Focusing to Infinity: Mark Wallace on Adorama training video says that when shooting fireworks, set focus just short of infinity. In his clip, he shows the infinity mark on his lens. I...

mrmal Loc: Saskatoon, Sask, Canada

Mark Wallace on Adorama training video says that when shooting fireworks, set focus just short of infinity. In his clip, he shows the infinity mark on his lens. I am shooting a Canon 60D and have a EFS 18-200 mm and an EFS 18-135 mm. Neither of these lenses show the infinity setting for Focus. On Manual focus, I think it is at the far end when you twist the focus ring. But which end is it? With the lens pointing to the subject is it turned clockwise or counter-clockwise to reach the infinity setting. Fireworks coming at us very quickly, July 1st in Canada and I want to be ready.Thanks for you advise.

boydimages Loc: California

mrmal wrote:

Mark Wallace on Adorama training video says that w... (show quote)

Turn the focusing ring as you look through the viewfinder. Focus on an object close to you, then farther away to see which way to turn focus ring.

SharpShooter Loc: NorCal

mrmal wrote:

Mark Wallace on Adorama training video says that w... (show quote)

Mrmal, Just focus on auto focus on some distant lights, then turn the auto focus to off. Check it every so often to make sure it hasn't moved. Remember the lens will focus beyond infinity. If you are off by even the slightest amount, all your shots will be OOF. Also keep in mind that you can not tell sharp focus non your LCD, so don't rely on it. Good luck. SS

EstherP

boydimages wrote:

Turn the focusing ring as you look through the viewfinder. Focus on an object close to you, then farther away to see which way to turn focus ring.

Keep in mind that on some cameras you can select in what direction to turn the focus ring when focussing manually.
Check your manual.
EstherP

LoneRangeFinder Loc: Left field

SharpShooter wrote:

Mrmal, Just focus on auto focus on some distant lights, then turn the auto focus to off. Check it every so often to make sure it hasn't moved. Remember the lens will focus beyond infinity. If you are off by even the slightest amount, all your shots will be OOF. Also keep in mind that you can not tell sharp focus non your LCD, so don't rely on it. Good luck. SS

"...beyond infinity..."?

EstherP

LoneRangeFinder wrote:

"...beyond infinity..."?

http://www.panoramas.dk/technics/focus.html
http://www.dpreview.com/forums/post/35055652
http://www.cambridgeincolour.com/forums/thread12967.htm

If you Google "focus beyond infinity" - there are many more websites explaining this. Since I don't know much about it myself, you'll have to wade through the good and bad explanations, I guess....
So much to learn, so little time <sigh>
EstherP

photoninja1 Loc: Tampa Florida

All the above can work, but I just shoot in autofocus and most of the time it sorks fine.

LoneRangeFinder Loc: Left field

EstherP wrote:

http://www.panoramas.dk/technics/focus.html
http://www.dpreview.com/forums/post/35055652
http://www.cambridgeincolour.com/forums/thread12967.htm

If you Google "focus beyond infinity" - there are many more websites explaining this. Since I don't know much about it myself, you'll have to wade through the good and bad explanations, I guess....
So much to learn, so little time <sigh>
EstherP

You can set your lens beyond the infinity mark, but one cannot focus beyond infinity since infinity refers to something without any limit...

Conceptually, at any rate, this would be the antithesis of hyper focal focusing.

jerryc41 Loc: Catskill Mts of NY

LoneRangeFinder wrote:

"...beyond infinity..."?

I think the correct expression is, "To infinity and beyond!" :D

Most lenses can focus past infinity. With all the advances in astrophysics these days, it's become a necessity. :D

That also allows for variation in manufacturing tolerances, allows for heat expansion, relieves strain on the focusing motor when focusing on "infinity."

mwsilvers Loc: Central New Jersey

LoneRangeFinder wrote:

You can set your lens beyond the infinity mark, but one cannot focus beyond infinity since infinity refers to something without any limit...

Conceptually, at any rate, this would be the antithesis of hyper focal focusing.

The answer is actually simple. A number of lens, often those of higher quality, allow you to focus manually past infinity to compensate for the very slight expansion of the elements due to ambient temperature shifts. You are still really only focused on infinity even if the distance window indicates you've gone past it. Additionally, although I have not read anything specific on this, i have sometimes noticed that atmospheric conditions such as visible waves of heat, seem to affect the focus at infinity. Both Canon and Nikon have written on focusing "past" infinity. Remember a camera lens is not a finely tuned laboratory quality measuring tool. There is variation.

jerryc41 Loc: Catskill Mts of NY

mwsilvers wrote:

Remember a camera lens is not a finely tuned laboratory quality measuring tool. There is variation.

That's why they're all so affordable. :D

JR1 Loc: Tavistock, Devon, UK

In fact you cant focus on or near infinity as infinity is what it says "without limit" so you can not focus on something that is never ending.

And if the fireworks are say 100-200-300 yards away why would you not focus ON them, that is like saying focus just before infinity mrk when shooting anything past 300 yaers

LoneRangeFinder Loc: Left field

mwsilvers wrote:

The answer is actually simple. A number of lens, o... (show quote)

I guess I was a little esoteric (or too theoretical).... something like identifying that point at which parallel lines intersect...

;-)

jerryc41 Loc: Catskill Mts of NY

LoneRangeFinder wrote:

.... something like identifying that point at which parallel lines intersect...
;-)

As I said earlier, astrophysics is making advances all the time. Those railroad tracks in the sky just might converge one of these days. :D

selmslie Loc: Fernandina Beach, FL, USA

EstherP wrote:

...If you Google "focus beyond infinity" - there are many more websites explaining this. ...

One of the links you gave shows the main reason: "The autofocus system needs to be able to "miss" infinity a bit without slamming into a mechanical stop, which would cause excessive wear." So it is mainly an autofocus issue rather than to accommodate temperature changes or imprecise assembly.

I once had a 500mm Nikon mirror lens that did not have a hard stop at the infinity position, probably because it was a large hollow lens that could be affected by heat. All of my other manual lenses do have the hard stop.