April 18, 2014, 01:41:34 AM

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Messages - dilbert

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1
Lenses / Re: Sigma vs Zeiss vs Canon
« on: Today at 01:18:02 AM »
@Dilbert: I refer you to Neuro's answers for all the spherical aberration stuff. Canon DOES purposely leave in spherical aberration by design, as it is a desirable effect in many circumstances.

As for your assuming, you assume that people are trying to justify what Canon does, when in actuality people are simply explaining what Canon does. You assume that people here "worship" Canon, when in fact some people are simply fans, others are simply customers and might otherwise not care about the brand. You assume a whole hell of a lot about people here man, and then you lash out at them with thinly veiled hostility and nasty words based on your INCORRECT assumptions.

All I'm saying is...might not want to assume, you would look like less of a donkey's rear end in the end.


Well I asked a collection of questions (to you) in this post:
http://www.canonrumors.com/forum/index.php?topic=20498.msg387881#msg387881
but you have not answered. Should I take from this that you do not wish to enlighten me with information and thus leave me in a place where I can only but make assumptions?

2

Not that it will help the 50L much, but you might want to report the data for the two lenses tested on the same camera, instead of different cameras.  Either drop the Sigma to 18 P-Mpix for the 1DsIII, or raise the 50L to 16 P-Mpix for the 5DIII.  Or just leave it alone if you'd prefer to artificially bias the data in favor of the point you're making.

Thanks for bringing it to my attention. Fixed

You'd think DxO could code the site so the same camera was selected by default.  But no...

Their website is a PITA to navigate and however they do their indexing is a mystery ...

... it may also mean that the majority of those that use the 50/1.2L for photography do so with a 1Ds Mk III.

3
Lenses / Re: Sigma vs Zeiss vs Canon
« on: Today at 01:11:16 AM »
@Dilbert: I refer you to Neuro's answers for all the spherical aberration stuff. Canon DOES purposely leave in spherical aberration by design, as it is a desirable effect in many circumstances.

How many of Canon's lenses have spherical aberration specifically designed into them?

And perhaps a better question to ask, if Sigma (and Zeiss?) can design sharp lenses that produce pleasing bokeh without spherical aberration then why can't Canon?

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As for your assuming, you assume that people are trying to justify what Canon does, when in actuality people are simply explaining what Canon does. You assume that people here "worship" Canon, when in fact some people are simply fans, others are simply customers and might otherwise not care about the brand. You assume a whole hell of a lot about people here man, and then you lash out at them with thinly veiled hostility and nasty words based on your INCORRECT assumptions.

What has this got to do with lenses???

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All I'm saying is...might not want to assume, you would look like less of a donkey's rear end in the end.

What concern of yours what I do or do not look like? hmm?

4

Not that it will help the 50L much, but you might want to report the data for the two lenses tested on the same camera, instead of different cameras.  Either drop the Sigma to 18 P-Mpix for the 1DsIII, or raise the 50L to 16 P-Mpix for the 5DIII.  Or just leave it alone if you'd prefer to artificially bias the data in favor of the point you're making.

Thanks for bringing it to my attention. Fixed

5
Wonder if this lens will be eligible for Sigma's "mount conversion" service?

I'm surprised that so far nobody has said DxO's results are meaningless because they don't represent bokeh in their tests results anywhere! But at least the first post on this thread doesn't disappoint with the expected putting down of DxO.

When DxO get a Nikon mount copy of this lens, I think we'll see a much better representation of its capabilities. In at least one score, the "megapixel" thing, the scores are obviously limited to what Canon cameras can provide.

Compared to the 50/1.2L

NameCanon 50/1.2LSigma 50/1.4A
Camera5D Mk III5D Mark III
Sharpness1621
Transmission1.4TStop1.7TStop
Distortion0.4%0.1%
Vignetting-2.4EV-1.5EV
Chr Aberration20µm6µm

6
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 17, 2014, 12:42:49 PM »
Remember that many of Canon's older lenses (of which the 50/1.8 and 50/1.4 are members) were designed for use with film and to be used in an era where people didn't regularly zoom in to minute levels of detail and compare notes with others all over the world. At best, said lenses were used to create images that were blown up to A3 size prints.


7
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 01:14:09 PM »
Would you like to address the comment I made about spherical aberration without referring to bokeh or polarisation?


Polarization was merely an analogy as an effect, like bokeh, that cannot be fully replicated in post-processing.  As for addressing your comment about spherical aberration without referring to bokeh, the point is that the residual spherical aberration designed into the 50L is there because the lens designers chose to emphasize bokeh quality over sharpness for the designof the lens.  If you're going to slam the 50L for not being as sharp as other 50mm lenses, the reasons behind that somewhat reduced sharpness are an integral part of that discussion. 


Acutally, I wonder if the Lytro camera would support the creation of S-A in software ... but that's not related to this.

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Next up, let's discuss the interactions between planets…but we must avoid referring to gravity in that discussion.  ::)


If spherical aberration is so important and necessary to photographers then why do lens manufacturers go to such great lengths to eliminate it?


As has been established and accepted by many people (other than you), Canon intentionally chose to not eliminate spherical aberration from the 50L design.


Apart from Canon stating that the 50L was designed for portraits, etc, is there any actual evidence of Canon deliberately not eliminating spherical aberration?

btw, let me refer you to the wikipedia page here:
http://en.wikipedia.org/wiki/Spherical_aberration
what does it say about the top lens?
Is that the word perfect used to describe a lens without spherical aberration?

What would be really good is if someone could find the patent for the 50/1.2L and translate the Japanese to see what that says about the design, specifically if it states something like "this lens element mitigates (or reduces or ...) spherical aberration by ..." or if the patent says the reverse.

8
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 01:03:22 PM »
My 35 Art´s AF is drifting again (a third AFMA with Focal showed a further 4 step adjustment, on top of the 7 steps I got between the one I did when I got it and Christmas), so I must admit I am a bit skeptical to that part of sigma. But since so many are happy with it, I hope my AF problem is a one-off.


I have a technical query here:

As far as I understand, the purpose of AFMA is not to 'fix' defective lenses, but calibrate a specified lens to a given camera to account for manufacturing tolerances.
Once the AFMA is done, the camera knows how much to compensate for this lens, and everything is hunky-dory.

But in what condition can AFMA drift as is happening in Eldar's case? Is it because something is moving within the lens and a gap is getting bigger or a cog is becoming more loose?

I am particularly interested since I just acquired a 35A (so far it looks like it is focusing right on target as shown below- spot focused on "6" using a peripheral point and center point respectively), I haven't run it through FoCal yet.

AFMA is purely a camera body firmware thing. It only reconfigures the body, it does nothing with the lens. Drift is a pretty odd thing, but I'd like to know more. Spherical aberration can result in the focal plane shifting when you stop down or open up. Since lenses usually focus wide open, then stop down for the shot, spherical aberration can result in your focal plane ending up in an unexpected place.

The Canon 50mm f/1.2 and Canon DSLR bodies include firmware that compensates for this. There is a known component of spherical aberration in that lens (by explicit design), so the focus shift caused by it can be mathematically compensated for. When you have your aperture setting tighter than f/1.2, the firmware will focus the lens with a compensation shift to ensure that once stopped down, the focal plane is where you want it to be.

If the Art 35 has some spherical aberration, it is highly unlikely that such a focus shift is compensated for. That would require paired firmware between the lens and body. Assuming that is actually the problem. If the focal plane is shifting at the same aperture, then that is a different problem, and likely due to the lens, rather than the body.

Hmm, an argument based on FUD - Fear, Uncertainty and Doubt.

Let me put this differently:
1) How many lenses do Canon provide spherical aberration correction for in camera firmware?
2) Do Canon DSLRs provide correction for spherical aberration in every Canon lens?
3) Do you think Canon want to have to correct for this in software?
4) Wouldn't it be easier to design lenses without spherical aberration and not need to correct for it anywhere?

9
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 12:52:10 PM »
I'm pretty sure that you can introduce spherical aberration through plugins or other software components if you really so desire. What you can't do is correct for poor image quality at capture time.

Actually, spherical aberration is an effect in three dimensional space.

If spherical aberration is so important and necessary to photographers then why do lens manufacturers go to such great lengths to eliminate it?

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Anyway, in the main the comments above about justifying Canon's current design and product are more about trying to ensure that people who worship Canon find a way to present Canon's offering as good and justified so that they feel good about owning Canon products. That's it. I'm sure someone will argue here that this comment is wrong, but you don't see anyone saying that they wish the 70-200/2.8 II had soft focus like the 50/1.2L and so on.

It has nothing to do with justifying or worshiping Canon. Your assuming something, then using your assumption to put words in peoples mouths as an attempt to win an argument. That's kind of you staple there, Dilbert. :P Why not try to put up a legitimate argument sometime, eh?

What exactly am I assuming?

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It simply has to do with exposing people to opinions other than their own. There is more than one way to design a lens, and there are reasons for designing lenses differently.  I honestly do not think it would be good for every 50mm lens on the market to have exactly the same specs, offer the same exact IQ, produce the same aesthetic.

That's priceless.

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It's better to have a diversity of options, because not everyone photographs the same things in the same ways that you do.

Of course. Nobody else is interested in lens that produce sharp images, have excellent colour rendition and contrast. Especially not a standard length zoom at 50mm.

If I recall correctly you like long telephoto lenses for birds, etc. Would you prefer a long lens that had the characteristics of the 50L or the Sigma 50/1.4 Art?

10
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 10:13:47 AM »
I'm pretty sure that you can introduce spherical aberration through plugins or other software components if you really so desire. What you can't do is correct for poor image quality at capture time.

There are polarization effect filters for post-processing, but they cannot properly replicate the effects of having a CPL on your lens at capture.  Similarly, adding spherical aberration in post will not correct for poor bokeh in the captured image. 

I'll just point out that I didn't mention polarization or bokeh, so I'll take your dalliance off topic as an indication that I was on the money but you can't admit it

Wrong again (or perhaps that should be, wrong as usual).  Obviously, you don't comprehend the relationship between spherical aberration and bokeh, and the analogy of polarization failed to enlighten you.


Would you like to address the comment I made about spherical aberration without referring to bokeh or polarisation?

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You're no more correct in this case then when you thought a lens was a camera, although I must say that was a particularly egregious example of your ability to totally miss the point.  Frankly, you have made dozens of similar, if less colossal, factual mistakes in this forum, and your credibility is basically nil.


Ok, so you're trending close to making personal attacks here, which is usually an indication of not having a sound argument of fact on a matter. Would you like to get back on topic or continue and get more personal with your remarks?

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No. The problem that we're seeing here is something called "confirmation bias", where people find any reason at all to support the idea that the Canon 50/1.2L is better.

Again you miss the point.  Is anyone saying the 50/1.2L is sharper?  Not that I've seen.  If you want to define "better" as sharpest, that's a judgement by you. 

The problem that we're seeing here is something called "false-consensus effect," where people believe that everyone's definition of 'better' or 'best' is the same as their own, personal definition.


Interesting thought. I'll have to ponder that one. I suppose this makes room for accepting that whilst the 50L is acceptable for some photographic uses, there are clearly those where the Sigma 50 Art is going to be better and that since people generally own a lens for a specific purpose that those who already own the 50L probably aren't going to see any benefit from changing to the S50A, right?

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False-consensus effect:
http://en.wikipedia.org/wiki/False-consensus_effect
"...a cognitive bias whereby a person tends to overestimate the extent to which their beliefs or opinions are typical of those of others."


hahahahaha

Following up one wikipedia reference with the use of another. You know they say that imitation is the most sincere form of flattery. Can I thank you now or later? :)

11
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 09:58:41 AM »
"In the case of the 50L (both of them), it was an intentional design decision by Canon."

Neuro could you please guide me where I could read more about this? Find this so difficult to believe. Thx.

In the press release Canon state that their target market is portraits, etc, which accounts for weak corner sharpness.

12
Lenses / Re: Review: Sigma 50mm f/1.4 DG HSM Art
« on: April 16, 2014, 09:57:09 AM »
...
Back to ScottyP, I think what many of us are trying to say is that sharpness and a flat field were clearly not Canon's highest priority in designing the 50L.  If you read the Press Release, you'll see that it was designed for, "[W]edding and portrait photographers, as well as professional photojournalists."  For these subjects, it is an excellent lens and the bokeh, color, and contrast are what makes it great.  Look at these photos on 500px if you think I'm crazy.

Yes, the Sigma is better at test charts, and yes, it looks like it will ultimately prove to be the better lens in terms of IQ.  No, it's not the only lens that does poorly on test charts but works better in actual use.
...


I think the tests done by TDP show that the contrast of the 50L isn't nearly as good as the S50A for the simple reason that good contrast requires sharp edges. Colour is yet to be seen. And yes, colour is important but again, if it preserves all colour as well as it does the white of the test chart, many many people will be very happy. Bokeh appears to be the cornerstone of why people are arguing that the 50L is better because there isn't a clear way to measure it and that how good/bad bokeh is depends on the viewer (i.e it is somewhat subjective.)

Canon's goal may have been met with the lens that they produced but in aiming to be "Zeiss-like" in IQ Sigma have leapfrogged Canon. I'd love to see someone demonstrate a photographic shoot where the 50L produces images that the S50A can't touch. Which is to say anything that you would use the 50L for you could equally use the S50A for.

13
Lenses / Re: Review: Sigma 50mm f/1.4 DG HSM Art
« on: April 16, 2014, 09:45:17 AM »
The 50L doesn't get any worse now that the Sigma is coming out

Well said.

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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.

So what do we know about the "mk II" of any Canon lens? First, it is more expensive than the "mk I" and by some margin too. So that would put a 50/1.2L Mk II at close to (if not more than) a MSRP of $2000 at launch - twice the price of the Sigma 50/1.4 Art. Next, unless Canon have also moved away from using a double gauss design, their lens will be subject to many of the same flaws as the current one. Now if Canon were to use a similar design to that of Sigma and Zeiss, it could be better but in order to be significantly (or even noticeably better) than the Sigma lens, it will have to equal or exceed Zeiss's Otus. I just can't see that happening. I'm not saying that it won't happen, but Zeiss lenses are considered the pinnacle of lens design for good reason. One thing that Canon can add to justify themselves is image stabilisation.

Sigma is asking some serious questions of Canon and also Zeiss.

When do you realistically expect Canon to deliver in a 50/1.2L mk II?
The 28/2.8 was 25 years old when it was replaced by the 28/2.8 IS USM.
The 35/2 was 22 years old when it was replaced by the 35/2 IS USM.
It was 18 years from 85/1.2L to 85/1.2L II.
The 35/1.4L is now 16 years old (without a replacement).
The 50/1.2L is only 8 years old (without a replacement).

How soon do you realistically think it will be before a 50/1.2L mk II appears?

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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.

Granted.

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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?

Let me answer that by saying that if I had both the 24-70 II and S50A in my bag and whilst using the 24-70 to frame a particular shot I found that it worked at or close to a zoom of 50mm then I'd swap the 24-70 II off and put the S50A on in a heartbeat (unless I had no time.) I actually do this quite often: if I'm using the 24-105 for landscape and a particular shot turns out to be a 35, 50 or 85 then I'll swap the lens off for a prime without any qualms.

14
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 08:17:31 AM »
I'm pretty sure that you can introduce spherical aberration through plugins or other software components if you really so desire. What you can't do is correct for poor image quality at capture time.


There are polarization effect filters for post-processing, but they cannot properly replicate the effects of having a CPL on your lens at capture.  Similarly, adding spherical aberration in post will not correct for poor bokeh in the captured image. 


I'll just point out that I didn't mention polarization or bokeh, so I'll take your dalliance off topic as an indication that I was on the money but you can't admit it :)

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Anyway, in the main the comments above about justifying Canon's current design and product are more about trying to ensure that people who worship Canon find a way to present Canon's offering as good and justified so that they feel good about owning Canon products. That's it. I'm sure someone will argue here that this comment is wrong...


Comments like the above are mainly about bashing Canon, made by people who have an inadequate grasp of the concepts behind lens design (and in one case, the inability to distinguish a lens from a camera). 


No. The problem that we're seeing here is something called "confirmation bias", where people find any reason at all to support the idea that the Canon 50/1.2L is better. The "in one case" comment is simply someone's inability to move on, which is a rather sad reflection of said person.

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.

15
Lenses / Re: Review: Sigma 50mm f/1.4 DG HSM Art
« on: April 16, 2014, 06:00:02 AM »
...
The Otus is epic and the Sigma doesn't even come close as far as I have seen. BUT that being said, none of the tests I've seen is the end all, so I won't judge it until I have tried it myself and seen what others here on CR have to show when they get it. But an Otus Killer it doesn't look like it...

Would you pay $560 less than the Canon 50/1.2L for the extra performance of the Sigma?
Would you pay $3000 for the small bit of performance that the Otus provides over the Sigma?
Which of the three lenses provides the best value proposition?

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