FORUMS: list search recent posts

Fast Lenses

COW Forums : Cinematography

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Sean Simms
Fast Lenses
on Aug 8, 2011 at 4:28:21 am

A cinematographer told me that fast lenses, such as a 1.2, would be good for low light shooting.......but I haven't tried them yet.....recently, I was talking to a still photographer about this and explaining that I wanted to shoot in a low lit room but have a wide depth of field......he said that he didn't think that could be done....he kept saying that fast lens were like a fast aperture and so one would get a narrow depth of field....so I'm just writing for my filmmaker's clarification...can I shoot with an aperture setting for a wide depth of field with a fast lens in low light.....???

thanks for your help.


Return to posts index

Todd Terry
Re: Fast Lenses
on Aug 8, 2011 at 4:47:10 am

Short answer, no.

Your photographer friend is right.

I shoot with fast lenses all the time, my superspeed cine primes are T1.3. A "fast" lens will allow you to shoot in lower lighting conditions, and will have a lower (bigger) f-stop to allow for lower light conditions. However, if you stop it down in order to increase the depth of field, just like any other lens it will still require more light for the same exposure.

A practical example or two, let's say you have a fast 35mm-format 50mm lens with a maximum aperture of 1.4, and a "normal" lens at T2.0. WIDE open (using the lowest f-stop), at 10 feet the fast lens will give you a depth of field about 10 inches deep. But the "normal" lens wide open will give you a DoF 1'3". BUT... stop both lenses down to f8, and your DoF is now more than 5' deep. BUT (again), they both need the SAME AMOUNT OF LIGHT for exposure. Just because one is "fast" it doesn't mean it needs less light for a given f-stop, it just means that t potentially needs less light at its maximum (lowest) f-stop setting.

For a more pedestrian example... say you have a Ford Focus and Corvette. The Corvette can go a lot faster than the Ford, but it doesn't have to. If you drive both at 60mph you'll still cover a mile a minute no matter which car you choose. Just because you can drive the Corvette faster, doesn't mean it will cover more distance faster than the Ford, if you are driving them both at the same speed. Shooting a higher f-stop in order to get that deeper depth of field will not mean you'll need less light, just because your lens is a superspeed.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



Return to posts index

Rick Amundson
Re: Fast Lenses
on Aug 8, 2011 at 2:53:52 pm

The only real option you have to keep any depth of field at that low light level is to use a wider angle lens. Using a depth of field calculator will give you an idea of how wide you need to be at a f1.3 to get the depth you want.

Best of luck!

Rick Amundson
Producer/Director/DP
Screenscape Studios
Bravo Romeo Entertainment
http://www.screenscapestudios.com
http://www.bravoromeo.com
http://www.indeliblemovie.com


Return to posts index


Todd Terry
Re: Fast Lenses
on Aug 8, 2011 at 3:11:19 pm

[Rick Amundson] "Using a depth of field calculator will give you an idea..."

I meant to mention that Kodak has a very good free smartphone app called "Cinema Tools." One of the things that it has is a very good and easy-to-use depth of field calculator. Its lowest f-stop only goes down to f1.4 (and my lenses are f1.3), but it's more than close enough to get a good idea of what's going on.

I use the Android app, but I'm sure there's an iPhone one as well.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



Return to posts index

Sean Simms
Re: Fast Lenses
on Aug 9, 2011 at 1:16:20 am

Thanks Todd....so it seems I'm better off with a wide as angle lens as I can use in the given situation because I want a rather deep depth of field in low light......getting a fast lens won't help because I would be using f stops that are going to be 4.8 or greater?

I'm trying to understand all of this because I just shot my first really good film and my cinematographer was shooting moving characters in low light who went in an out of focus....I wasted a lot of time reshooting as I didn't have enough money to get a good focus puller nor shoot additional days......if I had known this before hand, I would have paid for a wide-anlge lens.......or gotten a different cinematographer....as he should of known this was going to happen.....


Return to posts index

Todd Terry
Re: Fast Lenses
on Aug 9, 2011 at 4:41:58 pm

Well, it all just depends.

You're better off with a wide lens, yes, if you want deep depth of field... AND if it gives you the shots that you want. Directorially, you may not want the wide-angle look... or, it may work just fine.

Shooting with a wide lens will certainly give you a deeper depth of field than a longer lens. An 18mm lens (35mm format) at focused at 10 feet with an f-stop of 1.4 will give you a DoF that is a little over seven feet deep. Jump it up to f/2.8 and the DoF is now well over 20 feet deep. At f/5.6, the DoF is infinite. BUT, are you able to get a good exposure at f/5.6? The f/5.6 setting is going to require sixteen times as much light as the f/1.4 setting.

As a cinematographer, one of my questions in a situation like this would be, "Why do you have to shoot low light?" If you can't get the DoF with the focal length and aperture you are choosing, then you pretty much have to increase the lighting levels. That's what lighting directors and lighting instruments are for. :)

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



Return to posts index


david braman
Re: Fast Lenses
on Aug 9, 2011 at 6:22:37 pm

If you're shooting film...you're stuck. BUT if you're shooting video you could get a 1/3" chip HD camera (like the Panasonic 300) and slap you fast lens on that. Those small chip cameras have depth of field that you can not put out. There's a whole industry built around trying to shallow those puppies out.


Return to posts index

Rick Amundson
Re: Fast Lenses
on Aug 9, 2011 at 6:40:09 pm

What format are you shooting? That will help us narrow down the discussion. If it is film, you could use S16 and get a dof similar to a 2/3 video camera which is also deeper than 35mm.

The best suggestion so far ... get some lights!

Best of luck!

Rick Amundson
Producer/Director/DP
Screenscape Studios
Bravo Romeo Entertainment
http://www.screenscapestudios.com
http://www.bravoromeo.com
http://www.indeliblemovie.com


Return to posts index

Sean Simms
Re: Fast Lenses
on Aug 10, 2011 at 12:20:06 am

I am a writer, director, producer and production designer for my films.

I'm shoot with DSLR's 5D, 7D or 60D.

I like making narrative films with beautiful backgrounds so I want them to show up in the film.

I shoot under low light because I create a mood that is part of the beauty of the film.

If you want an example of something I shoot and why a short depth of field didn't work you can see my film "Tasha's Dream " here.





It's a ten minute short with an incredible background that is a cinematographer's dream but in some scenes one just doesn't see the details of the "art work"/production design because of the narrow dof.
(EX: In the first scene the girl is in front of a mirror but the beauty of the mirror frame is blurred)

You will also notice that their are places where the characters are in shadow with no detail.

And finally, I have been shooting with a high ISO (usually around 800) to compensate for the low-light but I did get more grain then I wanted.

My DP was young 21 (though he was making a living shooting commercials for people) and had seen my previous work so was willing to work for peanuts. (the total budget of this film was only $1,000) so I got something good for a little bit of money but next year I will be making a feature film version of Tasha's Dream (my first feature) and I want to get this low light shooting problem worked out before production.

I did not think of shooting with a "normal" HD video camera......like a sony z1u or maybe a E3 because I thought that the low light capabilities of the Cannon 5D (with its adjustable ISO and full 35mm frame sensor would pick up so much more).


Return to posts index


Todd Terry
Re: Fast Lenses
on Aug 10, 2011 at 1:02:30 am

[Sean Simms] "I shoot under low light because I create a mood that is part of the beauty of the film."

Well, I can appreciate that in theory....

BUT... you don't have to have an extremely dim have-to-squint-to-even-see-you set or location to get that mood. It's a combination of a lot of things... lighting, lens choice, f-stop selection, filtration, and a bunch of other things. An experienced cinematographer would be able to light the scenes from your sample video and give you the exact same "mood look" on screen as you have (and want), but at a much-higher overall light level... thus enabling you to shoot with a higher f-stop and greatly increase your depth of field. You probably just need to work with a DP who is more experienced and understands the look that you are going for and how to achieve it.

For what it's worth, I didn't think your YouTube video looked all that dark and moody... it could have easily been shot with more light levels to maintain the same "feel" yet increase your depth of field. Personally, I thought you lost most of the details you were wanting to preserve because the images were both a bit too dark and quite a bit too contrasty (key lighting maybe a bit hot compared to the ambient lighting). I think that was just as much or more of a factor than the shallow DoF was.

Also for what it's worth... I rather liked the shallow DoF look of it, which helped keep the frames from getting too busy and distracting with too much sharp detail not pertinent to the important action in a scene. But I do understand that's not what you want or are going for.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]