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unclened Joined: 07 Dec 2014 Posts: 7 |  Posted: Sat Dec 20, 2014 1:22 am Post subject: Infinity focussing question
I have the Aero Ektar 178 f2.5 and the 135 f4.7 Graflex lens on a Pacemaker Speed Graphic. I'm finding that the focussing margin for infinity focus and objects that are far away is really small. Near focussing is the opposite and has lots of margin. Is this normal? Can I adjust it in anyway to give me more latitude when focussing on faraway subjects?
Thanks in advance for any guidance offered. |
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45PSS Joined: 28 Sep 2001 Posts: 4081 |  Posted: Sat Dec 20, 2014 8:11 pm
Normal lens characteristics. |
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unclened Joined: 07 Dec 2014 Posts: 7 |  Posted: Tue Dec 23, 2014 2:25 pm
thank you, so am I right in understanding that depth of field is does not have linear relationship with subject distance? |
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Sirius Glass Joined: 06 Jun 2010 Posts: 162 |  Posted: Tue Dec 23, 2014 9:15 pm
At a given aperture the Depth of Field [DOF] increases as the focus move toward infinity.
For example at a given aperture the lens might focus from 3 feet /1 meter to 15 feet/5 meters when focused to 9 feet/3 meters. Extend the focus to 30 feet/10 meters and the lens might focus from 15 feet/5 meters to infinity. |
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