100-400 II Focus creep with long intervalometer runs

[[email protected]]

I've been doing much intervalometer work for time lapses and, particularly, for wildlife observation. I'm noticing that I am getting an increasing level of back focusing over time as the exposures rack up with an intervalometer run.

This is on my 7D2 today, but it's also happened as frequently with my 1DX I.

I suspect the vibration from thousands of clicks a few seconds apart from one another very slowly moves the focus ring. It's generally noticeable after about 1500 clicks. I have my bodies hooked up to power, so I'm doing quite long sets of exposures about 4 seconds apart.

To give a sense of scale, I was shooting a loon nest this afternoon, starting off with perfect focus on the sitting bird about 200 feet away, but by 2500 exposures, the focus had crept back about 15 feet behind. At f/8 this was way out of the focus plane.

I had the lens set to manual focus, IS on mode III (was clamped to a duck blind, but it vibrated a lot in the wind so mode II produces sharpest images).

I wonder if others have noticed this, and if there's anything that could mitigate this issue.

Thanks, -tig

 

[Jim Saunders]

I've seen big rubber bands wrapped around focus rings and some of the adjacent barrel.

Jim

 

[[email protected]]

Thanks, Jim. That sounds like a simple clever solution.

 

[arthurbikemad]

I've had a similar problem remote shooting, I love this lens but its rather crude at times mechanically. Focus creeps and so does the zoom, I am forever adjusting the tension for zoom, likes a say great lens but the workings are a pain!

 

[Mikehit]

I had the lens set to manual focus, IS on mode III (was clamped to a duck blind, but it vibrated a lot in the wind so mode II produces sharpest images).

I wonder if others have noticed this, and if there's anything that could mitigate this issue.

Thanks, -tig

I'd say it is the wind vibration causing a shift in focus rather than the effect of shutter actuation.
I have seen the rubber band used for zoom creep but no reason it should not work for focus creep. If you need to fine-tune the focus, would the natural recoil in the band fight against you?
A method (so far unused) but seems simpler to me would be to put a thin rigid strip lengthways on the lens so that it overlays the focus ring and use bands, cable ties or velcro strips round the non-rotating lens barrel to hod it in place.

 

[Mikehit]

One other question springs to mind: is the 100-400 a full-time manual lens? If so would fixing the focus ring in place solve the problem?