1d mkIII/40d Cross Type Sensors

[paul goode]

Could be completely wrong but I'm just wondering if the design of the 'high precision' sensors accounts for the 40d woes with taped tcs.
With my 100-400 and 500f4 my mkIII used in landscape mode often fails to get a focus lock on thin branches and would hunt until the battery goes flat. However, in portrait mode it will slam into focus every time. Reading the easy to follow (yeah right) bit in the manual about these sensors I think that is how the camera is meant to work so its not a problem.

But is that why the 40d's wont af with a taped tc? Has anyone tried using the camera in portrait mode or even at a bit of an angle to see if its any better. Tilting the mkIII a fraction off horizontal works most of the time.

Just a thought

Paul

[Keith Reeder]

Interesting, Paul - I'll give it a go tonight.

[gmax]

Could be completely wrong but I'm just wondering if the design of the 'high precision' sensors accounts for the 40d woes with taped tcs.
With my 100-400 and 500f4 my mkIII used in landscape mode often fails to get a focus lock on thin branches and would hunt until the battery goes flat. However, in portrait mode it will slam into focus every time. Reading the easy to follow (yeah right) bit in the manual about these sensors I think that is how the camera is meant to work so its not a problem.

But is that why the 40d's wont af with a taped tc? Has anyone tried using the camera in portrait mode or even at a bit of an angle to see if its any better. Tilting the mkIII a fraction off horizontal works most of the time.

Just a thought

Paul

An interesting speculation here: http://forums.dpreview.com/forums/read.asp?forum=1019&message=25546483

[postcardcv]

I've just given this a try - shooting with the 40D, 400 f5.6 and 1.4x tc with taped pins - a slight titl made no difference at all. However shooting in portrait did improve matters a fair bit, AF locked on first time ~50% of the time (though not a long test). However when I switched to on of the other foucs points the camera locked on just about every time.

[gmax]

I've just given this a try - shooting with the 40D, 400 f5.6 and 1.4x tc with taped pins - a slight titl made no difference at all. However shooting in portrait did improve matters a fair bit, AF locked on first time ~50% of the time (though not a long test). However when I switched to on of the other foucs points the camera locked on just about every time.

Just depressing .... :-C ... at the end of the story, will this camera work or not with this combo?

[paul goode]

MkIII works fine Max, doesn't even need the tape. ;) ;)

[postcardcv]

Just depressing .... :-C ... at the end of the story, will this camera work or not with this combo?

with the tc it will not AF properly with the central point but seems to work fine with the other AF points.

[gmax]

MkIII works fine Max, doesn't even need the tape. ;) ;)


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