Silly but frustrating question/problem.

[runnah]

Why don't lenses stop at infinity anymore? All my canon/nikon lenses go past infinity and require a slight backing off to get focused. Make sense? This is annoying when try to to do night shots with nothing to focus on. My old film camera's lens stop right on infinity so it's wicked easy to do fast focusing when it's needed.

 

[Scatterbrained]

Just focus on the moon.

 

[Big Mike]

I had always heard that it was because of the slight 'play' in the focus system, and/or to accommodate changes caused by temperature.

Imagine, if you will, that the lens stops at infinity, but then due to some slight misalignment or expansion/contraction due to temp change, the lens travel backed off just a little....the lens would no longer be able to focus at infinity.

Being able to focus slightly past infinity, ensures that you always can focus to infinity.

It is annoying though, I certainly agree.

 

[runnah]

I had always heard that it was because of the slight 'play' in the focus system, and/or to accommodate changes caused by temperature.

Imagine, if you will, that the lens stops at infinity, but then due to some slight misalignment or expansion/contraction due to temp change, the lens travel backed off just a little....the lens would no longer be able to focus at infinity.

Being able to focus slightly past infinity, ensures that you always can focus to infinity.

It is annoying though, I certainly agree.

That makes sense, but seems like something that should be engineered out by now. Maybe cause everything is plastic and the metal lenses of old had less temp variation.

 

[astroNikon]

the old lenses were designed to be manually focused thus had longer movements and more accuracy.

The newer stuff is all AF and when you manually adjust zoom & focus. it has a short movement thus some more "slack" is needed.

 

[Pejacre]

It's so you can go to infinity and beyond...

 

[CameraClicker]

Even my old lenses from the 1970's went past infinity. Or at least, past the infinity mark on the lens. Don't you need that extra bit for IR? Also, there are manufacturing tolerances as well as temperature fluctuations to allow for.

 

[snowbear]

Don't you need that extra bit for IR?

IR should be the opposite - focus a little closer than you do with visible light.