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First test of the Tamron 20 ƒ/2.8 Di III OSD M 1:2
#1
https://sonyalpha.blog/2019/12/20/tamron...m-12-f050/
stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm Æ’/5-6.3 DG OS HSM Contemporary, Samyang 12mm Æ’/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm Æ’/2.8, Samyang 8mm Æ’/3.5 fish-eye II | Zenit Helios 44-2 58mm Æ’/2 
Plus some legacy Nikkor lenses.
#2
Pretty good wide angle lens for not much money.
#3
Very high barrel distortion for a 20mm f2.8 prime. More than decent rendering for an UWA. A shame it is for Sony only for now.
#4
BC, I think Tamron will offer the trio for the rest of mirrotless brands.
#5
https://www.ephotozine.com/article/tamro...erformance

8.5% native barrel distortion is... wild. Smile I wonder what kind of value is considered the borderline of the fisheye territory?
#6
(01-01-2020, 12:01 PM)Rover Wrote: https://www.ephotozine.com/article/tamro...erformance

8.5% native barrel distortion is... wild. Smile I wonder what kind of value is considered the borderline of the fisheye territory?

There is some tradeoff between distortion and MFT resolution values for wide angle lenses.

I wonder if it is OK to leave distortion less corrected when every other parameter is more or less optimized, and leave the end user to decide what distortion correction to apply during post-processing. Obviously, landscape people will want better edge sharness, architectural people will look for straight lines.
#7
Do "landscape people" love barrel distorted trees?
And does that sharp Sigma 20mm f1.4 have lesser "MTF resolution"?
#8
Barrel distortion is in a strange territory even for landscape, indeed. Anyway it's a lens that must be tried to really evaluate it. I've never returned an Amazon item because I didn't like it, in this case I'll take the opportunity if needed... I hope it will be available before my next trip.
stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm Æ’/5-6.3 DG OS HSM Contemporary, Samyang 12mm Æ’/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm Æ’/2.8, Samyang 8mm Æ’/3.5 fish-eye II | Zenit Helios 44-2 58mm Æ’/2 
Plus some legacy Nikkor lenses.
#9
(01-02-2020, 09:41 PM)Brightcolours Wrote: Do "landscape people" love barrel distorted trees?
And does that sharp Sigma 20mm f1.4 have lesser "MTF  resolution"?

If you read my previous post more carefully, you will realize that I'm not taking a side which aberration is better than the other. What I'm stating is that there are certain physical laws that come into play when you are projecting 3D image on a 2D plane, and in the case of a wide angle lenses, over-correcting distortion is at the cost of softer corners, even when you do that in software.

What I'm saying is that there is probably certain balance, where you can decide for yourself which is more important to you - sharp corners or distortion-free image, and produce the desired effect with few tweaks. I'm not sure if over-corrected lenses will give you that opportunity.

I don't see what's the problem here. And what's so special about Sigma 20/1.4 clearly eludes me.
#10
(01-03-2020, 11:19 AM)faint Wrote: ...over-correcting distortion is at the cost of softer corners, even when you do that in software.

I'd say: especially when you do that in software.

Personally, I'd prefer to have a lens that delivers as little distortion as possible natively. At the aperture settings typically used for landscapes, border and corner sharpness is limited rather by diffraction than lens' performance. On the other hand, when shooting a subject with straight lines near the edges, less software correction is definitely welcome. But let's also be realistic: no WA natively delivers a completely distortion-free image, so if you're picky or the shot requires it, some correction needs to be done anyway. But with less native distortion to start with the correction penalty is considerably lower.

In any case: more than 8% distortion is outstanding, but not in a positive way...
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