DPChallenge: A Digital Photography Contest You are not logged in. (log in or register

DPChallenge Forums >> Tips, Tricks, and Q&A >> how do you set focussing distance on canon lens
Showing posts 1 - 9 of 9, (reverse)
04/01/2012 02:47:27 PM · #1
I am trying to do some night photography and finding it very hard to do it with my 24-105 mm canon lens as the distance scale is pretty vague. a hyperfocal chart i downloaded tells me that at 75 mm, f16 i should focus at 11.7 meters. but the distance scale shows only infinity beyond 5 meters. how can i set a distance of 11.7 ? i guess if the image info screen can tell me the focus distance, i will get some way of adjusting the focus, but i am unaware of any such info....

Thanks for your help.
04/01/2012 03:34:23 PM · #2
Autofocus on something about 12 meters away then switch to manual.
04/01/2012 03:35:06 PM · #3
Use the "live view" + digital zoom + manual focus and try to make focus on some light part of the scene
Second option is to focus when there is light and wait until it gets dark!
Good luck ;)
04/01/2012 03:36:12 PM · #4
The white numbers are meters, the green numbers are feet. The red numbers on the barrel are the index marks at different levels of zoom. If you put the appropriate index mark halfway between infinity and the white "5" you'll be fine at f/16.

04/01/2012 03:38:39 PM · #5
The distance scale would be very "compressed" beyond 5 m, so additional markings would be of little practical use. The easier way is to focus on something that's approximately that far away. At night, that can be a challenge, but using a light or a laser pointer can be a big help.
You can also look at the markings on the scale and estimate how much past the 5 m mark you need to be. This is going to be less accurate, but it can work in combination with a little trial and error. In other words, set it approximately, shoot, adjust, shoot again.
04/01/2012 05:07:55 PM · #6

@Bear_Music : i read somewhere the red markings are for infrared and so didnt bother about them. will try them out.
@James_so : that sounds practical.i will try to distance myself from a lighted object at 12m , hit MF and go to the scene. i guess i can memorise the relative distance on scale.
@kirbic: trial and error it is then.
@darkpixel : i dont have live view :(. but now i know one use of live view

thanks all.

04/02/2012 01:07:34 AM · #7
Another option is to set iso as high as it will go, open the aperture to full open/f1.8 with your 50, manual focus and shoot, chimp, tweak shoot, chimp ect, until you see what you want in the LCD with it zoomed to check focus. Then, without touching the focus, reduce iso, change aperture to what you want, adjust shutter speed to match, then get the good shot. At f16, DOF will be pretty huge anyway, so any focus choice beyond 10 or 12 ft should be pretty good to infinity.

Camera shake is critical when doing time exposures at night. That could be what is making your photos blurry.

ETA, if the focus is extra critical, the laser pointer and manual focus idea is probably the best and quickest method. If exposures are going to be long, you can use the high iso method to zero in on the correct exposure time then switch to what you want for the "good" shots.

Message edited by author 2012-04-02 01:13:57.
04/02/2012 02:06:29 AM · #8
Night photography at f/16 and about 75mm?
What are you planning on shooting if I may ask? I hope your subject is quite brightly lit up.
I'm pretty sure it isnt anything to do with the sky / stars (infinity focus) so why do you need hyperfocal distance then?
04/02/2012 07:34:34 AM · #9
The 30D has AF assist doesn't it?
Current Server Time: 10/21/2020 11:41:05 PM

Please log in or register to post to the forums.

Home - Challenges - Community - League - Photos - Cameras - Lenses - Learn - Prints! - Help - Terms of Use - Privacy - Top ^
DPChallenge, and website content and design, Copyright © 2001-2020 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Proudly hosted by Sargasso Networks. Current Server Time: 10/21/2020 11:41:05 PM EDT.