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next PZ lens test report: Sigma 50mm f/1.4 DG HSM | A on APS-C
No permission needed, I was quoting lensrentals and I'd be more than happy to replace the picture with the link. I just thought it would be more convenient for us readers.


i don't want to make you work.


To me the post was disappeared = deleted. Didn't know there's a possibility to hide. Therfore my harsh comment. With your permission, I'll edit that post.


I was checking lensrentals copyright rules before and didn't find anything which was forbidding copying. As far as I know American copyright is different from German: In Germany every picture is protected although a data sheet is nothing of creativity, so even the German right makes an exception which is bound to "Schöpfungshöhe". If there's no creative work aspect in a picture, sculpture or a building, it will be difficult to claim protection by law - but if in doubt, it's better not to copy.


In America, a creator of a picture needs to mention he or she doesn't want it to be copied - therefore the copyright remark, which is not necessary in Germany.


I respect your being against copyright violation, but I didn't see one in this case.

I am very sure that embedding foreign (commercial) images is a copyright violation. Just mentioning the source is insufficient. You can cite a few sentences but not the complete essence which was represented by this image.


I have replaced the image with the link

Thank you very much. I'm aware I'm no lawyer with competences in international copyrights  ^_^.


Edit: On second thought: As others were posting MTF charts and lens intersections here and there ( as example) - what's the difference? Being advertisement material or private effort of research? Would it make a difference if I ask Roger to clarify if he permits the material as picture?


The only reason for my question is, it's easier to read the context in a thread instead of link-hopping.


Scythels, you're right, especially with the fact that the worst Sigmas are better than the best Canons
Not really -


Sigma #1 is better than all the canons, but by a small margin.  It is fairly representative of the average 35A. 


Sigma #2 has enormous astigmatism spikes (almost 80% in some regions of the frame) and would look very soft, even if it maintains good sagittal resolution.


Sigma #3 is poorly assembled and heavily tilted.


Sigma #4 has decentering as bad as the first 23/1.4 Klaus got for testing - left side is under 1/4 as good as the right.


On the other hand, buyers might get something like sigma #5, which is nearly diffraction limited at the tested aperture (f/1.4) right out to the corners. 


Here's the resolution gain with several zeros... I still don't know the best way to represent this.


All of these tests are without the influence of a normal camera.  The test device works with collimated light and the result is measured with a diffraction limited microscope lens at f/1 (that is - the contribution of the measurement device is miniscule)





But less annoying than the AF variation of the camera/lens system itself

PDAF relies on the lens and body being aligned with each other.  Essentially, if the rear nodal point of the lens isn't just where it is expected to be (and the difference between perfect and very off is hardly a millimeter) the geometry "fails" and light won't come to a focus on the beam splitter in the PDAF system at the correct depth - resulting in front or backfocus tendancies.  It is a limit to the quality of manufacturing of the manufacture.


If your body's mount is 1mm too far forward, all of your lenses will front focus unless they are very far off/too shallow on the mount.  Unless your body is right where it should be, it's a crapshoot for if your lenses will line up with your body correctly (and because anecdotal stories apparently are very valuable - my 6D, 35 IS, and 70-300L are all perfectly aligned with each other out of the box).  Whether your sigma or your nikon or your canon or your pentax or your sony A is properly aligned matters very little.  Micro adjust it and move on.


If focus errors are different at different distances, it's a failure of the lens/lens motor.  The camera has a LUT which contains information on the drive speed of the AF motors of lenses (I could get into more detail, but it's outside the scope of this thread) - first party manufactures obviously don't include third party mfg data.  The camera expects the lens to focus at a certain rate, if the lens doesn't it's a failure of the lens to meet the camera's expectation and focus will miss.  If focus is randomly off in the way that the tested 50A at TDP is/was - the focus system wasn't designed with finely enough toothed gears and where the lens 'settles' lacks "proper" precision.


Canikon will charge a higher premium than Sigma for two reasons:


  1. High profit margins are profitable
  2. Buyer psychology - if canikon make the $2,000 70-200 telephotos, consumers equate that with quality- they need to maintain a reputation as the quality brand. (See also: white lenses at sporting events being built in marketing material for canon)
They also have tighter tolerances, at least canon's lenses are better engineered from a physical standpoint, and as well engineered optically.  The 35L isn't all that much worse than the 35A optically, and it's 14 years older.  The 24-105L trades evenly with the 24-105A (quality corners where the 24-105A lacks them), and is 7 or 8 years older.  While being smaller and lighter.  Planar lenses have much less engineering freedom (to change one element requires changing its partner behind the diaphragm) and also much less effort.  Canon can do a 50mm distagon as well as sigma.


Don't get me wrong, sigma is doing great things at great prices, but they are not eating canikon's cake en totale.

Were the Sigma 35 from one batch? How come you can test 5 copies?

Together with - at least sounding like - very professional instruments?

Are this test results your work? If not, whose? And why not naming the source?

Which 23/1.4 you're referring to? I'm sorry if I appear a bit sceptical, you're talking a lot about Canon and I just have no insight into their designs - nor am I professionally able to judge lens designs.


"They also have tighter tolerances, at least canon's lenses are better engineered from a physical standpoint, and as well engineered optically." How come you know about different tolerances? That's no public knowledge, as fas as I know. Sorry, unless you're no engineer from Canon or Sigma or Nikon I doubt this sentence as it is.


"Canon can do a 50mm distagon as well as sigma." Well, who's telling them not to do so?  ^_^ Especially if it's so easy asking for higher profit margins? I understand your explanation and agree with it - and given the problems lensrentals experienced with those 50/1.4 and connecting them to the dock, I guess some Canon users would be happy to get an excellent pendant like the 50/1.4 Art from Canon.


Don't get me wrong, my favoring of Sigma is not meant to say Canikon is rubbish and Sigma rules. I'm just saying Canikon would look a lot better if they were trading always evenly with Sigma - and with the exception of 24-105 (which is still less expensive and at least in wide range better than Nikon) they are not only 5-20% away with their prices.


I also never said Sigma is eating Canikon's cake - this is not my concern. My concern is to get the best glass with AF for a very great sensor - and if that's possible at reasonable price, why should I pay more for less or just "not much worse"?


Canon has no Sensor to put against and I can't adapt their fantastic lenses to my Nikon bodies.

Holy fuck I had a long reply but I hit backspace to end numbered listing, which caused the page to go back and dumped my reply.  This will be nowhere near as long now (fucking editor - threw away thousands of characters)


It's lensrentals data.  25 copies.  I processed it.


The machine is theirs, it's a great machine, but still lower grade than the one available to me in my university's lab (I'm an optical engineering major, working towards my master's.)




I am referring to Klaus' first 23 -


Canon won't make a 50mm prime distagon because it requires that it be too big and too heavy.  They have physical as well as optical constraints that they self-enforce.  They talked about this with the 50/1.0L vs 50/1.2L development.


I consider canon's sensors good enough - I have never required more DR than my 6D gives me, and in the dark it's as good as or better than any camera that's not a D3s/D4/D4s/Df/1Dx/A7s.  They are not the best, that is irrefutable, but "good enough".  The 7D introduced new sensor tech, I believe the 7D2 will as well.


Sigma has three truly great lenses - 35A, 50A, 120-300S, canon has dozens of truly great lenses.  Nikon has fewer, but still many, many more than sigma.  And they have better (more reliable) AF to boot.  Sigma can build a lens almost as good as the otus at tech benchmarks (like the 50A) with autofocus for 1/3 the price, but if they can't get every nearly every copy to autofocus completely consistently like first party lenses, the fact that it autofocuses is merely a convenience and not to be relied on. 
Thanks for the reply, Scythels, especially for the double work. Same happened to me twice. Thanks also for clearing the data source. I've seen the presentation context but didn't recall the details of the various solutions.


As for AF consitency: Yesterday I played with FoCal AFMA calibration. In the first steps of -20, -10, 0 +10, +20 the bar of the AFMA prediction remains green if the prediction is stable, or yellow if it's less predictable (= difficult to AF) or red, if it's very difficult. Several lenses showed yellow bars and one was red and went over 50 shutter releases to predict the proper AFMA. I say "predict" because I'm used to "less than 100% in-focus AF" on all lenses. Anyway, it were not the Sigma's showing a red line...


And there's not much of a difference between genuine fast glass and Sigma fast glass, I believe - but it's hard to tell as I throw away the out of focus ones. And I don't have the choice between various 35 or 50 or 24 or 85. What I try to do is taking just more than one shot, if focus is difficult and not possible with LiveView.


The one "truly great" you forgot was the 18-35/1.8 or you consider it as less truly great - which is okay by me, I just have a different opinion about it. This especially causes a lot of headache to Nikon's AF and to me, too. It's outstanding sharp if the AF hits the mark but fast wide angles on Nikon's DX bodies appear to be a hard task for the AF module (which is in 7100 the same as in D800).


Sigma needs to adapt their lenses to a couple of manufacturers, even their own bodies. Genuine lenses should being better than 3rd party, otherwise the manufacturers would do some serious faults. But if you call Canon's sensor "good enough", as Nikon owner I can call Sigma's AF "good enough", too  Wink I'm not used to much better AF reliability from the genuine manufacturer.

On second thought and to put things into a bit more real perspective: I'm sort of complaining about Nikon's AF. Nikon could score easily if they say, alright then, JJ, switch of the useless, unreliable AF and make it better manually. We'll see who's got more keepers.




They were right. An Otus would be a waste of money to me. Without LiveView I wouldn't stand a chance to compete with their AF. Luckily, I'm not constantly snapping at open aperture, but still... Next to it: It's already painful to focus with matte screen only, adjusting it to different lenses? No way.

Phase detect AF can always be open to errors, but there are many ways of focusing with modern DSLRs now, so what you can't achieve with PDAF, you can using LV and magnify or contrast detect or even  focus peaking, we have now many ways to skin the proverbial cat!

     There's always the traditional split screen viewfinder with manual focusing, after all that was all we had before AF..


 Surely we can get something out of that lot!

Dave's clichés
The 18-35 is good, and it's unique.  To be honest I forgot about it.  Make that four.


I can't speak to high-end nikon AF.  I shot nikon for two years on a D5100, for a year of which I saved and never bought a lens.  I planned out everything I would want from my camera system in the end, and canon came out about $1500 cheaper when I planned it out (much more than that now that I paid $1043 for my 70-300L - dem rebates).


Systems would have been:


D600, 35 ZF.2, 70-200/4G, 14-24 or 21ZE.  =1800+1100+1400+2000 = $6300


6D, 35 IS, 70-300L, 25ZE - 1400+550+1500+1700 = $5150


Lots has changed since then - 35A was released and 16-35 f/4L IS was released being the big two that would change my plans. 


The 35/2 distagon was my solution to nikon not making a quality fast 35 without ridiculous spherochromatism or other quality issues (and they still kinda don't Tongue ) but the 35A replaces that need.  The 25 ZE I would use on canon because of its 67mm filter thread making my entire kit use the same thread size of inexpensive filters.  The 16-35 IS just so happens to be as good as the 17 TS-E at 16mm, better than the 24L at 24mm, and as good as my 35 IS at 35mm - the extra cost of filters and step rings is made up by the lower cost of the lens. 


All I really do know is that my 70-300L focuses like a bat out of hell and never misses, my 35 IS is very fast, but not as fast as the 70-300, and also never misses.  That's for still shooting.  I shot ziplining once with the 70-300, subjects moving directly towards the camera.... it missed 2/253 images on the center point. 


Canon just is the creme de la creme for lens design as far as I'm concerned.  On hikes I can take my 70-300L and soon-to-own 16-35L IS with my 6D and have quality as good as anything short of a D800 with very heavy lenses that can handle the sensor - two lenses to cover from 16 -> 300mm is quite exceptional.  Eventually I'll add a 50/2 or 50/1.8 IS, whichever canon ends up releasing. 


Then for walkaround, I have a compact kit - 6D+35 - which has exceptional IQ and haptics in every regard... without being large or heavy!


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