# Canon RF 800 f/11



## Bengt Nyman (May 7, 2021)

Canon Professional Service Center reports that:

If your Canon RF 800 f/11 lens suddenly and consistently fails to focus and takes consistently very blurry pictures, try resetting the camera as a first step toward fixing the problem.

The above happened to me. My R5 camera was still working fine with my 35mm macro lens but not with the 800mm f/11 lens so I sent the lens to Canon Professional Service Center only to be told that there is nothing wrong with the lens. I have now reset the camera as they suggested and it is still working properly with my 35mm Macro lens. I am eagerly awaiting the return of my 800mm f/11 lens and I shall return with the result.


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## Bengt Nyman (May 14, 2021)

Bengt Nyman said:


> Canon Professional Service Center reports that:
> 
> If your Canon RF 800 f/11 lens suddenly and consistently fails to focus and takes consistently very blurry pictures, try resetting the camera as a first step toward fixing the problem.
> 
> The above happened to me. My R5 camera was still working fine with my 35mm macro lens but not with the 800mm f/11 lens so I sent the lens to Canon Professional Service Center only to be told that there is nothing wrong with the lens. I have now reset the camera as they suggested and it is still working properly with my 35mm Macro lens. I am eagerly awaiting the return of my 800mm f/11 lens and I shall return with the result.


No. It was still not working correctly after camera reset. So this time I sent both camera and lens to Canon Service.


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## Bengt Nyman (May 22, 2021)

Bengt Nyman said:


> No. It was still not working correctly after camera reset. So this time I sent both camera and lens to Canon Service.


Camera and 800mm lens have now been tested and returned from Canon. They found nothing wrong but fine-tuned the focus. My own tripod test with 10 sec delay confirms good focus. However, in the field stabilized focus is highly unreliable and most of the time very bad. I am attaching picture before the problem started and a comparable picture representing my attempts to capture pictures with that lens today. Has anybody else experienced a similar problem ?


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## AlanF (May 22, 2021)

Bengt Nyman said:


> Camera and 800mm lens have now been tested and returned from Canon. They found nothing wrong but fine-tuned the focus. My own tripod test with 10 sec delay confirms good focus. However, in the field stabilized focus is highly unreliable and most of the time very bad. I am attaching picture before the problem started and a comparable picture representing my attempts to capture pictures with that lens today. Has anybody else experienced a similar problem ?


The second shot doesn't look like a simple focus issue as both foreground and background are also blurred. It looks like a stability problem. Was the second shot hand held or on a tripod. If hand held, what was the shutter speed? Does it improve if you use electronic shutter?
Edit: Downloaded the image and read the EXIF data: 1/30s and 100iso looks to be the problem - I'd be using 1/2500s and iso 800 for that type of shot. If you look at the blades of grass around the animals, you can actually see the double images from lens or shutter shake.


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## dcm (May 22, 2021)

R6/RF800 combo here. I assume you were handholding and not a windy day. If so, I only see this type of result (second image) when the shutter speed goes too low while handholding. You might be expecting too much from the IS if you are setting ISO 100 and letting the camera choose the shutter. Often I set the ISO, but I get better results by setting the shutter and let the ISO vary with the RF800. Dxo PL4 (and others) do a nice job with higher ISO.

I'm not sure I'd go that slow, but at 1/30 I'd be on a tripod using a remote shutter. I can get good results at 1/250-1/500 if I have a fixed point (monopod, bean bag, window sill, etc.). Like Alan, I'm faster than 1/500 when purely handheld if I want a sharp result, 1/1000 if birds are involved. We all impart different amounts of shake. Give your combo a try on a tripod, fixed point, and handheld while varying the shutter speed to see if you get better results. This should confirm Alan's conjecture and help you find your sweet spot.

One thing to remember, the 1/focalLength shutter speed recommendation comes from film days when film "resolution" was generally < 16 megapixels. When we hit crop sensors, the recommendation was more like 1/(1.6 * focalLength) to compensate for higher pixel density without IS. I use 1/(2*focalLength) as a guide for my M6mII at 32 megapixels and would probably do the same with the R5. Meaning 1/1600 is minimum shutter speed without IS. This suggests you are looking for around 6 stops IS support at 1/25. Canon suggests the lens only provides 4 stops of shake protection so your result might be expected. I tend to be conservative, but it prevents fuzzy photos.


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## Bengt Nyman (May 22, 2021)

AlanF said:


> The second shot doesn't look like a simple focus issue as both foreground and background are also blurred. It looks like a stability problem. Was the second shot hand held or on a tripod. If hand held, what was the shutter speed? Does it improve if you use electronic shutter?
> Edit: Downloaded the image and read the EXIF data: 1/30s and 100iso looks to be the problem - I'd be using 1/2500s and iso 800 for that type of shot. If you look at the blades of grass around the animals, you can actually see the double images from lens or shutter shake.


Agreed. It was hand held with tree support and stabilizer on. Test shots through the range of possible shutter & ISO combos show no marked improvement. By letting the camera choose within Aperture priority there is no real improvement either. This strange general lack of focus started suddenly after months of good pictures. On tripod with shutter delay the lens performs well, both at Canon and by myself, however, in the field it suddenly does not. Why suddenly so different from earlier ?


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## Bengt Nyman (May 22, 2021)

dcm said:


> R6/RF800 combo here. I assume you were handholding and not a windy day. If so, I only see this type of result (second image) when the shutter speed goes too low while handholding. You might be expecting too much from the IS if you are setting ISO 100 and letting the camera choose the shutter. Often I set the ISO, but I get better results by setting the shutter and let the ISO vary with the RF800. Dxo PL4 (and others) do a nice job with higher ISO.
> 
> I'm not sure I'd go that slow, but at 1/30 I'd be on a tripod using a remote shutter. I can get good results at 1/250-1/500 if I have a fixed point (monopod, bean bag, window sill, etc.). Like Alan, I'm faster than 1/500 when purely handheld if I want a sharp result, 1/1000 if birds are involved. We all impart different amounts of shake. Give your combo a try on a tripod, fixed point, and handheld while varying the shutter speed to see if you get better results. This should confirm Alan's conjecture and help you find your sweet spot.
> 
> One thing to remember, the 1/focalLength shutter speed recommendation comes from film days when film "resolution" was generally < 16 megapixels. When we hit crop sensors, the recommendation was more like 1/(1.6 * focalLength) to compensate for higher pixel density without IS. I use 1/(2*focalLength) as a guide for my M6mII at 32 megapixels and would probably do the same with the R5. Meaning 1/1600 is minimum shutter speed without IS. This suggests you are looking for around 6 stops IS support at 1/25. Canon suggests the lens only provides 4 stops of shake protection so your result might be expected. I tend to be conservative, but it prevents fuzzy photos.


Thank you. Agreed. I have been impressed by this lens for BIF against the sky in spite of long distances. I have possibly come to expect too much while shooting larger animals on the ground, probably at even longer distances and with very different light conditions and exposure times. Also, earlier in the year with lower light angles from behind appears preferable to a sun overhead when it comes to animals on the ground. Thanks Alan and dcm, I will start using more rigid support for animals on the ground.


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## Bengt Nyman (May 25, 2021)

AlanF said:


> The second shot doesn't look like a simple focus issue as both foreground and background are also blurred. It looks like a stability problem. Was the second shot hand held or on a tripod. If hand held, what was the shutter speed? Does it improve if you use electronic shutter?
> Edit: Downloaded the image and read the EXIF data: 1/30s and 100iso looks to be the problem - I'd be using 1/2500s and iso 800 for that type of shot. If you look at the blades of grass around the animals, you can actually see the double images from lens or shutter shake.


Listen Alan, you already heard about this problem in February, and now you are pretending not to know anything about it. The R5 has AI phase detect focus which can learn new tricks, apparently both good and bad like for example ignoring the deer that you are pointing to and focusing on the reeds in the background instead. I could not understand why the Canon technician who checked my camera and lens pointed out that I could try to "reset my camera several times if needed". I suppose that might involve rolling the AI "improvements" back one step at a time. I have had this camera since 15 Oct 2020. How many times do you suggest that I should "reset" the camera ?


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## AlanF (May 25, 2021)

Bengt Nyman said:


> Listen Alan, you already heard about this problem in February, and now you are pretending not to know anything about it. The R5 has AI phase detect focus which can learn new tricks, apparently both good and bad like for example ignoring the deer that you are pointing to and focusing on the reeds in the background instead. I could not understand why the Canon technician who checked my camera and lens pointed out that I could try to "reset my camera several times if needed". I suppose that might involve rolling the AI "improvements" back one step at a time. I have had this camera since 15 Oct 2020. How many times do you suggest that I should "reset" the camera ?


You replied to my post once and agreed with what I wrote (three posts above) and for some odd reason have replied to it again but this time with a complaint about my pretending not to know about something you wrote in February? This is a new thread that you started a fortnight ago and I am replying to your post here. There have been thousands of posts since February and not many of us have photographic recall of past threads. If this is a follow up to something you have written earlier, say so at the beginning or add it to the the earlier thread.


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## Bengt Nyman (May 25, 2021)

AlanF said:


> You replied to my post once and agreed with what I wrote (three posts above) and for some odd reason have replied to it again but this time with a complaint about my pretending not to know about something you wrote in February? This is a new thread that you started a fortnight ago and I am replying to your post here. There have been thousands of posts since February and not many of us have photographic recall of past threads. If this is a follow up to something you have written earlier, say so at the beginning or add it to the the earlier thread.


Somebody else wrote about it February and you "gave advice". I wrote about it recently and both times you blamed a serious Canon problem on something else. Not good.


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## AlanF (May 25, 2021)

Bengt Nyman said:


> Thanks Alan and dcm, I will start using more rigid support for animals on the ground.


You even thanked me for my reply!


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## privatebydesign (May 25, 2021)

Bengt Nyman said:


> The R5 has AI phase detect focus which can learn new tricks,


That is not what Canon have said, as far as I can find they actually say the “AI” is preprogrammed and does not learn.


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## Bengt Nyman (May 25, 2021)

Say hello to Canon for me. They need to fix this, not try to deny it.


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## privatebydesign (May 25, 2021)

Bengt Nyman said:


> Say hello to Canon for me. They need to fix this, not try to deny it.


Or, you need to learn to use a camera.

Your first image looks like a crop from a badly underexposed image that was post processed horribly, whilst being shot with an 800mm lens at 1/200 second. Your second image shows extreme camera movement being shot at 1/30 second with an 800mm lens. They were both shot at 100iso which is ridiculous given the shutter speeds you used.

If you want to sort out your AF 'issues' put the camera in Tv and auto iso, put the shutter speed at 1/1000 and the iso range to cap out at 12,800 in auto. But that isn't what you want to hear, what you want to hear is Canon are bad they should do something for you. They did, they checked it out and it performs within specs.

You have a choice, learn from what you are being told even if you don't like it. Keep arguing with people that really don't care.


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## Tony_B (May 2, 2022)

Bengt: since your original post is almost a year old, I'm hoping your issue is by now resolved. I found my RF800 developed exactly the same issue, and after much consternation it returned to normal operation by turning ON the autofocus! This lens is excellent, also, in combination with the RF2x converter, it can autofocus on the moon and resolve image detail as small as 1 kilometer.


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