p.4 #1 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
Sami Ruusunen wrote:
Afaik the size and form of the last glass element influences the angle much more than the small differences in the exit pupil distance. Forexample in Zony 55/1.8 the last lens element if very close to the sensor (closer than some poor perfoming rf lenses) but it's almost as large as the front element and fairly flat from the backside. I imagine this kind of lens design requires much less optimizing for the thick sensor stack.
The exit pupil is where the light rays "appear" to be coming from, which is the crucial factor in determining the angle of incidence. What actually happens inside the lens is irrelevant as the sensor only "sees" the exit pupil.
If the large rear element close to the sensor straightens out the rays, then that means the lens has a long exit pupil.
Oct 06, 2014 at 10:15 AM
Steve Spencer Online • • • • • • • Upload & Sell: On
p.4 #2 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
Matt, I agree with you. To me a couple of things are clear. First, the Loxia 35 f/2 is quite a bit better than the ZM 35 f/2 on the Sony A7 cameras. Second, they both have the same exit pupil and the same number of elements and groups. So, how did Zeiss improve the performance of the Loxia over the ZM? It seems the simplest explanation (Ockam's razor) is that Zeiss redesigned the Loxia to take the cover glass into account. Supporting this argument is the materials provided by Zeiss explaining how this could be done, and someone who interviewed Dr. Nasse reporting that he indeed said this is what was done.
Perhaps there is room for skepticism, but where is the evidence for the skepticism? For me when the simplest explanation is also supported by the most evidence that seems like the best explanation and I will forgo my skepticism. At least for now, or more precisely at least until there is stronger evidence supporting the skepticism.
p.4 #3 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
Steve: I don't doubt that Zeiss are putting in an honest effort in the Loxia line. I think they are in it to impress even with a "cost effective" line of lenses.
I agree with your reasoning and it reflects my own. I doubt Zeiss would outright LIE about it - it would serve them no good and would come back to bite them over and over. They know many photogs today are smart people that know what they want.
I think there is an overemphasis on wording here and unless you are the one sitting with the relevant Zeiss rep it is easy to overlook the language barrier and draw misleading conclusions either way. If someone like Dr Nasse says "we have done it" I don't doubt it. Why should I?
But, if an unknown Zeiss rep or marketing director outside the Zeiss core says "we can do it" or "I think we have done it" there is room for skepticism to a certain degree.
Zeiss are quite communicative as of recent years and compared to say, Sony there is at least some sort of two way communication. I find it somewhat reassuring that you can communicate with an engineer and not just a "random" marketing guy that might know a lot less than you do about most things pertinent to photography.
p.4 #4 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
philber wrote:
Jochen, fact is, Loxia 50 is a "low-premium-priced" Planar. No way are you going to get a super-smooth bokeh. Does it get better? Yes. Great? No.
Is The ZE/ZF 50mm a "higher-premium-priced" Planar? I ask because I wonder if Zeiss is creating higher/lower priced lens lines. Or lens lines with different rendering characteristics (or maybe different "flavors"). I'm really interested in how the ZM 35mm/1.4 performs on the Sony A7. Zeiss will have 5 different FF 35mm lenses in production - ZE/ZF 35mm/2 & /1.4, FE 35/2.8, Loxia 35/2, ZM 35/1.4.
p.4 #5 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
Steve Spencer wrote:
Matt, I agree with you. To me a couple of things are clear. First, the Loxia 35 f/2 is quite a bit better than the ZM 35 f/2 on the Sony A7 cameras. Second, they both have the same exit pupil and the same number of elements and groups. So, how did Zeiss improve the performance of the Loxia over the ZM? It seems the simplest explanation (Ockam's razor) is that Zeiss redesigned the Loxia to take the cover glass into account. Supporting this argument is the materials provided by Zeiss explaining how this could be done, and someone who interviewed Dr. Nasse reporting that he indeed said this is what was done.
Perhaps there is room for skepticism, but where is the evidence for the skepticism? For me when the simplest explanation is also supported by the most evidence that seems like the best explanation and I will forgo my skepticism. At least for now, or more precisely at least until there is stronger evidence supporting the skepticism....Show more →
How do we know they have the same exit pupil? Did I miss something?
PS. Awaiting a confirmation about exit pupil, I might add that, supposedly Zeiss did make some subtle changes to accommodate the thick glass cover, this seems to me more like an emergency treatment to release the lens asap with minor modifications. And it shows in the performance. Ideally Zeiss would have redesigned the lens for a longer exit pupil and better overall performance.
p.4 #6 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
edwardkaraa wrote:
How do we know they have the same exit pupil? Did I miss something?
PS. Awaiting a confirmation about exit pupil, I might add that, supposedly Zeiss did make some subtle changes to accommodate the thick glass cover, this seems to me more like an emergency treatment to release the lens asap with minor modifications. And it shows in the performance. Ideally Zeiss would have redesigned the lens for a longer exit pupil and better overall performance.
My question as well. I have not seen the exit pupil listed for the Loxia Zeiss Biogon.
p.4 #8 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
Steve Spencer wrote:
Matt, I agree with you. To me a couple of things are clear. First, the Loxia 35 f/2 is quite a bit better than the ZM 35 f/2 on the Sony A7 cameras. Second, they both have the same exit pupil and the same number of elements and groups. So, how did Zeiss improve the performance of the Loxia over the ZM? It seems the simplest explanation (Ockam's razor) is that Zeiss redesigned the Loxia to take the cover glass into account. Supporting this argument is the materials provided by Zeiss explaining how this could be done, and someone who interviewed Dr. Nasse reporting that he indeed said this is what was done.
Perhaps there is room for skepticism, but where is the evidence for the skepticism? For me when the simplest explanation is also supported by the most evidence that seems like the best explanation and I will forgo my skepticism. At least for now, or more precisely at least until there is stronger evidence supporting the skepticism....Show more →
agreed.
edwardkaraa wrote:
I have seen this before but I don't really trust the shown results, because a huge DSLR lens like the Otus must have a very distant exit pupil and sensor glass shouldn't affect it in any significant way.
this is incorrect, 55/1.4 lenses produce many rays that come in at pretty oblique angles of incidence at full aperture despite the somewhat distant exit pupil (where the otus exels). when the lens is stopped down a ways your statement is true.
since the otus is designed for use on more than one brand zeiss probably optimized it for the average thickness of cover glass across brands, or maybe they designed it specifically for the d800 since it was the highest resolution sensor when the lens was designed.
p.4 #9 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
sebboh wrote:
agreed.
this is incorrect, 55/1.4 lenses produce many rays that come in at pretty oblique angles of incidence at full aperture despite the somewhat distant exit pupil (where the otus exels). when the lens is stopped down a ways your statement is true.
How do you know that Sebboh? any graph or article you can link to?
p.4 #10 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
edwardkaraa wrote:
How do you know that Sebboh? any graph or article you can link to?
sorry, i don't have the link. in another thread thesuade listed worst case angles of incidence for typical fast lenses at different apertures.
this is the reason digital sensors don't get as much light at f/1.2 and f/1.4 as film does and camera makers secretly boost iso a bit at those apertures (there is a DXO article on this somewhere).
p.4 #11 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
sebboh wrote:
sorry, i don't have the link. in another thread thesuade listed worst case angles of incidence for typical fast lenses at different apertures.
this is the reason digital sensors don't get as much light at f/1.2 and f/1.4 as film does and camera makers secretly boost iso a bit at those apertures (there is a DXO article on this somewhere).
Ok, I see what you mean. That is why the Otus is measured as a f/1.8 lens. But I always thought these oblique rays are invisible to the sensor, and wouldn't cause any image degradation. The WO performance of the Otus should be proof enough.
p.4 #12 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
sebboh wrote:
sorry, i don't have the link. in another thread thesuade listed worst case angles of incidence for typical fast lenses at different apertures.
this is the reason digital sensors don't get as much light at f/1.2 and f/1.4 as film does and camera makers secretly boost iso a bit at those apertures (there is a DXO article on this somewhere).
p.4 #13 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
edwardkaraa wrote:
Ok, I see what you mean. That is why the Otus is measured as a f/1.8 lens. But I always thought these oblique rays are invisible to the sensor, and wouldn't cause any image degradation. The WO performance of the Otus should be proof enough.
indeed, the wide open performance is proof enough – the otus performs better with 2mm filter glass than with no glass, shown here (make sure you read all the article).
some of the oblique rays don't reach the sensor but some do and they all go through astigmatism inducing diffraction of the filter stack.
p.4 #14 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
sebboh wrote:
indeed, the wide open performance is proof enough – the otus performs better with 2mm filter glass than with no glass, shown here (make sure you read all the article).
some of the oblique rays don't reach the sensor but some do and they all go through astigmatism inducing diffraction of the filter stack.
I've read the article, and it seems the 1st copy of the Otus performs really well without the added glass layer:
p.4 #17 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
edwardkaraa wrote:
I have seen this before but I don't really trust the shown results, because a huge DSLR lens like the Otus must have a very distant exit pupil and sensor glass shouldn't affect it in any significant way.
sebboh wrote:
this is incorrect, 55/1.4 lenses produce many rays that come in at pretty oblique angles of incidence at full aperture despite the somewhat distant exit pupil (where the otus exels).
The way understand it (and I'm not an optical engineer) is that the rays form a right angle triangle, where the base of the triangle is the exit pupil distance, and the height of the triangle is the exit pupil radius, and the hypotenuse represents the ray angle. So large aperture lenses (with greater exit pupil radius) can still have steep angles of incidence, despite a longer exit pupil distance.
So large aperture and short distance is the absolute worse combination, but narrow aperture/short distance, and very large aperture/longer distance can be problematic as well.
p.4 #18 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
uhoh7 wrote:
Philber, Does the Loxia have a hard infinity stop?
For myself, I'll take the 50cron v4 over both the 55 and this lens on my A7.
It was also excellent on the A7r.
I mean really excellent.
Here is an article on the Zeiss ZM lenses by Puts where he interestingly says of the ZM 50/2 Planar:
"For several generations the Planar design has tried to challenge the Summicron 50mm and never became as good. Now at last we have a lens that equals the Summicron-M 50mm and is even a trace better in the curvature of field area."
I suppose the same description would apply to the Loxia 50/2.
I'm positive the Loxia's have hard infinity stops. They are full, mechanical MF and not focus by wire.
Oct 06, 2014 at 01:57 PM
Steve Spencer Online • • • • • • • Upload & Sell: On
p.4 #19 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
edwardkaraa wrote:
How do we know they have the same exit pupil? Did I miss something?
PS. Awaiting a confirmation about exit pupil, I might add that, supposedly Zeiss did make some subtle changes to accommodate the thick glass cover, this seems to me more like an emergency treatment to release the lens asap with minor modifications. And it shows in the performance. Ideally Zeiss would have redesigned the lens for a longer exit pupil and better overall performance.
I thought somebody who has a subscription to Lloyd Chambers site, where I understand he publishes the exit pupils, reported this, but maybe I am remembering incorrectly. I think you have a subscription, so you can tell me whether I am off base or not. Maybe he hasn't posted this information yet, and maybe he has the exit pupils are different. I could easily be wrong. But I think the general point I was making still applies. The 35 Loxia definitely does quite a bit better than the ZM 35, or at least it seems that way so far, and Zeiss did something to improve that performance. They seem to be saying that they tweaked it for the cover glass. Why should we doubt them? It seems like the simplest reason for the increase in performance and it is what they said they did. Until I see evidence it is something else I will go with that explanation.
p.4 #20 · Zeiss Loxia 50mm f:2.0 Vs Sony-Zeiss FE 55 f:1.8
Steve Spencer wrote:
I thought somebody who has a subscription to Lloyd Chambers site, where I understand he publishes the exit pupils, reported this, but maybe I am remembering incorrectly. I think you have a subscription, so you can tell me whether I am off base or not. Maybe he hasn't posted this information yet, and maybe he has the exit pupils are different. I could easily be wrong. But I think the general point I was making still applies. The 35 Loxia definitely does quite a bit better than the ZM 35, or at least it seems that way so far, and Zeiss did something to improve that performance. They seem to be saying that they tweaked it for the cover glass. Why should we doubt them? It seems like the simplest reason for the increase in performance and it is what they said they did. Until I see evidence it is something else I will go with that explanation....Show more →
Roger's blog at LensRentals does keep a running database of exit pupil distance but the Loxia is not there yet. The ZM 35/2 Biogon is though and is listed as 34mm's. Maybe you are thinking of this database?
there is at least some sort of two way communication. I find it somewhat reassuring that you can communicate with an engineer and not just a "random" marketing guy that might know a lot less than you do about most things pertinent to photography.