edwardkaraa wrote:
Of course that is also possible, but I hope you're wrong, because the samples show some undercorrection of the astigmatism and field curvature in the corners and borders. This performance would not be satisfactory to me.
At infinity the exit pupil is probably closer to the sensor, which will exacerbate the problem, the correction for astigmatism may be optimised for closer focus distances.
Matt Grum wrote:
The only source I've seen for the thickness of the A7R filter stack is the LensRentals blog post which states it is approximately 3mm but is very difficult to measure. Sounds like it could actually be 2.5mm
It seems possible that the stacks are the same height across Sony sensors but slight differences in filter composition, AA filtration and pixel pitch give rise to the differences in rangefinder lens performance between the different A7 bodies.
Pretty sure they're just referring to the A7, A7R and A7s, which may well all have 2.5mm stacks.
I sent an email to Zeiss asking about the 35mm Biogon
"The ZM 35/2 Biogon is well known for performing badly on the Sony A7r due to ray angles and the position of the exit pupil. What design changes have been made for the Loxia 35/2 Biogon for emount to eliminate this problem?"
I got the reply this morning
"Thanks for your inquiry.
Compared to the Biogon T* 2/35 ZM, the Loxia was changed in its optical and mechanical design (e.g.different air gaps between some lens elements) to improve it for the thick filter plates in front of the sensor of the A7/7R/7S.
Of course, the main characteristics of the original Biogon lens design will be kept, but the image results will be improved compared to an adapted ZM lens of this type.
Further details about this lens and sample images will be available when the lens is ready for the market (estimated end of this year).
For further details, please do not hesitate to contact us.
With Best Regards
Bertram Hönlinger"
Matt Grum wrote:
At infinity the exit pupil is probably closer to the sensor, which will exacerbate the problem, the correction for astigmatism may be optimised for closer focus distances.
Yet, optimizing correction outside of the center for closer distances versue infinity makes less practical sense. If that is the case, particularly with a lens labeled "Biogon", it would seem like it was not a choice but rather due to an inherent restriction of the design.
the 50/2 looks like a big step up from the zm version in terms of corner resolution based on the mtfs. seems they give up a bit in zone b to achieve this, but not much. the differences in mtfs between zm and loxia on both lenses give me hope that they will draw a little different too.
Compared to the Biogon T* 2/35 ZM, the Loxia was changed in its optical and mechanical design (e.g.different air gaps between some lens elements) to improve it for the thick filter plates in front of the sensor of the A7/7R/7S.
Of course, the main characteristics of the original Biogon lens design will be kept, but the image results will be improved compared to an adapted ZM lens of this type.
I fully expect the ZM corner issues to be improved, but not fixed, which is a problem.
Tariq Gibran wrote:
Yet, optimizing correction outside of the center for closer distances versue infinity makes less practical sense. If that is the case, particularly with a lens labeled "Biogon", it would seem like it was not a choice but rather due to an inherent restriction of the design.
That's fine, and taken with the above this will be a great lens for street photography, but if this is the case then I take issue with the following passage taken from the press release:
ZEISS wrote:
With a full-frame focal length of a moderate wide angle, this lens is a specialist for nature, landscape and architectural photography
Matt Grum wrote:
I fully expect the ZM corner issues to be improved, but not fixed, which is a problem.
That's fine, and taken with the above this will be a great lens for street photography, but if this is the case then I take issue with the following passage taken from the press release:
Landscape specialist?
Yeah, I really don't think we will know for sure until someone around here gets one and it's put through it's paces at the end of the year. I am impressed by the Loxia 50 so maybe there is hope.
Sep 02, 2014 at 08:40 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
Well with the mtf's published today it is clear that our worst fears were not realized. These are not simply rehoused versions of the ZM lenses. They certainly have a ZM heritage. Very similar optical designs and physical size. They have very low distortion but quite a bit of vignetting (even the DSLR lenses from Zeiss have quite a bit of that, however).
It is also interesting, however, that with some pretty modest changes the lens perform quite a bit differently. As sebboh pointed out from the MTF, it looks like the 50 will have quite good sharpness across the frame stopped down. If fact if you compare the MTF of the 50 with the MTF of the Contax G 45 f/2, they look a lot a like. A little bigger zone B dip for the 50, but not by much, and a little better performance far into the corners. Also the 50 has just a bit better MTF wide open. I suspect if people like the the Contax G 45, then they will like the Loxia 50 and we already know that the 45 performs quite well on the A7 cameras. I think a good way to think about the 50 is that is will be a slightly longer Contax G 45 that has been optimized for the A7 cameras, and the price doesn't look like it will be too bad either. I am pretty sure as a planar design that its bokeh until f/4 or so will be challenging to put it mildly, but that was true of the 45 as well. If this analysis is right, then IMO, Zeiss could have made a lot worse beginnings with the Loxia line than this lens.
Looking at the 35 its MTF is very different from the ZM 35 f/2. And the news here is neither all good nor all bad, but let's start with the bad. If people wanted this lens for a sharp across the frame landscape lens, then I think they will be disappointed. It is clear that the astigmatism is fairly large in the corners and even some in the edges. Don't look for the lens to be all that sharp wide open either. What it will be or so the MTF suggests is very sharp over the central half of the image stopped down and by very sharp I mean there ought to be excellent bite. It should have great 3D stopped down and could be a very nice lens for close ups (if this performance holds) and environmental portraits. As has been discussed in the last couple of pages the ZM version also has bokeh that isn't to everyone's tastes (and certainly not mine), given these MTF's and even the sample pictures I actually have some hope that the bokeh has improved (but it had a long way to go, so I still might not like it). So, IMO, it is a lot less clear how this lens will perform. It is pretty much a given it won't perform like the ZM 35 f/2 did on the Sony A7 cameras (a very good thing it won't) and not like it performs on Leica digital M (not necessarily a good thing). If you are looking for a sharp across the frame landscape lens, then I think you will be disappointed (it may be pretty good on APS-C, however), but if you want a versatile 35 for street photography, environmental portraits, and maybe even close ups with a good 3D effect, then you might very well like it. For me the big test will be how good is the bokeh, and that will take some time to sort out.
Regarding MTFs, it should be considered that the ZM MTFs are almost certainly calculated without digital sensor consideration since these were originally marketed for use with the Ikon film cameras. I would expect that even the thin filter stack of Leica M will change/degrade the values somewhat, making a direct comparison a bit tricky. That said, my use of the ZM50/2 seemed to be pretty close, in impression, to its published MTF values...
The Berlin Backstage 50/2 samples do look good and the selection of people photos, with subject placement off center at wider apertures, is reassuring.
I also noticed the 35/2 weak edge performance of the official Zeiss sample of the Reichstag. I would guess it was shot at quite a wide aperture based on the greatly defocused foreground and degree of vignetting.
As far as I'm concerned "BOKAW" is an excuse for not having a good DOF wide open. Personally I would like to have lenses that are in focus fro 0 to ~. Bokaw makes my eyes go "BONKERS"
Paul Gardner wrote:
As far as I'm concerned "BOKAW" is an excuse for not having a good DOF wide open. Personally I would like to have lenses that are in focus fro 0 to ~. Bokaw makes my eyes go "BONKERS"
get a pinhole camera, or you know, shoot an ultrawide at f/11.
Based on the Flick'r gallery, I am very pleased with what I am seeing from the Planar. Wide open performance seems miles ahead of my ZE 50 Planar, and also of my ZM 50 Planar. My guess is that it will be a delight at f:2.8. At the other end, I feared uninspired performance as the price to be paid for close up, as is the case with the Sony-Zeiss 24 and 55, but this seems hardly to be the case. And it seems that I'll get mine in October, too. Yummee!
As regards the 35, I'm daft when it comes to reading MTF, but I am not sure that infinity performance will be so weak, based on the church-and-dome shot, which looks pretty good to me. Very good, actually. We'll see, but, at this time, I am not eager to sell my FE 35 f:2.8.
A good amount of LoCA in that window at f4 though. Really, as I suspected, it behaves a lot like the Contax G45. Definitely more pop than what I've seen from the SEL55/1.8, so A7x owners will have their choice of two noticeably different but excellent 50's.
rscheffler wrote:
Regarding MTFs, it should be considered that the ZM MTFs are almost certainly calculated without digital sensor consideration since these were originally marketed for use with the Ikon film cameras. I would expect that even the thin filter stack of Leica M will change/degrade the values somewhat, making a direct comparison a bit tricky. That said, my use of the ZM50/2 seemed to be pretty close, in impression, to its published MTF values...
The Berlin Backstage 50/2 samples do look good and the selection of people photos, with subject placement off center at wider apertures, is reassuring.
I also noticed the 35/2 weak edge performance of the official Zeiss sample of the Reichstag. I would guess it was shot at quite a wide aperture based on the greatly defocused foreground and degree of vignetting....Show more →
Both Zeiss ZM and Leica M lenses official MTF are measured on a Zeiss optical bench. The performance is measured irrespective of the used medium. I agree that the filter stack will have an important effect on IQ as reported by lens rentals a while ago.
>>Totally agreed. So far the 35 seems to be the weaker of the two. But I will reserve my judgement until we see more samples with exif. <<
Agreed, as well, but it would be nice to have an up to date symmetrical wide angle lens without floating lens elements, or aspherical elements. Just because. Retro, or old school desires, I guess.
Steve Spencer wrote:
It is also interesting, however, that with some pretty modest changes the lens perform quite a bit differently.
Small note: as pointed out by TheSuede already, you can only see the curvatures in the block diagrams — not the glass types, which are at least as important.
I'm encouraged by the L-50 and not surprised by the L-35. My Breath-Holding moment will come with the unveilling of the new ZM 35 f/1.4. THAT will (If it excels) trigger an M7 purchase becoming my main peeps camera. Crossed fingers...
Would have to test for myself, but initial images look good.. Hoping that by the time the Loxia lenses come out, Sony has something else out other then the A7/r/s.
sector99 wrote:
I'm encouraged by the L-50 and not surprised by the L-35. My Breath-Holding moment will come with the unveilling of the new ZM 35 f/1.4. THAT will (If it excels) trigger an M7 purchase becoming my main peeps camera. Crossed fingers...
You'll be waiting a while.. Zeiss has all ZM lenses on the back burner from what they told me.
