D5200 with Sigma 1.4x 1401 tele converter on Sigma 150-600c, will it autofocus?

Started 5 months ago | Discussions thread
Jocksa Senior Member • Posts: 1,054
Re: Expensive route to poor quality images

David Lal wrote:

I've tried teleconverters (TC) in the distant past but obtained better image quality simply by cropping. TC + consumer zoom lens=poor images generally. On a top notch prime a TC might in good light might give acceptable results.

I've seen passable results with 1.4 x TC on a Nik 70-200/F2.8 but still not stunning.

Save your money. How many pixels do you need anyway? What will you do with the images?

Both zooms and teleconverters have come a long way optically. The 70-200/4 I mentioned above is widely accepted as being optically very good. I did some tests with the 2x TC and found that at some lens settings the quality of the image was better with the TC than without. So for example, with the lens at 100mm and the 2x TC, the image was better than the lens on its own at 200mm.

What this means is that the degradation caused by a modern teleconverter on a compatible lens is within the limits of the difference in quality along the range of a zoom that is already acknowledged as pretty sharp.

The thread is here if you're interested How bad is a 2x teleconverter on f/4 telezoom?: Open Talk Forum: Digital Photography Review (dpreview.com) To save you reading beyond the first post, Picture 1 is with the teleconverter.

As I said above, despite decent optical performance, f/8 just wouldn't support reliable AF so I chopped the 2x for a 1.7x.

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