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Lucky's Dad

Lucky's Dad

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Hello! I'm trying to understand the focus distance scale on the Canon EF 24-105 f4.

If I were to calculate the hyper focal distance to be 3.8m given a particular aperture and focal length, then would I simply put that over the fixed distance scale in order to set it or do I need to align it to the red scale depending on the focal length. Does the fixed marker assume 105mm?
Any info would be greatly received.
 
James Hope said:
Hello! I'm trying to understand the focus distance scale on the Canon EF 24-105 f4.

If I were to calculate the hyper focal distance to be 3.8m given a particular aperture and focal length, then would I simply put that over the fixed distance scale in order to set it or do I need to align it to the red scale depending on the focal length. Does the fixed marker assume 105mm?
Any info would be greatly received.
Click to expand...

Red marks are for infrared focusing, ignore them. Easy way of setting hyperfocal distance on this thread, post #15 http://www.talkphotography.co.uk/forums/showthread.php?t=384043
 
what would be really useful on the 17-40L would be aperture markers.

I had Sigma 12-24mm and it had aperture markers, it was very very useful and easy to use, just set aperture than put Infinity to that aperture value. it's a real shame 17-40L didn't have it. I've searched high and low for such sticker, but no luck.

would you care to make one for us, Hoppy? for at 17mm, f8 to f22.
 
wuyanxu said:
what would be really useful on the 17-40L would be aperture markers.

I had Sigma 12-24mm and it had aperture markers, it was very very useful and easy to use, just set aperture than put Infinity to that aperture value. it's a real shame 17-40L didn't have it. I've searched high and low for such sticker, but no luck.

would you care to make one for us, Hoppy? for at 17mm, f8 to f22.
Click to expand...

DoF markings on the Sigma 12-24 only apply to one focal length, and to use on full frame cameras only. These markings also depend on the distance values on the lens being accurate, and often they're not. DoF scales on the lens barrel are just impractical these days.

Best way is to jot a few key hyperfocal distance settings inside the lens cap, and use the method described on the thread linked above. It's easier and more accurate :)
 
awesome ideas! thanks.

will make one for 17-40L and laminate it. i rarely use lens caps, certainly not the crappy Canon ones.
 
wuyanxu said:
awesome ideas! thanks.

will make one for 17-40L and laminate it. i rarely use lens caps, certainly not the crappy Canon ones.
Click to expand...

The point is, you only need a few numbers.

Hyperfocal distance focusing only really applies to wide-angles in practise, so a few key focal lengths, at higher f/numbers only because that's what you'll be using. You can guess the settings inbetween easily enough - in reality HFD focusing is not the precise science the numbers might lead you to believe.

My 17-40L lens cap has just nine HFD numbers on it. Distance at 17mm, 24mm and 35mm, with apertures f/5.6, f/11, and f/22.

NB, they key piece of knowledge to making this technique easy to use is that the HFD is always exactly double the distance to the nearest subject you want sharp.
 
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