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Minolta 200mm f/2.8 APO + Minolta x2 focus speed

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Miranda F View Drop Down
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Joined: 11 January 2014
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2019 at 13:32
Originally posted by Maxxuman Maxxuman wrote:

Micro hunting was what I described it as - the lens/converter combo rapidly adjusting back and forth over a small distance without locking focus. I wouldn't call that overshooting and haven't seen that term used to describe the behaviour. The problem was reported by some users when the High Speed lenses were introduced in the film days. Minolta changed its converters as a result and presumably kept the slower gearing to err on the safe side. But I haven't seen any reports of the issue occurring on digital bodies. I can't speak to what Nikon did.


As a control engineer, I would call that inadequate damping, and in mechanical systems it is usually the result of excess mechanical play or response delay. Reducing the mechanical or electronic gearing can help, as can increasing the deadband (region of no response). The problem is coping with multiple combinations of lens and camera body.
Miranda F & Sensorex, Sony A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
 



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Kilkry View Drop Down
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Post Options Post Options   Quote Kilkry Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2019 at 15:36
Originally posted by dxqcanada dxqcanada wrote:

Ok, just got my 2x version 1 from michelb ... even though it is raining a bit, I decided to try out the combination on my A77m2.
It does like to micro hunt, and it is a bit slower (expected) but not "slow".
I will have to try further when the sun comes out ... one day.


I had the original 2x tc if I remember correctly and I didn't like how it AF:ed with my A77 compared to the 1,4tx (with the 200 2,8 HS). Microhunting unless very contrasty targets. IQ hit too. Never used it.
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