Thought you guys might like to see an example of the 100-400 mk2 in a test setting here you can see my sigma teleconverter just check out the depth of field at 100mm at F4.5 . To explain the setting this is the fire place ledge about an inch behind the converter is decrotive wall paper the depth of field is so extream you can not see the wall behind it. This is on a 600d so its really 160mm.
Yes, it appears to be quite shallow, probably due to a relatively short distance between the camera and the subject.
Do search on YouTube for " DotTune Focus ".
The Dot Tune method suggests that you calibrate and test focus at a distance of 50x the focal length.
(50) x (100mm) x (1.6 crop factor) = 8000 mm
(8000 mm) x (1 inch/25.4mm) = 314.96063 inches
(314.96063 inches) x (1 foot/12 inches) = 25.24672 feet.
That calculation suggests that you need to be just over 25 feet away from a focus target. There are many focus samples, both 2D and 3D, that you can download and print from the internet. I think a flat, 2D poster is good to check front/back focus. A 3D target made from folded cardboard, or photo paper, are best for testing, measuring, and calibrating Depth-Of-Field.
For the DOF calculator I use, for a FF camera at 100mm at F/4.5 at about 1m distance the DOF is .987 to 1.014 meters, or a total DOF of .027 m, which is pretty close to 1 inch.
Telephotos can really mess with your intuitive notions of depth of field
well the DOF is not what i exspected I exspect this at 2.8 not 4.5
The 600D is not listed for this online calculator. Neither is my 6D. So, these are ball park figures. dofmasterDOTcom
I used what I thought to be the MFD, minimum focus distance. Hope this helps.
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