RF800mm lens fuzzy on EOS R5 Mark II

[CVOHDrider58]

I have the R5 Mark II. Recently i purchased the RF 800 F11 IS STM lens. I have not been able to get the lens to focus. It is like it gets close but the image remains fuzzy. Is there something wrong with the lens or something I am doing wrong?

[jrhoffman75]

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@CVOHDrider58 wrote:

I have the R5 Mark II. Recently i purchased the RF 800 F11 IS STM lens. I have not been able to get the lens to focus. It is like it gets close but the image remains fuzzy. Is there something wrong with the lens or something I am doing wrong?

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Hi. Please provide more info.

1. what mode is your camera in? One Shot AF?

2. Are you trying to focus beyond the minimum focusing distance?

3. Does the subject have sufficient contrast?

4. Do other lenses work OK?

[ebiggs1]

"I am doing wrong?"

Without further info my first guess you are too close to the subject. A sample with all your settings would be helpful to solve this dilemma You can also try a full camera reset to factory default settings. You may have set something incorrectly.

[johnrmoyer]

Are you certain that the "fuzzy" comes from focus? Is any portion if the image in focus? What software are you using to view the image?

The depth of field might be very shallow.

F/11 will result in small aperture diffraction blur with that camera sensor. In the camera when saving a JPG or in Canon DPP software, "digital lens optimizer" will remove some of the small aperture diffraction blur if the ISO is not too high. When the pixels are closer together on the sensor, there will be more small aperture diffraction blur.

If the ISO is high, then noise reduction will blur the image.

In Canon DPP software when editing the CR3 file, one may view the focus points that were selected by the camera.

In Rawtherapee, the "capture sharpening" will remove small aperture diffraction blur.

[wq9nsc]

800mm is a natural for wildlife photography but with a "best" aperture of f11 it is going to force either high ISO, slower than optimal shutter speed, or a combination of both if illumination is poor.  Post some example photos with your exposure (shutter speed, aperture, and ISO info intact) which will be helpful.

I have an EF 800 f5.6 which is 2 full f stops "faster" and with poor lighting it pushes ISO higher than I would like even with my 1DX III which handles high ISO quite well.

Rodger

[johnrmoyer]

Like wq9nsc, I often use 800mm. But I spent a fraction of the money so I also have F/11 wide open.

https://www.rsok.com/~jrm/2024Oct22_Salt_Plains/2024oct22_eagle_IMG_2015c.html 

Bald Eagle (Haliaeetus leucocephalus) at sunrise at Salt Plains National Wildlife Refuge in Alfalfa County, Oklahoma, United States on October 22, 2024

Camera Model Name	Canon EOS R5
Lens Model	EF100-400mm f/4.5-5.6L IS II USM +2x III
Focal Length	800.0 mm
Exposure Time	1/400
ISO	500
F Number	11.0
Camera Temperature	38 C
Measured EV	13.38
Measured EV 2	29

[normadel]

If you look at the manual for this lens at:

https://www.usa.canon.com/support/p/rf800mm-f11-is-stm

you will see the minimum focus distance is 19.69 feet.  Are you closer than that?

Even if you're not, image magnification of close subjects with an 800mm lens will be very large, resulting in very little depth of field.. Magnification and aperture are what determine depth of field.

[wq9nsc]

BEAUTIFUL composition John!!!

Rodger

[kvbarkley]

Rodger also hinted at it, but you might be getting motion blur if your shutter speed is not fast enough - like 1/800 of a second!

[ebiggs1]

"like 1/800 of a second!"

And 1/1600 is even better. In any case these should be and the point is, they are the slowest SS for a big lens like the 800mm. So without further info the culprit might be too close and too slow SS or both.