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Author Topic: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8  (Read 6518 times)

kennyyounger

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Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« on: July 28, 2015, 05:56:49 pm »

I just received my Sigma 50mm f/1.4 ART. It's a beautiful lens, and incredibly sharp at large apertures.

But I shoot mostly landscapes, and find that stopping this lens down to my typical f/8 on a tripod, I can't seem to get much more sharpness out of it than my Canon 24-105mm f/4L IS @50mm and f/8. Maybe a little better on vignetting and chromatic aberration but even then, I really had to pixel peep to tell. The one area that I really noticed improvements was distortion; the Canon has noticeably worse distortion. Clearly it's better in certain ways, but it doesn't seem worth adding to my bag (and back... it's 1.8lbs!).

Does anyone else have this lens? What are your thoughts on these fronts? Could I have a bad copy?
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Some Guy

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #1 on: July 28, 2015, 07:30:57 pm »

Interesting you noticed the CA.

I have the 35mm ART and I used their tuning puck to fine tune the AF which helped as it tunes over four different distance ranges.

However, I also have the latest beta of Reikan FoCal and I let it run though the test on a Nikon D800E and compared it against the 24-70mm f/2.8 Nikon.  The Nikon had far better CA results than the Sigma which surprised me for a zoom.  The beta software will draw out the Red, Blue, and Green "best focus tuning curves" during the testing and the Sigma was pretty far apart against the Nikon's curves so the unsharpness may be the result of the CA matter with my 35mm ART.  Sort of interesting, but I like the looks and size of the Sigma over the Nikon (It's better looking, imho.) and it is faster at f/1.4 so I'll keep it for when I need a fast prime.  Not a big deal breaker, but it's got some issues.

Fwiw, I also own the first iteration of the Tokina 11-16mm f/2.8 DX lens and it was really bad for CA.  They came out with the II version shortly after that to address some of it.  In FoCal, the software has issues even trying to give me a decent AF Tuning number it is so bad.  My first FoCal beta came out with "You need to set your camera's AF to -45" which is impossible on a Nikon as it only goes to -20.  Go figger.

SG
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kennyyounger

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #2 on: July 28, 2015, 07:36:17 pm »

Yeah, the CA isn't too bad on either lens at f/8. The Sigma really shines at f/1.4 there's hardly any there, too.

Do you own another lens besides the 35mm ART that can do 35mm? Have you ever compared the two at 35mm f/8? Does the Sigma offer much improved sharpness?
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Some Guy

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #3 on: July 28, 2015, 07:58:35 pm »

Yeah, the CA isn't too bad on either lens at f/8. The Sigma really shines at f/1.4 there's hardly any there, too.

Do you own another lens besides the 35mm ART that can do 35mm? Have you ever compared the two at 35mm f/8? Does the Sigma offer much improved sharpness?
Here is the Sigma 35mm ART and the Nikkor 24-75m f/2.8 zoom set at 35mm and run in FoCal.  Both shot wide open though.

You can see in the Sigma on the left of the attachment the three color curves do not overlap, hence CA issues.  The Nikon zoom on the right has the curves closer together and better "Quality of Focus" too by 100 points on the left Y-axis scale (Sigma 1550, and Nikon 1650.).  Hence why I was surprised the 24-70mm zoom did a bit better than the Sigma 35mm ART prime for all its hype.

No doubt there are good ones and bad ones out there too in both varieties.  Right now I think the sharpest I own is the 300mm f/4 PF Nikon followed by the 70-200mm f/2.8.  With the 300mm I captured the four moons of Jupiter last month during the Venus and Jupiter conjunction and posted it somewhere on here.

SG
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spidermike

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #4 on: July 29, 2015, 03:11:45 am »



But I shoot mostly landscapes, and find that stopping this lens down to my typical f/8 on a tripod, I can't seem to get much more sharpness out of it than my Canon 24-105mm f/4L IS @50mm and f/8.

This does not f8 is pretty much an ideal aperture on a lot of lenses so it does not surprise me - even kit lenses can be hard to tell apart from high quality lenses at f8. When buying a premium lens pay a price for other qualities: quality of construction, performance wide open, edge to edge sharpness. And, as you have noticed, distortion - to some people that distortion is intensely annoying and the price of the prime lens is  worth it. To others they are OK with the compromise and the additional price of the ART lens is 'm'eh'.
Now, if you had said there was virtually no difference at f4, I may have been a bit more surprised.

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Jimbo57

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #5 on: July 29, 2015, 05:03:40 am »

I just received my Sigma 50mm f/1.4 ART. It's a beautiful lens, and incredibly sharp at large apertures.

But I shoot mostly landscapes, and find that stopping this lens down to my typical f/8 on a tripod, I can't seem to get much more sharpness out of it than my Canon 24-105mm f/4L IS @50mm and f/8.

I guess my question would be, "Why did you imagine you would get much more sharpness?" (Or at least, assuming that you are not being muffed over by illusory statistics from optical laboratories, "Why did you think you would get more sharpness that you could actually discern in your prints?)
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NancyP

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #6 on: July 29, 2015, 09:22:42 am »

I get pretty good performance from quality film-era lens designs at f/8. My fleaBay Army Surplus AIS Nikkor 50 f/1.2 is darn sharp at f/2.8 to f/8. I have been pleasantly surprised by the utility of the $150.00, 130 gram Canon EF 40mm f/2.8 STM plastic pancake lens for landscape. Despite the pain of doing manual focus on a focus-by-wire lens, I find myself using this lens in a multi-prime landscape/macro hiking kit just for the high performance/ weight ratio .
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Some Guy

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #7 on: July 29, 2015, 11:43:18 am »

Based on my comparison out of the FoCal charts above, I decided to send the Sigma in for a check and repair.  With the Nikon showing all AF Fine Tuning at the same point (Yes, all my Nikon bodies backfocus to some degree even after they fix them!) and the Sigma wavering so much from Green -10 to Red -17, I'll let them decide if it's a bad copy or not.  Might meet their spec's too.  Dunno.

SG
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Dave Ellis

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #8 on: July 29, 2015, 03:15:16 pm »

I just received my Sigma 50mm f/1.4 ART. It's a beautiful lens, and incredibly sharp at large apertures.

But I shoot mostly landscapes, and find that stopping this lens down to my typical f/8 on a tripod, I can't seem to get much more sharpness out of it than my Canon 24-105mm f/4L IS @50mm and f/8. Maybe a little better on vignetting and chromatic aberration but even then, I really had to pixel peep to tell. The one area that I really noticed improvements was distortion; the Canon has noticeably worse distortion. Clearly it's better in certain ways, but it doesn't seem worth adding to my bag (and back... it's 1.8lbs!).

Does anyone else have this lens? What are your thoughts on these fronts? Could I have a bad copy?

With any lens, the sharpness is dependant on lens abberations and the effects of diffraction. The amount of diffraction depends on the f stop, the smaller the aperture the more diffraction. At large apertures eg f/2.8, the sharpness is determined mainly by lens abberations as diffraction is insignificant. However as you start to stop the lens down, lens abberations will start to decrease and diffraction will start to increase. With a prime lens like the Sigma Art, by the time you get to f/8 diffraction will be having more effect on sharpness than abberations. It is therefore not surprising that the quality of the lens does not really show up so much at smaller apertures.

Dave
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kers

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Re: Sharpness of Sigma 50mm ART vs 24-105L both @ f/8
« Reply #9 on: August 08, 2015, 10:55:34 am »

Hello Kenny,
You did not say what camera you are using... Canon , but how many MP and is it FF or not.

On a 36mp camera or the new 50MP Canon camera you will probably see things more clearly than at 21 MP. Especially in the corners...
@ F8 most of the lenses will do fine @21mp.

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