Reikan Focal Pro Accuracy for AFMA

Started Apr 25, 2014 | Discussions thread
OP nitroman Regular Member • Posts: 151
Colour Temperature and Focal Pro AFMA Accuracy

I agree Oscar ... AFMA results need to be consistent to be of value.

Interestingly enough, I've been playing with the AFMA on my Canon 50mm f1.2 L and come to the conclusion that this lens is the bitch of the bunch. It's such an indisyncratic lens that consistent results are tricky to obtain whatever method i use.

I've also been playing with Magic Lantern Auto Dot Tune AFMA ...

Having achieved perfect focus using Live View and Canon Eos Utility at 100%, Dot Tune then works out the best AFMA setting automatically on my 5D2 and is pretty consistent.

When the AFMA is calculated using ambient daylight, it requires a different AFMA number to when my target is lit by my 650w tungsten hologen fresnel light. Initially i put this down to colour temperature variation and different channels focus at different wave lengths - therefore a different AFMA. However, when i add a colour Lee 201 lighting gel to convert tungsten (3200k) to daylight (5500k), the AFMA remains the same. This must mean that it's not the colour temperature that affects the AFMA but the infra red light emited by the tungsten bulb. This would obviously make sense as infrared focuses at different wavelengths !

@ Oscar, this might also explain why your LCD moire pattern AFMA method is pretty consistent as there is little infrared from an LCD screen. Although I've yet to try it ...

Basically, test the AFMA under the light you are shooting under as other light sources will affect the AFMA setting. This is a pain as AFMA is also affected by subject distance, zoom setting and even ambient thermal temperature making finding the right AFMA setting almosr bl*ody impossible !!!

Does anyone else agree ?!

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Canon EOS 5DS
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