C100: Sigma 17-70 coverage

M

MPM

Active member
HI all,

Just wondering if anyone has used this lens on their C100/300 and also if by any chance it covers the whole sensor or does the ef-s function need to be used?

Also, for those that have used the ef-s function, does the image noticibly become softer or worse etc.

Cheers heaps,

Phil
 
The 2 EFS lens I have (18-135stm and old 2004 18-55mm kit lens) do not not need to be in EF-S mode. From what I've gathered is that there are allot of EF-S lenses that do not require this mode to be set. Maybe others will chime in.
 
Got the lens...it covers the sensor without efs mode which is cool.

Seems nice and sharp too but haven't used it that much.

It does shift aperture when zooming. I was hoping it would hold constant at f4 from 17-70 but it shifts to 5.6 at the long end (shows on the C100 reading) but so did my 17-40L and 24-105L (though the aperture still read f4 on these).

Build feels solid, focus throw is tiny as expected.

So far I'm happy, especially with the range and the OS.

Will try and get some frame grabs up at the end of the week.

Cheers,

Phil
 
MPM said:
I was hoping it would hold constant at f4 from 17-70 but it shifts to 5.6 at the long end (shows on the C100 reading) but so did my 17-40L and 24-105L (though the aperture still read f4 on these).
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Wait what? I thought the 17-40L and especially the 24-105 where constant f/4 though out the focal range?
 
Hi Tim,

Yeah they are constant but they both will get darker at the long end. From memory when shooting video it's about one stop.

It's very frustrating!
 
MPM said:
It does shift aperture when zooming. I was hoping it would hold constant at f4 from 17-70 but it shifts to 5.6 at the long end (shows on the C100 reading) but so did my 17-40L and 24-105L (though the aperture still read f4 on these).
Click to expand...

This reads as if the aperture actually changes to 5.6, but you mean that the image gets darker and that the C100 indicates the underexposure?
 
AndreeOnline said:
This reads as if the aperture actually changes to 5.6, but you mean that the image gets darker and that the C100 indicates the underexposure?
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That's kind of what it sounds like to me, As you get to 105mm the image gets darker similar to if you would stop down but the camera still reads the aperture at f/4. Very interesting.
 
Tim Nitsch said:
That's kind of what it sounds like to me, As you get to 105mm the image gets darker similar to if you would stop down but the camera still reads the aperture at f/4. Very interesting.
Click to expand...

Hey guys,

Yeah after reading what I wrote, it does sound confusing...sorry.

The Canon lenses don't change aperture reading, but they do lose light (if that makes sense) at the long end.

This Sigma actually changes f stop which, after reading what I originally wrote, doesn't make sense at all. I have contacted the people I bought the lens off with this complaint and they said they will talk to Sigma and see what they say.

Any thoughts on this one? I figure if Sigma states the lens as 2.8-4, the reading on camera should stay constant at f4 throughout the range, yeah?

Cheers all,

Phil
 
MPM said:
I figure if Sigma states the lens as 2.8-4, the reading on camera should stay constant at f4 throughout the range, yeah?
Click to expand...

Yes, definitely. It should stay at f4. Might be a simple software bug of sorts.

This issue aside, I've taken up an interest in this lens. I have the 24-105L f4 IS which I basically like, but it's not quite wide enough to really cover all bases as a "slap it on and leave it on" lens.

The 17-70 range is pretty unique and it even starts at f2.8 and ends up 'worst case' at f4 (I'm going with that for now).

I'd like to see some images from people using this lens on a C100 or C300! If you can't contribute footage, but have some experience with it, don't hesitate to share some info. Thanks!
 
The shop I bought this lens off said they contacted a Sigma agent and they said it was normal for the lens to change aperture like. I disagreed and the lens is on the way back for a refund.

Phil
 
I had a similar problem with the Canon 15-85 f3.5-5.6. It was the perfect zoom range for me but I could not keep it at a constant f5.6 due to aperture flicker when zooming.

I hope canon come out with an equivalent to the Sony 16-70 f4.
 
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