Jump to content


Photo

DOF when using 35mm lenses on 16mm


  • Please log in to reply
13 replies to this topic

#1 Scott Dolan

Scott Dolan
  • Basic Members
  • PipPip
  • 36 posts
  • 1st Assistant Camera

Posted 24 July 2008 - 11:57 PM

Hi All,

Just wondering if anyone can clarify something for me...

Often when shooting on 16mm I'm working with 35mm Ultra Primes, and I'm just wondering what sort of CoC I should be working to in this setup?
I know that UP's have a reduced DOF compared to regular 35mm primes due to aspherical elements and UP DOF tables need to be used. However I'm not sure what I should be working to when using these lenses on 16mm cameras.
Does anyone have an approximate CoC they work off?

Cheers
  • 0

#2 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 27 July 2008 - 02:23 PM

Use the search function. We answer this, or a question very much like this, every other week or so.
  • 0

#3 Scott Dolan

Scott Dolan
  • Basic Members
  • PipPip
  • 36 posts
  • 1st Assistant Camera

Posted 30 July 2008 - 06:35 AM

Use the search function. We answer this, or a question very much like this, every other week or so.



If you read the question you'll see its actually quite specific. I would never post a question without first searching through the pre-existing forums as I am only new on here and am sure many many topics have already been covered. Unfortunately not this one.
I wasn't asking for people to make sly remarks and fester negativity. I was hoping someone would have an answer.

But thanks for your input Chris.
  • 0

#4 firdaus

firdaus
  • Basic Members
  • PipPip
  • 10 posts
  • 1st Assistant Camera

Posted 29 August 2008 - 10:20 AM

hi scott...

i'm often work with 35mm up on 16mm..
so i dont care about the CoC because just meke me confuse...
i only depend on my american cinematographer manual in DOF table

dont make your self headache about too much formula...just measure the actor and trust your self

succes for you

thanks


daus
  • 0

#5 Stephen Williams

Stephen Williams
  • Sustaining Members
  • 4708 posts
  • Cinematographer
  • Europe

Posted 29 August 2008 - 11:33 AM

Hi All,

Just wondering if anyone can clarify something for me...

Often when shooting on 16mm I'm working with 35mm Ultra Primes, and I'm just wondering what sort of CoC I should be working to in this setup?
I know that UP's have a reduced DOF compared to regular 35mm primes due to aspherical elements and UP DOF tables need to be used. However I'm not sure what I should be working to when using these lenses on 16mm cameras.
Does anyone have an approximate CoC they work off?

Cheers


Hi,

The CoC you chose depends on how big you want to show the final result. A 50mm lens always has the same DOF as another 50mm lens, it does not matter if the lens was designed to cover 16mm, S16mm, Academy 35 , S35 or Vistavision (Still 35mm).

Stephen
  • 0

#6 Adam Frisch FSF

Adam Frisch FSF
  • Sustaining Members
  • 2009 posts
  • Cinematographer
  • Los Angeles, USA

Posted 29 August 2008 - 02:12 PM

But, what confuses many, is that although it is correct that a 50mm lens made for 35mm and a 50mm lens made for 16mm will have the same DoF and the same field of view, it will not when you put the 50mm made for 35mm on a 16mm. That lens will not have the same field of view and the same DoF.

The reason is that you're now only using the middle part of that lens on 16mm (i.e. you've zoomed in), so in effect it will have a field of view much closer to a lens much longer, say a 70-90mm. This obviously affects the DoF as you're now using a format with inherently more DoF (a smaller gage has more DoF) in combination with a longer lens.

I've said it before - field of view should have been the standard way to classify and distinguish lenses as focal length in mm is misleading.
  • 0

#7 Bruce Taylor

Bruce Taylor
  • Sustaining Members
  • 482 posts
  • Other
  • Los Angeles

Posted 29 August 2008 - 04:25 PM

I wish I knew of a concise reference for these excellent DoF questions.

A 50mm is a 50mm is a 50mm, no matter the size of the gate or sensor behind it, as pointed out by Mr. Williams.

CoC and it's use in determining the perception of DoF has variables to be considered.

"firdaus" probably has the best way to apply all the theory in practice:

"dont make your self headache about too much formula"

That works for me!

Bruce Taylor
www.Indi35.com
  • 0

#8 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 29 August 2008 - 04:29 PM

I've said it before - field of view should have been the standard way to classify and distinguish lenses as focal length in mm is misleading.


That would be all well and good if people only shot one format.

Unfortunately, if we referred to lenses by their field of view we would call a 50mm on 35mm the same thing as a 25mm on 16 and a 12mm on super 8. Now THAT would be confusing to me because every lens designation would have to be followed by a format or, worse, a lens would be known my multiple designations. :blink:
  • 0

#9 Adam Frisch FSF

Adam Frisch FSF
  • Sustaining Members
  • 2009 posts
  • Cinematographer
  • Los Angeles, USA

Posted 29 August 2008 - 09:07 PM

But what's the difference today? A 50mm is not a 50mm, no matter what. A 50mm is only a 50mm in 35mm (or whatever format it was made for). If we're going to insist on giving the focal length as a measure of how wide or narrow a field of view a lens sees, we have to start incorporating the gage it's filmed on. This is essential.

Th reality of this world is that there aren't many 16mm lenses around. For instance, when you order the 18-85mm range for a 16mm package you get the 35mm lenses. This in effect means that you're getting a 32-180mm range field of view weather you like it or not. That's fine, as long as you know that there is a pretty big gap between your 16mm (16mm) lens to the 18mm (35mm lens), that now will look rather 32-ish.
  • 0

#10 Dan Diaconu M

Dan Diaconu M
  • Basic Members
  • PipPip
  • 30 posts
  • Other

Posted 30 August 2008 - 01:21 AM

I think the whole "confusion" starts from the fact than no one has looked at "a lens" relative to the frame size used.

The "normal" lens for any given format is the lens providing the same perspective (field of view) as the naked eye.
The "normal" lens for any given format is the lens equal to the diagonal of the frame.

In 24X36mm still photography, the diagonal is 43.26mm and that's why the "50" is considered "normal".
The "normal" in motion picture is the 35mm (do the math)

In medium format fotography, the 80mm is the normal, and so on.
Same goes for any video camera (do the math for 1/5", 1/3" 2/3", etc)

Anything wider than the "normal" is regarded as wideangle.
In still photography, the "35mm" is the first wideangle (but the same 35mm lens is the "normal" in motion picture).
Why? Frame size.

The first telephoto in motion picture is the 50mm (providing the same "look" as in still photography the "portrait" 85mm does).

Feel free to have your own opinion on this (and any other matter) but the math doesn't change.

A word about sharp/soft (bokeh):
When a lens is focused at a (say) 3 ft and the aperture is wide open (say 1.4) only the section of the scene will be sharp
at precisely 3 ft . As other elements in the frame are closer and further away (from 3 ft) their image gets softer.
If we were to shoot X-mass lights, their contur will be softer and the image will get larger. less bright and diffused creating
a circle of diffusion. Stepping down the aperture, only the smaller section of the lens gets used (providing a sharper image) the aberations get corrected and "diffused" image gets "sharper". The circle of diffusion gets smaller up to the point where it may be only a small percentage larger than the image created at 3ft and thus we will accept it as sharp. (close enough to be undistiguesed from the sharp one).

The DOF engraved on the lens points out what "acceptable" is in terms of sharpness.
Stop it down to (say) 8 and read the distance on the focus ring from-where to-where you will get a sharp image.

Back in the good ol days was circle of diffusion folks. Now... there is nothing but confusion.
My 2c.
  • 0

#11 David Gylje

David Gylje

    New

  • Basic Members
  • Pip
  • 6 posts
  • 2nd Assistant Camera
  • Sweden

Posted 30 August 2008 - 08:26 AM

please correct me if I'm wrong.

A 50mm lens will give a different field of view on different formats (35mm, S16...). That's because the gate (or sensor in the case of video or digital photography) is different in size. If you mount a 50mm lens on a 16mm camera you will only use a smaller inner part of the picture the lens projects and the lens will have a narrower field of view/it will be more telephoto (as opposed to if you mounted the lens on a 35mm camera). As explained by others.

The depth of field will however be the same for a 50mm lens (or any specific lens) whether you mount it on a 16mm camera or a 35mm camera (or a 2/3 chip camera). Given of course that the stop is the same, the distance to subject is the same and you choose the same circle of confusion to calculate (or look up) the depth of field.

The reason people tend to talk about formats with smaller gates/sensors as having more depth of field is that you will use wider angle lenses shooting on those formats. For a close-up shooting on 16mm maybe you would use a 50mm lens. For the same shot but shooting on 35mm you would use a 100mm lens instead . A 50mm lens has more depth of field than a 100mm lens.
  • 0

#12 Adrian Sierkowski

Adrian Sierkowski
  • Sustaining Members
  • 7118 posts
  • Cinematographer
  • Los Angeles, Ca

Posted 30 August 2008 - 09:35 AM

David you are correct as far as my understanding.
  • 0

#13 Dan Diaconu M

Dan Diaconu M
  • Basic Members
  • PipPip
  • 30 posts
  • Other

Posted 30 August 2008 - 10:16 AM

A 50mm lens will give a different field of view on different formats (35mm, S16...).


The 50mm provides the same field of view (I guess), is just the frame size that can't record it all (S16mm).
DIfferent wording....same effect.

The reason people tend to talk about formats with smaller gates/sensors as having more depth of field is that you will use wider angle lenses shooting on those formats.



Isn't it so?
  • 0

#14 Patrick Neary

Patrick Neary
  • Basic Members
  • PipPipPipPip
  • 873 posts
  • Cinematographer
  • Portland, OR

Posted 30 August 2008 - 08:06 PM

For instance, when you order the 18-85mm range for a 16mm package you get the 35mm lenses. This in effect means that you're getting a 32-180mm range field of view weather you like it or not.


Hi-

I have to say that this hasn't been my experience.

I used to own a nice set of 35mm cooke speed panchros, and would use them interchangeably between an old 16bl and 2C. If I wanted a 40mm for the 16mm camera, I would put the 40mm on the 16mm camera. It didn't (and doesn't) matter that the lens was designed for 35.

Your mileage may vary. :)
  • 0


Visual Products

rebotnix Technologies

Glidecam

Broadcast Solutions Inc

The Slider

Ritter Battery

Media Blackout - Custom Cables and AKS

Rig Wheels Passport

Technodolly

Metropolis Post

Abel Cine

Aerial Filmworks

CineLab

FJS International, LLC

CineTape

Opal

Wooden Camera

Paralinx LLC

Gamma Ray Digital Inc

Willys Widgets

Tai Audio

The Slider

Broadcast Solutions Inc

CineLab

Tai Audio

Ritter Battery

Aerial Filmworks

Willys Widgets

Wooden Camera

Glidecam

Media Blackout - Custom Cables and AKS

rebotnix Technologies

CineTape

Gamma Ray Digital Inc

Technodolly

Visual Products

Abel Cine

Metropolis Post

FJS International, LLC

Rig Wheels Passport

Paralinx LLC

Opal