The Sigma 150-600 S sharpness in the long end

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Tord S Eriksson
Tord S Eriksson Forum Pro • Posts: 10,068
The Sigma 150-600 S sharpness in the long end

The other day I noticed that my copy of the Sigma S seemed to be a bit sharper at 575mm than at 600mm. The difference was barely noticeable, but it became evident when I added my TC-1401. Thus, at 800mm, it was decidedly sharper than at 840mm.

I found that very interesting — has other in this forum found the same thing?!

The focusing distance was around 7 meters (23 ft), and I tried to eliminate factors like an eventual shake (used timer, and a sturdy tripod), and AF oddities (used two different cameras). Used the cameras focusing, checking by enlarging the live view, each time.

Another thing I noticed was that at 550mm the 150-600 S wasn't sharper than the Sigma 100-400 with the TC-1401 (both at f/10).

Scary!

I also shot with the S at 400mm, with the TC mounted (resulting in a combined focal length of close to 550mm), and I could not find the image quality worse, than without the TC (at 550mm).

So it seems I need to invest in a second TC, one for the 100-400 and one for the 150-600 S!

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tordseriksson (at) gmail.....
Canon, Olympus, Pentax, Ricoh, Sony, and Nikon user/owner.

 Tord S Eriksson's gear list:Tord S Eriksson's gear list
Olympus C-8080 Wide Zoom Ricoh GR Nikon 1 V1 Nikon D600 Nikon 1 V2 +25 more
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