IS on or off when shooting from a boat?

[Spuriousfish]

Recently I took some shots of dolphins from a boat which was sitting in a reasonable swell. The majority of shots where disappointing.

I was shooting with a 7D + 70-200mm F4 IS L. IS was on and set to Mode 1. Focus was set to AI FOCUS AF, which was not what I intended but that's what was set.

Shutter speed was in the region of 1/1600 and burst mode set.

Does any have any suggestions as to the best setup for this i.e what should IS be set to and also what is the best focus mode?

Thxs
Colin

 

[travellingcello]

At 1/1600 IS isn't doing anything anyway, I can't be sure but it should probably be turned off?

 

[Rojibo]

Can you post some shots? At a guess you either missed focus or the DoF wasn't big enough. Depends how bad the movement was but 1/1600th is pretty fast.

 

[Spuriousfish]

I'm not at home right now but will try and post some in a couple of days.

My thoughts are is that it's a focus thing rather than movement.

Colin

 

[jon ryan]

Doubt if IS would make any difference. Rojibo's DoF sounds like a good call. Problem may have been the low contrast between sea and dolphin and lack of anything hard edged confusing the AF lock. If you get another chance, try around f/10 and maybe manual focus. And if you have a polo filter, I'd use it - helps protect the lens from salt as well as cutting glare.

 

[Orville]

I would take an educated guess and say that IS will be pretty much useless on a small boat, on anything other than calm waters. IS corrects shake, but cannot compensate for large movements. If anything, IS will make things worse. However, if you happened to be sitting on a Nimitz class aircraft carrier it would probably work well, so long as the target was motionless.