Focusing on infinity with Canon STM lens

Hi all!

I recently tried taking some landscape and cemetery photos with my 6D MII and the Canon EF 24-105mm f/3.5-5.6 IS STM in full moon light. (Yes, I know that's not an ideal lens for nighttime photography.) Getting the right focus was by far the most difficult thing about it. Most photos - if, luckily, not all - ended up severely misfocused despite my best manual efforts. (And frostnip in my fingers. LOL)

I've read more about focusing in the night since, but what I can't figure out is this: How do you focus on infinity with a lens whose focus ring just keeps going around? Is it even possible?

Thank you in advance!

You need to be sure that camera is “awake “ to focus an STM lens.

Switch lens to MF and turn focus ring until image is sharp in viewfinder.

Set the lens to MF, pick a very distant object,the moon, if visible is ideal, half press the shutter button then turn the focus ring until the image is sharp. One advantage of STM lenses is that once manually set you can’t accidentally change focus by moving the focus ring.

SunfyreArt wrote:

What's the purpose of half-pressing the shutter button before you focus manually? I can't seem to find a difference. Not in the manual modes at least.

And there's the problem that I can't really tell on the screen in the night whether distant objects are in focus. Often, especially with trees for example, I thought it looked in focus, but on closer inspection on the computer later it wasn't. Usually, objects somewhere in front of it were in focus instead.

1. STM lenses are "focus by wire", so the camera needs to be powered on to focus the lens

2. Since its night photography I assume you are using a tripod. Switch to Live View and enlarge to max. Be sure to select a focus point that is on your target. If you have auto focus point selection enabled the camera will generally try to lock on the closest item.

Half pressing the shutter button engages the focus motor allowing you to manually focus. Set up on a tripod, point the camera to a distant object, enable live view, magnify the image 10x, half press the shutter, turn the focus ring until the image is sharp, let go of the shutter button then compose and take your shot.

If you can't focus on tbe rear screen in 10x 1:1 magnification, you have an eye problem.

Yes you only need to half-press the shutter to manually focus when you're in AF mode. In manual mode just focus away.

SunfyreArt wrote:

Ah. I don't need to half press the shutter button when the lens is switched to manual focus though. AF is often more hindrance than help anyway in such dark... darkness. ^^

I hadn't thought to magnify it though. *blush* That might help some indeed. (Y)

1. Yes, my mistake. No need to half press in MF.