How was this look achieved? Shallow DOF techniques

[Nick Gardner]

The only reason to use a diopter is to get closer focus, making the shot more of a close up, which is image magnification, which reduces depth of field. A macro, or a close focusing lens does the same thing. There is no magic n a diopter.

Nick

 

[Nick Gardner]

And 138mm diopters cover most lenses and fit in the 138 holder of most matte boxes. If you want to play, you can buy cheap diopters that screw onto the front of still lenses. Interestingly enough, you still use round diopters on anamorphic lenses.

Nick

 

[Scott Crawley]

Yeah that smooth silky background is nice. Great for compression without the artifacts too.

While what you say about compression is true you do understand that I meant lens compression, right; the perceived reduction of depth?

 

[paulherrin]

no, i think he's talking about r3d compression and the lack of fine details in a blurred section of an image.

 

[Will Keir]

That's what I was talking about. In high detailed scenes you can get compression artifacts, especially using 2k high FPS. So I've learned 90 fps at 5k ws is good enough slow mo and I don't suffer the compression artifacts, which look a lot like noise by are different.

no, i think he's talking about r3d compression and the lack of fine details in a blurred section of an image.

 

[Matthew Scott]

This is an IS lens and can be used on a shoulder cam? Even slight movements at 300mm track quite a bit, more than I'm comfortable.

Okay, so a "crazy amount of shake" is how you described a 300 prime handheld, I was just saying that with the Nikkor VR lens it's not crazy at all. Yes, you have to have a nicely balanced shoulder setup, but it's okay.

 

[Will Keir]

Nick,

Are you saying a diopter cannot be used to throw the background out of focus? Increasing blur and the appearance of separation.

The only reason to use a diopter is to get closer focus, making the shot more of a close up, which is image magnification, which reduces depth of field. A macro, or a close focusing lens does the same thing. There is no magic n a diopter.

Nick

 

[Will Keir]

http://www.red.com/tools/depth-of-field

A very handy tool indeed. It's nice to actually see the numbers, giving a vague "feel" for sharpness some accurate scientific data.

Do they make DoF calculators pocket sized to take with you on set?

You're a clever guy. Whip out a DOF calculator and find your sweet spot. Six to eight inches of depth is enough to keep most faces in focus from eyes to ears, and longer lenses yield more shallow DOF and are more kind to facial features.

Find what you like. Good hunting.

 

[Scott Crawley]

There are many apps for iPod touch and iPhone. Some of them are free. I use pCam. It's $30 well spent. It has a number of useful tools in it, not just a DOF calculator. I'm sure somebody still prints laminated paper calculators, but I haven't looked for one in... Decades.

Check out this application on the App Store:

pCAM Film+Digital Calculator Thin Man Inc. Category: Photo & Video Updated: Sep 16, 2013 115 Ratings

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A very handy tool indeed. It's nice to actually see the numbers, giving a vague "feel" for sharpness some accurate scientific data.

Do they make DoF calculators pocket sized to take with you on set?

 

[Will Keir]

The DoF Calc is great but it doesn't tell me how much separation and blur the background will have. That's why I made this thread, I was hoping someone would jump in that has already done the kind of thing I'm after.

Only testing will give me what I'm after. I'll find the sweet spot and be on my way to great repeatable results.

For steady or shoulder motivated shots, I'm thinking my range is 3'-6,' from subject with a 5"-10" window to nail my DoF. With Super Speeds opened all the way that gives me a DoF of:

5.5" at three feet on an 18mm.
11.5" at six feet on the 25mm.
5.8" at six feet on the 35mm, out to 13.1" at nine feet.

Looks like using that 50mm is going to be tuff until about 9' where I have a 6.4" DoF window.
For shoulder work, forget any thing longer because of the requirement of being close to my actors.

Gaining a few stops of light from the Dragon sensor is going to be really nice.

 

[Will Keir]

Here's the crazy thing:

If I want to shoot 45 degree shutter I need to gain 2 stops of light somehow.

If I want to shoot 45 degree shutter at 121 FPS, I need 4 stops.

Where am I going to get that light in dark woods? hahaha I know the answer. Pray, "God give me light!"

 

[Eric Santiago]

Where am I going to get that light in dark woods? hahaha I know the answer. Pray, "God give me light!"

Dragon?

 

[Will Keir]

What does this number represent and what is it called?

A useful estimate of shallowness is divide the focal lenght by the aperture. So an 85 1.4 = 60. Where as a 200 f2 = 100. The tele wide open will certainly get you shallower

 

[Will Keir]

So when using a DoF calculator on a prime anamorphic lens, you use half the value of the focal length in the calculator? So a 50mm you would enter 25mm?

Will - was about to reply then saw David's answer - so no need for anything more from me really

I'd suggest a 35mm or 50mm Squarefront as a starter prime. 35 being 17.5 in Hfov or 50mm being 25mm in Hfov. 50mm will probably be a cheaper pickup as 35mm Squarefronts are pricey ATM.

 

[Will Keir]

So a 50mm with a +2 diopter is the same DoF as a 100mm without?

The only reason to use a diopter is to get closer focus, making the shot more of a close up, which is image magnification, which reduces depth of field. A macro, or a close focusing lens does the same thing. There is no magic n a diopter.

Nick

 

[Scott Crawley]

The short answer to your question is shooting longer lenses at shorter distances will give you less total depth and increased separation. Use a good calculator that will give you the near limit, far limit and total depth, that is all the info you need. Again, the shorter the Total Depth, the more OOF your BG will be. (And the harder it will be to pull focus.) If you are planning to shoot slo mo in the dark woods with 8 in total DOF then good luck to you. Spend most of your money on your 1st AC ;-) I hope there won't also be large movements involved that the operator will need to track. If so, you will also need a very good operator and quality camera support. (A geared head may just be in order.)

Bokeh qualities vary from manufacturer to manufacturer and model to model and the curvature and number of leaves in the iris play a major role. Getting to know the variety of lenses available and their particular characteristics like bokeh, is a large part of the fun so try out as many as you can and keep detailed notes for yourself.

The DoF Calc is great but it doesn't tell me how much separation and blur the background will have. That's why I made this thread, I was hoping someone would jump in that has already done the kind of thing I'm after.

Only testing will give me what I'm after. I'll find the sweet spot and be on my way to great repeatable results.

For steady or shoulder motivated shots, I'm thinking my range is 3'-6,' from subject with a 5"-10" window to nail my DoF. With Super Speeds opened all the way that gives me a DoF of:

5.5" at three feet on an 18mm.
11.5" at six feet on the 25mm.
5.8" at six feet on the 35mm, out to 13.1" at nine feet.

Looks like using that 50mm is going to be tuff until about 9' where I have a 6.4" DoF window.
For shoulder work, forget any thing longer because of the requirement of being close to my actors.

Gaining a few stops of light from the Dragon sensor is going to be really nice.

 

[Will Keir]

The slow motion bit is a wild man jumping off and rock mid air... hehehe

If you are planning to shoot slo mo in the dark woods with 8 in total DOF then good luck to you. Spend most of your money on your 1st AC ;-) I hope there won't also be large movements involved that the operator will need to track. If so, you will also need a very good operator and quality camera support. (A geared head may just be in order.)

 

[Nick Gardner]

So when using a DoF calculator on a prime anamorphic lens, you use half the value of the focal length in the calculator? So a 50mm you would enter 25mm?

No, you use the 50mm figure on an anamorphic DOF chart. Get p-cam, or a samcine calc, or any of the other hundreds of DOF charts out there. You should have one on set at all times, the 1st AC should have most of the hyperfocal distances memorized.

So a 50mm with a +2 diopter is the same DoF as a 100mm without?

No, The diopter just shifts the focus range of the lens closer. Say close focus was 3 feet, you put on a diopter, you can now focus down to 1.5 feet, BUT, you can't get to infinity anymore. Using a diopter has exactly the same effect on DOF as using a longer lens, using a CF modified lens, or a macro. Basically, you are just getting tighter, the diopter lets you get closer. That is all. If you really want to read up on diopters, there are all kinds of nice charts and info in the ASC manual (which should always be on set as well tucked into some body in the camera depts bag).

Nick

 

[Will Keir]

What a great thread, so lucky for all the input I received. Thank you all.

 

[Jeff Kilgroe]

Uh, oh, Will's digging up more old dead things...

Oh, man... I saw a couple things in my brief skimming of this thread this time around that are totally incorrect. But hey, I'm not going to touch it now... That was like 8 months ago! Heh heh.