Half-Frame lens field of view and crop factor

polka

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Joined
May 1, 2008
Messages
167
Format
Medium Format
35mm half-frames are not 18x24 (the exact half of 24x36, but in general a little more than 17x24 because you need at least 1mm to separe two adjascent frames. It depends on the camera.
POLKa
 

Chan Tran

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Joined
May 10, 2006
Messages
6,763
Location
Sachse, TX
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35mm

That's why I think we should not use the crop factor any more. We had all the different formats before and didn't need the crop factor. One thing I don't like about the crop factor because it makes the 35mm format as the one all other formats are measured by. I often joke that I only use full frame because I can't figure out the crop factor.
 

abruzzi

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Joined
Mar 10, 2018
Messages
2,997
Location
New Mexico, USA
Format
Large Format
Nothing has created more confusion in the world of photograph than "crop factor" (no, not even the zone system.) I used to frequent a mostly digital forum and almost every day I'd see one or the other strange misreading of what it was and how it worked. One person was asking some questions about using an 25mm APS-C lens on a Micro 4/3 camera and was convinced that he needed to do two calculations--APS-C to FF, then FF to M4/3 because a APS-C 25mm was different than a FF 25mm--so (25*1.5)/2. People on the forum tried to patiently explain that 25mm was an unalterably real world physical value that was independent of sensor size, but he kept arguing and arguing until I decided never to click on that thread again.

Today I just tell people to look in the viewfinder to figure it out, and learn that each sensor/film size has its own view of a focal length.
 
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