be deeper on a 2/3" or smaller sensor -- it's not the sensor size the dictates DOF, it's the focal length as related to the aperture diameter. Of course, this is the ratio indicated by the f number.

CoC values vary and different calculators use or weigh them differently. That's a whole other discussion entirely...

Since we're talking about 2/3" Scarlet, let's use its sensor dimensions instead of just talking about a 2/3" sensor. 3072 pixels wide @ 0.0032mm gives us 9.83mm of horizontal imager to work with. That equates to a 21.4 degree horizontal AOV if you're using a 26mm focal lenght -- borrowing from your 26.4mm above. For S35 / APS-C cameras, you would need a 63mm focal length to get the same framing. 95mm if you want the same framing on FF35.

You say you don't like the background separation with the 2/3" camera. Yeah, it does have a different look. In part some of this out of focus region will have a look dictated by the lenses used. However, you will still have DOF fall-off and properties of much shorter focal lengths when using cameras with smaller sensors. While it's possible to achieve the same framing and DOF of an 85mm lens on S35 by using a 35mm lens on the 2/3" scarlet, you will have all the DOF properties, look and feel of that 35mm lens and not the 85mm.

David says there's about a 2 stop difference in DOF between 2/3" and S35. I think 2 to 2.5 stops will be a good rule to follow when comparing "normal" focal lengths. When you start drifting into more wide focal lengths or longer choices, then that 2 stops is not going to apply as the scale is not linearly related to focal length. Thus, the difference in DOF is far greater than 2 stops when comparing equivalent AOV lens selections between 2/3" to FF35.

Terry VerHaar said:
I think David Mullen has covered all this quite eloquently but from the standpoint of "just a regular guy" (as compared to a big time Hollywood DP) my own experience with the RED ONE at f/2.8 (and sometimes wider) has me biting at the bit to get my Scarlet Fixed at f/2.4. For a whole lot of the stuff I shoot on the RED ONE (indie film stuff) we often have to shoot in less than perfect lighting conditions and, when we have a little less light than we want, we get VERY shallow DOF and staying in focus can be a bear.
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This is a great point and consideration. Shooting wide-open all the time on S35 is best reserved for artsy-fartsy stuff and student films that scream "I'm a complete noob!". There's also the "look at my shiny new 35mm adapter" crowd...

Far too many people worrying about how fast their glass can be or should be. Most 35mm oriented glass performs best from F5.6 to F11 anyway. I think RED's upcoming mini primes with a T1.5 aperture on all but the 50mm are going to be great. We should be able to shoot comfortably at T2~T2.8 and still get most of the DOF characteristics we're after much of the time. But like I said, too many people are focusing on the wrong aspect of this. Films like the Benjamin Button were shot on 2/3" cameras and I thought that one looked great.
 
Jeff another side to the different focal lengths issue is the difference in perspective. It's less severe if you're using glass that was actually designed for your sensor size, but if you look at footage shot on m4/3 GH2s using 35mm glass at a 2x crop....a 25mm cropped 2x doesn't get you the same shot as a 50mm, people.

I'm just thankful I can use 16mm glass on Scarlet and don't have to deal with THAT mess.
 
Lee Saxon said:
Jeff another side to the different focal lengths issue is the difference in perspective.
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Yes, that too. But for an aspherical or rectilinear lenses that are attempting to be distortion free, there should be relatively little difference in perspective by comparison.

As for the 16mm glass, it will work great, provided you can find all the focal lengths you're looking for. Might get tricky finding a good wide angle that's as wide as you will want.
 
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Lee, when you use the term "35mm" you really should specify whether you mean FF35 or S35 cine.

A 4/3 sensor is 17.3 x 13mm, FF35 is 36mm wide and Super-35 cine is 24mm wide. But I'm not sure if all 17.3mm is used for a picture taken on a 4/3 camera.
 
Jeff Kilgroe said:
This is a great point and consideration. Shooting wide-open all the time on S35 is best reserved for artsy-fartsy stuff and student films that scream "I'm a complete noob!".
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that's a fact.. I find too shallow depth of field a limitation.. in many ways..
for example when you need to increase your depth field by stopping down on a large sensor you'll loose your light sensitivity.. thus costing more money to light your scenes..
certain sensor size has its cons and pros.. and I hate shooting a portrait where the eye is in-focus and the nose isn't..

say if you shoot a portrait with a 50mm lens at f/5.6 on an S35 sensor is the same as shooting with 25mm at f/2.8 on a 2/3" sensor.. with the smaller sensor you get more light which means less grain which means cleaner image with same depth of field..

for super wide shots, yes its a limitation on 2/3" sensor, but, what about telephoto.. it won't be much enjoyable on a FF35 sensor..
 
David Mullen ASC said:
Well, actually it should. You take a 25mm lens image and crop it in half vertically and horizontally then you've created the same view as a 50mm lens ON THE SAME CAMERA.
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Yeah I know FoV is the same, but you've got all the extra barrel distortion...I guess it depends on the quality of the lens in question and how far you're cropping...I'd assume with the tiny sweet spot of a FF35 lens you'd be using with a 2/3" sensor you wouldn't see any of it.
 
The bottom line is, a 2/3" sensor with f/2.4 aperture allows for more (or less) depth of field than is practical for most instances. If you are looking for the extreme shallow focus for whatever unique scenario or shallow focus on a wide-ish frame, then rent out a 5D Mk II for that scenario.

Consider this - on a APS-C DSLR (T2i, 7D, etc.) with the kit lens, zoom in to the tele end (i.e. 55mm) and observe the depth of field characteristics. Is that shallow focus for you? Because you will get something similar from your Scarlet Fixed at 25mm, f/2.4.

If you strive for deep focus, however, the Scarlet Fixed is the perfect option (especially at night).
 
The bottom line is, a 2/3" sensor with f/2.4 aperture allows for more depth of field than is practical for most instances.
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Absolutely. But, I'm also wondering how the fixed will be for very deep DOF and how diffraction on the smaller sensor will play a part. My thinking is that for 95% of what I do, the fixed will be fine. But, if I need to shoot very deep with lots of detail and have the budget, then renting an Epic, and presuming I already have the other component parts, then I would be able to shoot at a smaller equivalent aperture, while still retaining detail.

It's all guess work until we know how the fixed will perform.
 
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