April 24, 2014, 10:34:24 PM

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Messages - Random Orbits

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1
Eldar, have you tried the same test using a different lens?  The TDP review linked below shows how different bokeh is affected by the different lens designs.  If you use a light source that produced the known effect with the Otus and then tried your S35, then you can compare the results with each other and to TDP to see whether or not it is a lens design/manufacturing issue.  The S35 isn't as clean as the new 35 f/2 IS, but the pattern should be different if the effect is dominated by the lens manufacturing technology and not by wavefront interference that jrista mentioned.

http://www.the-digital-picture.com/Reviews/Canon-EF-35mm-f-2-IS-USM-Lens-Review.aspx

FWIW, just going by memory, I don't remember having the onion ring effect with the 85L II or the 135L, but I do remember running into it using the 24-70L II and the 28 f/2.8 IS with Christmas tree lights.

I posted an example with the Sigma 35A (see page 13 of this thread). Very clear onion rings. I also tried the 85/1.2L II at f1.2 (donĀ“t believe I posted that). It does not show so clear rings, but they are definitely visible. Sharper lens, sharper rings, it seems.


I remember reading somewhere that the rings could be due to the grinding/polishing process of the aspherical elements.  According to the TDP link, it looks like the Canon 35 f/2 IS is remarkable in the smoothness of the OOF region.  It might be worth bringing the Otus and S35 to a camera store and comparing it with the 35 f/2 IS.  If the 35 f/2 IS performs notably better than the other two on the same subject then you'd have your answer.

2
Thanks Jrista, I need some support.

I have just returned from a heated debate with my boss (or wife if you like). She was not overly enthusiastic when I said I would change all light sources in the house to either candles, halogen point source or gas light bulbs, to avoid onion ring bokeh in my out of focus light source images ...  ::) What happened to sickness & health, support and encouragement and all that ...  :-\


Eldar, have you tried the same test using a different lens?  The TDP review linked below shows how different bokeh is affected by the different lens designs.  If you use a light source that produced the known effect with the Otus and then tried your S35, then you can compare the results with each other and to TDP to see whether or not it is a lens design/manufacturing issue.  The S35 isn't as clean as the new 35 f/2 IS, but the pattern should be different if the effect is dominated by the lens manufacturing technology and not by wavefront interference that jrista mentioned.

http://www.the-digital-picture.com/Reviews/Canon-EF-35mm-f-2-IS-USM-Lens-Review.aspx

FWIW, just going by memory, I don't remember having the onion ring effect with the 85L II or the 135L, but I do remember running into it using the 24-70L II and the 28 f/2.8 IS with Christmas tree lights.

3
No, but I have a Schneider (parent company of B&W) variND filter (up to 11 stops, see link below).  IQ is fine, but max ND affect is a function of lens focal length.  At 24mm, I could get about 2-3 stops minimum before X-banding happens (depends where the sun is) .  With the 70-200 II at 200mm, I was getting about 7-8 minimum.

http://www.bhphotovideo.com/c/product/851445-REG/Schneider_68_031177_77mm_True_Match_Vari_ND_Filter.html/?m=Y&gclid=CIDI6dSj-L0CFYZAMgod-lcAJA

You might want to check whether or not the outer diameter is the same as for both sections.  Although mine fits a 77mm lens, it's diameter is 96mm at the front to reduce vignetting for WA lenses.

4
In regards to negativity... it does seem to be within my tolerance range.  Most peddle are more than decent here and those that aren't... I don't know their names so when I see their subsequent posts I don't make the connection.

I am surprised that people are throwing the 50 art under the bus before they have even used it.  I use auto focus 95% of the time, but I really don't consider the art deaf on arrival nor do I believe that all subsequent arts will be rendered useless.

It seems that people are indeed jumping the gun.

I'll wait... I'll test at the store... And I'll come to my own conclusion.  Reviews are nice... but I wouldn't call them all scientific.  Isolating variables can be challenging and scientists don't always do an adequate job of doing so... so I won't hold reviewers to a higher standard.

And after having said all that... I jumped the gun on dismissing the 6d... And in retrospect I have a good deal of esteem for the 6d...

I don't think it's being thrown under the bus; forums tend to focus on the details.  Potential AF-issues aside, it still handily outperforms the Canon offerings in many IQ-metrics, and for many, the Sigma will win out that in segment.  I too will wait to see how it does once it is widely available, but it does mean that I won't pre-order it.  I haven't pre-ordered any of my camera equipment.  I'll give it a year and wait for the first wave of price reductions.

5
What does AFMA have to do with it?  It has to do with controlling variables in a test environment to ensure the results you are receiving.  And despite your protestations, there is an element of accuracy from AFMA related to the precision.  We have no way of knowing which of the sample 10 photos is most representative of the most optimum focus his particular camera and lens combination is capable of producing.  I can also provide you with test results .pdfs where a non or mis-calibrated lens performed more poorly on the focus consistency tests than it did once properly calibrated (AFMA).  That is contrary to the idea that accuracy is unconnected to precision in this application. 

I don't know the algorithms involved, so I cannot hypothesize to any degree of accuracy why that might happen.  But it does...often enough to convince me there is something to it.

And I have to wonder if you read my post completely.  I mentioned my experience in your vaunted "real world" conditions that not only refutes, at least in the 35mm's case, any sort of worrisome AF consistency issues, but that also corroborates what I saw in much more controlled test conditions shooting those pesky test charts. 

What you're calling "real world scenarios" is what we call in my line of work "operational testing".  Beware that all "real world scenarios" or "operational testing" is not equal for purposes of drawing conclusions from them.  Test design and controls have a lot to do with the fidelity of data produced.   And I'm saying given the paucity of information regarding test controls on TDP's "real world" shooting, we cannot faithfully put much stock in an idea that this 50mm indeed has any AF issues worth worrying about. 

I'm not trying to defend Sigma, per se.   I'll dump the Sigmas in a heart beat if the evidence gives me reason to doubt their performance.  But I'm similarly not going to simply buy some anecdotal "evidence" as proof without ensuring the evidence is properly controlled to produce the results noted.  In this case, the most glaring control missing is sample size.  I believe TDP did some fairly exhaustive shooting, probably using fairly common tools, including tripod when necessary.  But the results are based on a sample size of 1 lens, which is not adequate to properly draw conclusions from.  It's not good enough to dress up a review and AF performance test with accounts of how much and how varied the conditions were that produced the results, even if I grant you 2 test configurations based on his mention of testing both 1DX and 5DMkIII bodies with the lens.  Not for me, anyway.  I need more data.

AFMA improves accuracy but not precision, and I'm pretty sure that TDP knows to AFMA lenses before evaluating them for their reviews.  If you don't trust this review, you might as well not trust ANY of TDP's reviews unless you know that the review process that they used for this lens is different than any other.  And the subject distance for that series of infocus/out-of-focus shots is constant.  If the degree of OOF were constant, then the dock with the multiple distance adjustments might have been of use, but they weren't.  My point is this:  TDP finds that the lens that Sigma sent them (not bought retail) can have balky AF.  What is more likely -- that TDP's copy has a unique software build that is different from all the others or that all the ones being evaluated (pre-retail) all have the same software.  Yes, it was 1 copy but it was one that Sigma chose.  More reviews/user experience will be available over time, but that TDP found a difference in S35 and S50 AF performance is significant.

And yes, others in this forum have had issues with S35's AF.  Eldar has had to change the AFMA amount over time.  Why?  Perhaps Sigma had to use a different lens ID for the S50 than the S35 and Canon's AF algorithms treat them differently... or not.  Perhaps you assumed that all Sigma's new lenses will AF like the S35s you evaluated, but perhaps that is a bad assumption.

I have worked with software/hardware testing, and you can call it operational testing or whatever you want.  We "test" every line of code, but there are still issues that are found once the hardware is in the field.  But the problems identified in the field are just as valid as those found during the test phase in the lab.  The field problems are often hard to duplicate because the environment/exact state under which the error occurred is unknown.  Not everything can be duplicated in a controlled environment.

6
I don't know how TDP conducted the test other than the layman's description that he posted, but I'm highly skeptical that there are serious issues with the AF.  First, we know nothing of the pre-configuration of the lens and/or camera system.  Was it properly calibrated for AFMA?  Was it calibrated and checked with the Sigma dock?  I would not draw any conclusion about any lens, OEM or otherwise, for which I didn't do some basic configuration and calibration with my equipment that it is interfacing with. 

We also know little of the lighting conditions under which the photos were taken. 

What does AFMA have to do with it?  AFMA might improve the accuracy (zero mean the error) but it will not affect precision.  LensRentals has noted that the newest lenses and the 5D3/1DX have better accuracy/precision than other combinations.  Software is software, and Sigma's reverse engineering of the software is not good enough.  Until they do, this will always potentially be an issue.  They can probably update the software using the dock, but who knows when that will be done.

One of the reasons why I like TDP so much is his experience in using a wide array of lenses/bodies.  Using it in real world scenarios gives a better overall evaluation than shooting test charts on walls where AF is not used at all.

7
Lenses / Re: New TS-E Lenses for Photokina [CR2]
« on: April 21, 2014, 11:29:09 AM »
Maybe they'll be tilt, shift and swing lenses?

Pardon my ignorance, but what is a swing lens?

I think dilbert is suggesting a lens that can tilt in two axes at the same time.  For view cameras, tilt referreded to up/down and swing left/right movements.

8
Lenses / Re: New TS-E Lenses for Photokina [CR2]
« on: April 21, 2014, 11:20:04 AM »
Way to go Canon.  These are the lenses we all are waiting for!

Curious as to the timing.  How big are the 45/90mm TS-Es markets?  Thought that the 35L and 100-400L would have been replaced first, but more releases are better than none.

Really interested in what the unique feature would be.  Perhaps integrated macro rail into the lens foot?

9
Lenses / Re: Will Sigma 50/1.4 Art push Canon to release a 50/1.2L II?
« on: April 21, 2014, 11:11:33 AM »
As neuro mentioned "Cheaper sells". If rumor "Canon 50mm f2 IS" comes out tommorrow, the price needs to be right.

Since I'm not video guy, I prefer fast prime over IS - SHALLOW DOF.

Save that IS for UWA

I wouldn't be surprised if it came out around 800 initially and then street for a couple hundred less in a year or so.  I don't do video either, but I can see the value of IS for places like museums/churches where tripods aren't allowed, and for near macro (i.e. 0.3-0.4x) where you want to stop down to extend the DOF.

10
Lenses / Re: Will Sigma 50/1.4 Art push Canon to release a 50/1.2L II?
« on: April 21, 2014, 08:13:29 AM »
No, I don't think Sigma's release will affect what Canon is doing much at all.  It probably takes 3+ years for Canon to do R&D, optimize, field test, spool up tooling, and then release.  If Canon started thinking about a retrofocal design for the 50mm after the Otus came out, the R&D effort would have started before the Sigma came out.

I wouldn't be surprised if the 50 IS were a modified Gauss design.  It won't be as good as the Sigma, but will come with IS and will be smaller (like the 24, 28 and 35 IS).  The 50L replacement is more interesting.  The Sigma and Zeiss lenses are heavy.  Can Canon make it f/1.2 while keeping the weight and price competitive?  Or will Canon be forced to go to f/1.4?

11
Lenses / Re: Have to make a choice, finally!
« on: April 20, 2014, 01:25:19 PM »
Why not get the 17-40 and 70-200 now and wait on the rest?  See if the mix would change once the Sigma 50 is out.

12
The Canon has a more useful focal length range, which saves a lot of lens changes and makes it more versatile.  22mm is a natural focal length for a couple people or for environmental portraiture.  For indoor group photos, you'll probably be stopping down and using a bounce flash anyway.  For landscapes, your not using wide open either.  Another thing to consider is that the Tokina has a low max magnification (0.09x vs. 0.17x for Canon), so if you want to blur out the background for a close subject (i.e. flower), the Canon can do it better.

13
Lenses / Re: Canon IS Primes for landscapes?
« on: April 18, 2014, 07:40:43 PM »
Have you considered Canon's 24-70 f/4 IS?  It'll be similar to what you're considering stopped down, and carrying zoom might be easier than a few primes.

The new Canon IS lenses are nice and compact (I've used the 24 and 28), and they can be had for decent prices when they go on sale or through the refurb store.

14
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 08:46:16 AM »
Confirmation bias:
http://en.wikipedia.org/wiki/Confirmation_bias
".. is the tendency of people to favor information that confirms their beliefs or hypotheses."

Personally I'd love for the Canon 50/1.4 to be better than the Sigma 50/1.4 Art because then I wouldn't need to carry around the Sigma lens, but I simply can't justify that thinking given the results that have been presented. Same with the 50/1.2L.

I can't wait for the Sigma 50/1.4 Art to be tested by DxO and for it to wipe the floor with the 50/1.2L. I can already see the posts from those with Red Ring Fever putting down DxO, etc. What a laugh that will be to see.


Yes, but seeing schadenfreude in action can be just as ugly.

15
Lenses / Re: Review: Sigma 50mm f/1.4 DG HSM Art
« on: April 16, 2014, 08:13:54 AM »
I don't get it. Bryan's test at TDP is a complete blowout; not even close. The Sigma is sharper in center and much much much sharper than the 1.2L away from center and in corners, and the CA on the 50L is bad, while nearly non-existent on the Sigma.
In comparing any two other lenses, where there is no brand loyalty or investment-justification involved, that kind of test result would simply be a clear blowout, and there would be no further discussion. Not here though. Here we see the defensive comments and a retreat to the trenches of the intangibles like bokeh (which is not clearly different in any sample shot I have seen anyone point to specifically) and creaminess, and the supposed uselessness of test charts (but only for this lens).

What don't you get?  I'm sure people that have the 50L love the fact that some are saying their lens sucks and that the Sigma is the bee's knees.  I think it's more the attitude of some posters that are getting people to be defensive.  The 50L doesn't get any worse now that the Sigma is coming out, and for many that have the 50L, the decision is not as clear cut, especially if they're waiting for the 50L II to come out before making a decision to switch the S50A.

I've tried Canon's 50 f/1.4 and have the 50L and my experience is that the 50L is better than the 50 f/1.4 wide open to about f/2.8, which is consistent with the results of LensRentals 50mm shootout while TDP shows the 50 f/1.4 to be a better performer.  But the 50L AFs a lot better and can be used wide open.  The 50 f/1.4's AF was not accurate from f/1.4-f/2.

With Sigma's success with the S35, I'd expect the S50 to perform well AF-wise.  Over time, I'd suspect that many would trade the 50L for the S50A, but it is a bit premature when it still is not available to everyone.  And if one has the 24-70 II, then the 50L would be used for portraiture/low light only, so edge/corner performance is not as important.  The S50 is even better than the 24-70 II at 50mm.  Is everyone now going to say that the 24-70 II sucks too for landscape and that the S50 A should be used instead?

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