70-200 2.8 - Possible Issue

S

Slicker

Messages
315
Name
Paul
Edit My Images
Yes
Hi,

I think I may have a little problem with my 70-200 2.8 - its the non IS version.

It seems to struggle to autofocus in the 3m position. I can focus it manually and it looks ok but still like the use of the autofocus.

It auto focuses ok in the 1.5 setting.

Also - I was at the Farnborough iar show and noticed that some of my pictures looked a little on the soft side. I was using this lens with a Canon 2xTC..... might just be that they were still pretty far away!

Any thoughts?

Thanks
Paul
 
My understanding is that any lens tends to struggle with a 2x converter on it to AF....
Aren't there only a few cameras in the range that will still 'happily' AF with a 2x converter on it ? and I don't think the 400D is one of them.. :(
 
right... I was able to autofocus with the 400D with it in the 1.5 setting. is the 3 setting it tried and hunted but never locked...

Sadly my 7D didn't turn up in time!

also - I think I have seen the same issue without the TC
 
With the 2x converter on you really reduce the amount of light getting into the camera and AF takes a huge hit. The 70-200 is a great lens right enough.

At the 3m setting, what are you trying to focus on and were they all with the 2x?
 
The 2 settings on the 70-200mm are as you stated 1.5m - ∞ and 3m - ∞ if you switching between both, the autofocus might get abit confused especially if you adjusting the focus.

However you were also using a 2x TC with this lens, this would definitely generate soft images, its not a great combination, especially looking at images from Farnborough in the transport forum, the light conditions were challenging at best over the weekend and I think that would have been another factor in why that lens was struggling.
 
When you put the 2x converter on a 70-200 f2.8 it stops it down by a couple of stops to a f5.6 which is the minimum for auto focusing meaning it will struggle a little.

A friend of mine who had both the f4 and f2.8 version says the f4 just snips the 2.8 for image sharpness.
 
I am sure I have noticed the issue with general pictures, landscapes, portraits etc when I use the 3m setting. I am not sure if there is a problem with my lens or not... I will have to have another play with it without the TC and see what happens...

Thanks for the comments

Paul
 
simonbell19 said:
When you put the 2x converter on a 70-200 f2.8 it stops it down by a couple of stops to a f5.6 which is the minimum for auto focusing meaning it will struggle a little.

A friend of mine who had both the f4 and f2.8 version says the f4 just snips the 2.8 for image sharpness.
Click to expand...

How sharp is the f4 @ f2.8 ? :thinking:
 
You must log in or register to reply here.
Back
Top