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Using split-diopters


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#1 David Mullen ASC

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Posted 29 March 2016 - 12:16 AM

Someone sent me an email today asking about how to use split-diopters but in the switch from Verizon to AOL running my email account (Verizon sold their email business in several states to AOL), several emails have disappeared today off of my computer, probably never to return, including that one.  Don't know if the sender was a member of this forum but here goes...

 

She asked me about a split-focus shot at around f/2.0 to f/2.8 where the background object was 10 to 15 feet away.  First of all, split-diopter deep-focus trick shots don't actually get better the more you stop down because the split becomes too sharp (of course, there is the opposite problem if you use too-long of a lens and the split is too fuzzy and large.)  So f/2.8 is fine for a split-diopter shot on a slightly wide-angle to medium focal length.

 

Second, you set the focus of the lens to the distant object covered by the clear (no glass) part of the filter, and then pick a strength of diopter (+1/2, +1, etc.) until the foreground covered by the glass comes into focus.  Once you get close-enough, you may have to adjust the camera distance to the foreground object slightly to fall in line with the diopter filter strength better.  Usually moving forward or back a few inches is not going to affect the background focus.


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#2 Bill DiPietra

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Posted 29 March 2016 - 12:45 AM

Well, then is timely.  I was watching Nicholas Ray's King of Kings for the first time yesterday and saw that there was a plethora of diopter (and a few deep focus) shots.  Having never used diopters myself, I was being to wonder how they worked. 

 

So thanks for the information, David!


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#3 David Mullen ASC

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Posted 29 March 2016 - 01:32 AM

I posted a frame from that movie just a few months ago:

kingofkings1.jpg

 

The night shots are a bit too blurry for split-diopters at times, mainly due to the super low depth of field from shooting 8-perf 35mm anamorphic using 25 ASA film.  But in this day shot, there is almost too much depth of field -- the split line is quite sharp, luckily buried in the tree trunk.


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#4 Bill DiPietra

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Posted 29 March 2016 - 12:05 PM

I posted a frame from that movie just a few months ago:

kingofkings1.jpg

 

The night shots are a bit too blurry for split-diopters at times, mainly due to the super low depth of field from shooting 8-perf 35mm anamorphic using 25 ASA film.  But in this day shot, there is almost too much depth of field -- the split line is quite sharp, luckily buried in the tree trunk.

 

Yes, some were almost too obvious.  It's funny you chose that shot because when I was watching it, I was paying more attention to the composition - how Peter's upper body fits seamlessly into the frame of the tree-trunk.


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#5 Shawn Sagady

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Posted 18 April 2016 - 02:30 AM

This is really awesome David and I have been noticing more and more where this gets used.  I had no idea but now that I know... Thank you for the post and information!


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