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Author Topic: Sony 100mm f/2.8 STF GM  (Read 1299 times)

shadowblade

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Sony 100mm f/2.8 STF GM
« on: February 09, 2017, 03:26:19 PM »

http://www.sonyalpharumors.com/sony-100mm-f2-8-stf-fe-image-samples-mtf-graph/

Looks like a very interesting lens - f/1.4-level background blur with the depth of field (and increased sharpness) of shooting at f/2.8.

It probably has a very slow T-stop, though.

Probably most useful for portraits, but, depending on maximum magnification, it could also be very useful for macro work.

Hope they also make one in 135mm, like the original Minolta.
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scyth

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Re: Sony 100mm f/2.8 STF GM
« Reply #1 on: February 09, 2017, 03:38:38 PM »

Hope they also make one in 135mm, like the original Minolta.

too exotic to have 2 in the system... I bet nobody does 2 different (focal length) STF lenses in one mount.
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davidgp

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Re: Sony 100mm f/2.8 STF GM
« Reply #2 on: February 09, 2017, 04:21:24 PM »

shadowblade

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Re: Sony 100mm f/2.8 STF GM
« Reply #3 on: February 09, 2017, 04:29:02 PM »

too exotic to have 2 in the system... I bet nobody does 2 different (focal length) STF lenses in one mount.

Not really. If you think about it, it's just another bokeh-focused lens  if you can find a use for both an 85/1 4 and 135/2.0 or 200/2.0, or two different macro lenses, you can just as easily use two different STF lenses. It's just another way to achieve a desired effect.
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Jim Kasson

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Re: Sony 100mm f/2.8 STF GM
« Reply #4 on: February 09, 2017, 06:11:25 PM »

http://www.sonyalpharumors.com/sony-100mm-f2-8-stf-fe-image-samples-mtf-graph/

Looks like a very interesting lens - f/1.4-level background blur with the depth of field (and increased sharpness) of shooting at f/2.8.

It probably has a very slow T-stop, though.

Probably most useful for portraits, but, depending on maximum magnification, it could also be very useful for macro work.

Hope they also make one in 135mm, like the original Minolta.

The diameter of the blur circle is that of an f/2.8 lens, not of a f/1.4 one, but it drops off faster. See here for a comparison of the 135 STF to two other 135 lenses, all at f/2.8.

It's a T/5.6 lens, indicating more aggressive apodization than that of the 135 STF.

Jim



RobertJ

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Re: Sony 100mm f/2.8 STF GM
« Reply #5 on: February 09, 2017, 09:54:46 PM »

I have the Laowa 105mm f/2 (T3.2) in E mount for my A7RII.  The CA/fringing control is out of this world amazing on this lens.  Better than any APO lens on the market, IMO, including the Otus lenses.  It's not as sharp, but it's a really great lens at all apertures, especially 2.8 and 4.0.

Phillipreeve.net has a review here: https://phillipreeve.net/blog/review-laowa-stf-105mm-f2-0-t3-2/

See a comparison of the purple fringing of the Zeiss 100mm Makro to the Laowa (credit to Phillip Reeve):

Laowa 105mm @ f/2: https:[email protected]/27798991273/sizes/o/

Zeiss 100mm MP @ f/2: https:[email protected]/28310129632/sizes/o/

I'm sure the Sony will be much sharper than the Laowa, as they really do make really sharp lenses, like the 90 macro and 85 GM, however, CA is a different story.  We'll have to see.
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shadowblade

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Re: Sony 100mm f/2.8 STF GM
« Reply #6 on: February 09, 2017, 11:45:51 PM »

The diameter of the blur circle is that of an f/2.8 lens, not of a f/1.4 one, but it drops off faster. See here for a comparison of the 135 STF to two other 135 lenses, all at f/2.8.

It's a T/5.6 lens, indicating more aggressive apodization than that of the 135 STF.

Jim

Strictly speaking, yes. But the falloff is such that the background just merges into a big blur, without clear circles.
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Paulo Bizarro

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Re: Sony 100mm f/2.8 STF GM
« Reply #7 on: February 10, 2017, 04:16:32 AM »

I started a thread in the other forum a few days ago:

http://forum.luminous-landscape.com/index.php?topic=116308.0

shadowblade

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Re: Sony 100mm f/2.8 STF GM
« Reply #8 on: February 10, 2017, 11:12:52 PM »

Will be a very interesting comparison between this one and the 85/1.4 GM.

Similar background blur (in fact, this one may be even better and smoother, despite being only f/2.8), similar focal length. The 100mm gives you much more of the subject in focus and should produce a very blurred background even when stopped down, but requires 4 times the exposure time due to the slow T-stop. It should also be sharper, since the lens is of a simpler optical design than the f/1.4.

Any idea if the nature of the blur is controllable, or fixed?

Maybe the 85mm for indoor or low-light, no-flash portraiture and the 100mm for when you have flash available. Either would work in a studio setting, since you can control the backdrop. But I can see the 100mm really shining in location shoots with portable lighting.

What I'd really like to do is attach an extension tube to this lrns and use it to shoot macros. It already has 0.25x magnification, so achieving greater magnification for small  subjects shouldn't be difficult. And the ability to achieve nicely-blurred backgrounds even when heavily stopped down could be very useful - with macro subjects, you rarely have the luxury of choosing your background and often need to shoot at f/16, so the ability to blur a busy background to oblivion would be very useful indeed.
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Jim Kasson

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Re: Sony 100mm f/2.8 STF GM
« Reply #9 on: February 10, 2017, 11:50:36 PM »

Will be a very interesting comparison between this one and the 85/1.4 GM.

Similar background blur (in fact, this one may be even better and smoother, despite being only f/2.8), similar focal length. The 100mm gives you much more of the subject in focus and should produce a very blurred background even when stopped down, but requires 4 times the exposure time due to the slow T-stop. It should also be sharper, since the lens is of a simpler optical design than the f/1.4.

Any idea if the nature of the blur is controllable, or fixed?

Maybe the 85mm for indoor or low-light, no-flash portraiture and the 100mm for when you have flash available. Either would work in a studio setting, since you can control the backdrop. But I can see the 100mm really shining in location shoots with portable lighting.

What I'd really like to do is attach an extension tube to this lrns and use it to shoot macros. It already has 0.25x magnification, so achieving greater magnification for small  subjects shouldn't be difficult. And the ability to achieve nicely-blurred backgrounds even when heavily stopped down could be very useful - with macro subjects, you rarely have the luxury of choosing your background and often need to shoot at f/16, so the ability to blur a busy background to oblivion would be very useful indeed.

That's not gonna work with this lens. The apodization looses strength as the lens is stopped down and you start to use only the center of the apodization element. With the 135 T/4.5 lens the STF range stops at T/6.7.

Jim

shadowblade

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Re: Sony 100mm f/2.8 STF GM
« Reply #10 on: February 11, 2017, 12:06:11 AM »

That's not gonna work with this lens. The apodization looses strength as the lens is stopped down and you start to use only the center of the apodization element. With the 135 T/4.5 lens the STF range stops at T/6.7.

Jim

Damn - I was hoping the secondary aperture would be just as adjustable as the primary.

Still, if the range is t/5.6-t/9, shooting a portrait at f/4 should allow both eyes to be sharply in focus, even when the plane of the subject's face isn't parallel with the focal plane.

No chance of a macro lens designed this way, optimised for smaller apertures?

Those flower shots look impressive. It'd be nice to know the settings.
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