Help with R8 Focusing Issues

[SumanV]

Hi, I recently bought an R8 from a photographer and I need help in understanding the camera and any user/device issues. I come from an RP and still have it. My main problems are in using the R8 with EF 400mm f5.6L and that is the only lens I have used with the camera

I focused on the moon during the lunar eclipse and got the blue confirmation. After some time, the box became red and the lens refused to focus (box was on the moon all the time). Also, it did not make any attempt to focus. I restarted the camera, but the issue persisted until magically it started to focus again. I had issues like this before where the AF completely stops for some time and becomes active again. At that time, I didn't think much of it but my latest experience prompted me to ask for help. (I'll be visiting the Canon service center later this week) 

At the time I was having focus issues, I also tried to manually focus by setting the switch on the lens to MF. I moved the focus ring, but the lens simply did not respond. The distance scale did not change. It was as though the lens died on me. After some time, the distance scale moved! I also noticed that the lens was behaving erratically with the distance scale not showing any movement for a few times.

When the lens was in MF mode, the focus aid box appeared. The confirmation from the aid was also erratic. It showed confirmation a few times and a gray box at other times. All this time, the subject was in focus, and I did not move the focus ring!

I got the camera sensor cleaned and the lens also cleaned at the service center a few weeks before.

Is there a problem with my R8 and/or lens? I'd appreciate any tips/advice from experienced members regarding these issues. I have other issues with getting sharp pictures for birds in flight, image quality and understanding the AF system but I'll ask these after this issue gets resolved.

Thanks,

Suman

[SumanV]

Thanks again, Rodger. You have made a lot of interesting points which are new to me. In my case, when the AF issue was happening, I turned the switch on the lens to MF mode. Would the camera still control the lens at this point? I think it should not, but I do not know.

The canon execs warned me that they would stop supporting the lens in the near future when I visited them a month back. I hope that they would check the lens and repair it if needed. Going to a third party service provider would be my last option.

Regards

Suman

[SumanV]

Thanks for the tip about the monopod. I'm still new to the R8 and there are some quirks I need to understand to efficiently use the camera. My major worry is that I should not have a defective R8 especially because I bought it second hand!

Regards

Suman

[SumanV]

A small update regarding the issue.

1) Preview AF was turned off

2) Lens drive when AF impossible was set to enable i.e. it will still try to achieve focus

I visited the service center and told them of the issues I had. The exec suspected it to be a lens issue and stated that the older lens may not be optimized for the newer mirrorless bodies. He suggested to use RF lens, and he was confident that it will perform much better. I decided to hold off on the inspection and repair for now.

I am still not happy with the sharpness. I might be expecting too much. I will post some images for feedback.

[Waddizzle]

“ I do not know if this is relevant or important, but the issue started when I moved the focus box to one edge of the screen. “

This is very important.  The AF system will try to focus where the zag point is located.