11-19-2011, 11:32 PM
[quote name='Brightcolours' timestamp='1321732917' post='13043']
85mm on your Nikon gives approximately the field of view of a 85 x 1.5 = 127mm lens.
The aperture of the lens is 85mm / 1.8 = 47.2mm. For that 127mm lens that means: 127mm focal length, 47.2mm aperture: 127 / 47.2 = f2.69
Now that did not make your head hurt, I am sure.. Very simple really <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />
[/quote]
Yep, that is simple... thanks BC. I didn't know it worked like that.
[quote name='Brightcolours' timestamp='1321732917' post='13043']
I agree with Studor13, DOF "scales" and calculation tools are a bit nonsensical.
You use a certain aperture size for either the look of the photo, or the light conditions. Not to get a "measured" depth in focus (which is nonsense anyway).
If you do not want a blurry background, no need for a 85mm f1.8 lens. If you need a whole person somewhat in focus, no need to fiddle with DOF blah either, just set the lens to f5.6 and you will be fine.
[/quote]
Yes, but it's useful (to me) to know how shallow the depth of field is for a given focal length at typical distances, at a given aperture. Yes, I want to blur the background, but how much? And is there a balance between how much to blur the background and leeway in the depth of field...
If I knew I could always get the intended point of focus spot-on and had 3cm in front and behind the intended focus plane which were going to be sharp, then I'd trust sticking to f/1.8... but until I'm sure of the equipment, maybe I'll stop down a bit to get a bit more leeway, but still blur the background (though obviously not as much as wide open).
85mm on your Nikon gives approximately the field of view of a 85 x 1.5 = 127mm lens.
The aperture of the lens is 85mm / 1.8 = 47.2mm. For that 127mm lens that means: 127mm focal length, 47.2mm aperture: 127 / 47.2 = f2.69
Now that did not make your head hurt, I am sure.. Very simple really <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />[/quote]
Yep, that is simple... thanks BC. I didn't know it worked like that.
[quote name='Brightcolours' timestamp='1321732917' post='13043']
I agree with Studor13, DOF "scales" and calculation tools are a bit nonsensical.
You use a certain aperture size for either the look of the photo, or the light conditions. Not to get a "measured" depth in focus (which is nonsense anyway).
If you do not want a blurry background, no need for a 85mm f1.8 lens. If you need a whole person somewhat in focus, no need to fiddle with DOF blah either, just set the lens to f5.6 and you will be fine.
[/quote]
Yes, but it's useful (to me) to know how shallow the depth of field is for a given focal length at typical distances, at a given aperture. Yes, I want to blur the background, but how much? And is there a balance between how much to blur the background and leeway in the depth of field...
If I knew I could always get the intended point of focus spot-on and had 3cm in front and behind the intended focus plane which were going to be sharp, then I'd trust sticking to f/1.8... but until I'm sure of the equipment, maybe I'll stop down a bit to get a bit more leeway, but still blur the background (though obviously not as much as wide open).