Canon 300mm 2.8 mk2 Help Please.

soupdragon

soupdragon

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Tony
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Hello.
I have the entitled lens and use it with a 1dx mk2.
Can anyone tell me if it is possible to slow down the AF speed of the lens. I understand that the AF speed, by design, is slower when using 1.4X or 2.0X extenders however, I'm unsure if it's possible to slow it down using lens or camera settings.

My thanks in advance for any help afforded.
 
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Why would you want to? I would imagine putting an ND filter on it would cut down so much light it would slow it down?
 
MatBin said:
Why would you want to? I would imagine putting an ND filter on it would cut down so much light it would slow it down?
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Well, it seems my critical focus hit rate is higher using the lens with a 1.4X extender as opposed to the naked lens.
Having done a bit of internetting, the only thing I can find that effects the AF is the use of a converter.

So by that I have concluded that slower AF equates to more accurate AF.
 
Most of the older 1D bodies had a variable speed rate setting in menu , have you thoroughly gone through the menu options ?
 
Im not Stalking you from the other forum :) I just happen to be here as well but slowing down the FPS will give the camera more time to focus between shots that too might help .
Rob.
 
I suspect that you need to change the first image priority to 'focus' rather than 'release' or 'equal' (page 122 of the user guide)
 
soupdragon said:
So by that I have concluded that slower AF equates to more accurate AF.
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eeerm not really no... It either aquires focus or it doesn't .. Its when you press the button ..... if your pressing it when not in focus then your OOF .. A faster AF will mean better keeper rate.. A slower AF as your asking means less and in sports we do value faster AF

Personally i think you are on the wrong track for your problem...
 
KIPAX said:
eeerm not really no... It either aquires focus or it doesn't .. Its when you press the button ..... if your pressing it when not in focus then your OOF .. A faster AF will mean better keeper rate.. A slower AF as your asking means less and in sports we do value faster AF

Personally i think you are on the wrong track for your problem...
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You're probably right but, I currently get a better keeper rate with my 85 1.2 which is notoriously difficult to use.
 
davidy233 said:
I'm pretty sure slower AF doesn't equate to more accurate AF
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It can, contrast detect AF for example is more precise but slower than Phase detect. That's not all to do with speed of course but it's an example where slower can indeed be more accurate.
 
What type of subjects are you shooting with the 300mm? Same or different to the 85mm?

Certainly in terns of the AF points available, the 85mm f1.2 and the 300mm f2.8 are both "Type A" lenses so you get the same AF points, including 5 x dial cross type in the middle. Putting the 1.4x converter on the 300mm turns it into a "type C" lens so the middle 5 dual cross type AF points become single cross type. In all cases, accuracy should be the same though.

Also, from P113 onwards in the manual, what focussing mode(s) are you using - particularly what characteristics if using AI Servo?
Oh, and final question - have you ensured the lens is properly set up with the focus micro-adjustment? In theory the 300mm may be slightly front or back focussing, but may happen to be ok with the 1.4x and with the 85mm?
 
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I agree with others - slower af probably won’t /shouldn’t help.
Sounds like adjusting the tracking sensitivity may solve your problem. In that currently your lens/camera may be switching priority due to small movements in either subject or camera - and switching focus position. ‘Slower’ af would solve this as the lens takes longer to af etc.

Can you give some examples of what/who you are shooting ?
 
Thanks all.
It appears to have been a combination of the things quoted.

I use AI servo because, in truth, I'm not particularly stable when holding a camera. I upped the AF tracking sensitivity and this went a long way to negating my swaying although there is now more audible servo action than before.
Having done that it became evident the lens was front focusing (this was obscured by my movements originally). Having dialed in plus 6 or 7 the hit rate is now much more in keeping with what I expected.
 
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