VietVet wrote:
I have a canon 100-400L II lens that I use on my EOS R & 7Dii. I purchased a canon 1.4 converter V-III but am finding the images are very soft. (extremely disappointed). I’ve tried upping the shutter speed etc. but still soft focus on all images. The mentioned lens used as is takes perfectly sharp images. Any way to solve this issue?
I have no idea why you are having problems with that lens and TC combo.
I use the 100-400L II a lot and experimented with using my 1.4X on it a little (I rarely need that much focal length).
I've found it to be the BEST combination of zoom and teleconverter I've ever seen in nearly 40 years shooting. The lens/TC combo is nearly as sharp as the lens alone (which is excellent).
I have not used on a mirrorless camera, but do regularly use on 7D Mark II, like you. One difference, my Canon EF 1.4X is the II... not the III like you're using. I would think your newer version would be better, if anything.
With the 7DII, you are limited to using only the center AF point when the TC is on the lens (an effective f/8 combo). That shouldn't be a limitation on your R.
EDIT: I do not use "protective" filters on my lenses except in the rare cases where they are actually needed. Someone mentioned a filter may be the problem. It is true that the original Canon 100-400mm (push/pull version) does not work well with filters. It "goes soft" even when a high quality filter is installed. I have no idea why that happens, but many users of the push/pull 100-400mm are pleasantly surprised to learn how good it is simply by removing the filter they've had "protecting" it since new. To my knowledge, the 100-400mm II does not have any problem with filters.... but you never know. If using one, try shooting with it.
EDIT: Someone mentioned Micro Focus Adjustment, which might help on your 7DII, but isn't needed or even possible on a mirrorless like your R, where the AF sensors are embedded directly in the image sensor (so it's impossible for them to become out of calibration with each other).
Show us some sample images and maybe we can make some suggestions.
Below was shot with my 100-400II with 1.4X II on 7DII (and no filter). Lens was wide open (f/8), ISO 1600, 1/800 shutter speed, hand held (IS on, as always with this lens). It was shot RAW, converted to JPEG in Lightroom with minimal crop and only the default level of sharpening. After sizing for 8x10 print (300 ppi) I did apply a little selective sharpening in Photoshop: