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Super35 "Crop Factor" ??


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#1 Jay Young

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Posted 25 December 2015 - 05:25 PM

Before I go yelling on Reddit, I figured I would ask people smarter than myself about it; 

 

There was a thread talking about crop factor on Reddit today, and one of the comments mentioned that "Hollywood has been shooting

crop factor 1.6 forever as Super 35 is basically the same as APS-C". 

 

And then I wanted to yell. 

 

However, I soon realised that crop factor appears to have come from sensor sizes smaller than "full frame" (from here on 8/35), and all other cameras being equal shoot 4-perf...   

 

Is it just me or should we not be comparing 3-perf to 8-perf anyway? 

And for that matter, should not all "full frame" digital cameras be digital VistaVision in the first place?  

 

All that thinking lead me to wonder if there is actually a crop factor on 4/35 cameras or not.  Surely lenses created specifically for 4/35 may not cover the full 8/35 frame? No?  However, all lenses made for 8/35 should be able to produce an image circle large enough to cover 4/35? 

Am I completely wrong in my thinking?   Furthermore, if I take a stills lens, mount it on a Super35 camera, will I in fact get a crop of 1.5+-? 

 

If I'm totally wrong, that's wonderful and I'll have a deeper understanding of all this crop factor jazz.

 

 


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#2 Phil Rhodes

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Posted 25 December 2015 - 06:41 PM

I take a very dim view of the term "crop factor". Hollywood doesn't consider itself to have been shooting any sort of crop factor. It leads to a lot of misunderstanding of basic optical physics based on the idea that lenses actually change focal length when used on different cameras, which is of course untrue. As you suggest, there's also confusion over what basis crop factors are taken from - I know what a 50mm lens looks like on a super-35 camera, but it'd be absolutely ridiculous to work on the basis that I knew what an 80mm lens looked like on full-frame 35 and therefore selected a 50mm lens to achieve the same effect.

 

There may, I suppose, be circumstances where oddball sensor sizes are in use, such as that of the 2.5K Blackmagic Cinema Camera, which hovers somewhere between 16mm and micro four-thirds, where some sort of numerical conversion factor may be useful. But it's best to talk about focal lengths as they actually are. If you're shooting a full-frame camera, and you want a normal field of view, you want an 80mm lens. Not a 50mm lens times one and a bit.

 

P


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#3 David Mullen ASC

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Posted 25 December 2015 - 06:51 PM

The crop factor calculations are only useful if they help clear up what sort of field of view you'd get when moving from a format you are used to to a smaller or larger format. So when Hollywood started shooting on 2/3" HD cameras in the early 2000's many cinematographers had to do some conversions in their heads to get used to the new field of view characteristics compared to Super-35.

My only objection is this obsession in beginners with the crop factor compared to Full-Frame 35mm, as if most people shoot that format and therefore need everything converted from it to figure out what focal length to choose.

It all comes from still photography where the 8-perf 35mm 36x24mm film frame was a standard for decades. However most people today do not come from a background of shooting FF35 for decades, and certainly most filmmakers do not have a background of shooting VistaVision for decades.
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#4 Albion Hockney

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Posted 25 December 2015 - 07:31 PM

Phil most consider a 50mm lens on full frame 35 "normal view" directly between wide angle and telephoto. In filmmaking or with super 35mm sensors that lens is the 35mm. Obviously "normal" view is up for debate but this as far as I know is the general consensus - maybe I'm wrong though?
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#5 Jay Young

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Posted 26 December 2015 - 08:03 AM

David I totally agree.  I DID shoot FF35 for decades as a stills photographer, and still do.  In this sense a 50mm lens might be considered normal, at least to me. 

 

However when I look through a motion picture camera I don't automagically think "Oh, I need to use this lens because it multiplies correctly based on some number" in stead, I just choose the normal field of view lens for that camera and go from there. 


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