I thought I would write this short note for information, as the slightly disappointed recipient of the above Sigma teleconverter. For some time, I have been considering purchasing this converter to fit both my Sigma 150-600 C lens and Canon EOS760D camera. I have been really pleased with the Sigma lens which has worked fine with this camera, yet there are occasions when the subject is still out of reach or, a favourite subject would benefit from finer detail. In my pre-purchase research it became clear that the camera's 'autofocus' capability 'may not' necessarily work. Sigma do not specify which models will be affected, but say - 'compatible where autofocus at f8 can be achieved'. On that basis and using anywhere from f6.5 to f12 for shooting, I went ahead with the purchase. In line with what I had read on many blog comments, I powered up the combination and the camera defaulted to Manual Focus at f9. Not a hint of autofocus at any f number or any position along the zoom lens (mm). I have read where buyers have 'returned the goods' or 'wasted their money' or 'thrown it in a drawer!' The problem when senior years start creeping up on you is, your eyes may not be quite up to peering into a small viewfinder, at what is certain to be an already far away object! Having spent my working life as an engineer and, rather like 'a dog with a bone' when given a diffiicult breakdown, this converter wasn't going to end up in a drawer! There will be a way I can make this work. The solution I have found to be more than acceptable is as follows - Extend the zoom lens to the desired position and make the best focus you can, manually. Switch the camera to 'video' (camera achieves focus) and start video. Subject viewable on camera screen. Press shutter button fully down - video is interrupted momentarily and a 'still' shot is taken (saved as a separate file). The taking of a still shot during video is described in Canon's instructions, but not the application I am using it for - to get an autofocus at 840mm!! The saved image is not as you may expect, a small file, but is of the same size as would normally be taken i.e 5 or 6 Mb. There is no doubt, more testing will be required in the field but for now, comparable images of a Sky dish at the far end of the street show a 'more acceptable' focus than my guestimate. Manual focus Auto focus
I hope this proves useful and would welcome any comments. Comments are closed.
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