All 300mm's not equal
Aug 23, 2015 23:43:53 #
coj
Loc: NJ, USA
Apaflo wrote:
A totally bogus concern. The focal length is what the discussion is about, and the physical length of the lens has no significance at all.
Thanks for the education. Some of this is a little beyond me right now, but I love the technical info I find here. I have found that I have learned a lot by reading this forum. I was talking to a friend of mine the other day that I used to think was a photo guru. I realized that a lot of the things I talked about were over his head, all thanks to the info I have garnered here.
Aug 24, 2015 12:19:23 #
kb6kgx
Loc: Simi Valley, CA
imagemeister wrote:
That's what most people call it .....
Never heard the term. Guess Im not most people. What is focus breathing. You didnt answer the question.
Aug 24, 2015 12:24:30 #
Leitz
Loc: Solms
kb6kgx wrote:
Never heard the term. Guess Im not most people. What is focus breathing. You didnt answer the question.
http://bobatkins.com/photography/technical/focus_breathing_focal_length_changes.html
Added: A bit simpler than saying zoom lens close-focus focal length decrease.
Aug 24, 2015 13:09:43 #
Leitz wrote:
http://bobatkins.com/photography/technical/focus_breathing_focal_length_changes.html
Added: A bit simpler than saying zoom lens close-focus focal length decrease.
Added: A bit simpler than saying zoom lens close-focus focal length decrease.
It is not a zoom lens issue. The same effect is seen with fixed focal length lenses.
It is a change in angle of view caused by the use of Internal Focus design.
Aug 24, 2015 13:18:45 #
Leitz
Loc: Solms
Apaflo wrote:
It is not a zoom lens issue. The same effect is seen with fixed focal length lenses.
That makes it even simpler - close-focus focal length decrease. Any ideas how we can shorten it even more? :lol:
Add on: I haven't compared, but am wondering if there would be a difference between a long lens and telephoto of the same focal length?
Aug 24, 2015 13:42:00 #
Leitz wrote:
That makes it even simpler - close-focus focal length decrease. Any ideas how we can shorten it even more? :lol:
Add on: I haven't compared, but am wondering if there would be a difference between a long lens and telephoto of the same focal length?
Add on: I haven't compared, but am wondering if there would be a difference between a long lens and telephoto of the same focal length?
Easy: call it "focus breathing".
Aug 24, 2015 13:43:37 #
Leitz
Loc: Solms
Apaflo wrote:
Easy: call it "focus breathing".
:XD: Now we're right back where we started!
Aug 24, 2015 13:54:33 #
Leitz wrote:
:XD: Now we're right back where we started!
There was no point in moving from there, if the object is just to say it in a simple way.
But the real problem is not the simplicity, it's the accuracy of the description. Bob Atkins even fell into that trap at one point in his otherwise excellent focus breathing article when he inferred in one sentence that the issue was comparing fixed focal length lenses to zoom lenses. (But that was the only technical error in a long article, so it's hard to criticize him for that.)
Generally focus breathing is just a non-issue that results from Internal Focus design.
Aug 24, 2015 14:36:25 #
Leitz
Loc: Solms
Apaflo wrote:
Generally focus breathing is just a non-issue that results from Internal Focus design.
Agreed it's a non-issue, but "focus breathing" is hardly descriptive, and quite a few people say "Huh??" when they hear it!
Aug 24, 2015 14:50:05 #
Leitz wrote:
Agreed it's a non-issue, but "focus breathing" is hardly descriptive, and quite a few people say "Huh??" when they hear it!
it has been the accepted term for over 40 years that i know of.
Aug 24, 2015 14:55:08 #
Leitz wrote:
Agreed it's a non-issue, but "focus breathing" is hardly descriptive, and quite a few people say "Huh??" when they hear it!
So?
"Focal length" isn't intuitive either, and I'd bet the average photographer can't accurately describe what it means. Same with "bit depth", "ISO", an many other common terms.
The big difference is that those are common terms that beginning photographers hear very early on. And they make a difference to how they learn photography. But "focus breathing" has no great significance, and they may not hear about if for literally years.
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