Canon Autofocus in back light

virginie24jb wrote in post #16567448
I'm sorry, what do you mean by "at hyper-focal distance"?

http://www.cambridgein​colour.com …s/hyperfocal-distance.htm

Azathoth wrote in post #16567996
http://www.cambridgein​colour.com …s/hyperfocal-distance.htm

Thank you. I didn't know about the hyperfocal distance.

How do you find that hyperfocal distance while out shooting? Do you focus "roughly" at 1/3? Do you use the calculator?

I see that some people manage to have very sharp images with a big aperture of 3.5 or 4 and I was wondering how they managed that. I guess I just found the answer with your help. Thanks again. I'll have to try this.

Just keep that calculator URL on your phone so that you can have easy access to it or HERE'S ONE that you can download and print to carry with you.

rrblint wrote in post #16578279
Just keep that calculator URL on your phone so that you can have easy access to it or HERE'S ONE that you can download and print to carry with you.

I'm one of the few remaining people that don't have the internet on their phone so I'll have to go with paper.
On the one you gave me, it seems that the distance of the subject doesn't matter. Or did I read that wrong?

Thank you for the link.

You're most welcome.

If you focus at the HFD, as long as your subject is within the DOF range for the given aperture and focal length, it will be in "acceptable" focus. So, for example if the DOF range is say 3 meters to infinity and your subject is 5 meters away, if you focus at HFD, your subject will be in acceptable focus. However if your subject is 1.5 meters away then it would not be in acceptable focus and your would need to recalculate the HFD at a smaller aperture and refocus there to get more depth of field.

Go out and try it. It's really a lot simpler than it sounds explaining it. After a little bit of practice I bet you won't even need to carry that chart around with you anymore as you'll be able to estimate it with reasonable accuracy.

Thank you again for your explanation. I'll try that as soon as I can.

I installed the software on my old PC and it really seems like this is irrelevant for focal length under 17mm as the hyperfocal distance is really close.

Yes, the shorter the focal length the more irrelevant the focus distance and aperture become(as far as DOF is concerned). This is the reason why I said it would be easy for you once you get out and try it.

Okay... I went out again this afternoon and tried with a few shots but I still don't get it.

Nothing special here. This is an example. Shot at 112mm, with f/7.1 with my 18-135 STM lens. So given the graphic of the software, the hyper focal distance should be about 80 meters (or 260 feet). How do I know where that is?! I tried using the bottom focus point but I don't see any difference with my other shots in terms of shaprness.

Hi Virginie,

Ages ago in the ancient old film days most all lenses had accurate distance and DOF scales right on the lens barrels...Sure made it easier. These days I just "guesstimate" the distance and you definitely want to use manual focus. I would also recommend a tripod for your landscapes as camera shake can also ruin your sharpness. I would also recommend using f11 for lots of DOF.

If there is some object in frame that is about at hyperfocal distance you can manually focus on that, if not just try focusing to infinity(all the way in) and then moving it out by maybe a 10 -20 degree rotation. Try a test shot and check for sharpness and DOF. If it's off in one direction or the other then adjust the focus more or less toward infinity. One other thing to be aware of is the fact that the distant hills and near foreground will appear to be out of focus when you are looking through the viewfinder as you are looking through the lens wide open instead of being at your chosen aperture. Don't let that bother you. When you check the shot on the LCD, if you've found the proper focus, they will be nicely in focus.

One other thing Virginie: The brightness of the sky is causing underexposure. Try adding about +1 stop of exposure compensation. This will cause the sky to be blown out. That can be corrected with a CPL or GND filter, but that is a lesson for another day.