Camera Labs

So what exactly is Focusing to Infinity? I've heard of it mentioned a few times in landscape, long distance, and astronomy photography. I was going to ask during the Google+ hangout but missed it A few comments sounded like it was good.

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Mike "The Squirrel"
Canon 550D | Canon EF 35mm 1:2 | Canon 50 f/1.8 II | Sigma 18-125mm DC OS | Tamron SP 70-300mm Di VC USD | Canon 430EX II
Military Issued Canon 40D | Canon 55-250mm IS

We missed you Mike!

Infinity is simply a long way away. For a lens it's the point at which everything from a certain distance onwards is effectively in the same plane of focus. For a wide angle elns, that may be everything from a few meters away, but for a big telephoto, it may be everything beyond several hundred meters.

It's indicated on a lens by a number 8 on its side.

So say I'm doing an evening shot that is too dark for the camera to capture focus and even for me to focus manually, If I know it is far off just go to manual and focus all the way out to Infinity? Or say I'm doing some action shots that are far off (race or aircraft) I could put it on infinity so I don't have to wait for the auto-focus and slow the shot? As long as I know both shots above are far enough out for that lens?

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Mike "The Squirrel"
Canon 550D | Canon EF 35mm 1:2 | Canon 50 f/1.8 II | Sigma 18-125mm DC OS | Tamron SP 70-300mm Di VC USD | Canon 430EX II
Military Issued Canon 40D | Canon 55-250mm IS

Exactly Mike. Same for stars. It's best to switch to manual focus, then focus to infinity. This also prevents the camera's AF from searching back and forth incessantly.

If you have a camera with live view, you can always use this to confirm the focus, then switch to manual focus to stop the camera subsequently adjusting it.

I'm doing that very often - outside in the dark I'm often using a strong laser pointer in order to get the focus perfectly right.

I always hate it when I forget switching the camera to MF after having the focus right in different situations like shooting the moon.

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Canon EOS 500D + Canon EOS 5D Mark III
Canon EF 24-105mm 4L IS USM + EF 100-400mm 4.5-5.6L IS USM + EF 100mm 2.8L Macro IS USM + Sigma 12-24mm 4.5-5.6 EX DG HSM + Canon Speedlite 580 EX II + Nissin Speedlite Di 466

Seeing as your thinking about focusing to infinity it would be worth learning a bit about hyperfocal distance too.

I posted a bit on my blog and including a card with a table on to live in my camera bag HERE

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Canon EOS 550D (with Magic Lantern)
18mm - 135mm Kit Lens, 50mm f1.8, Sigma 30mm f/1.4 EX DC HSM
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My Blog - http://www.ianganderton.wordpress.com

Never set a lens to MF and go right to infinity, where the lens indicates infinity is actually SLIGHTLY past infinity, and you'll notice it. Your results will come out much less sharp than if you fine tune the shot. The best way to do this is to switch into live view, magnify part of the subject and rotate the focus ring ever so slightly until you get the perfect focus.

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-Evan

Gear: 7 Nikon Nikkor AI-S and AF-S lenses, SB-700 flash, Nikon D7000, Nikon FM, variety of accessories

"There are no rules for good photographs, there are only good photographs."
- Ansel Adams

You're right - some lenses have a hard stop at infinity, whereas the majority do not.

a useful tip, not mine I am sure I read it on the forum, is to focus your lens on a far away object during daylight hours and then put a mark on that spot. That way at night in the dark you can just put it back to that spot in manual focus.

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Canon Powershot S95, Canon 7D, 15-85, Canon 85 1.8 USM, Sigma 30 1.4, 50mm 1.8, Canon 100 2.8L IS Macro, Canon 70-300L IS USM+Kenko 1.4 Pro 300DGX, Canon 430EX II and RS 4 Classic

Indeed I noticed that before - that's why I'm using my laser pointer. The other alternative is going to infinity and back again a little bit. That works well if you get a feeling for "how much" you have to go back.

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Canon EOS 500D + Canon EOS 5D Mark III
Canon EF 24-105mm 4L IS USM + EF 100-400mm 4.5-5.6L IS USM + EF 100mm 2.8L Macro IS USM + Sigma 12-24mm 4.5-5.6 EX DG HSM + Canon Speedlite 580 EX II + Nissin Speedlite Di 466

If only Buzz Lightyear's catchphrase had been:

"To infinity..... and then back a little bit"

Exactly, Gordon !

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My photos on Flickr...

Gordon!

We had Termination Dust in the mountains today so I was playing an you all are correct. If I go to Infinity (Thanks Gordon now I smile everytimt I type it) It is out of focus, but if I back of just a bit it works.

One more item to check off the list of learning.

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Mike "The Squirrel"
Canon 550D | Canon EF 35mm 1:2 | Canon 50 f/1.8 II | Sigma 18-125mm DC OS | Tamron SP 70-300mm Di VC USD | Canon 430EX II
Military Issued Canon 40D | Canon 55-250mm IS

You're welcome!

If you have time to compose the shot on a tripod though, I'd still ignore the focus distance marks and just do it through live view with magnification.