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next PZ lens test report - Sigma 14mm f/1.8 DG HSM ART


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#41 JoJu

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Posted 23 November 2017 - 03:27 PM

I'm baffled, seriously. What else are the MTF charts there for?

 
To know about a specific lens - sensor - converter cmbination. I'm aware that with your prehistoric RAW converter from 2011 and my C1 10 and soon 11 from these days, the results already will be different. And you two guys keep on with your sermon that we readers cannot cross compare lenses - which is a fact. But we also cannot tell about a lens (some even without optical rating, others with rating - alone that is not very useful if you look at some Canon 5D "R" tests) which performs well at 21 MP how it will behave at around 50 MP. So, to me the MTF numbers are only telling something within a system, but fail as an absolute scale. Which is what lenscore provides provided (their last test was from months ago)
 

And what does this rating tell you if you want to know how the lens performs on a sensor that is very different?


Telling me? Nothing of relevance. To my own decisions your ratings do not matter. Your findings and charts do matter, but the rest... And what also does matter - and I repeat myself because you two testers don't care much about USB docks and consequently the improvements these docks can give the lens in cooperation with a certain AF module - is the possible customization of DSLR lenses which no first party DSLR manufacturer has to offer.
 
 

I'm not sure why you keep coming back to this single point. Each lens is tested and judged across the whole specification set it offers. The Nikkor starts at f/2.8, and it is fairly great at its largest aperture already.

 
I come back to this point because either there is a comparable rating system with transparent rules or two guys are throwing in some decorative stars  :D I'm fine with both. Please don't feel offended but when I'm researching about a lens, PZ/OL is only one address and not the most important to me.
 

The Sigma starts with a bigger aperture, and thus is rated across a larger aperture range. At f/1.8, it shows weaknesses at the borders and corners. Which, by the way, I think can even be seen in the full res sample you posted (the lady at the lake). I don't find the border anyhow impressive in there and think they match the findings quite well.

 
The lady was out of focus (although not willingly) the walls opposite the river are sharper in my memory. I understand your remark that way that wide open lenses will always have a handicap compared to less wide open lenses. This is one disadvantage of this kind of rating: Most wide open lenses perform as well or better at f/2.8 or f/4. The slow lenses cannot be faster, but the wide open ones can be stopped down. Therefore a comparison works between wide open OR less wide open, but not a wide open compared to a less open one. You rated the Nikkor on a 24 MP camera - I see the pictures with 45 MP and am surprised about sharp borders. Wide open, that is. This weekend - if the weather allows it - I can compare both lenses on the same camera. Maybe I'm wrong, and the Nikkor is still better, but at the moment it looks the other way.
 

If a lens offers a large aperture, we expect it to be great across the frame at that setting to receive a great rating,, when it comes to MTF, it's as simple as that.

 
Rubbish. At least speaking of an ultra wide angle lens, just show me a single picture where you take a picture of something with a perfectly flat focus area which needs to be sharp across the frame - test charts are an exception, no real life  :lol: If you need sharpness across the frame you also need best ISO, lowest vibration and a possibility to adjust the frame carefully. That all points towards a good tripod and then it doesn't matter to stop down for max resolution.
 

Beside: looking at the available data, I still have doubts the Sigma matches the Nikkor at 14/2.8


And I cannot or will not say it matches unless I can prove it. But if I can prove it, the next beer is on you. drinb27x24.gif



#42 JoJu

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Posted 23 November 2017 - 03:33 PM

To be honest, seeing how much effort you put into arguing against the rating in this particular case, one might get a slightly different impression ;)

 

Doubting a rating and caring about are two different things. Now I turn around the bad "imputation": Rating down a Sigma UWA and giving no rating for a Canon UWA zoom can be interpretetd as some kind of tendency...

 

Just kidding...

 

:lol:

 

I'm sure the Canon is 5 stars, no doubt. Has to be, because these days it's so super easy to polish an UWA.



#43 mst

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Posted 23 November 2017 - 04:34 PM

But we also cannot tell about a lens (some even without optical rating, others with rating - alone that is not very useful if you look at some Canon 5D "R" tests) which performs well at 21 MP how it will behave at around 50 MP. So, to me the MTF numbers are only telling something within a system, but fail as an absolute scale.


And that's the issue: there is no absolute scale. Lenses perform differently on different sensors. You can see it in the reviews where you can caompare 50MP and 21 MP results. You will also see it in the upcoming reviews of the Nikkor AF-S 24/1.8: it will have a fairly high rating on the D3x, but a lower one on the D7200. Knowing an "absolute" scale does not tell you anything about how a lens performs on a particular camera.

We do system tests, by design, and by choice. And we're not trying to hide it.

Telling me? Nothing of relevance. To my own decisions your ratings do not matter. Your findings and charts do matter, but the rest... And what also does matter - and I repeat myself because you two testers don't care much about USB docks and consequently the improvements these docks can give the lens in cooperation with a certain AF module - is the possible customization of DSLR lenses which no first party DSLR manufacturer has to offer.


To each his own. Personally, true, I don't care much about the USB docks. Nor the adjustment options in-camera. Maybe I'm just lucky, but with the majority of the lenses I've handled over the recent years, I haven't had AF issues. At least none I could reliably blame on either lens or camera.
 

Please don't feel offended but when I'm researching about a lens, PZ/OL is only one address and not the most important to me.


Not offended at all. In fact that's what we have been advising readers more than once in the past: there's more than one opinion out there, and procedure and priorities are different. Never rely on one review, especially if your priorities are different from the reviewer's.
 

Rubbish. At least speaking of an ultra wide angle lens, just show me a single picture where you take a picture of something with a perfectly flat focus area which needs to be sharp across the frame - test charts are an exception, no real life  :lol:


Not rubbish. If I shoot with the main subject not at the image center (not that uncommon), I'd like to be able to judge what level of sharpness I can expect off-center. Of course I don't shoot flat objects at f/1.8 (outside of the lab) 


And I cannot or will not say it matches unless I can prove it. But if I can prove it, the next beer is on you. drinb27x24.gif


Deal ;)

Wish I had more time, because I'm actually heading to Geneva right now, but I'm on a tight schedule unfortunately. Would have been a great opportunity otherwise... because a 14-24 is traveling with me ;)
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#44 JoJu

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Posted 23 November 2017 - 04:50 PM

I take my own 14-24 if you don't mind  :D but there's this gorgeous 135/1.8 here which - contrary to the 14/1.8 hasn't fell down and broke a part of the thermally (but not fallingly...) stable front hood. Well, the lens and camera took it better than the wooden floor  :unsure:

 

 

Not rubbish. If I shoot with the main subject not at the image center (not that uncommon), I'd like to be able to judge what level of sharpness I can expect off-center. Of course I don't shoot flat objects at f/1.8 (outside of the lab) 

 

Sure, because each DSLR can focus right down the corners  ^_^

 

Alright, alright "use LiveView for Zeiss' sake" would be the appropriate answer. Got it. But will rip apart the Nikkor anyway. Ha.



#45 mst

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Posted 23 November 2017 - 05:50 PM

Ouch!

Hope it's just the hood that took some damage... which is probably annoying enough.

I happen to have a visible damage in the floor of my corridor, too, where my Berlebach tripod hit it recently when falling over... luckily without a camera mounted.

I sent you an email regarding the 135... I'm afraid we have to postpone that to next year...
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#46 JoJu

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Posted 23 November 2017 - 05:54 PM

The damage of the hood is cosmetical and with acrylic cyano (super)glue (?) it's fixed. I'm a bit worried about AF-module and lens movement, but so far it's a tiny doubt - everything appears to work alright (within the limits, which I saw before as well). I just still don't know how it could happen, but the bang was clear enough to know it happened. 30 years ago that would have been the start of a massive depression, these days "it's only a tool".

 

E-Mail is answered, no problem, I will not sell it in the next few years...   :)



#47 Rover

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Posted 24 November 2017 - 07:23 PM

Alright... the "What does this mean ?" popup seen at the end of every review isn't working. Looks like the page the link points to is not there. :) It's the same in every review I've checked.



#48 JoJu

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Posted 25 November 2017 - 04:05 PM

I made a reply with some comparisons between the Sigma 14/1.8 and the Nikon 14-24/2.8 in another thread.



#49 GoldRingNikkor

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Posted 10 December 2017 - 08:57 AM

 

Rubbish. At least speaking of an ultra wide angle lens, just show me a single picture where you take a picture of something with a perfectly flat focus area which needs to be sharp across the frame - test charts are an exception, no real life  :lol: If you need sharpness across the frame you also need best ISO, lowest vibration and a possibility to adjust the frame carefully. That all points towards a good tripod and then it doesn't matter to stop down for max resolution.

 

Night sky. Stars in the corners. People don't buy a giant 14/1.8 to shoot brick walls at f/11.


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#50 Brightcolours

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Posted 10 December 2017 - 08:59 AM

It does well with that night sky.



#51 GoldRingNikkor

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Posted 10 December 2017 - 09:04 AM

No, I didn't test at infinity but at f/1.8 there was quite some field curvature anyway. Even in the theoretical event that the lens is better at infinity, the field curvature would hit astro-photographers.

 

I was going to ask about that as well. The charts at f/1.8 don't look that great - I was wondering if the image periphery would be better at longer focus distances (sometimes lenses aren't as good close up). Unfortunately in the sample image section all the wide open ones are close-ups and all the near-infinity shots are stopped down. In any case, it is more likely than not that the issues are real and apply to infinity focus too, but then I would have to wonder why others rave about the lens for astro...



#52 GoldRingNikkor

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Posted 10 December 2017 - 09:07 AM

It does well with that night sky.

 

That's what I hear, yes. Just pointing out that "no subject ever needs sharp corners at f/1.8" is a rather flawed argument when applied to a lens like this one...



#53 JoJu

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Posted 10 December 2017 - 01:16 PM

I think you misunderstood me, GoldRingNikkor,  ;)

 

I think, it's literally impossible to get a 14 mm lens with that aperture at the same time doing extraordinary things with test charts at test chart distance and doing well wide open at infinity. Like you said, night sky is one of the fields for it - and unfortunately, if you check it's corners, sharpness is there, but coma as well (butterflies instead of pin points).

 

All I was saying is that for these kind of lenses it's tough to find subjects with a flat field which need to be shot wide open.



#54 Klaus

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Posted 11 December 2017 - 06:50 AM

A fast ultrawide lens that is dead sharp in the corners at 50mp doesn't exist.

Your best bets will be the Otus 28mm f/1.4 ( not really wide ) or the Leica Summilux 21mm f/1.4 ( on Sony Alpha ).

Even then - these lenses will still have lots of vignetting at f/1.4.

Alternatively - go down with your megapixel requirements.
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#55 dave's clichés

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Posted 11 December 2017 - 09:10 AM

    Star shots are all about wide apertures and limited time exposures (20 secs or less without a astro-mount), so the Sigma is going to be seriously looked at by astro-shooters....corners and all!

 

   My Samyang was back-focusing so much, I thought I was getting pre "big-bang" exposures......black frames.....it was clear to me that I was back focusing beyond the formation of the universe.....big league stuff huh?

 

   I spent many hours daydreaming about my breakthrough and was already preparing for the scientific world's reception of my "White papers".......explaining this time/distance fabric situation with all the appropriate calculations of how to find the exact plane of focus in order to capture the actual glorious moment of the"Big Bang" itself .....

 

      Sat back,eyes closed, gin+tonic in hand, bathing in my newly discovered eureka moment, the world was finally my oyster,.... then.... I looked up to notice that I had forgotten to remove the lens-cap....

 

 

     It was at this point I decided to write a thesis on over-active neurons and the lifetime of confusion they had caused me!

       

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#56 JoJu

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Posted 11 December 2017 - 10:44 AM

At high resolution there are already visible startracks at 20 sec. 

 

It's the question if a star tracker and a less fast lens (but well corrected) might be the better idea for static milky way shots. In your otherwise great picture the corners are also notshowing pointy stars but some stripes. For example, an Irix 15/2.4 has an adjustable infinity hard-stop, costs less than 1000 bucks, so a bit of money is left for getting a star tracker.

 

The question is also, if - except some star tracking experts and lens nerds - will complain about these things if the see a beautifully composed picture with a milky way no on usually sees with bare eyes at our light polluted night skies?

 

I think, the Sigma is meant for more than only milky way shots - it's sort of good for these kind of stuff, but less good than specialized gear. However, that specialized gear doesn't help much with wide angle wide open shots. The bokeh is very neat and I really love the lens for this kind of things. If I were "only "in milky way shots, I'd look for something else.



#57 dave's clichés

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Posted 11 December 2017 - 12:10 PM

     You asked what subject is on a flat plane to the corners.....astro photography is just that!

  

  I think you will find the most of the star deformations are caused by the maximum exposure of around 20 seconds, 10-15 secs is the point at which stars start to make trails ....which are always worse in the corners.



#58 JoJu

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Posted 11 December 2017 - 12:23 PM

Please stop giving general time values which are incorrect unless you name the sensor resolution. The higher that is, the shorter the time has to be, if the camera is static looking towads the sky. And instead standing on a "planet that's revolving, revolving at 900 mph" according to monty Python's scientifically accurate galactical song. Calling our galaxy a flat plane is pretty bold, too  :P

 

There's infinity, infinite infinity and your Samyang giving it a fourth dimension touch.

 

I wonder who will be waiting for us somewhere at infnity, waiting with a giant text board. Oh, and you don't think I will try to find coma stars in your tiny picture?

 

The funny thing with the Sigma is, there are some coma stars in the corners. But not all stars in the corners show coma.  :blink:



#59 JoJu

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Posted 18 December 2017 - 01:12 PM

I just got a nice parcel back from Sigma Switzerland.

 

Last week on Monday I sent them 4 lenses to check - their Swiss guarantee includes one free check per year. For some it was the first time to make the travel. One got the front ring replaced (for free), the others were checked and the 14/1.8 needs to go again to replace broken and glued lens hood against a new one coming from Japan - but I didn't want to leave the lens there for 3 weeks.

 

Now I'm again thinking about closing the 85/1.4 gap with a Sigma - or go the Tamron way this time.  -_-






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