June 23, 2018, 06:14:41 PM

Author Topic: Leaked: Sigma 70mm f/2.8 DG MACRO | Art  (Read 5308 times)

noncho

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #15 on: February 26, 2018, 02:24:34 PM »
I still have the old Sigma 70 2.8, which is very good optically. It's noisy and not that fast focusing, but does it's job.
So I would not change it for a bit better, but still not OS lens. 

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #15 on: February 26, 2018, 02:24:34 PM »

ahsanford

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #16 on: February 26, 2018, 02:30:01 PM »
Besides being 70mm, but what will make this special?  2X?  f/1.8?  If both, I'm interested.

Not every new Sigma lens has to be "special" in some way. This one only has to be a nice sharp competitively-priced 70mm f/2.8 1:1 macro lens.

...that is externally focusing like the EF 50mm f/2.5 compact macro.   Ouch. 

Can someone tell me what that's a good thing?  The EF-S 60mm and EF 100mm L and non-L are all internally focusing, are they not?  Why does this Sigma need to telescope out so dramatically? 

- A

aceflibble

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #17 on: February 26, 2018, 04:50:32 PM »
Internally-focusing macros have to use strong focus breathing to focus down to 1:1 (let alone beyond), and it takes a bigger toll on transmission, too. For example, the Canon 100mm f/2.8L IS Macro, when it's at absolute 1:1, is actually about 72mm t/7.4. (Give-or-take for minor copy variation and specific shooting scenario; I haven't used the EF-S 60mm or non-L 100mm to have their measurements to hand.) Of course weight and cost also go up.

Externally-focusing macro lenses can go to whatever magnification you want without changing the actual focal length, and though of course light is lost as the lens extends, it's usually not actually as much of a loss as when the lens has to shift everything around internally. That's the benefit to simpler designs like this. So this Sigma probably stays at 70mm no matter what magnification you want, and likely gets no darker than t/5 or so.

It used to be that externally-focusing lenses also had less trouble with distortion, but these days that's mostly equalised.

All that said, I would expect the most likely reason for going for external focus is simply cost. Sigma have proven they can nail extremely demanding optics, but they are still somewhat obligated to keep their prices below first-party options. With Tamron undercutting them even further, I wouldn't be surprised if Sigma doubled down on their own penny-pinching.

FramerMCB

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #18 on: February 26, 2018, 05:10:11 PM »
Internally-focusing macros have to use strong focus breathing to focus down to 1:1 (let alone beyond), and it takes a bigger toll on transmission, too. For example, the Canon 100mm f/2.8L IS Macro, when it's at absolute 1:1, is actually about 72mm t/7.4. (Give-or-take for minor copy variation and specific shooting scenario; I haven't used the EF-S 60mm or non-L 100mm to have their measurements to hand.) Of course weight and cost also go up.

Externally-focusing macro lenses can go to whatever magnification you want without changing the actual focal length, and though of course light is lost as the lens extends, it's usually not actually as much of a loss as when the lens has to shift everything around internally. That's the benefit to simpler designs like this. So this Sigma probably stays at 70mm no matter what magnification you want, and likely gets no darker than t/5 or so.

It used to be that externally-focusing lenses also had less trouble with distortion, but these days that's mostly equalised.

All that said, I would expect the most likely reason for going for external focus is simply cost. Sigma have proven they can nail extremely demanding optics, but they are still somewhat obligated to keep their prices below first-party options. With Tamron undercutting them even further, I wouldn't be surprised if Sigma doubled down on their own penny-pinching.

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Tanispyre

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #19 on: February 26, 2018, 05:10:44 PM »
The old 70mm Sigma macro was one of the best short macros (short for me is < 100mm) optically I have ever used.  Easily it out performed the Canon 50 F2.5, Nikon 60 F2.8, and the Tamron 60 mm F2 macro lenses I have used.  The Canon EF-S 60 mm was pretty close optically, but as the Sigma was full frame I would probably give the nod to the Sigma.  If all they did was update the housing and focusing, then this will still be an excellent lens.

ahsanford

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #20 on: February 26, 2018, 05:18:02 PM »
Internally-focusing macros have to use strong focus breathing to focus down to 1:1 (let alone beyond), and it takes a bigger toll on transmission, too. For example, the Canon 100mm f/2.8L IS Macro, when it's at absolute 1:1, is actually about 72mm t/7.4. (Give-or-take for minor copy variation and specific shooting scenario; I haven't used the EF-S 60mm or non-L 100mm to have their measurements to hand.) Of course weight and cost also go up.

Externally-focusing macro lenses can go to whatever magnification you want without changing the actual focal length, and though of course light is lost as the lens extends, it's usually not actually as much of a loss as when the lens has to shift everything around internally. That's the benefit to simpler designs like this. So this Sigma probably stays at 70mm no matter what magnification you want, and likely gets no darker than t/5 or so.

Ask, and the forum educates.  Thank you for a super helpful post -- very much appreciated!

A

slclick

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #21 on: February 26, 2018, 05:18:16 PM »
Are we positive it's NOT much more than a 1:1? With the external focusing, it could be offering up more magnification.
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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #21 on: February 26, 2018, 05:18:16 PM »

scyrene

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #22 on: February 26, 2018, 06:43:45 PM »
Internally-focusing macros have to use strong focus breathing to focus down to 1:1 (let alone beyond), and it takes a bigger toll on transmission, too. For example, the Canon 100mm f/2.8L IS Macro, when it's at absolute 1:1, is actually about 72mm t/7.4. (Give-or-take for minor copy variation and specific shooting scenario; I haven't used the EF-S 60mm or non-L 100mm to have their measurements to hand.) Of course weight and cost also go up.

Externally-focusing macro lenses can go to whatever magnification you want without changing the actual focal length, and though of course light is lost as the lens extends, it's usually not actually as much of a loss as when the lens has to shift everything around internally. That's the benefit to simpler designs like this. So this Sigma probably stays at 70mm no matter what magnification you want, and likely gets no darker than t/5 or so.

It used to be that externally-focusing lenses also had less trouble with distortion, but these days that's mostly equalised.

All that said, I would expect the most likely reason for going for external focus is simply cost. Sigma have proven they can nail extremely demanding optics, but they are still somewhat obligated to keep their prices below first-party options. With Tamron undercutting them even further, I wouldn't be surprised if Sigma doubled down on their own penny-pinching.

That's really interesting, thanks! I've always meant to compare my 100L with the 24-105L at ~100mm to see if they differ, but now I know what to expect :)
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Sharlin

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #23 on: February 27, 2018, 04:12:45 AM »
Are we positive it's NOT much more than a 1:1? With the external focusing, it could be offering up more magnification.

This picture shows the lens at 1:1 and what appears to be maximum extension.

The nifty thing about the lens is that the inner barrel only extends as far as the lens hood (which is attached to the outer barrel). So with the hood on the external length of the lens doesn't change.

chrysoberyl

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #24 on: February 27, 2018, 07:58:44 AM »
Minus: focus by wire.  I don't care; if the long throw really is long.
Plus: compatible with Sigma TC's.  There's that 2:1 magnification I want without sacrificing infinity focus.

Quite an intriguing lens!  Maybe the one for backpacking.
« Last Edit: February 27, 2018, 09:14:47 AM by chrysoberyl »

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Re: Leaked: Sigma 70mm f/2.8 DG MACRO | Art
« Reply #24 on: February 27, 2018, 07:58:44 AM »