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Why not just always use a zoom lens? What different affect does it have form a prime lens?


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#1 scott karos

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Posted 05 December 2014 - 10:11 AM

Might sound like a stupid question, but let me explain.

 

I listened to an interview with Louis CK talking about his show Louie. He mentioned that he doesn't use a zoom lens and instead decides to take the extra time and money to have prime lenses.

 

So lets say you have a 25mm prime lens you want to use on a project. Whats the difference if you use a zoom lens set to 25mm? Does it have a different effect? Does a 25mm prime look different than a 25mm on a zoom?


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#2 Michael LaVoie

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Posted 05 December 2014 - 11:13 AM

Typically zooms are slower than primes and they're also heavier and can breathe more when racked.  Sometimes less sharp.   Those are some generalizations to why you'd favor a prime.

 

I can't answer for Louis personally but if I had to guess, he's trying to make sure that the look of the show is more consistent with feature films or single camera episodic television (Lost, Mad Men, etc.) rather than a reality or sitcom looking show.  Even though is budget is likely substantially smaller and the lighting and set design in Louie isn't as elaborate, he can still make the effort to at least compose frames that are more cinematic than typical television.  A primes lens set forces you to decide on a frame and placement.

 

I will sometimes find a shot with a zoom but then settle on what I like and switch to a prime that's close to that focal length.   Not because the zoom won't give me the same effect necessarily but I believe that an audience is more used to the look of certain common focal lengths for certain shots and sticking to that keeps you consistent with "professional" looking cinematic footage.   

 

My A.C. knows we're behind in schedule when I start asking for the zoom lenses. 


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#3 Phil Rhodes

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Posted 05 December 2014 - 11:16 AM

Short answer is better quality, assuming constant f-stop, cost, size, and weight. Very sharp zoom lenses tend to be slower, bigger, heavier, and much more expensive than similarly sharp primes. At the top end, the very best zooms are still not as good as the very best primes, and are still more expensive.

 

That's not to say there aren't good zooms out there. Something like the Fuji Cabrio 19-90, which is an ENG-style zoom lens for PL-mount cameras, costs £25,000, and probably isn't much sharper than a basic stills lens such as  superb Canon 60mm EFS macro, which is worth under £300.

 

This is the case because zoom lenses have, by default, a lot more bits of glass in them, which sap quality and cost money. Basically, you can get a lot more for the money with primes, albeit at the cost of swapping lenses to get the angle you need. Zooms also flare differently and possibly more so for the same reason.

 

P


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#4 John E Clark

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Posted 05 December 2014 - 11:31 AM

Might sound like a stupid question, but let me explain.

 

I listened to an interview with Louis CK talking about his show Louie. He mentioned that he doesn't use a zoom lens and instead decides to take the extra time and money to have prime lenses.

 

So lets say you have a 25mm prime lens you want to use on a project. Whats the difference if you use a zoom lens set to 25mm? Does it have a different effect? Does a 25mm prime look different than a 25mm on a zoom?

 

Since I use SLR/DSLR lenses, the markings on the barrel may or may not be accurate, simliar to the f-stop vs. t-stop issue. When I select '25mm' mark on the zoom, is it the same as last time, does any small error 'cause a problem'... I've never developed a verification chart for the witness marks vs 'real angle of view' of my zoom lenses...

 

The zoom lenses were almost required for the Wedding work the Wife did, which is why we have about 4 or 5 of them... I would imagine most 'event' photographers had the same problem and solution.

 

I do have one 28mm prime, about a 45 year old f/2 Nikon lens... but that's it.

 

I've looked at buying some c-mount Super 16mm for my BMPocket camera and anything 'I would like to buy' is $500+... well more like $1000+... so I'm using my 14-140 zoom that I got as part of my GH-1 kit. (The Wife doesn't allow me to use her superior 16-35mm zoom, but still it's a f/4 lens... which is pretty 'slow' in any case...).

 

So, with prime lenses one knows one has a consistent focal length, usally 'better' optics for a given price, and 'lighter' if that was important...


Edited by John E Clark, 05 December 2014 - 11:36 AM.

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#5 David Mullen ASC

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Posted 05 December 2014 - 12:23 PM

Zooms are also more prone to flare or veil / glare when pointed into lights due to all the elements in them.


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#6 George Ebersole

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Posted 05 December 2014 - 06:03 PM

My experience; most shoots I've been on with a Panaflex a zoom lens was used.  Most shoots I've been on with an Arri, a prrime was used.  I don't know if that means anything.

 

Zooms are slower, and I can't remember the last time I actually saw a zoom shot in a feature.


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#7 Bruce Greene

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Posted 06 December 2014 - 09:22 AM

I just finished color grading a feature. Most was shot with Ziess ultra primes, and a little with Arri zooms made by Fuji.

And I have to say, the zoom lens was obviously different looking. And not in a good way.

Firstly, the color was yellow. And with a little bit less contrast. But, even after color matching, the zooms still "look" a little bit different. And it's hard to describe, and it's not always obvious , just to make my response unclear... There was something that was just more pleasing about the prime lenses, but I can't say what exactly!

Of course no one buying a ticket will see this difference :)
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#8 dan kessler

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Posted 06 December 2014 - 07:27 PM

It depends on what you're shooting.  Zooms are good for documentary
or news gathering, where it's handy to have a range of focal lengths
available without stopping to change lenses.

As already mentioned, zooms tend be bigger and heavier than primes.

The longer and faster you want the lens to be, the bigger it gets.
If you don't need a long lens that often, why be burdened with hardware
that mostly accommodates the long end?

For motion picture storytelling, the majority of the shots are at the
shorter end of the focal range.  Also, the zoom capability is only
occasionally (if ever) needed in this application.
 


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#9 Satsuki Murashige

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Posted 06 December 2014 - 08:37 PM

I would factor in two things. One, I think most of us tend to shoot differently with a zoom lens vs a set of prime lenses. Even if I am trying to use the zoom as a variable prime and avoid zooming, I usually find myself tweaking the focal length while setting up a shot to adjust for framing instead of moving the camera. Likewise, the temptation is very strong to punch in for quick tighter coverage just because it is so easy. This inevitably creates a less precise aesthetic for framing and lensing.

We often forget that when setting a specific frame, every focal length creates a distinct feeling of foreground to background separation and its own sense of space, not to mention all the other specifics of lensing. So with a zoom lens, you are giving up precision for more utility - sort of like using a Leatherman multi-tool instead of a specific screwdriver. It's good to be as precise as possible in filmmaking, so that you can be sure you are communicating exactly what you intended.

The second factor is more prosaic. Zoom lenses tend to be longer and heavier than primes for similar maximum apertures. This creates specific problems for handheld, Steadicam, gimbal shots, and other applications where the camera needs to be as compact and balanced as possible.
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#10 Albion Hockney

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Posted 09 December 2014 - 11:08 AM

All of the technical reasons mentioned are right on....just wanted to add one point...Satsuki seems to have just touched on it but passed precision I think using primes changes the way you work.

 

 

With a set of primes and making choices about the implications of differnt focal lengths before shooting a film you are creatively limiting yourself and it forces you to find certain frames and think a certain way. I think this is super important

 

as someone who had done a good deal of documentary work in addition to narrative (shot on both primes and zooms) I can say with zooms you always take advantage of the fact you can reframe with the lens but when you have a prime you think more and you are forced to make better frames. Im sure some people are past this and it might not have such a strong effect on the way they work, but for me its huge.

 

on some productions I have worked with directors where we use as few as 2-3 lenses and limit ourselves in that way.


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#11 Bill DiPietra

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Posted 10 December 2014 - 05:12 AM

If you read the first chapter of "Optics & Focus" it really de-mystifies the lens in general.
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