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How much temperature shifting affects infinity?
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PostPosted: Fri Jun 25, 2021 7:45 pm    Post subject: How much temperature shifting affects infinity? Reply with quote
This regarding high focal length lenses i currently use 300mm (sometimes with with 2.0x teleconverter) to shoot objects 500 or more meters away and its vital to be able to focus at infinity because at high distances objects that appear blurred because out of focus.


Read today that temperature changes can affect metal as well as glass properties that can break the infinity, can someone go in more detail on how exactly temperature shifting can affect infinity?

1. Should i focus my lenses past infinity to compensate for temperature change?

2. Would it make sense to set "spot on infinity" in the winter (-25C) then if in summer (+25C) lens goes over infinity from temperature change its not as bad or its more difficult to predict how lens would behave?

Last edited by NiceDays on Sat Jun 26, 2021 6:25 am; edited 1 time in total


PostPosted: Fri Jun 25, 2021 8:27 pm    Post subject: Reply with quote
Welcome NiceDays

Simple expansion due to heat, contraction due to cold, affects in a complex way all lens components glass, metal, plastic. Using Live View to zoom in 10x to set exact focus is preferred, no need to take into account complex temperature effects. A sturdy tripod on a solid surface is required to prevent blur due to vibrations...

PS You may want to edit the Subject of your Post. Smile

Last edited by visualopsins on Fri Jun 25, 2021 10:03 pm; edited 2 times in total


PostPosted: Fri Jun 25, 2021 9:46 pm    Post subject: Reply with quote
Yes temperature will alter the size of components in your lens, expansion of metal bodies on black telephotos shows this in particular.
However the markings on adapted lenses are never very accurate. The best bet is to ignore the marked infinity along with other distances & focus by looking through the viewfinder or at live-view (using focus aids if available).

With more distant subjects particularly in hot weather the blur you're seeing can often be atmospheric turbulence, not poor focus as all.
There's not much us mere mortals can do about that, other than to take multiple shots & select the best ones.

Camera shake can of course also become a serious issue with longer lenses. I'm quite sure I have numerous examples of shots ruined by each of these factors as well as all the possible combinations... Rolling Eyes
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