focus on infinity???

debbie · 07-02-2008, 12:11 PM

well, I just wonder, if I would foucus on something very far away, the moon for example, should not the focus ring be set to infinity?? Or is it something strange with the lens if it´s not??

Jewelltrail · 07-02-2008, 12:14 PM

Debbie:

You are correct, the Moon is at infinity.

Regards,

Ernest

pasipasi · 07-02-2008, 12:22 PM

Some lenses can focus beyond infinity. Then the focus ring is like a millimeter from infinity.

Talisker · 07-02-2008, 12:30 PM

If it's a zoom lens then the focal point may vary slightly at different focal lengths, so the lens has to refocus as you zoom (its cheaper that way) - thus the position of the focusing ring changes. Not all lenses have the barrels marked to reflect this.

**Canada_Rockies** · 07-02-2008, 08:45 PM

Many long lenses focus past infinity. This allows the changing length of the lens due to temperature changes to still allow the lens to reach infinity. As the temperature of a metal lens barrel drops, the length of the barrel gets shorter, and one must focus out a bit further to attain infinity focus.

07-02-2008, 12:11 PM	#1
debbie Senior Member Join Date: May 2008 Location: stockholm Photos: Albums Posts: 111	focus on infinity??? well, I just wonder, if I would foucus on something very far away, the moon for example, should not the focus ring be set to infinity?? Or is it something strange with the lens if it´s not??

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07-02-2008, 12:14 PM	#2
Jewelltrail Veteran Member Join Date: May 2008 Location: Rhode Island Photos: Albums Posts: 4,180	Debbie: You are correct, the Moon is at infinity. Regards, Ernest

07-02-2008, 12:22 PM	#3
pasipasi Veteran Member Join Date: Feb 2008 Location: Oulu Photos: Gallery Posts: 532	Some lenses can focus beyond infinity. Then the focus ring is like a millimeter from infinity.

07-02-2008, 12:30 PM	#4
Talisker Senior Member Join Date: Nov 2007 Location: Isle of Skye, Scotland Photos: Gallery Posts: 262	If it's a zoom lens then the focal point may vary slightly at different focal lengths, so the lens has to refocus as you zoom (its cheaper that way) - thus the position of the focusing ring changes. Not all lenses have the barrels marked to reflect this.

07-02-2008, 08:45 PM	#5
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Many long lenses focus past infinity. This allows the changing length of the lens due to temperature changes to still allow the lens to reach infinity. As the temperature of a metal lens barrel drops, the length of the barrel gets shorter, and one must focus out a bit further to attain infinity focus.