1.4x tc problem with 100-400L

[scraggs]

Hi all
I treated myself to a Kenko 1.4 tc which arrived today which I coupled to my 100-400 & 400D, now I taped the 3 pins and have autofocus but noticed that with IS switched on all shots were blurred if I turned it off the shots were increadibly good, anyway on further shots I noticed that with IS on, the focus point was over to the left after the shot was taken, and after the shot was taken it would slowly move back to the right to where I had origanaly focused.
A little hard to explain but I tried these shots tripod mounted to eliminated error, has anyone come across anything like this before ?

[sgamuk]

i had the same problem before. make sure you turn off your IS when mounted on tripod. otherwise, the autofocus will wander to either left or right or could be up or down while you're holding the shutter halfway. after you release the shutter, the autofocus goes back to original position and you'll hear a little snapping sound.

check this thread:
http://photography-on-the.net/forum/...ghlight=sgamuk

[scraggs]

I have just taken a few more shots with it untaped handheld with IS on.
Its weird if I leave it at F8 at 400mm it doesnt move and the shots are really sharp but if I stop down 1 or more stops it moves as you are taking the shot and the shots are terrible.
It appears that at any length so long as its not stopped down its fine.
I have taken the tc off and there is nothing wrong with the lens at all.

[Roy C]

Originally Posted by scraggs

I have just taken a few more shots with it untaped handheld with IS on.
Its weird if I leave it at F8 at 400mm it doesnt move and the shots are really sharp but if I stop down 1 or more stops it moves as you are taking the shot and the shots are terrible.
It appears that at any length so long as its not stopped down its fine.
I have taken the tc off and there is nothing wrong with the lens at all.

Which Camera are you using?. I have heard of IS problems with this lens and a taped converter when being used on a 400D body.

[scraggs]

Yes I am using it on a 400D but tried it untaped and taped and in both cases unless fully open the af point moves whilst taking the shot.
I am at a bit of a loss with it, perhaps the tc is faulty, like I have said the lens is fine without the tc.

[oldsquawk]

With the pins untaped you are manually focusing, right? It's not unusual for the IS to make the image move a little as it adjusts the element to correct for vibration. You have to be sure that you have the shutter button pressed halfway down for 1 sec to allow time for the IS to start up properly. If you are just pushing the shutter button with no delay, the IS is moving the element it controls during the exposure. Hold the shutter button down halfway, let the IS turn on and move the element into proper position, then make the exposure. The reason it looks more radical with the 1.4x tc installed is because the 1.4x tc is magnifying the image and any image movement is magnified, too. You gotta give the IS time to turn on. IS cannot work instantly. Also, IS is to be turned off in this lens when used on a tripod.

[xpsentity]

Like all said;

IS OFF when on a tripod. It's the older design, and cannot sense it.

When you have IS on while the lens is tripod mounted, it confuses the IS in to... hunting around; and consequently, screwing up your shots.

[scraggs]

Well after quite a few more shots I have come to the conclusion that something must be wrong with the tc. As I said before the shots are really crisp handheld wide open but terrible as soon as you stop the lens down.
I wouldnt have thought there could be a lot to go wrong with it but it must have some circuitry inside it.
Back to Hong Kong it goes