Extender Help

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Gregory Hicks

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I have a Sigma 70-200 HSM 2.8

If i get the sigma 1x4 extender what happens to this lens with regards apature and focal length????

Thanks Guys
 
You get 1.4 times the focal length, so it becomes a 98-270.
You also get 1.4 times the minimum aperture (1 stop) which becomes f4.
 
It doesn't change the minimum focus distance, so you'll get an image that's 1.4 times larger at the minimum distance.
 
Stoptime said:
It doesn't change the minimum focus distance, so you'll get an image that's 1.4 times larger at the minimum distance.
Click to expand...
Not strictly true Frank, the working distance (object lens to subject distance) remains the same but the minimum focus distance (focal plane to subject) increases by an amount equal to the physical length of the T/C. In telephoto usage then this is fairly insignificant but it becomes more of a factor with macro type shooting.

Bob
 
The minimum focus distance of the 70-200 is 1 metre.
The physical length of the Sigma 1.4 extender is around 0.018 metre.
It's insignificant, in this case.

I was simply being helpful, not trying to impress.
 
It comes down to perception and an extra 18mm to Frank is clearly insignificant :notworthy: ...whereas I've had occasions where it would have been very welcome :'(
 
I use my Kenko DGX 1.4x TC on my Canon 70-200 f4 and the IQ is still excellent with the converter on. It takes my f4 up to f5.6 which means I still get AF and great IQ at 280. My TC even retains AF with my 100-400 f4-5.6 L even though it takes it to f8. I chose the Kenko as its compatable with more of my lenses than the Canon is.
 
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