Math calibration question
- Thread starter KIPAX
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- Paul Beastall
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I would have thought the converter shouldn't change the focusing?
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I don't know why I bother getting out of bed some days
I was going to post well done it was a trick question and you passed the test... But lets face it ..who am i fooling... Duh.... Your right it doesn't change the focus... Why oh why did I think like that?..
Cheers.....sigh
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No worries - we all have days like those. Thank goodness my old clunker cameras don't have all this high tech stuff to confuse me!
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Not wanting to hijack this but I'm going to calibrate my 500mm f4 this weekend any tips ?
I'll be using a really sturdy tripod and static "targets" to focus on, and am I right in making the assumption that this would work better on prime's???:shrug:
I'll be using a really sturdy tripod and static "targets" to focus on, and am I right in making the assumption that this would work better on prime's???:shrug:
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I find it very difficult on static subjects.
I think I am right in saying calibrate to distance and thats a good way with a 500 My 300 deffo needed calibrating but everything looked fine close up.. even without calibration... use object/person way off.
I calibrated my 300 using the full length of a football pitch with my son stood at one end while I took pics at different settings ( oh shush he got extra spends for it ) he was on a terrace and everytime i waved he moved a step to one side.. thus when i got home i could tell the different setting by the position he was in. ie orig at 0 .. next position at +1 and so on to +20
I found it easier to test looking at facial features .. and I never need to focus furthur than that.
I think I am right in saying calibrate to distance and thats a good way with a 500
My 300 deffo needed calibrating but everything looked fine close up.. even without calibration... use object/person way off.I calibrated my 300 using the full length of a football pitch with my son stood at one end while I took pics at different settings ( oh shush he got extra spends for it
) he was on a terrace and everytime i waved he moved a step to one side.. thus when i got home i could tell the different setting by the position he was in. ie orig at 0 .. next position at +1 and so on to +20I found it easier to test looking at facial features .. and I never need to focus furthur than that.
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No, because the camera commands the lens to move the focus. So, the callibration is about changing when the camera thinks the lens is in focus. Once calibrated, the image on the sensor should be the same as on the focus sensor. Therefore, a change from the teleconverter should not impact the callibration. In the same way as when you add an extension tube, you change the focus scale but not the point where the camera thinks the image is in focus.
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I don't know why I bother getting out of bed some days
I was going to post well done it was a trick question and you passed the test... But lets face it ..who am i fooling... Duh.... Your right it doesn't change the focus... Why oh why did I think like that?..
Cheers.....sigh
Actually, you were going in the right direction and you do need to calibrate with the converter on. The camera senses the presence of the converter and uses the values accordingly.
The logic behind this is as follows;
A t/c doesn't affect the minimum focus distance of the lens therefore the lens must be focussing on a plane within the converter (at the rear element) and the converter doing the rest. If the converters "focal plane" is not at the exact same distance as the sensor would be (without a converter) then the two calibration values will be different.
I hope that made some sense.
Bob
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Don't just sit there stuffing yourself....agree or argue :shake:
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OK - I withdraw my comment. I thought it was about calibrating the focus sensor to focal plane. Sorry for confusion.
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Just to eliminate any doubts, this is a quote from some "tech tips" by Chuck Westfall (Canon's North American CEO)
If an extender can be attached, the camera recognizes whether it is 1.4x or 2x and makes a different shift adjustment from when no extender is attached. When an extender is attached, the adjustment screen will display the lens name and extender name.
Bob
If an extender can be attached, the camera recognizes whether it is 1.4x or 2x and makes a different shift adjustment from when no extender is attached. When an extender is attached, the adjustment screen will display the lens name and extender name.
Bob