It shouldn't be a big problem. c should be 1/1200 inch (0.021mm) Then you simply put in all the values in the formula in inches. After calculating, transform inches into feet - I think one foot (12 inches) is 304,8 mm (if 1 inch = 25.4mm) or close to that.
For 6x9 negs CoC (c) should be 1/450 inch (0.055mm). The same value can be used for 6x6 or 6x7 since the height is the same. Alle the best Jens Bladt mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt -----Oprindelig meddelelse----- Fra: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sendt: 9. april 2004 20:00 Til: [EMAIL PROTECTED] Emne: Re: Zone Focus - what is it? In a message dated 4/9/2004 4:37:32 AM Pacific Standard Time, [EMAIL PROTECTED] writes: Hyperfocal distance (H) is a way to dertemine the distance to focus the lens for a given aperture and focal length to ensure maksimum DOF, when you want sharpness to infinity (e.i. landscape photograph): H = FxF/fc F being Focal length f being f-number (aperture) c being the diameter of Circle of Confusion (CoC could be 0.021mm for 35mm negs enlarged to a 8x10 print). At 70mm lens f8 "H" would be (35mm neg): 70x70/8x0.021 = 29167 mm = 29.2 meter This means, that if you set the distance to 29.2m, you will get sharpness (on a 8x10 inch print) from infinity to as close as you can get at f 1:8 If you are a landcape photographer, you should have a table in your camera bag giving "H" for the most used focal lengths at let's say f22 or 32. At f22 the math should be: "H" = 70x70/22x0.021mm = 10.6 meter The near limit of sharp focus is: Fu(F+cf)/FxF+ufc (u being the used distance in mm) 70X10606(70+22x0.021)/70x70+10606x70x0.021)= 5338mm = 5.3m. The image (8x10) will appear sharp from 5.3m to infinity at f22 when focus distance is set to 10.6m Source: Andrew Hawkins & Dennis Avon; "Photography", UK 1979. all the best Jens Bladt -------------------- I wish you could put that in inches and feet then I *might* get it. It's one of the things I never quite *got* in the photography classes I took. (And not getting still shows up sometimes in my landscape shots.) I've sort of been going with the "focus 1/3 of the way into the scene" bit. Works sometimes, others, it doesn't. What really stumps me is when I want something close-up in focus and also want infinity in focus. I don't think it's always possible, but it does seem to be possible sometimes. I think it depends a great deal on the lens (mm -- what it can focus on), but it also seems to depend on *where* you focus. (I.E. A landscape shot framed by fairly close-up a tree or a tree branch.) Marnie aka Doe Unfortunately, my head doesn't translate meters into anything.
