Back Button Focus

Hi All.

Hope you are all keeping safe in these trouble times.

I wondered how many of you use the back button focus option. I currently have the 760D and have been struggling a little with focus on certain things.

The main focus issue i;m having is shooting Railway images, moving locos at around 60-70mph. I'm using a shutter speeds of around 1/640. I was initially using one shot focus mode but recently swapped to AI servo.

I'm not sure if it;s me, most likely or i have an issue with the camera. I'm just not able to get a crisp image.

I read an article on back button focusing and wondered if anyone shot a similar subject using this method?

Thanks Andy.

whittle74 wrote:

Hi All.

Hope you are all keeping safe in these trouble times.

I wondered how many of you use the back button focus option. I currently have the 760D and have been struggling a little with focus on certain things.

The main focus issue i;m having is shooting Railway images, moving locos at around 60-70mph. I'm using a shutter speeds of around 1/640. I was initially using one shot focus mode but recently swapped to AI servo.

I'm not sure if it;s me, most likely or i have an issue with the camera. I'm just not able to get a crisp image.

I read an article on back button focusing and wondered if anyone shot a similar subject using this method?

Thanks Andy.

Hi Andy... Hmm... Couple things come to mind

1: Are you handheld and panning or are you on a tripod pre-focusing on a certain spot.

If you are handheld, then BBF would work fine and using Servo. You just keep your thumb on the BB tracking your subject making sure it is "acquired" and hen press the shutter when you want (keeping the BB pressed).

If you are on tripod you could still use BBF if you don't move the camera, pre-acquire focus and then take your hand off the BBF... This puts the camera in One Shot.. Then when you train gets into position fire away.

Shutter speed 400. fstop f7.  ISO 1000.

high speed continuous. AI servo. camera 7D MK11