p.16 #1 · Zeiss "Batis" AF lens line to be released for FF E-mount
'ZM 85/2 (the sharpest 85 stopping down)'
At f5.6 the Batis is about a dead heat with the ZM Sonnar 85/2 at f4.
In the middle - a radius of 10mm, so almost to the short edges, an area where distortion will be a tiny factor - at f1.8 the Batis 85 is a virtual dead heat with the Otus 85 at f1.4, a little stronger acutance/overall contrast (5lpmm), a little weaker on detail (40lpmm). No one serious shoots for fine detail at f1.8..this is super detail in portraits and enviro portraits. It's clearly stronger than the Leica 90AA at f2.
At f4 for both Batis and Otus lenses, the Otus is a half step stronger in the same 10mm image height area, but is better in the outer frame. Bottom line: expect truly great images even at f1.8 from the Batis. It's a game changing lens that many users might have paid $1500 or more to get, and it's only on Sony FE.
Thanks to Zeiss for providing MTF early and LC for publishing it. I'm off to the BH site.
p.16 #2 · Zeiss "Batis" AF lens line to be released for FF E-mount
philip_pj wrote:
'ZM 85/2 (the sharpest 85 stopping down)'
At f5.6 the Batis is about a dead heat with the ZM Sonnar 85/2 at f4.
In the middle - a radius of 10mm, so almost to the short edges, an area where distortion will be a tiny factor - at f1.8 the Batis 85 is a virtual dead heat with the Otus 85 at f1.4, a little stronger acutance/overall contrast (5lpmm), a little weaker on detail (40lpmm). No one serious shoots for fine detail at f1.8..this is super detail in portraits and enviro portraits. It's clearly stronger than the Leica 90AA at f2.
At f4 for both Batis and Otus lenses, the Otus is a half step stronger in the same 10mm image height area, but is better in the outer frame. Bottom line: expect truly great images even at f1.8 from the Batis. It's a game changing lens that many users might have paid $1500 or more to get, and it's only on Sony FE.
Thanks to Zeiss for providing MTF early and LC for publishing it. I'm off to the BH site....Show more →
Of course, the one thing that all of these lenses have in common, EXCEPT for the Batis, is less than 1% distortion.
There will be a little resolution hit towards the borders and corners of the Batis after correction.
Sean Reid had a great article not so long ago (subscription) which clearly demonstrated the loss of resolution from the double interpolation that must occur for distortion correction (the image is first corrected for distortion, the first interpolation, cropped and finally resized/ interpolated back up to the original MP output size). The Zeiss 12/2.8 Touit was one of the lenses used in his example and it suffered quite a bit. That lens of course has a lot more than 3% native distortion. Some of the Fuji's also require a lot of correction (like the 27mm) but then with a few, Fuji has gone out of it's way to "get it right" optically (as have Zeiss with the Loxia's). Getting distortion optically right really does show/ pay-off, for instance, with the Fuji 14/2.8 and 23/1.4. Just my opinion, but if I'm trying to extract the most out of a high resolution FF sensor and paying a heck of a lot for a lens, I'm generally not alright with throwing away some of that potential resolution. That said, the posted portrait images from the lens do look really outstanding.
p.16 #3 · Zeiss "Batis" AF lens line to be released for FF E-mount
On the 25mm, very interesting lens given the good pricing and size/weight.
A lot of sophisticated users really like the ZEF 25/2 - for good reason. But this Batis 25/2 is very different in several key aspects. It's 335 grams against 570/600 grams for the ZEF, to which you had to add adapter weight and bulk and cost to use on FE cameras.
Distortion (native, uncorrected) is just 1.6% barrel in a shallow curve, so correction is unnecessary for many/most compositions.
Corners are much, much improved at all apertures, and curvature appears non-existent.
Performance at f2 is interesting, as suspected it's tuned here for general usage, with ultra flat, almost overlaid lines with weak detail but strong acutance, and a it's good bet to have fine bokeh.
At f4 it has a slightly weaker center than the ZEF lens, but with far nicer outer frames, with a fair amount of smoothly declining astigmatism, it looks like an old Sonnar...but at the very corner you get an average of 55% for fine detail compared with just over 30% for the ZEF.
F5.6-f8 look great, so it will do excellent landscapes. I'd prefer it to Leica's 24/3.8 wide open on these data, though it may a little weaker at f8 than that fine lens. So they have managed to produce a $1300 WA for FE with minor distortion and Super Elmar IQ, that's all the more impressive given its ability at f2. Going forward, another hard to resist lens with excellent value/performance.
p.16 #4 · Zeiss "Batis" AF lens line to be released for FF E-mount
Fair comments, Tariq, agreed. But it's better than many of us hoped for, centers will be spectacular and final images will tell the tale. The 25mm will shake things up too, and both of these will draw many into the fold, I'd suspect.
The question to put is this: If you want this level of performance at this price/size/weight/convenience, what else can do it? Zeiss is no doubt confident of a one word answer to that one!
p.16 #5 · Zeiss "Batis" AF lens line to be released for FF E-mount
philip_pj wrote:
Fair comments, Tariq, agreed. But it's better than many of us hoped for, centers will be spectacular and final images will tell the tale. The 25mm will shake things up too, and both of these will draw many into the fold, I'd suspect.
The question to put is this: If you want this level of performance at this price/size/weight/convenience, what else can do it? Zeiss is no doubt confident of a one word answer to that one!
That 25 looks really enticing.
If you want/need AF and OIS in an 85, particularly for E-Mount, this very well may be the only game in town. I don't know though how, for instance, a Nikon shooter would judge it against the under $500 85/1.8G Nikkor for that system.
p.16 #6 · Zeiss "Batis" AF lens line to be released for FF E-mount
As we saw with the brouhaha along similar lines upon the release of the FE55, they would scratch their heads, never knowing the difference. ;-) And good for them too.
But just a few notes on why your dramatic comment is misleading - once placed in context.
Distortion is the kindest aberration for lens designers to grapple with, and in modern digital era lens design one they will let 'float' more as a trade off for other far more important considerations - like cost, size and weight, and other aberration control. The best lenses will of course exhibit very little of it - for this FL range 0.5-1.0%.
You have to realize distortion is an outer frame phenomenon for the most part, as it increases with image height - this is why makers provide charts so users can evaluate a plot of the aberration. [As an aside it varies with other attributes, factors which may have been written into the correction data, perhaps including focal distance.]
The reason why distortion is one aberration CZ have not worried much about in many lenses is that it is easily and, in image quality terms, fairly painlessly dealt with. They rightly point out that 2% is the general threshold for even noticing distortion in final images, and that is the figure of many fine Zeiss lenses - primes as well as zooms. The 50MP has 1.5%, the ZE 35/2 over 2% for example.
Now, designers must consider use cases for lens - not many users of fast 85s are going be worried about edge distortion for f1.8-f2.8 shots, it's almost all OOF. Even stopped down for open landscape work it's still not a big concern, if best quality in the outer frame is needed. But, and this is important - nothing will diminish the central image quality of this lens. They are not alone...>
"other high-end cameras have been doing it for years. Every single Hasselblad H-series body (those with a dedicated digital back) corrects for its 28mm f/4 lens this way, as has Phase One. And that Leica S system? Yup. All the lenses are imperfect and corrected digitally."
The Leica Summarit-S 70mm f/2.5 ASPH has about 2.4%.
philip, you answer Lee's relevant question about the losses related to software correction of distortion with a few links describing in general what distortion is, how it is corrected and that not only Leica does it.
Lee's question, supported by Tariq, is right on the money. Roger Cicala found a 14% drop in resolution in the center of the image after software correction of distortion. The loss is mostly not related to the magnitude of the distortion but to the fact that correction resamples the whole image.
p.16 #8 · Zeiss "Batis" AF lens line to be released for FF E-mount
Really very interesting discussion about the Batis lenses. I have a question, does anyone know how the DOF indications are being calculated? I mean, on what print size/viewing distance/COC are these numbers actually based?
p.16 #9 · Zeiss "Batis" AF lens line to be released for FF E-mount
alundeb wrote:
Lee's question, supported by Tariq, is right on the money. Roger Cicala found a 14% drop in resolution in the center of the image after software correction of distortion. The loss is mostly not related to the magnitude of the distortion but to the fact that correction resamples the whole image.
Yeah the problem is the barrel distortion correction generates a non-rectangular image, which has to be cropped and enlarged. If you were to do the correction in Photoshop and use content aware fill to replace the missing areas (or better yet do it by hand) you wont compromise sharpness in the centre. This is quite a lot of effort to go to though if you're looking for an architectural 85mm, look elsewhere.
If you are using the lens for portraits with shallow depth of field then simply turn all distortion corrections off (this is my bet for why they accepted higher than average distortion for this focal length).
But now I may have to get both the Batis 85mm and the Sony 90mm
p.16 #12 · Zeiss "Batis" AF lens line to be released for FF E-mount
Matt Grum wrote:
Yeah the problem is the barrel distortion correction generates a non-rectangular image, which has to be cropped and enlarged. If you were to do the correction in Photoshop and use content aware fill to replace the missing areas (or better yet do it by hand) you wont compromise sharpness in the centre. This is quite a lot of effort to go to though if you're looking for an architectural 85mm, look elsewhere.
If you are using the lens for portraits with shallow depth of field then simply turn all distortion corrections off (this is my bet for why they accepted higher than average distortion for this focal length).
But now I may have to get both the Batis 85mm and the Sony 90mm ...Show more →
Matt, you seem to have a good handle on these things - at this point, what do you see as the pros/cons for the 85/1.8 vs the 90/macro and/or how would you use either/both ?
The degree of interpolation required for the actual distortion correction as well as the amount required in the subsequent resizing process (since a lens with greater distortion will undergo more cropping) will mean the magnitude of optical lens distortion is directly related to resolution loss during correction. More correction and thus heavier interpolation results in more resolution loss. How the distortion is distributed throughout the image will also be a factor (if it's mostly off axis, the center will be less impacted than the borders/ corners). Another consideration might be what effect correction has on bokeh. For instance, we might get oblong shaped bokeh off axis (is this what we are seeing with this Zeiss 85 in the sample images?)
Not a lot for most people. Distortion correction generally improves the look of a photograph and a small sacrifice in resolution isn't too important with today's cameras and lenses, even in the corners.
But when someone wants to argue that they buy a lens with high distortion because it has higher resolution and distortion is easy to fix in post . . . well, it had better be a lot higher, or it's a fool's argument.
I'll add one other note. It's well known among lens designers (I'm not one, but I read their textbooks and journals) that when designing a lens correcting distortion often reduces resolution. In ancient times (i.e. film days) distortion correction was a first priority. After all, it's really hard to stretch film to correct distortion. In current times, lens designers seem to be more willing to leave the distortion to get higher resolution.
I agree with that - I'd rather have the option of correcting or not correcting myself. But I think it's important for photographers who ARE very interested in the best resolution to realize they'll be giving some of that back when they correct in post. If two lenses have identical resolution in testing but one has more distortion, that one will have less resolution after the distortion is corrected.
p.16 #15 · Zeiss "Batis" AF lens line to be released for FF E-mount
Tariq Gibran wrote:
The degree of interpolation required for the actual distortion correction as well as the amount required in the subsequent resizing process (since a lens with greater distortion will undergo more cropping) will mean the magnitude of optical lens distortion is directly related to resolution loss during correction. More correction and thus heavier interpolation results in more resolution loss. How the distortion is distributed throughout the image will also be a factor (if it's mostly off axis, the center will be less impacted than the borders/ corners). Another consideration might be what effect correction has on bokeh. For instance, we might get oblong shaped bokeh off axis (is this what we are seeing with this Zeiss 85 in the sample images?)...Show more →
The magnitude of the resolution loss is 13% in the center while correcting less than 4% distortion. I discussed this with Roger when he published the blog post, and he agreed that the resampling itself contributes more than the stretching.
p.16 #16 · Zeiss "Batis" AF lens line to be released for FF E-mount
Tariq Gibran wrote:
The degree of interpolation required for the actual distortion correction as well as the amount required in the subsequent resizing process (since a lens with greater distortion will undergo more cropping) will mean the magnitude of optical lens distortion is directly related to resolution loss during correction. More correction and thus heavier interpolation results in more resolution loss. How the distortion is distributed throughout the image will also be a factor (if it's mostly off axis, the center will be less impacted than the borders/ corners). Another consideration might be what effect correction has on bokeh. For instance, we might get oblong shaped bokeh off axis (is this what we are seeing with this Zeiss 85 in the sample images?)...Show more →
Unless they've done it in a very lazy way the distortion correction and resize operation will be implemented as a single transformation, but the result is the same and you are right that the degree to which the centre of the image ends up being enlarged depends on how much of the image area is lost which in turn depends in part on the magnitude of the distortion. It also depends on the type of distortion, pincushion distortion correction does the opposite and makes the image larger so no loss occurs.
edit: according to Diglloyd, distortion in the Batis 85mm is pincushion so there should be no losses in the centre, correction will cost you some of the field of view, but that shouldn't be a problem for an 85mm lens either.
The bokeh, compression artifacts and everything else will be distorted in the corners by the corrective transformation. Whether you will really see an impact in the bokeh I don't know, as the bokeh will be non-circular in the corners of a fast 85mm lens anyway due to viewing the entrance pupil from an angle (resulting in hard vignetting from the lens barrel).
alundeb wrote:
The magnitude of the resolution loss is 13% in the center while correcting less than 4% distortion. I discussed this with Roger when he published the blog post, and he agreed that the resampling itself contributes more than the stretching.
This is absolutely correct, Tariq's point was just that the amount of resizing depends on the distortion thus a 4% distortion lens loses more resolution in the centre than a 2% distortion lens, even though the distortion correction itself (the straightening of curved lines) is not the principal cause.
p.16 #17 · Zeiss "Batis" AF lens line to be released for FF E-mount
I'm a bit old fashioned regarding lenses and optical vs software corrections.
I don't mind a bit of distortion as long as it looks acceptable when not corrected. However, I am totally against designing a lens with software correction in mind.
I know in practice, it makes little difference but I have a psychological barrier that keeps me from buying such lenses.
I have owned previously the ZA 1.8/55 and 2.8/35, both fell into the former category, with distortion quite acceptable when not corrected. I am not very keen on the Batis 1.8/85 anymore eventhough I was quite excited about it initially. Too bad.
p.16 #18 · Zeiss "Batis" AF lens line to be released for FF E-mount
Great to see both a high quality & fast 35 and 85 in E-mount now, along with the SWA zoom. It's only really a 135mm that I'd need, class-wise, for a full switch. My main SLR system is still coping fine, but I do see e-mount as the eventual, logical solution when it's time passes. So now the only really Q. is the body, and I'm sure they'll release something 9 series or more aimed at professionals soon.
p.16 #19 · Zeiss "Batis" AF lens line to be released for FF E-mount
Matt Grum wrote:
edit: according to Diglloyd, distortion in the Batis 85mm is pincushion so there should be no losses in the centre, correction will cost you some of the field of view, but that shouldn't be a problem for an 85mm lens either.
Lloyd may have this backwards (and I was incorrect earlier as well in stating the loss would be at the borders/ corners as I assumed barrel distortion). Typically, with barrel distortion, the center suffers less while the borders/ corners suffer more. The opposite occurs with pincushion distortion correction according to this:
"Correction also redistributes an image's resolution; with pincushion removal, the edges will appear slightly sharper (at the expense of the center), whereas with barrel removal the center will instead appear slightly sharper (at the expense of the edges)."
p.16 #20 · Zeiss "Batis" AF lens line to be released for FF E-mount
ecarlino wrote:
Matt, you seem to have a good handle on these things - at this point, what do you see as the pros/cons for the 85/1.8 vs the 90/macro and/or how would you use either/both ?
Published MTFs are difficult to compare between the two lenses, as the curves from Zeiss are measured and specified at 10, 20 and 40 lp/mm, whereas Sony's are simulated, don't take into account diffraction and are specified at 10 and 30 lp/mm. At f/2.8 the Sony looks very impressive, the 30 lp/mm line roughly on par with the 20 lp/mm line from the Zeiss, which even taking into account the fact it's simulated vs measured I would put the Sony slightly ahead.
At f/8 the Sony is almost perfectly diffraction limited out to 17mm (86% of the image area), that means it literally couldn't be any better. It's hard to say how much of the Zeiss MTF performance at f/8 is due to diffraction but it's not really possible for the Zeiss to be any better than the Sony.
There are no figures for distortion for the Sony lens but it's hard to imagine it will be anything like 3%. I expect the Sony to be the lens to choose for out and out sharpness wide open and stopped down as well as lack of distortion. This makes it more suitable for landscape and architecture shots. The Zeiss Sonnar will likely have better bokeh, and ought to hold it's own stopped down - it will be fine for landscapes but maybe not cityscapes on account of the distortion.
I'm still torn, as I don't need AF in a macro lens, and want my travel kit as small and light as possible. The Zeiss comes in 125g lighter, which is not going to be massively noticeable, but more importantly 38mm shorter, which means it will go in a smaller bag, look less conspicuous etc. I will probably end up owning both as a fast portrait lens is sometimes necessary, and I will need some form of macro, but can't say which I will get first or which I will bring on trips.
