Manual focusing with long lenses - "pop" techinique?

Started Nov 2, 2009 | Discussions thread
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Peter Shute
Peter Shute Regular Member • Posts: 198
Manual focusing with long lenses - "pop" techinique?

Apologies for posting this twice. I replied to a very old thread, and it appeared in the list under an irrelevant subject line

Godfrey wrote:

"Twist the focusing ring from infinity to closest focus at a medium speed. Then the other direction after a short pause. And again and again. Do it slow enough that you can watch the focus transition from blur to sharp to blur, but fast enough that the transition to critically sharp "pops" for a moment as you turn. OBSERVE the focus transition carefully, over and over again. Get a feel for how much time/how much angular displacement of the focusing ring causes how much focus transition to occur."

See http://forums.dpreview.com/...forums/read.asp?forum=1022&message=30472013 for the original posting I have quoted from.

Can anyone please tell me if this "pop" technique works for long focal lengths, say 300 or 400mm? Does it perhaps depend on the pitch of the focus helix thread, i.e. how far you have to turn the barrel between closest focus distance and infinity?

On my 300mm lens (E-520, f5.6, 6m - infinity in 3/4 turn) I have to turn it uncomfortably fast to see a "pop".

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