hans98ko wrote:
Also there is this so call CA error kicking into effect.
If you're thinking about color shift (due to the oblique illumination angle), that's an issue with wideangle rangefinder lenses, not with f/1.2 lenses. For other claims about CA due to microlenses I have never seen any proof.
cogitech wrote:
Apparently you, like the scientist at DxO, assume that increased light is the only benefit of large aperture lenses. I know this is not the case, therefore I disagree with any conclusions based on that assumption.
No, I am no scientist at DxO but is a scientist and researcher in other way. I also did not assume that increased light is the only benefit of large aperture lenses because I worked with (not for) quite a number of optical manufacturers even those who supplied optics to most of the known brands (for commercial and military application).
AhamB wrote:
If you're thinking about color shift (due to the oblique illumination angle), that's an issue with wideangle rangefinder lenses, not with f/1.2 lenses. For other claims about CA due to microlenses I have never seen any proof.
If you had followed the development of the 50-58mm f1.2 lenses you will find out that almost all have one or more elements to correct the so called CA issue. Especially the 58mm f1.2 Noctilux lens which was specifically mentioned on their advertisement.
you are reading far too much into what he said. there are a small group of users for whom that is the most important aspect of having a fast lens. some of them are very vocal about it. on occasion, i have the same requirements.
Herb...
cogitech wrote:
Apparently you, like the scientist at DxO, assume that increased light is the only benefit of large aperture lenses. I know this is not the case, therefore I disagree with any conclusions based on that assumption.
hans98ko wrote:
No, I am no scientist at DxO but is a scientist and researcher in other way. I also did not assume that increased light is the only benefit of large aperture lenses because I worked with (not for) quite a number of optical manufacturers even those who supplied optics to most of the known brands (for commercial and military application).
Then I do not understand your conclusions above.
If you understand that sensor light loss does not reduce or remove all of the advantages of large aperture lenses, then why conclude that the EF 50/1.2 is "not much better than" the other Canon 50s? It doesn't make sense.
Again, despite the light loss at the sensor (which is quite variable from one dSLR to the next), there are other aspects of large aperture lenses that surely justify, to at least some photographers, the higher price of said lenses. To call it a gimmick is ridiculous, unless you completely ignore the less measurable advantages of larger aperture lenses. This seems to be the mistake the scientist at DxO is making, and you seem to agree with him.
I understand your point, but it is very different from the conclusions drawn by the DxO scientist or the statements by hans98ko above.
If we assume for the sake of argument that more light is the only benefit of large aperture lenses, and we take the DxO study into full consideration, what other option is there?
Use a slower lens? What does this achieve?
Use a camera with a sensor that is better at gathering that extra light? The benefits are obvious.
I know what my choice is.
HerbChong wrote:
you are reading far too much into what he said. there are a small group of users for whom that is the most important aspect of having a fast lens. some of them are very vocal about it. on occasion, i have the same requirements.
cogitech,
Let me ask you these simple questions:
How much of a difference can you see from pictures taken from an EF 50mm f1.2L, EF 50mm f1.4 and EF 50mm f1.8? If your answer is a lot than you are saying that Canon can't even design a good time tested 50mm lens.
What are the advantages you get out of this about one stop difference of exposure when you can actually boost it on any digital cameras or on external software?
Is it worth while to paid such a high price difference? For me no, at lease not on present days DSLR. Maybe for its build quality and weather seal. But than again not all EF 50mm f1.2L are built equally. We have heard users complaining about its AF adjustment and having to stopped down a couple of stops and so on.
hans98ko, the answer is that the difference between the three lenses at max aperture is MASSIVE. What you get is different DOF, different bokeh, different color rendering and so on. They are three completely different lenses and have very different rendering style.
If something is worth paying more for depends on your budget and interest. A majority of the people taking photographs today don't think it is worth buying a DSLR but stick to their P&S cameras and mobile phones.
hans98ko wrote:
cogitech,
Let me ask you these simple questions:
How much of a difference can you see from pictures taken from an EF 50mm f1.2L, EF 50mm f1.4 and EF 50mm f1.8? If your answer is a lot than you are saying that Canon can't even design a good time tested 50mm lens.
denoir,
For DOF, bokeh and color I would get myself a Sigma 50mm f1.4 and the slightest difference of only f0.2 would not make a differnce to me.
Provided I get one of those good ones without known AF issue.
It does not include the EF f/1.2 and f/1.4 versions, but for certain they would not look the same as the f/1.8.
Sorry, to have to say that all these tests does not mean anything to me when we have being testing in the lab with proper test setup, targets and lighting.
Just wanted to know if there was a breeze blowing at the time and if the leaf was being kept stationary? If there was clouds in the sky affecting the lighting condition? You see your test shown is invalid.
hans98ko wrote:
denoir,
For DOF, bokeh and color I would get myself a Sigma 50mm f1.4 and the slightest difference of only f0.2 would not make a differnce to me.
Provided I get one of those good ones without known AF issue.
everybody will obviously make their own choices based on the data and what is important to them. i don't see anything that empirically says the canon 50/1.2 is not worth the money (note: i am in fact a scientist, but i fail to see the relevance of any of that). i would also choose the sigma over any of those canons, but there are a number of other f/1.2 lenses i would choose over the sigma for most applications.
another aside: while there may be a diminishing rate of return (in increased light) for increasing the aperture size, i can still see the difference between an f/1.2 lens and an f/1.4 lens even on a crop body. sometimes it is still worth using the f/1.2 lens for that marginal bit of increased light.
as i said, you are reading far more into the one sentence in the review than is warranted. the guy being quoted is quite right. what is the point to choosing an ISO speed if the camera is changing things under you anyway? getting a fast lens whose T-stop is far slower than marked and changing the ISO to compensate is definitely cheating. it's the same as Canon's constant aperture readout on macro lenses at 1:1 magnification.
Herb...
cogitech wrote:
I understand your point, but it is very different from the conclusions drawn by the DxO scientist or the statements by hans98ko above.
If we assume for the sake of argument that more light is the only benefit of large aperture lenses, and we take the DxO study into full consideration, what other option is there?
Use a slower lens? What does this achieve?
Use a camera with a sensor that is better at gathering that extra light? The benefits are obvious.
hans98ko wrote:
Sorry, to have to say that all these tests does not mean anything to me when we have being testing in the lab with proper test setup, targets and lighting.
Spoken like a true scientist. Your observation skills are surely lacking if you do not see the differences. Probably the scientist from DxO would not see the differences either.
Just wanted to know if there was a breeze blowing at the time and if the leaf was being kept stationary? If there was clouds in the sky affecting the lighting condition? You see your test shown is invalid.
Since I took the photos, I will answer your questions. There was no wind and the lighting was consistent.
HerbChong wrote:
getting a fast lens whose T-stop is far slower than marked and changing the ISO to compensate is definitely cheating...
That is not what is happening. It is the light loss at the sensor that is the issue, and my point is that this is no reason to question the benefits of large aperture lenses or call larger aperture lenses a "gimmick".
I can't believe that this isn't immediately obvious to you Herb. Honestly.
hans98ko wrote:
denoir,
For DOF, bokeh and color I would get myself a Sigma 50mm f1.4 and the slightest difference of only f0.2 would not make a differnce to me.
Provided I get one of those good ones without known AF issue.
I think this illustrates the problem in this discussion. As you point out, it would make no difference to you - and that's fine. People have different priorities.
The thing is that many people in this forum are a bit more selective than that. Many here have 10+ different fast 50mm lenses because they like various unique aspects of the rendering. Comparing a Sigma 50/1.4 to a Canon 50/1.2 is like comparing a dog to a cat. Yes, both are animals with four legs but still quite different. The main difference between the Canon and the Sigma is not that the Canon sucks in half a stop light more. It is in the sharpness, the color rendering, the sharpness-to-blur transition, the bokeh etc etc
The point is that while you may not see a difference most people here in the alt forum not only will see a great difference but that difference will be the determining factor when getting a lens.
sebboh wrote:
(note: i am in fact a scientist, but i fail to see the relevance of any of that).
I am encouraged to know that there are scientists who can see the other benefits of large aperture lenses aside from light gathering, and I hope I have not insulted you with my comments.
My point is to illustrate how many scientists take the reductionist approach to the point where they cannot see the forest for the trees. The scientific method is sound, and can be applied in the lab to obtain empirical data of measurable aspects of lens performance. Other times we just need to sit back and look at the images, to see the immeasurable aspects which are just as important (more important to many). The reductionist scientist often fails to do this and as such reaches ridiculous conclusions such as in this case; questioning the real benefits of large aperture lenses or calling them a "gimmick".
Like Sebboh, I just don't see the hangup on this "scientist" thing.
Obviously a faster tstop is an important aspect of a wide aperture lens, as is its rendering and in my field of work (as a scientist doing microscopy, I LOVE aperture) sharpness of image before I run into diffraction. Yes, there's a diminishing return on larger and larger aperture, but that's like most things in life.
In all honesty, misfocus by microlenses is going to both affect lens rendering and t-stop by not focusing the the very tangential rays--effectively lowering the fstop. Probably helps a bit with spherical aberration though.
Romain wrote:
And I don't get their conclusions either. Yes a T stop is not a F stop, and the T stop is different on each camera. But on a given camera a f/1.4 lens will still be faster and have a shorter depth of field than an f/2 lens, and that's all that matters.
A finer point worth making:
The T stop for a given lens is not 'different on each camera'; it DOES NOT vary under any conditions, including changing cameras, sensors, or film, since it is a photometric measurement of the transmission of the lens onto a measuring instrument.
You could, however, say that the T stop is EFFECTIVELY different, or 'behaves as if different' with each camera and be correct in that statement..
the light loss is being covered up by boosting the ISO without showing any difference in the readouts. the cameras continues to read ISO X but in fact it is ISO X*y where y is some factor that depends on the lens and the aperture. that is the gimmick.
Herb...
cogitech wrote:
That is not what is happening. It is the light loss at the sensor that is the issue, and my point is that this is no reason to question the benefits of large aperture lenses or call larger aperture lenses a "gimmick".
