lmTrying Loc: WV Northern Panhandle

I thought mirrorless cameras did not need micro focus adjustments due to the elimination of the mirrors. That was a part of the reason I upgraded from a Canon XSi to an RP instead of a 80D or 90D. (Plus a lot of other reasons.)

VietVet Loc: Brooklyn, NY

Thanks Elliot, I like the extra reach I get without having to crop in post so I have no intention of giving up. It’s a used converter so maybe an easy and not costly fix. I’ve already dropped my EF to RF adapter so that’ll cost me another $100.00us.

elliott937 Loc: St. Louis

I actually tried third party converters before purchasing the Canon version. The third party converters just did not do the same quality job the Canon product did. Supports the adage 'you get what you pay for'.

DLewis Loc: Aurora, CO

I have the same Tamron lens and extender and use them on my EOS RP and have never noticed soft images. They are as sharp with this combo as with my Canon EF 100-400mm f/4.5-5.6L IS II USM Lens and extender. Sorry I can't be of much more help.

TriX Loc: Raleigh, NC

The Canon extenders are excellent quality and produce fine results when they are used with the lenses they were designed for. I prefer the more conservative EX 1.4 (which I have and use), but the EX 2.0 performs well when used with certain Canon primes such as the 300 f2.8L (which is an outstanding lens if you can deal with the 6 lb weight).

VietVet Loc: Brooklyn, NY

Nonetheless, thanks for your reply. Appreciate all info I can get.

VietVet Loc: Brooklyn, NY

I would love to get the new 600 2.8 but a little too costly for me at this time. Thanks for your response TriX.

photodoc16

VietVet,
Same set up and had same questions. When I conducted my own tests including a tripod and the 1.4 TC I found that the focus was sharp. So...It was the operator. I have since been careful to shoot at high speeds (>1/1000) and to make many more short bursts hand held. The results have been much better. This debate continues with just as many users swearing that the images remain sharp even with the TC as those who doubt it.
Good luck,
Photodoc16

VietVet Loc: Brooklyn, NY

Thanks Photodoc16. I’m thinking it may be something I did. Looking back on the images I’ve noticed some missteps on my part. I’ve got one of the custom profiles set for shutter priority and thought I had it set to 1250 but I’ve noticed it’s on auto adjustments which I don’t want and I thing I gotten so slow shutter speeds. Will do a complete test when I return from vacation.

largeformat Loc: Bend, Oregon

To narrow it down, choose a static subject - truly static, not just stationary; use a solid tripod and switch IS off; use Live View MF to eliminate any AF errors. Also shoot in good light at a low ISO speed. If you can get good results in those conditions, you know it's not an image quality issue with the lens or the TC.

Then with the same setup, go back to AF and check the microadjustment both with and without the TC.

elliott937 Loc: St. Louis

Excellent test method there.

TriX Loc: Raleigh, NC

Right procedure, but no MFA on an R body.

John N Loc: HP14 3QF Stokenchurch, UK

I have experienced problems with a cheaper 70-300 Canon Lens before - as has more neighbour - and in both cases removal of a filter cured the problem. If you have a filter on it, try removing it, even if the filter was O.K. previously. It might work well with a lens / convertor combination.

amfoto1 Loc: San Jose, Calif. USA

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:

EF 100-400mm II with EF 1.4X II on 7D Mark II

(Download)

VietVet Loc: Brooklyn, NY

All except the micro adjustment's because the EOS R is a mirrorless camera with no adjustments.