Telephoto Lens Help!

[topsweep1506]

Just bought a 2x telephoto lens for my Canon 1000d that i fit to my Canon 75mm-300mm lens.

The problem being that when the lens is used on full (300mm) the images come out all grainy and the auto-focus dosent focus properly on the subject ive tried the manual focus but that is no different

Dont know if im missing something or have not set something properly

Any help apppriecated

TONY

[huntso]

Not an expert on extenders, but think they need an aperture of f/5.6 or less to autofocus which I reckon you won't get with your lens at 300mm

Best get a second opinion on that, but you might need a faster lens for that sort of focal distance

[frogesque]

My guess is the focus range can't cope with the 2x diopter. If they are both genuine Canon products check to see if there is a known issue. If not take it back to the shop or send it to Canon for a replacement.

If it's a mismatch between different manufacturers (eg. Sigma and Canon) then you may just have to live with it and not use the full 300mm x2.

[IanM]

Hi Tony

The 2 x adapters are light killers, and will make autofocus struggle or just give up. The graininess is noise as the the camera is compensating for the low light reaching the sensor by upping the ISO to cope with low light.

I only use the 1.4x adapter, it will make an f4 lens work as an f5.6, so makes life easier. If you are using a lens with a maximum aperture less than f4 then an adapter is only really useful in bright light for shots that don't involve any sort of action.

Ian