I am impressed by theSuede's knowledge and contribution to this and other threads. Thanks. (Just had to get that out there.) It's refreshing to see such real knowledge on these threads.
Being a film-only shooter, it's also nice to not have to worry about much of these related issues (microlens sensor angle, telecentricty, CA (for the most part), purple fringing, etc. ). Of course there's other things to worry about....
Well I can live with an ISO increase of 1/3 a stop. Luckily it's only that much.
I believe that is why Sony was reluctant to allow unchipped lenses to auto expose, initially. The new firmware claims that exposure at wider apertures may not be "correct" with unchipped lenses.
cogitech wrote:
Yet another reason to keep lovin' my 5D.
The conclusion of the DxO chief scientist: "I am therefore inclined to question the real benefit of faster lenses.” - Spoken like a true scientist.
I will have my "older" 5D, 20D, and F3.5 - 4L lenes a very long time !
Every time Canon makes a "new and improved" version {Camera / Lens}
it reminds me 21st Century digital photo has obtained high IQ but
photographers who buy the marketing scam have demented into very low IQ.
Does all this also mean digital shows more vignetting than film?
I know, I shouldn't have to ask but I have a feeling it is that way. I never scanned and post processed any of my old negatives. From the darkroom I don't recall I worried about vignetting as often as I do today. Frankly, I very seldom cared to dodge the corners at all. With digital I like to have presets including vignetting compensation in my raw converter. So, I'm not sure. Maybe it is all this pixel peeping having made me more finicky about a lot of things (edwardkaraa seeing film having more DOF than digital may be something similar).
cogitech wrote:
As I said, if you still do not understand, I am wasting my time.
I think it's better to leave it, Paul. It's almost the same as a thread I responded to on another forum, where someone compared a 24-70L to a CZJ 135/3.5, and people acted surprised that the 24-70L didn't have a $1400 advantage in IQ... Yeah, it's a marketing scam.
I don't think the main benefit of faster lenses anymore is that they require less exposure. In fact it depends not only on f-number but also on the light transmission function of the lens. Olympus 55/1.2 will require twice as long exposure as Canon 50/1.2L - I've tested it so I know for a fact. But it will still have shallower depth of field and dreamier bokeh than Canon 50/1.4.
Ataboy wrote:
(...)
Olympus 55/1.2 will require twice as long exposure as Canon 50/1.2L - I've tested it so I know for a fact.
So have I. I got a difference of about 2/3 of a stop. I call it knowing by experience.
Back then in a post somewhere I wrote about the old fast OM primes usually being slower than expected (compared to other very fast lenses - OM21/2, 50/1.2, 55/1.2, even 50/1.4 a little). The topic was something else, it was just a sidenote. I was of course told I was wrong. Well,, this is off topic again.
Does all this also mean digital shows more vignetting than film?
I know, I shouldn't have to ask but I have a feeling it is that way. I never scanned and post processed any of my old negatives. From the darkroom I don't recall I worried about vignetting as often as I do today. Frankly, I very seldom cared to dodge the corners at all. With digital I like to have presets including vignetting compensation in my raw converter. So, I'm not sure. Maybe it is all this pixel peeping having made me more finicky about a lot of things (edwardkaraa seeing film having more DOF than digital may be something similar)....Show more →
Well, I can confirm it's pixel peeping on both accounts. My observation of more DOF and less vignetting with film comes from scanning at 4000 dpi which gave 21 mp files, almost as large as the 5D2.
cogitech wrote:
I agree, Edward. I saw the vague discussion of this in the LL article and I had the same thoughts. Perhaps at least some sensors offer the advantage of less DOF and simultaneously better-defined focal plane than (some) films. LL seems to suggest the opposite. Or, at least is seems so.
OTOH, some may in fact consider shallower DOF to be a disadvantage.
That is how I understood it as well. Could be true in theorie though in practice it certainly is not the case.
Dec 15, 2010 at 12:41 PM
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Jonas B wrote:
So have I. I got a difference of about 2/3 of a stop. I call it knowing by experience.
Back then in a post somewhere I wrote about the old fast OM primes usually being slower than expected (compared to other very fast lenses - OM21/2, 50/1.2, 55/1.2, even 50/1.4 a little). The topic was something else, it was just a sidenote. I was of course told I was wrong. Well,, this is off topic again.
Hi Jonas,
It is and it isn't off topic. It may be that it exposes as a slower lens becauset the camera is not doing the stealth ISO shift for the Oly like it is for a native lens like the Canon 50 1.2L. It may be that the Oly isn't letting in less light, but you are shooting the Oly at a lower ISO than the Canon or similar OEM lens because the camera is making a hidden shift to higher ISO. One implication for alt users that this thread has raised for me, is whether having a chipped vs. a non-chipped lens affect whether the camera does this hidden ISO shift. Can anyone who has a chipped and non-chipped adapter for the same lens (f/1.2 chipped to f/1.2 would be ideal) see if it meters the same chipped and non-chipped? If you prefer the camera not to change the ISO, then one solution might be using non-chipped adapters for all lenses. My adapters are all chipped, but I wonder if that is such a good thing now.
theSuede wrote:
Olympus even went so far as to implicitly specify a maximum incident ray angle conforming to using F/2.0 in their recommendations for lenses for their µ4/3 and FT formats. This means that you can use a F/1.4 construction IF you plan an at least 2:1 telecentricity into the lens - it will result in approximately the same angles. This is pretty normal for a modern WA construction. F/1.4 in a WA telecentric lens like a distagon or similar base (telecentric is a misused word here... "lens with large pupil magnification ratio" is better) behaves like a symmetric design F/2.0 of twice the focal length. Telecentric 24F/1.4 > losses like a 48F/2.0 ...Show more →
I am not sure what you are trying to say here. At a given f-number, the incident ray angle does not depend on focal length or other design specifics. That is, in the image center. Only the corners benefit from lenses with a large pupil magnification.
no-one has said that in this entire thread, including the DXO guy, except you.
Herb...
cogitech wrote:
If you think that large aperture lenses only maintain their benefits on a film camera, you are mistaken, and it is because you still think the only benefit of such lenses is light gathering (which is apparently the same mistake that the DxO scientist is making).
cogitech wrote:
I agree, Edward. I saw the vague discussion of this in the LL article and I had the same thoughts. Perhaps at least some sensors offer the advantage of less DOF and simultaneously better-defined focal plane than (some) films. LL seems to suggest the opposite. Or, at least is seems so.
OTOH, some may in fact consider shallower DOF to be a disadvantage.
LL is not known for being knowledgeable about depth-of-field issues. The only way for sensor structure to influence the size of a (larger) blur disk is for individual cells not to register light at all. That is not going to happen.
Perhaps I have made an error in interpreting the following:
DxO guy: "Our measurements all point in the same direction: as you go further than f/ 4 – to f /2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.”
So, he is saying he is inclined to question the real benefit of faster lenses, based on the fact that the dSLR is not efficient enough to fully utilize the light transferred by said faster lenses (at large apertures). How else can one interpret this, other than to conclude that the statement was made by one who thinks light gathering is the sole benefit of faster lenses? He in fact uses the term "benefit" (not plural).
On to our local example: "Now! You see why many EF 50mm f1.2L users complained about the lens is not much better than the EF 50mm f1.4 or even the cheapy EF 50mm f1.8? Only those who have the extra cash and not know how to spend it will buy into the marketing gimmick....For those who use the AIS 50mm f1.2 on film cameras will be a different story."
So, based on the DxO report, the author here concludes that we should all now realize that users of the EF 50/1.2L think it is not much better than these other two Canon 50s (and that they think so due to the issue discussed in DxO's article), and that only stupid rich people will buy into the "gimmick" of the 50mm f1.2. However, if you use a fast lens on a film camera this does not apply. Again, the assumption is that the sole benefit of fast lenses is light-gathering ability. If not, why come to these erroneous conclusions and make such ridiculous statements?
If I have misinterpreted these statements, please explain how.
HerbChong wrote:
no-one has said that in this entire thread, including the DXO guy, except you.
If we are losing marginal rays--how is that not affecting the "effective" aperture of the lens? It's not going to be a linear effect over the whole chip either (more severe in the corners).
Admittedly at large apertures, these marginal rays are likely way off focus (spherical aberration).
cogitech wrote:
Perhaps I have made an error in interpreting the following:
DxO guy:
So, he is saying he is inclined to question the real benefit of faster lenses, based on the fact that the dSLR is not efficient enough to fully utilize the light transferred by said faster lenses (at large apertures). How else can one interpret this, other than to conclude that the statement was made by one who thinks light gathering is the sole benefit of faster lenses? He in fact uses the term "benefit" (not plural).
I'm coming at this from the "numerical aperture" definition, so bear with me.
Larger apertures by definition bring light in from shallower and shallower angles (larger gathering angle). We're good on that. Microlenses aren't perfect by any stretch of the imagination, and will not effectively focus the marginal rays into the active part of the photosite. Thus we'll call them lost.
In effect, we're losing the very rays that opening up our aperture gives us. Now, this is definitely a diminishing returns (f1.2 will still have a lower effective aperture than f1.4, but it's not going to be be a 1/2 stop any more). So it's not only Tstop-but fstop.. That's my take away message from the DXO scientist. Not that I agree with his assessment, but don't reduce his point to JUST t-stop.
In practical terms, because we've never had infinitely thin recording media, this effect is less pronounced than "theory" would predict. Hope that helps.
Daniel Heineck wrote:
I'm coming at this from the "numerical aperture" definition, so bear with me.
Larger apertures by definition bring light in from shallower and shallower angles (larger gathering angle). We're good on that. Microlenses aren't perfect by any stretch of the imagination, and will not effectively focus the marginal rays into the active part of the photosite. Thus we'll call them lost.
In effect, we're losing the very rays that opening up our aperture gives us. Now, this is definitely a diminishing returns (f1.2 will still have a lower effective aperture than f1.4, but it's not going to be be a 1/2 stop any more). So it's not only Tstop-but fstop.. That's my take away message from the DXO scientist. Not that I agree with his assessment, but don't reduce his point to JUST t-stop.
In practical terms, because we've never had infinitely thin recording media, this effect is less pronounced than "theory" would predict. Hope that helps....Show more →
I understand all of this and I am not debating the minutia of the study. I am questioning the conclusion. It think it is entirely possible to do such a study and discuss the results without "questioning the real benefit of fast lenses", but this requires one to be aware that there is a lot more to fast lenses than "more light".
Whether the extra light gets there or not, the images look different. This is what is missing in the analysis and this is what I have shown in my comparison photos.
Are the camera companies duping us by automatically increasing the gain to compensate? Sure. Is this a reason to question the "benefit" of fast lenses and/or reject fast lenses as a "gimmick"? No. Not even close.
do you really think he doesn't know anything about bokeh or light falloff or that they don't matter? as i said, you are reading far too much into a deliberately imprecise statement than justified.
yet some people really do buy a fast lens specifically to get higher shutter speeds wide open and that is the most important thing with everything else except center sharpness secondary. i shoot under those conditions several months of the year. when i am shooting that way, i don't care about light falloff or bokeh because if i can't get my shutter speeds up while holding ISO to limit noise, i don't get the shot.
having a camera boosting the ISO on me degrades my expected image quality and at ISO 6400, i don't have much to work with. if the camera is going to compensate for a one stop transmission or sensor loss wide open but less stopped down, i might as well shoot with a lens a stop slower or stop down my lens. the camera won't be compensating as much and i get higher image quality at the cost of somewhat slower shutter speeds. bokeh, DOF, and corner light falloff are nearly irrelevant under these conditions.
some sports shooters have similar requirements. they shoot indoors at the high ISO edge and will choose the highest ISO possible commensurate with their tolerance for sensor noise to stop fast action. having the camera increase the ISO on them as they open up increases the noise. good bokeh and low corner falloff are nice to haves.
Herb...
cogitech wrote:
So, he is saying he is inclined to question the real benefit of faster lenses, based on the fact that the dSLR is not efficient enough to fully utilize the light transferred by said faster lenses (at large apertures). How else can one interpret this, other than to conclude that the statement was made by one who thinks light gathering is the sole benefit of faster lenses? He in fact uses the term "benefit" (not plural).
Jonas B wrote:
I checked how a Panasonic Summilux-D 25/1.4 on a µ4/3 Panasonic G1 camera worked out with all the electronics engaged and with no communication between the camera and the lens respectively. There was no difference between the resulting images.
Hi Mike,
The link worked. My brain did not.
The Zone10 author Ken Norton claims: On a FourThirds camera, the maximum aperture is around F1.7 depending on the specific camera body it is installed on. (And also mentions APS-C cameras as possible problems.)
Does Ken Norton think of a 50mm lens when saying max aperture is "F1.7" on a 4/3 camera? Surely the rear lens element size differs with the focal length as well as with the lens construction?
When reading the part about the loss of contrast with 4/3 cameras not seen on FF cameras when using super fast lenses I can't help to wonder if Ken Norton is to take seriously at all. In my experience (no scientific measurements though) all the super fast lenses I have tried on FF cameras and 4/3 and µ4/3 cameras has lower contrast wide open compared to stopped down. I don't think there was a real difference between the cameras here.
Unless you are a personal good friend of Ken's I would like to hear your comments on the topic....Show more →
Well, not a friend, though I should be so fortunate. A talented engineeer and photog. I only "know " him from the OM list. I can't read his mind though I could ask him. I took the statement on F1.7 to mean he measured the miror box and assumed a symmetric design and no fancy footwork with the pupil mag ratio.
I think he is correct about the loss of contrast in some situations on 4/3 using fast lenses. Perhaps in many situations it is more related to veiling flare and the shape
of the rear element and proximity to the sensor or perhaps in part the bezel of the mirror box as he states. I thought it relevant to mention as many here (including me) like to mount these FF or film designed fast lenses cross-platform, but it may not work well all the time especially at the widest apertures. See this link---they referred to "ghosting" mounting OM lenses on the EP-1 that I don't think I see on my OM's on film or 5DII, though I don't have a MFT body yet to directly compare. I'll defer to the formidible optics experts on this list as to the precise explanation. http://www.biofos.com/cornucop/omz_ep1.html
