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Archive 2009Explain the 50mm L problem
p.4 #1Explain the 50mm L problem
When the lens was introduced I was excited. I liked the build quality and the promised optical benefits, so I bought it, but was disappointed, and after trying two samples, returned both. I more or less wrote off the lens.
Then last summer on a whim I got a loaner from CPS and *that* copy turned out to be great. (Interestingly, the lens had a 'refurbished' sticker on it.)
So I recently acquired a new copy, and I am quite satisfied with it. (Interestingly, the store had a used copy which I looked at first, but that copy was a lot like the first two I bought and returned.)
I had a very good copy of the 1.4, which I compared against my latest copy of the 'L'. The 'L' is sharper wide open, without the halation or CA (though perhaps marginally less sharp stopped down). It also has nicer bokeh, as is well known. However, a bit more surprising was the subtle difference in contrast and color "depth". Files captured with the 'L' have a clearly visible "3D" quality not present in the files captured side by side with the 1.4. (Sorry for the overworked Leica metaphor, but it's an apt description of my subjective impression.)
Bottom line: there is sample variation in this lens, but when it is good it is very good indeed.
Then last summer on a whim I got a loaner from CPS and *that* copy turned out to be great. (Interestingly, the lens had a 'refurbished' sticker on it.)
So I recently acquired a new copy, and I am quite satisfied with it. (Interestingly, the store had a used copy which I looked at first, but that copy was a lot like the first two I bought and returned.)
I had a very good copy of the 1.4, which I compared against my latest copy of the 'L'. The 'L' is sharper wide open, without the halation or CA (though perhaps marginally less sharp stopped down). It also has nicer bokeh, as is well known. However, a bit more surprising was the subtle difference in contrast and color "depth". Files captured with the 'L' have a clearly visible "3D" quality not present in the files captured side by side with the 1.4. (Sorry for the overworked Leica metaphor, but it's an apt description of my subjective impression.)
Bottom line: there is sample variation in this lens, but when it is good it is very good indeed.
Mar 18, 2009 at 04:37 PM
p.4 #2Explain the 50mm L problem
Galibier wrote:
Relying purely on my memory of the focus tests I conducted, the focus shift gradually increases beginning about f/2 and levels off about f/4. With my 50/1.2, the shift is never great, and in fact the focus never shifts beyond the depth of field. In other words, the intended point of focus stays just within the front edge of the depth of field, although the point of sharpest focus has moved rearward. At apertures smaller than about f/4 or f/5.6, the depth of field has expanded enough so that the focus shift is irrelevant. At distances greater than a few...Show more →
I took the approach Galibier describes, since I like the FL and wanted the speed and rendering qualities of the 50L. After shooting it awhile, I thought it'd be smart to test for focus shift, confirmed it at 3-4 feet at f1.8 to ~ F4, pondered the data, and concluded that calibration might help to distribute the shift more proportionately front to back. Canon-Irvine did the work and, indeed, the lens' focus shift is now more evenly placed front to back. Effectively, DOF covers the focus shift at all apertures at close distance. I was pleased initially with the lens (prior to calibration), now even more so.
Honestly, many of the negative 50L comments I read prior to my purchase were helpful. I wanted the lens to work for me and was prepared to expend the effort and patience with Canon to get it right.
As an aside, I understand that the 50L was used extensively for the recent SI swimsuit shoot by luminaries like Walter Iooss, Jr. (Yes, I've watched the videos, I admit it, absolutely.) Rumor has it that 50L focus shift was the topic of choice among the shooters and models. Ya think?
Edited on Mar 18, 2009 at 06:12 PM · View previous versions
Relying purely on my memory of the focus tests I conducted, the focus shift gradually increases beginning about f/2 and levels off about f/4. With my 50/1.2, the shift is never great, and in fact the focus never shifts beyond the depth of field. In other words, the intended point of focus stays just within the front edge of the depth of field, although the point of sharpest focus has moved rearward. At apertures smaller than about f/4 or f/5.6, the depth of field has expanded enough so that the focus shift is irrelevant. At distances greater than a few...Show more →
I took the approach Galibier describes, since I like the FL and wanted the speed and rendering qualities of the 50L. After shooting it awhile, I thought it'd be smart to test for focus shift, confirmed it at 3-4 feet at f1.8 to ~ F4, pondered the data, and concluded that calibration might help to distribute the shift more proportionately front to back. Canon-Irvine did the work and, indeed, the lens' focus shift is now more evenly placed front to back. Effectively, DOF covers the focus shift at all apertures at close distance. I was pleased initially with the lens (prior to calibration), now even more so.
Honestly, many of the negative 50L comments I read prior to my purchase were helpful. I wanted the lens to work for me and was prepared to expend the effort and patience with Canon to get it right.
As an aside, I understand that the 50L was used extensively for the recent SI swimsuit shoot by luminaries like Walter Iooss, Jr. (Yes, I've watched the videos, I admit it, absolutely.) Rumor has it that 50L focus shift was the topic of choice among the shooters and models. Ya think?
Edited on Mar 18, 2009 at 06:12 PM · View previous versions
Mar 18, 2009 at 04:37 PM
p.4 #3Explain the 50mm L problem
Tom Abbott wrote:
The 50L is awesome. Hobbyists seem preoccupied by focus shift, photographers seem to love what this lens can do for them.
What kind of a nonsensical statement is that exactly? Since when don't Professional photographers depend on the focus accuracy of their lenses at all distances and apertures
The 50L is awesome. Hobbyists seem preoccupied by focus shift, photographers seem to love what this lens can do for them.
What kind of a nonsensical statement is that exactly? Since when don't Professional photographers depend on the focus accuracy of their lenses at all distances and apertures
Mar 18, 2009 at 04:42 PM
p.4 #4Explain the 50mm L problem
Lars Johnsson wrote:
Ye the issue is blown out of proportion in forums like this 
To keep it a bit more in perspective, here are a few others that also had focus shift when they where tested.
Canon EF 20-35mm f/3.5-4.5 USM
Canon EF 24mm f/2.8
Canon EF 17-35mm f/2.8 USM L
Canon EF 85mm f/1.2 USM L
Canon EF 20mm f/2.8 USM
Canon EF 50mm f/1.8 II
And a lot of Nikon, Tamron, Pentax and so on also have it
Ok, and take note of how many are still in production, what does that tell you? Posting a list of other lenses (all of which except for two have been discontinued) doesn't make up for the 50L's shortcoming and certainly doesn't make it OK. BTW, I haven't heard of any focus shift issues with either the 24/2.8 or the 50/1.8II.
M Vers wrote
I don't understand it when people say that the issue is blown out of proportion. It's a major design flaw characteristic in a $1400 'L'uxury lens....what exactly do you expect? If you buy the lens to use only at f/1.8 and wider and f/8 and narrower or at a distance of +6ft then that's great--but what about those who want use it close to mfd (6ft or less) at f/2-f/5.6? I've always been intrigued by this lens, and more recently the sigma 1.4, but the focus shift/AF issues have staved me off every single time I get close to buying one. BTW I have used various copies of this lens, while not extensively, on multiple occasions as well as the Sigma (only one copy) so I can say I do have first hand experience with the issue(s). Yohan, I should have just '+1'ed your post To keep it a bit more in perspective, here are a few others that also had focus shift when they where tested.Canon EF 20-35mm f/3.5-4.5 USM
Canon EF 24mm f/2.8
Canon EF 17-35mm f/2.8 USM L
Canon EF 85mm f/1.2 USM L
Canon EF 20mm f/2.8 USM
Canon EF 50mm f/1.8 II
And a lot of Nikon, Tamron, Pentax and so on also have it
Ok, and take note of how many are still in production, what does that tell you? Posting a list of other lenses (all of which except for two have been discontinued) doesn't make up for the 50L's shortcoming and certainly doesn't make it OK. BTW, I haven't heard of any focus shift issues with either the 24/2.8 or the 50/1.8II.
Mar 18, 2009 at 04:43 PM
p.4 #5Explain the 50mm L problem
I'm sorry, this "logic" is just stupid. Any lens you buy, especially a very expensive lens, should be capable of being put to general use. Granted there are people on this list that think shooting everything wide open makes all their photos more wonderful, but it doesn't. When their kids are grown and all they have are freaky shots with just eyes in focus they will realize that their GAS got in the way of their judgement. The reason you would buy the 50L over the EF 50/1.4 is because you want a *better* lens... and being better includes f2-4 at near distances. The bokeh from the 50/1.4 in not very good so it will not serve you "equally well."
>>The plain fact of the matter is that if you are shooting in such a way that the focus shift is a problem, then the 50/1.4 would serve you equally as well - and save you $1000.
>>The plain fact of the matter is that if you are shooting in such a way that the focus shift is a problem, then the 50/1.4 would serve you equally as well - and save you $1000.
Mar 18, 2009 at 05:17 PM
p.4 #6Explain the 50mm L problem
deepbluejh wrote:
If you shoot at close distances, between the apertures of F2 and F4, and use center point AF, the plane of focus will shift slightly upon taking the picture.
This is not an issue when:
1. Shooting with a faster aperture than F2-F2.8
2. Using anything besides center AF point
3. Shooting a subject more than about 8 feet away.
Quite honestly, this "issue" has been blown so far out of proportion that is has become a running joke in the forums. If you are buying the 50L for serious fast aperture work, then this "issue" isn't an issue at all. Even when it is...Show more →
This doesn't even make sense to me. You can't use the center af point, shoot a subject that's closer than 8 ft and can't stop down to slower than f/2-2.8? I'd certainly call all of the above problems.
If you shoot at close distances, between the apertures of F2 and F4, and use center point AF, the plane of focus will shift slightly upon taking the picture.
This is not an issue when:
1. Shooting with a faster aperture than F2-F2.8
2. Using anything besides center AF point
3. Shooting a subject more than about 8 feet away.
Quite honestly, this "issue" has been blown so far out of proportion that is has become a running joke in the forums. If you are buying the 50L for serious fast aperture work, then this "issue" isn't an issue at all. Even when it is...Show more →
This doesn't even make sense to me. You can't use the center af point, shoot a subject that's closer than 8 ft and can't stop down to slower than f/2-2.8? I'd certainly call all of the above problems.
Mar 18, 2009 at 05:20 PM
p.4 #7Explain the 50mm L problem
mh2000 wrote:
I'm sorry, this "logic" is just stupid. Any lens you buy, especially a very expensive lens, should be capable of being put to general use. Granted there are people on this list that think shooting everything wide open makes all their photos more wonderful, but it doesn't. When their kids are grown and all they have are freaky shots with just eyes in focus they will realize that their GAS got in the way of their judgement. The reason you would buy the 50L over the EF 50/1.4 is because you want a *better* lens... and being better includes f2-4...Show more →
I'm not sure if I'd classify his logic as "stupid". While I agree with you the lens is not 100% dependable and is not worth the $1400 beans it costs, it still can do 1.2-1.8 very well and for many photographers out there this is where they live--regardless of your own personal shooting style. As for the bokeh thing, if you recall correctly you know where I stand on that one
In fact if anyone is curious here is a head to head between the 50/1.2 and 50/1.4--bokeh is very similar.
I'm sorry, this "logic" is just stupid. Any lens you buy, especially a very expensive lens, should be capable of being put to general use. Granted there are people on this list that think shooting everything wide open makes all their photos more wonderful, but it doesn't. When their kids are grown and all they have are freaky shots with just eyes in focus they will realize that their GAS got in the way of their judgement. The reason you would buy the 50L over the EF 50/1.4 is because you want a *better* lens... and being better includes f2-4...Show more →
I'm not sure if I'd classify his logic as "stupid". While I agree with you the lens is not 100% dependable and is not worth the $1400 beans it costs, it still can do 1.2-1.8 very well and for many photographers out there this is where they live--regardless of your own personal shooting style. As for the bokeh thing, if you recall correctly you know where I stand on that one
In fact if anyone is curious here is a head to head between the 50/1.2 and 50/1.4--bokeh is very similar.Mar 18, 2009 at 05:24 PM
p.4 #8Explain the 50mm L problem
RobertLynn wrote:
This is not an issue when:
1. Shooting with a faster aperture than F2-F2.8
2. Using anything besides center AF point
3. Shooting a subject more than about 8 feet away.
Quite honestly, this "issue" has been blown so far out of proportion that is has become a running joke in the forums. If you are buying the 50L for serious fast aperture work, then this "issue" isn't an issue at all. Even when it is a "problem", it is only very slight.
I've been using the lens in a wedding/portrait situation for the past 8 months or so and it has *never* been an issue for me. Not once.This doesn't even make sense to me. You can't use the center af point, shoot a subject that's closer than 8 ft and can't stop down to slower than f/2-2.8? I'd certainly call all of the above problems.
Perhaps I wasn't clear. My point was that there is only a very narrow band of circumstances where this infamous "shift" is even a slight issue. Outside of that, the lens performs predictably. Even when shooting in the "problem zone", the shift is easily circumvented. But hey, all of this is trival for most people.
Again, it feels like this topic is beat to death about once a week here in this forum. I'm shocked there is anyone who frequents this forums who isn't fully abreast on the 50L and all of its quirks.
With all of that said, I'm exhausted of explaining this. I'm done.
deepbluejh wrote
If you shoot at close distances, between the apertures of F2 and F4, and use center point AF, the plane of focus will shift slightly upon taking the picture.This is not an issue when:
1. Shooting with a faster aperture than F2-F2.8
2. Using anything besides center AF point
3. Shooting a subject more than about 8 feet away.
Quite honestly, this "issue" has been blown so far out of proportion that is has become a running joke in the forums. If you are buying the 50L for serious fast aperture work, then this "issue" isn't an issue at all. Even when it is a "problem", it is only very slight.
I've been using the lens in a wedding/portrait situation for the past 8 months or so and it has *never* been an issue for me. Not once.
Perhaps I wasn't clear. My point was that there is only a very narrow band of circumstances where this infamous "shift" is even a slight issue. Outside of that, the lens performs predictably. Even when shooting in the "problem zone", the shift is easily circumvented. But hey, all of this is trival for most people.
Again, it feels like this topic is beat to death about once a week here in this forum. I'm shocked there is anyone who frequents this forums who isn't fully abreast on the 50L and all of its quirks.
With all of that said, I'm exhausted of explaining this. I'm done.
Mar 18, 2009 at 05:39 PM
p.4 #9Explain the 50mm L problem
people seem to forget that most people only follow the threads that are interesting to them at the time... so if you had no interest in the 50L until now, why would you have been reading all the threads leading up to this one? So chastizing someone for asking a new question for them just because it has been "beat to death" by others is meaningless and frankly rather rude IMO.
>>Again, it feels like this topic is beat to death about once a week here in this forum. I'm shocked there is anyone who frequents this forums who isn't fully abreast on the 50L and all of its quirks.
>>Again, it feels like this topic is beat to death about once a week here in this forum. I'm shocked there is anyone who frequents this forums who isn't fully abreast on the 50L and all of its quirks.
Mar 18, 2009 at 06:22 PM
p.4 #10Explain the 50mm L problem
I had missed your bokeh comparison (never saw it), but looking at it now, it doesn't say much about bokeh IMO... much too benign and blurred, the differences that interest me come into play at less blur and more contrast messy backgrounds.
So what do you propose, buy a 50/1.8 or 50/1.4 to swap out whenever you venture into the 50L's trouble zone?
I agree with a number of other reviewers that many will not shoot within the trouble zone because they are either shooting wide open or at distances greater than 6ft at other apertures, but that doesn't make the problem non-existent, which is what a large number of posters on this and other threads imply.
M Vers wrote:
>>The plain fact of the matter is that if you are shooting in such a way that the focus shift is a problem, then the 50/1.4 would serve you equally as well - and save you $1000.I'm not sure if I'd classify his logic as "stupid". While I agree with you the lens is not 100% dependable and is not worth the $1400 beans it costs, it still can do 1.2-1.8 very well and for many photographers out there this is where they live--regardless of your own personal shooting style. As for the bokeh thing, if you recall correctly you know where I stand on that one In fact if anyone is curious here is a head to head between the 50/1.2 and 50/1.4--bokeh is very similar.
So what do you propose, buy a 50/1.8 or 50/1.4 to swap out whenever you venture into the 50L's trouble zone?
I agree with a number of other reviewers that many will not shoot within the trouble zone because they are either shooting wide open or at distances greater than 6ft at other apertures, but that doesn't make the problem non-existent, which is what a large number of posters on this and other threads imply.
M Vers wrote:
mh2000 wrote
I'm sorry, this "logic" is just stupid. Any lens you buy, especially a very expensive lens, should be capable of being put to general use. Granted there are people on this list that think shooting everything wide open makes all their photos more wonderful, but it doesn't. When their kids are grown and all they have are freaky shots with just eyes in focus they will realize that their GAS got in the way of their judgement. The reason you would buy the 50L over the EF 50/1.4 is because you want a *better* lens... and being better includes f2-4 at near distances. The bokeh from the 50/1.4 in not very good so it will not serve you "equally well.">>The plain fact of the matter is that if you are shooting in such a way that the focus shift is a problem, then the 50/1.4 would serve you equally as well - and save you $1000.
In fact if anyone is curious here is a head to head between the 50/1.2 and 50/1.4--bokeh is very similar.Mar 18, 2009 at 06:31 PM
p.4 #11Explain the 50mm L problem
jamie isn't chastising anyone, mh. he's expressing the view that the topic is so often covered that few forum participants would not have had ample opportunity to obtain information about the 50L, if they're so inclined. where is the chastisement in such an expression? in pointing out that the topic has seen plenty of coverage? in implying the information is here in significant depth? in implying that any further explanation or *defense* of the lens is probably redundant?
jamie's an experienced user. he gets quoted and criticized by people who don't own and possibly have never even used the lens. if i were in his shoes, i'd be exhausted and give up too.
maybe your fora antenna need a signal gain adjustment ...
jamie's an experienced user. he gets quoted and criticized by people who don't own and possibly have never even used the lens. if i were in his shoes, i'd be exhausted and give up too.
maybe your fora antenna need a signal gain adjustment ...
Mar 18, 2009 at 06:46 PM
p.4 #12Explain the 50mm L problem
50 ml lenses should be outlawed anyhow. Terrible FL. (Eyeballs would have been better made at 35 mm FL as well.)
Mar 18, 2009 at 06:55 PM
p.4 #13Explain the 50mm L problem
The only problem for me is the price.... I just got a 50 1.8 II
http://mfoto.smugmug.com/photos/490225360_hS49u-XL.jpg
http://mfoto.smugmug.com/photos/490225360_hS49u-XL.jpg
Mar 18, 2009 at 06:59 PM
p.4 #14Explain the 50mm L problem
all I know is that if I asked a question and people reply this has been "beaten to death" I'd find it rude. This is not a repository of static information, but a forum where people come to discuss topocs that they are interested in... if someone doesn't want to respond, then it is better not... just like I rarely open up 24-70L vs. 24-105L threads... but if I was buying one of those lenses I would probably want to chat about it... it's all supposed to be good fun... that's all I'm saying.
Mike Tuomey wrote:
jamie isn't chastising anyone, mh. he's expressing the view that the topic is so often covered that few forum participants would not have had ample opportunity to obtain information about the 50L, if they're so inclined. where is the chastisement in such an expression? in pointing out that the topic has seen plenty of coverage? in implying the information is here in significant depth? in implying that any further explanation or *defense* of the lens is probably redundant?
jamie's an experienced user. he gets quoted and criticized by people who don't own and possibly have never even used the lens....Show more →
Mike Tuomey wrote:
jamie isn't chastising anyone, mh. he's expressing the view that the topic is so often covered that few forum participants would not have had ample opportunity to obtain information about the 50L, if they're so inclined. where is the chastisement in such an expression? in pointing out that the topic has seen plenty of coverage? in implying the information is here in significant depth? in implying that any further explanation or *defense* of the lens is probably redundant?
jamie's an experienced user. he gets quoted and criticized by people who don't own and possibly have never even used the lens....Show more →
Mar 18, 2009 at 07:04 PM
p.4 #15Explain the 50mm L problem
I think it is a possibility that in the future you will be able to microadjust focus not only by lens, but also by aperture (i.e. [email protected] [email protected] [email protected]). When this day arrives, the 50L will be the best 50 out there.
Mar 18, 2009 at 07:20 PM
p.4 #16Explain the 50mm L problem
Makten wrote:
I'd really like to see a test proving that these MF lenses you are talking about doesn't give focus shift, and have equal IQ to the L. Almost all fast normal lenses does focus shift, regardless of design, brand or anything else.
.
Check any of the old tests from Modern Photography, I have posted many of them on my site. They list the focus shift, measured in mm.
Using MF lenses on EOS, usually you are focusing with stop-down metering so it's a non-issue. For a few hundred I can put up with that on a 50/1.2 MF lens. For a $1400 L canon EF autofocus lens, I can't put up with it.
I'd stack the OM 50/1.2, Rokkor 58/1.2, Canon FD 55/1.2AL or FD 50/1.2L, Pentax 50/1.2 against the Canon EF 50/1.2L anyday regarding IQ. They would not be embarassed, and infact would likely trounce the Canon in some ways.
I too want to love the EF 50/1.2L but can't.
And no, the 50/1.0L doesnt' have any focus shift issue.
If canon wasn't lazy/cheap/in-denial about it, they could likely easily fix it on the 50/1.2L, add a floating element and it's pretty much solved. They knew how to do this well enough in the past, no excuse for not doing it now.
Mauro Moretti wrote:
I think it is a possibility that in the future you will be able to microadjust focus not only by lens, but also by aperture (i.e. [email protected] [email protected] [email protected]). When this day arrives, the 50L will be the best 50 out there.
Canon could do this right now if they wanted to. point-and-shoot and rangefinder AF cameras in the 80s had this programmed into their firmware then, so it's certainly doable now, and no need to even manually microadjust. Just build a lookup table in the ROM.
FWIW
-Ed
I'd really like to see a test proving that these MF lenses you are talking about doesn't give focus shift, and have equal IQ to the L. Almost all fast normal lenses does focus shift, regardless of design, brand or anything else.
.
Check any of the old tests from Modern Photography, I have posted many of them on my site. They list the focus shift, measured in mm.
Using MF lenses on EOS, usually you are focusing with stop-down metering so it's a non-issue. For a few hundred I can put up with that on a 50/1.2 MF lens. For a $1400 L canon EF autofocus lens, I can't put up with it.
I'd stack the OM 50/1.2, Rokkor 58/1.2, Canon FD 55/1.2AL or FD 50/1.2L, Pentax 50/1.2 against the Canon EF 50/1.2L anyday regarding IQ. They would not be embarassed, and infact would likely trounce the Canon in some ways.
I too want to love the EF 50/1.2L but can't.
And no, the 50/1.0L doesnt' have any focus shift issue.
If canon wasn't lazy/cheap/in-denial about it, they could likely easily fix it on the 50/1.2L, add a floating element and it's pretty much solved. They knew how to do this well enough in the past, no excuse for not doing it now.
Mauro Moretti wrote:
I think it is a possibility that in the future you will be able to microadjust focus not only by lens, but also by aperture (i.e. [email protected] [email protected] [email protected]). When this day arrives, the 50L will be the best 50 out there.
Canon could do this right now if they wanted to. point-and-shoot and rangefinder AF cameras in the 80s had this programmed into their firmware then, so it's certainly doable now, and no need to even manually microadjust. Just build a lookup table in the ROM.
FWIW
-Ed
Mar 18, 2009 at 08:16 PM
p.4 #17Explain the 50mm L problem
Ed Sawyer wrote:
If canon wasn't lazy/cheap/in-denial about it, they could likely easily fix it on the 50/1.2L, add a floating element and it's pretty much solved. They knew how to do this well enough in the past, no excuse for not doing it now.
FWIW
-Ed
Is it possible, given your observation that Canon has the technical ability to "fix" the shift issue, that their decision reflects a concern that adding a floating element might compromise the goal of making a lens that renders very much like a sonnar (or ernostar) design? The 50L's elements seem quite similar to that of the sonnar and ernostar. My perception of the 50L's bokeh is that it is especially sonnar-like.
Zeiss considers focus shift in its current M-mount sonnar an unavoidable by-product of the design, for example. Zeiss doesn't consider focus shift in the sonnars as a flaw, actually more like a feature.
If canon wasn't lazy/cheap/in-denial about it, they could likely easily fix it on the 50/1.2L, add a floating element and it's pretty much solved. They knew how to do this well enough in the past, no excuse for not doing it now.
FWIW
-Ed
Is it possible, given your observation that Canon has the technical ability to "fix" the shift issue, that their decision reflects a concern that adding a floating element might compromise the goal of making a lens that renders very much like a sonnar (or ernostar) design? The 50L's elements seem quite similar to that of the sonnar and ernostar. My perception of the 50L's bokeh is that it is especially sonnar-like.
Zeiss considers focus shift in its current M-mount sonnar an unavoidable by-product of the design, for example. Zeiss doesn't consider focus shift in the sonnars as a flaw, actually more like a feature.
Mar 18, 2009 at 08:42 PM
p.4 #18Explain the 50mm L problem
Mike that doesnt' surprise me about Zeiss. (it's a feature! Really! ;-) Actually the fact that they admit it is at least a step ahead of canon.
I'd be surprised if Canon even bothered to keep track of what zeiss is up to, much less to try to make a lens that rendered like one of theirs. I think they have their own ideas by now (I should hope so!) of what they want to achieve. Perhaps they did aim at a sonnar look, but it seems doubtful to me. Their older 50L-class lenses all had floating elements as do the L-class primes that bracket the 50 (the 35L and 85L). I can only surmise cheapness/laziness/etc., given that.
Even if you allow for the idea they wanted to copy a sonnar design, they could have programmed a lookup table of override data to accomodate for the focus shift, based on apeture and focus distance.
I'd be surprised if Canon even bothered to keep track of what zeiss is up to, much less to try to make a lens that rendered like one of theirs. I think they have their own ideas by now (I should hope so!) of what they want to achieve. Perhaps they did aim at a sonnar look, but it seems doubtful to me. Their older 50L-class lenses all had floating elements as do the L-class primes that bracket the 50 (the 35L and 85L). I can only surmise cheapness/laziness/etc., given that.
Even if you allow for the idea they wanted to copy a sonnar design, they could have programmed a lookup table of override data to accomodate for the focus shift, based on apeture and focus distance.
Mar 18, 2009 at 09:53 PM
p.4 #19Explain the 50mm L problem
also, the EF 50/1.2L looks much more like a traditional Gauss design to me than a sonnar/ernostar layout.
Mar 18, 2009 at 09:57 PM
p.4 #20Explain the 50mm L problem
Ed, you are right about the design origin, thanks for that. As to the feasibility of adding a floating element, I've borrowed a comment posted by *wimg* at POTN:
"Essentially, I reckon the 50L is too short FL-wise, in a Gaussian design at such a large aperture and optimized for excellent bokeh, to have a floating rear element, where the 85L is long enough. Unfortunately it is also a little too short to make it into a telecentric design, and too long for a WA design. One could argue Canon could have created a 40 or 45 mm F/1.2L, or a 60 or 70 mm F/1.2L, to get around the issue, but those are rather close in focal length to existing fast Ls ., athough I would have loved a 60L or 65L F/1.2."
Canon may have had more than just cheapness/laziness at the root of the issue ... but about the AF workaround, I believe Konica did so with its Hexar AF about 15 years ago. Very do-able, apparently.
"Essentially, I reckon the 50L is too short FL-wise, in a Gaussian design at such a large aperture and optimized for excellent bokeh, to have a floating rear element, where the 85L is long enough. Unfortunately it is also a little too short to make it into a telecentric design, and too long for a WA design. One could argue Canon could have created a 40 or 45 mm F/1.2L, or a 60 or 70 mm F/1.2L, to get around the issue, but those are rather close in focal length to existing fast Ls ., athough I would have loved a 60L or 65L F/1.2."
Canon may have had more than just cheapness/laziness at the root of the issue ... but about the AF workaround, I believe Konica did so with its Hexar AF about 15 years ago. Very do-able, apparently.
Mar 19, 2009 at 04:27 AM