Why do lenses focus past infinity?

Is there something beyond infinity? Infinity + 1?

Probably a dumb question, but I never understood this. I've messed up some night shots using manual focus and accidentally putting the focus past infinity.

Hahaha. I did the same thing this morning just before sunrise. I am curious as well, maybe for landscapes like really, really, really far away??

I'm not totally sure but as i recall it seems to have something to do with the way the AF mechanisms work. I have several old MF lenses and as you mention, set it all the way to infinity and it's in focus. All my AF lenses are not like this.

It is regarding the expansion of materials on the lens in warmer temperatures that would make it hard to focus at infinity if they did not account for it by providing the 'beyond infinity' focus point.

Yeah, well, but that's just like my opinion man.

Obviously you're not a fan of Buzz Lightyear, who taught us all that indeed there is something beyond infinity. "To infinity ... and beyond!" It's called "beyond"

rick_reno wrote in post #13604652
Obviously you're not a fan of Buzz Lightyear, who taught us all that indeed there is something beyond infinity. "To infinity ... and beyond!" It's called "beyond"

If they ever put "Beyond" on a lens that focuses passed infinity I will buy it no matter how much it costs or how much I'll use it

for temperature tolerances I've heard

but mostly so the AF mechanism doesn't get hammered when racking back and forth around infinity.

as I remember, it's made for infrared shooting purpose ...

According to a Canon rep at a local photo and imaging show recently it's so the AF mechanism can focus on infinity perfectly by minute adjustments backwardds and forwards. i.e. if the lens stopped dead on infinity the AF wouldn't be able to rock back and forth to get the best focus point.

Agree with Newworld666.
Wish I could recall the sources of the info.

I have in front of me three Nikkor manual focus lenses. They all adjust exactly to the center of the infinity mark.

These were made long before autofocus, but as I recall temperature changes did exist 40 years ago.

So I think we can forget the claim that it's temperature expansion - but an autofocus lens definitely needs to be able to go beyond the focus point in order to zero in on the right point. If that point is far away, it'll move past infinity focus in the process.

-js

number six wrote in post #13606402
I have in front of me three Nikkor manual focus lenses. They all adjust exactly to the center of the infinity mark.

These were made long before autofocus, but as I recall temperature changes did exist 40 years ago.

I checked the two FD mount manual focus lenses I have and it's the same. The lens stops exactly at infinity and when checked on the camera, things at infinity are in perfect focus.

El Duderino wrote in post #13604546
Is there something beyond infinity? Infinity + 1?

Probably a dumb question, but I never understood this. I've messed up some night shots using manual focus and accidentally putting the focus past infinity.

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yeah i hate when that happens.
I think it is because of star shooting?

newworld666 wrote in post #13604746
as I remember, it's made for infrared shooting purpose ...

Not this; infrared is brought to infinity focus longer (i.e. before infinity on the focus scale) than visible light. Ultraviolet would be a different matter, but that doesn't go through the glass of a normal lens.