Here is the Canon RF 100-400mm f/5.6-8 IS USM

Jul 21, 2010
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Nice shot. Out of interest though, does the red dot not disturb wildlife? I ask out of genuine interest, as a long-time user of the hood-knob technique too (like PBD), but am always interested in learning what works for others.
It’s not a laser, the red dot only shows in the camera-mounted device (which you look through instead of the viewfinder).
 
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Dragon

EF 800L f/5.6, RF 800 f/11
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AlanF

Desperately seeking birds
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It looks very nice on the R6. Is it as snappy sharp on an R5?
The 1.4xTC takes it to f/11, just on the edge of the diffraction limit for the R6 (f/10) but beyond that for the R5 (f/7.1). The bare 100-400 is great on the R5, but not so hot with the TC attached, though it does give some extra resolution.
 
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Dragon

EF 800L f/5.6, RF 800 f/11
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The 1.4xTC takes it to f/11, just on the edge of the diffraction limit for the R6 (f/10) but beyond that for the R5 (f/7.1). The bare 100-400 is great on the R5, but not so hot with the TC attached, though it does give some extra resolution.

Thanks. Happy with my EF100-400 II for now, but small and light has its attraction in some situations.
 
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AlanF

Desperately seeking birds
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Thanks. Happy with my EF100-400 II for now, but small and light has its attraction in some situations.
I found the EF 100-400mm II to be excellent with and without the 1.4xTC on the R5 and 5DSR. My wife can no longer manage the weight of that lens although it is light enough.
 
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Dragon

EF 800L f/5.6, RF 800 f/11
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I found the EF 100-400mm II to be excellent with and without the 1.4xTC on the R5 and 5DSR. My wife can no longer manage the weight of that lens although it is light enough.
Have you seen any difference in performance between the EF and RF TCs? I still don't have any RF lenses that support a TC, so haven't had any reason to spring for an RF TC. If I get the RF 800 f/11, then I might need the 1.4.
 
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Dragon

EF 800L f/5.6, RF 800 f/11
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Have you seen any difference in performance between the EF and RF TCs? I still don't have any RF lenses that support a TC, so haven't had any reason to spring for an RF TC. If I get the RF 800 f/11, then I might need the 1.4. Can't see that the 2x adds much looking at the charts.
 
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LogicExtremist

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Sep 26, 2021
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A couple of points: First, if you use the EF-S 55-250mm f/4-5.6 IS STM on an R-series camera, you are forced to use crop mode which greatly limits the available resolution. Second, I have compared the EF-S 55-250mm f/4-5.6 IS STM used on an SL1 to the RF 100-400mm used on an RP and the image quality is definitely better for the RF 100-400mm used on an RP.
Thanks, good to know the Rf 100-400mm on FF gives better image quality that the 55-250mm on APSC, that's a really helpful answer! :)
 
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Jul 21, 2010
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At the risk of sounding really dumb - could you expand on what you mean by this?
As @Bdbtoys suggests. Position the hood attachment knob at the 'top' of the lens, and look over the top of the camera to 'sight' down the hotshoe and over the knob, and you can locate the subject then confirm in the VF and shoot.
 
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gruhl28

Canon 70D
Jul 26, 2013
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I haven’t dropped one yet, but I did once drop my 5DII, ~1 m onto pavement – it was fine optically (lens tests unaffected) and cosmetically, but all my AFMA values shifted by 10 units.
LOL, did dropping it really shift your AFMA values by 10? How odd.

EDIT: I think I misinterpreted what you wrote. I thought you meant that all the values you had entered were updated by 10, which would be odd, but thinking more about it you probably meant that you had to change the values because a sensor shifted slightly - that would make much more sense.
 
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Jul 21, 2010
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LOL, did dropping it really shift your AFMA values by 10? How odd.

EDIT: I think I misinterpreted what you wrote. I thought you meant that all the values you had entered were updated by 10, which would be odd, but thinking more about it you probably meant that you had to change the values because a sensor shifted slightly - that would make much more sense.
Yes, I had to change the values because the drop caused a change in the alignment between the image sensor and the AF sensor (the lens tests showed the image sensor was not affected, so either the AF sensor or more likely the submirror assembly shifted by a few µm).
 
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Dragon

EF 800L f/5.6, RF 800 f/11
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At the risk of sounding really dumb - could you expand on what you mean by this?
This comment and even the answers you got assume that you are familiar with the construction of the Canon Big White lenses. The hood attaches with a clamp that is tightened by a knob that can be placed most anywhere around the lens. See the other answers and you can put the picture together.
 
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Jethro

EOS R
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This comment and even the answers you got assume that you are familiar with the construction of the Canon Big White lenses. The hood attaches with a clamp that is tightened by a knob that can be placed most anywhere around the lens. See the other answers and you can put the picture together.
Thanks, yes I got the drift. But it gives me an idea I can try to apply to other lenses - to 'sight' the object externally first.
 
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