100-400 lens

[billy46]

Hi there i have a 100-400 lens on a 7d when you look through the view finder and half press the shutter what you are looking at the picture goes up on the lens and when you release the shutter the picture drops down don't know if it is meant to do this and another thing when you take photos they dont look sharp we have tried this on another camera and it does the same the photos look fuzzy round the edges and not quite in focus does any one have a answer to this thanks

[wavemachine]

It could be the weight of the lens causing you to naturally drop slightly after pressing the shutter, have you tried shooting from a tripod to see if the result are any sharper.

Try shooting with IS switched on and off at fast shutter speeds, if necessary bump the ISO up and see what results you get.

[MattUK]

It's probably the image stabilisation. When you half press the shutter, the lens tries to 'lock on, and keep the view as still as possible - but sometimes it looks as though there's an initial jump at first

[Cathus]

agree with Matt, happens with my 100-400, also happens after you've locked on & then recompose sometimes it jumps out again.

You'll probably find images less sharp at 400mm than they are at 350, this is common on most large zooms. you'll also need to keep the shutter speed up, in my experience with this lens even with IS if you shoot at below 1/400 sec at maximum focal length they are prone to camera shake & therefore can blur quite easily.

I usually suggest sticking it on a tripod, slapping a nespaper or maagzine on the wall & firing off test shots at different apertures & focal lengths to find the best settings, try hand held also & compare the results

[matt wilson]

I have one and use a 50 d .Have you tried fine tuning the focus for the lens .